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Title: Topics in nutrition and food science.


1
Topics in nutrition and food science.
  • Dr M. Altamimi

2
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3
Characteristics of Modern life
  • Urbanisation
  • Ready to eat food, fast food and processed food.
  • High calories (fat and carbohydrate) low fibre.
  • Low in vitamins and minerals.
  • Packaging. Not natural preservation.
  • Refrigeration and freezing.
  • Less physical activity.

4
  • Office based jobs.
  • Chronic diseases, obesity etc.
  • Aging, people live longer.

5
  • Diet together with physical exercise plays a
    major role when we try to prevent or postpone the
    onset of chronic conditions such as the metabolic
    syndrome.
  • The food industry has already reacted to this
    challenge and a large number of products have
    been either reformulated or re-positioned to meet
    the current need for healthier foods.

6
WHO
  • Chronic diseases are diseases of long duration
    and generally slow progression. Chronic diseases
    are by far the leading cause of mortality in the
    world, representing 63 of all deaths. 36 million
    people died from chronic disease in 2008.

7
Noncommunicable diseases
  • Cardiovascular diseases account for most NCD
    deaths, or 17 million people annually, followed
    by cancer (7.6 million), respiratory disease (4.2
    million), and diabetes (1.3 million). These four
    groups of diseases account for around 80 of all
    NCD deaths, and share four common risk factors
  • tobacco use
  • physical inactivity
  • the harmful use of alcohol and
  • poor diets.

8
Bad habits
9
Stages of life and R F
  • In the uterus
  • intrauterine growth retardation (IUGR)
  • premature delivery of a normal growth for
    gestational age fetus
  • over nutrition in utero
  • Intergenerational factors.

10
  • Infancy
  • Retarded growth in infancy can be a reflected in
    a failure to gain weight and a failure to gain
    height. Both retarded growth and excessive weight
    or height gain can be factors in later incidence
    of chronic disease. Such as CVD
  • There is increasing evidence that among term and
    pre-term infants, breastfeeding is associated
    with significantly lower blood pressure levels in
    childhood.
  • Consumption of formula instead of breast milk in
    infancy has also been shown to increase diastolic
    and mean arterial blood pressure in later life.
    Obesity

(type 1 diabetes, coeliac disease, some childhood
cancers, inflammatory bowel disease) have also
been associated with infant feeding on
breast-milk substitutes and short-term
breastfeeding
11
  • Childhood
  • low growth in childhood and an increased risk of
    CHD has been described, irrespective of size at
    birth.
  • Relative weight in adulthood and weight gain have
    been found to be associated with increased risk
    of cancer of the breast, colon, rectum, prostate
    and other sites.
  • Higher blood pressure in childhood (in
    combination with other risk factors) causes
    target organ and anatomical changes that are
    associated with cardiovascular risk, including
    reduction in artery elasticity.
  • High blood pressure in children is strongly
    associated with obesity,

12
  • Most chronic diseases are present at later period
    of life - the result of interactions between
    multiple disease processes as well as more
    general losses in physiological functions (due to
    risk factors)
  • lack of oxygen and adapted metabolism.

13
Angiogenesis
  • Angiogenesis is a process of new blood vessel
    growth that occurs in the human body at specific
    times in development and growth.
  • Although crucial for embryonic development and
    wound healing, angiogenesis also contributes to
    disease, such as in the growth of solid tumors,
    chronic inflammation, atherosclerosis, ischemia,
    and diabetic retinopathy.

14
Inducers
  • A number of inducers of angiogenesis have been
    identified, there is an emerging concept that
    reactive oxygen species (ROS such as )

superoxide anion O2- hydroxyl radical (OH-),
lipid radical (LOO-), peroxy radicals (XOO-)
and singlet oxygen (O-).
Free radicals
ROS are products of mitochondrial respiration
(energy production).
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Dietary sources of ROS
  • High fat diet and deep fries
  • High sucrose (or refined carbohydrates )diet
  • Protein sugar in high temperature (glycation)
  • Low fruit and veg. diet
  • Low vitamin and mineral diet (antioxidant).

Life style stress, pollution, smoking and low
activity.
18
Golden rule
  • More free radicals chronic diseases faster
    aging.
  • Less free radicals healthier body.

19
How to slow down generation of Free radicals?
  • Homework.

20
Comparison
B
A
Distance 10,000 km Fuel consumption 50,000
liter
Distance 200, 000 km Fuel consumption 1000,000
liter
Waste? Maintenance? Type of fuel?
21
The challenges for nutrition in the twenty-first
century
  • 1. Application of new scientific knowledge in
    nutrition.
  • 2. Improved scientific knowledge on dietdisease
    relationships.
  • 3. Exponential increase of health-care costs.
  • 4. Increase in life expectancy.
  • 5. Consumer awareness of nutrition and health
    relationships.
  • 6. Progress in food technology.

22
Functional foods
History
Japan 1940-1950 economical food with minimal
nutrients. 1950-1970 safe and hygienic food with
better taste. 1970- 1980 convenient food. Easy
or precooked food. 1980- Food for specific
health use (foshu). 1990 - Functional food.
(project)
23
  • The project also proposed for the first time the
    new concept of functional food and defined food
    functions as primary (nutritional), secondary
    (sensory) and tertiary (physiological). Food with
    physiological functions was of particular
    interest, because such food would be useful for
    improving the health of the general public

24
Definition
  • no simple, universally accepted definition of
    functional food exists. Examples
  • food and drink products derived from naturally
    occurring substances consumed as part of the
    daily diet and possessing particular
    physiological benefits when ingested.
  • food derived from naturally occurring substances
    that can and should be consumed as part of the
    daily diet and that serve to regulate or
    otherwise affect a particular body process when
    ingested.
  • food similar in appearance to conventional food,
    which is consumed as part of a usual diet and has
    demonstrated physiological benefit and/or reduces
    the risk of chronic disease beyond basic
    nutritional functions.

25
The main aspects of this working definition are
  • the food nature of functional food that is not a
    pill, a capsule or any form of dietary
    supplement
  • the demonstration of the effects to the
    satisfaction of the scientific community
  • the beneficial effects on body functions, beyond
    adequate nutritional effects, that are relevant
    to improved state of health and well-being and/or
    reduction of risk (not prevention) of disease
  • the consumption as part of a normal food pattern.

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F F Science
  • By reference to the new concepts in nutrition
    outlined above, it is the role of functional food
    science to stimulate research and development of
    functional foods

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Claim promise of improvement
  • Disease reduction claims meaning
  • consumers have difficulties to differentiate
    between the terms disease risk reduction and
    prevention of diseases.

31
How to write a claim
32
EFFECT OF FOOD PROCESSING ON FUNCTIONALITY OF
FOODS
In foods containing vastly different
phytochemicals, the physiological activity due to
food processing may be a result of more than one
mechanism. Consequently, there may be a
decrease, increase, or a slight change in the
content and functionality of phytochemicals.
No/slight effect carotenoids comprising of
b-carotene and lycopene are generally stable to
heat treatments encountered in blanching,
cooking, and pasteurization/sterilization.
Interactions between polyphenols and ascorbic
acid may slow the degradation of the latter
during storage.
33
Decrease in content and activity of
phytochemicals a classic example is that of the
technological indicator, ascorbic acid, which
is by far the most sensitive nutrient, and can be
damaged during most treatments. Chemical and/or
enzymatic oxidations are reported to decrease the
antioxidant efficacy of polyphenolics, while
leaching into the cooking water is mainly
responsible for loss of folates.
34
Heat processing of Brassica vegetables of the
Cruciferae family greatly reduces their
functionality . Manufacture of black tea causes
a higher degree of enzymatic aerobic oxidation of
flavonoids, resulting in lower antioxidant
activity. Some processing operations such as
peeling and juice clarification can remove the
polyphenolics .
35
Increase in content and activity of
phytochemicals partially oxidized
polyphenolics that result during food processing,
have been recently shown to exhibit higher
antioxidant activity than the corresponding
non-oxidized forms, due to increased ability to
donate a hydrogen atom
A moderate increase in carotenoid bioavailability
and enhanced phytochemical nutrient function in
cereal processing
36
Examples of functional ingredients
Vitamin antioxidant mineral premixes tomato
powder, garlic powder, onion powder, spice mixes
amino acids, chitosan Omega-3-fatty acids (fish
and flax seed) whey protein powder Guarana
extract, G. biloba extract, ginseng extract,
rosemary probiotics natural antioxidants (from
tea) shield liquid antioxidants vegetable
peptones
37
essential fatty acids concentrates performance
proteins natural fruit based flowering
compounds natural colours total extracts of
medicinal plants antioxidants soy ingredient,
soy proteins, soy protein hydrolysate soya
protein isolate concentrate super critical
extracts of spices and herbs glutamine
peptides lactoferrin, milk calcium lycopene,
garcinia, raw herbs whey protein concentrate
wheat fiber, b-carotene A. vera gel powder.
38
Risk factor or state Design a Functional Food
CVD
osteoporosis
diabetes
Irritable bowl syndrome (IBD)
Pregnant woman
39
OXIDATIVE STRESS AND ROS
  • Oxidative stress rusting of tissues.
  • Oxidative stress is imposed on the body s cells
    when the level of ROS outweighs the reducing
    capacity of antioxidant and antioxidative stress
    mechanisms

ROS
40
Sources of ROS
  • Endogenous sources of ROS
  • tissue injury
  • via auto - oxidation reactions in the presence of
    transition metal ions. Fe 2 or Cu
  • during cytochrome P450 cycling.
  • at inflammatory sites by activated and
    phagocytes.

41
  • Exogenous sources of ROS
  • Exposure to ultraviolet (UV) radiation.
  • Overexercise.
  • Extrinsic xenobiotics found in tobacco smoke.
  • Heavy metals.
  • Organic pesticides.
  • Lipid hydroperoxides in particular are
    potentially toxic products of peroxidized
    polyunsaturated fatty acids (PUFAs) derived from
    dietary fats.
  • Compounds present in foods such as transition
    metal ions, heme from meats, isoprostanes,
    additives, lipids,

42
DEFENSE SYSTEMS
Endogenous antioxidants and antioxidative defenses
  • Glutathione ( GSH )
  • tripeptide of ? glutamylcysteinylglycine.
  • directly scavenge free radicals or act as a
    substrate.
  • GSH present in foods and secreted in the bile can
    contribute to GSH concentrations in the
    intestinal lumen.

43
  • Antioxidative stress enzymes
  • glutathione peroxidase (GPx).
  • glutathione S -transferase ( GST ).
  • Catalase
  • Additional antioxidants
  • uric acid.
  • bilirubin - bound albumin, and albumin itself.
  • Histidine - containing peptides such as
    carnosine.
  • Melatonin.
  • Amino acids, peptides, and even proteins.
  • Se, Zn, Cu, Mn and riboflavin can all have
    co-factor functions for one of the above enzymes.

44
Phytochemicals with antioxidant activities
  • Polyphenols
  • 5000 polyphenols and over 2000 flavonoids having
    been identified.
  • Phenolic acids, Flavonoids, Lignans

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  • Amides
  • strong antioxidants capsaicinoids in chili
    peppers.
  • Carotenoids
  • Lycopene, ß carotene, xanthophylls such as
    zeaxanthin.

49
Mechanism of action
  • direct radical scavenging
  • (2) downregulation of radical production
  • (3) elimination of radical precursors
  • (4) metal chelation
  • (5) Inhibition of xanthine oxidase
  • (6) elevation of endogenous antioxidants.

Curcumin and flavonoids have been shown to
upregulate intracellular GSH synthesis and
increase antioxidant enzyme activities
50
METABOLISM AND BIOAVAILABILITY OF FLAVONOIDS
  • The extent of absorption of dietary polyphenols
    in the small intestine is relatively small.
  • Bacterial enzymes may catalyze several reactions.
  • Anthocyanins were found in the cerebellum,
    cortex, hippocampus. important for learning and
    memory.

51
Antioxidant and C D
  • CVD
  • Antioxidant prevent LL oxidation.
  • Cancer
  • Block activation to carcinogens.
  • DNA repair.
  • Inhibit the formation and growth of tumors.

52
Dietary Fiber
  • Dietary fiber (DF) has been consumed for
    centuries and most food labels in the supermarket
    now list dietary fiber.
  • Even though fiber is not considered a nutrient,
    health professionals and nutritionists agree that
    fiber is required in sufficient amounts for the
    proper functioning of the gastrointestinal tract.

53
Definition
  • DF is the edible parts of plants or analogous
    carbohydrates that are resistant to digestion and
    absorption in the human small intestine with
    complete or partial fermentation in the large
    intestine.

54
Why ?
  • DF consumption has established the basis for
    associating high-fiber diets in epidemiological
    studies with reduced risk of most of the major
    dietary problems in the U.S.A. namely, obesity,
    coronary disease, diabetes, gastrointestinal
    disorders, including constipation, inflammatory
    bowel diseases.

Chronic diseases
55
Classification Of Dietary Fiber
  • dietary fiber has been to differentiate dietary
    components on their solubility in a buffer at a
    defined pH, and/or their fermentability in an in
    vitro system using an aqueous enzyme solution
    representative of human alimentary enzymes.

56
Solubility
  • Soluble fiber dissolves in water
  • This includes gums, mucilages, pectin and some
    hemicelluloses.
  • found in all types of peas and beans like
    lentils, split peas, pinto beans, black beans,
    kidney beans, garbanzo beans, and lima beans, as
    well as oats, barley, and some fruits and
    vegetables like apples, oranges, and carrots.

57
Benefits
  • For people with diabetes, eating foods that
    contain soluble fiber can help control or lower
    the level of sugar in their blood and decrease
    insulin needs
  • It may also help lower blood cholesterol levels,
    especially LDL-cholesterol or the bad
    cholesterol.

58
  • Insoluble fiber does not dissolve in water.
  • Whole grains, wheat and corn fiber, and many
    vegetables like cauliflower, green beans, and
    whole potatoes are good sources of insoluble
    fiber.
  • aids digestion by trapping water in the colon.
  • helps prevent two kinds of intestinal diseases,
    diverticulosis and hemorrhoids.

59
Fermentability
  • Fibers that are well fermented include pectin,
    guar gum, acacia (gum arabic), inulin,
    polydextrose, and oligosaccharides.
  • Generally, well fermented fibers are soluble in
    water, while partially or poorly fermented fibers
    are insoluble.

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Physiological Effects of D fiber
  • major physiological effects of dietary fiber
    originate from the interactions with colonic
    content throughout its fermentation.
  • It influences several metabolic processes,
    including the absorption of nutrients,
    carbohydrate and fat metabolism, and cholesterol
    metabolism.

63
  • influences the colonic structure and barrier
    function, and as the large intestine encompasses
    a significant body of the human immune system.
  • Some form gels (pectins), while others have a
    high water holding capacity (WHC).
  • its ability to adsorb or bind bile acids and its
    fermentability by microorganisms in the gut.

64
Colonic Fermentation And Its Consequences
  • The large intestine is the most heavily colonized
    region of the digestive tract, with up to 1011
    -1012 anaerobic bacteria /gram.
  • end products produced from the fermentation,
    including gases (methane, hydrogen, carbon
    dioxide), short chain fatty acids (SCFA).
  • Increases in microbial mass from fiber
    fermentation contribute directly to stool bulk

65
  • Gas production from colonic fermentation can also
    have some influence on stool bulk.
  • Poorly fermented cellulose produces very little
    acid during its fermentation, most of which is
    only acetic acid by contrast, in the case of
    more fermentable fibers, large quantities of SCFA
    are formed.
  • The metabolic end products of fermentation
    including the gases, SCFA, and increased
    microbiota, play a pivotal role in the
    physiological effects of fiber and implications
    for local effects in the colon and systemic
    effects

66
PHYSIOLOGICAL FUNCTIONS OF DIETARY FIBER
  • Dietary Fiber And Cancer
  • Colon cancer is one of the leading causes of
    cancer morbidity and mortality among both men and
    women in the Western countries, including the
    U.S.A.
  • Dietary Fiber And Carbohydrate Metabolism
  • An association between insufficient dietary fiber
    intake and increased risk of diabetes has been
    postulated since 1970s.

67
  • Dietary Fiber, Lipid Metabolism, And
    Cardiovascular Disease
  • bind bile acids increasing their excretion and
    decrease cholesterol in the liver.
  • SCFA are absorbed from the colon to the liver.
  • Dietary Fiber, Mineral Bioavailability And Bone
    Health.
  • certain highly fermentable fibers have resulted
    in improved metabolic absorption of certain
    minerals, such as calcium, magnesium, and iron,

68
  • Dietary Fiber, Role In Gut Barrier Function And
    Gastrointestinal Disorders.
  • SCFA stimulating repair in a damaged colon.
  • barrier to prevent foreign materials from dietary
    or microbial origin from crossing into the
    internal body cavity. Prevent Intestinal
    permeability or leaky gut syndrome.

69
Probiotics
  • Intestinal tract is home to one hundred trillion
    (1014) microorganisms.
  • called the intestinal microflora.
  • over 400 different species of microbes.
  • The 400 species of microbes living in your body
    are fighting for space. They want to live, thrive
    and reproduce in your intestinal tract, an
    environment that offers the ideal temperature,
    humidity and food sources.

70
  • Depending on the type of bacteria, there is a
    different effect on the body bacteria can have
    healthy, e.g.,
  • immune-boosting benefits or cause harm to the
    body.
  • A careful balance is necessary for health.

71
  • Bad microbes live in your intestines and normally
    do not cause any disease-like symptoms.
  • Bad microbes flourish in an alkaline environment.
  • Opportunistic and neutral the majority.
  • Good microbes found in the body, called
    probiotics.
  • Probiotics have a positive impact on the bodys
    health. They prefer a more acidic intestinal
    environment. Many of the probiotics are called
    lactic acid bacteria.

72
They define the term probiotic as live
microorganisms which when administered in
adequate amounts confer a health benefit on the
host.
How do they work? What are these health
benefits? How can we get them? What species can
provide them? Whats the relationship with
Chronic diseases? How can we maintain them?
73
Some history
  • Pasture 1880,
  • Eli Metchnikoff 1908,
  • Tisser 1900,
  • W W I Nissil
  • Southeast Asia, Boulardi. Cholera.
  • 1950, group of scientists, found out that mice
    that were given oral antibiotics, which kill all
    bacteria, including probiotics, were more
    susceptible to infection.

74
  • Yakult Company of Japan in the 1930s. Yakult
    Company introduced a fermented milk product that
    contained a probiotic culture.
  • The term probiotic was not actually coined until
    the 1960s.
  • In 1978, Dr. Tomotari Mitsuoka, illustrated how
    the composition of intestinal flora changes
    during a lifetime.
  • Probiotics decrease with aging.
  • WHY?

75
How Do Probiotics Work?
  • The intestinal microflora has the metabolic
    activity potential equal to that of the liver,
    the most active organ in the body!
  • The exact mechanisms of action by which
    probiotics elicit their beneficial effects are
    not fully understood.

76
Suggested mechanisms
  • Probiotics Compete for Receptor Sites

77
  • Change secretion to mask receptors

mucus
78
  • Probiotics Affect the Immune System
  • Gastrointestinal tract is equipped with effective
    immune system, the most number of lymphoid is
    around the gut.
  • Immune system is the key element of what to enter
    your body or not to.
  • By producing antibodies these are messengers for
    all tissues connected with immune system.
  • Probiotics supplementation is useful in a wide
    variety of immune-based ailments including
    allergies, asthma, eczema and irritable bowel
    disease.

79
  • probiotics help balance good and bad messengers
    of the immune system by keeping the system in
    check.
  • The result is healthy immune reactions and a
    healthier you. A careful balance of inflammation
    is required in the intestinal tract.
  • Too much of an immune reaction can result in
    inflammation and damage to the intestines
    reducing their ability to digest and absorb
    nutrients I B D.

80
  • Too little immune reaction allows pathogens to
    grow in the intestines, causing infectious
    diarrhea, which can develop into a chronic
    illness such as allergies.
  • All in all, it appears that probiotics
  • reduce allergic reactions
  • improve overall immunity
  • promote proper immune reactions against pathogens.

81
  • Probiotics Consume Available Nutrients
  • There are lots of nutrients available in the
    digestive tract that support the needs of lactic
    acid bacteria to grow. By consuming a large
    portion of the available nutrients suitable for
    microbes, lactic acid bacteria restrains the
    growth of bad microbes.
  • Probiotics Create an Acidic Environment
  • Many bad microbes do not like a low pH.

82
  • Probiotics Produce Beneficial Enzymes
  • The enzyme activity of probiotics has been found
    to help fight infectious disease, lactose
    intolerance, immune system deficiencies, and
    urogenital and vaginal diseases.
  • Probiotics Produce Antimicrobial Effects
  • Many of the probiotic strains of bacteria are
    able to produce substances that kill bacteria,
    called bacteriocins

83
  • Probiotics Support Gut Barrier
  • Lactobacilli and Bifidobacteria produce fats that
    encourage the growth of cells that line the
    intestinal tract. These fats are called short
    chain fatty acids. These fats also have
    nutritional effects on the intestinal cells,
    keeping them well nourished and healthy.
  • Gut integrity.

84
  • Probiotics Encourage Healthy Microflora
  • In clinical trials, the use of combinations of
    probiotic species has been found to offer greater
    health benefits than any one of the probiotic
    species alone.
  • Example
  • Lactobacillus reuteri produces protein to enhance
    the growth of other lactobacilli.

85
Manufacture of ProbioticBacteria
  • Lactic acid bacteria (LAB) have been used for
    many years as natural biopreservatives in
    fermented foods.
  • Dried concentrated probiotic cultures are the
    most convenient form for incorporation into
    functional foods, given the ease of storage,
    handling and transport, especially for
    shelf-stable functional products.

86
Probiotics are the main bioactive component of
these fermented FF and numerous economic
indicators show that probiotic-enriched products
are still on the forefront of innovation in the
FF sector
  • The probiotic yogurt market in Latin America grew
    32 annually from 2005 to 2007
  • In the overall USA FF market, in 2004, fresh
    dairy products grew by 910 compared to 2 for
    cheese.
  • The European food and beverage probiotics is
    expected to rise from its 2006 position of 62
    million to 163 million by 2013

87
Selection of Strains
  • the microbes should have GRAS (Generally Regarded
    As Safe) status, have a long history of safe use
    in foods, be non-pathogenic
  • acid and bile tolerant
  • should be viable (debatable).
  • the bacteria should tolerate different
    technological stresses, such as acid, osmotic,
    cold, heat and drying stress.

88
  • Selecting the appropriate strain for a particular
    food can be divided in four categories
  • Performance in the gastrointestinal tract (GIT)
  • Industrial production.
  • Safety of the microorganisms.
  • Health benefit.

89
Question
  • Who do you think the most group of people in the
    community need functional foods, and Why?

90
Potential Protective Effectsof Probiotics
Against Colorectal Cancer
  • Colorectal cancer (CRC) is the fourth most
    frequent cause of cancer related mortality in the
    world.
  • Approximately 944,000 new cases were diagnosed
    globally in 2000 and this accounts for 9.2 of
    all new cancer cases.
  • the developed world suffering the highest rates
    and India one of the lowest

91
  • Evidence suggests that diet plays an important
    role in the aetiology of colorectal cancer.
  • associations between overweight/ obesity (waist
    circumference), processed meat, alcohol and
    increased risk of colorectal cancer.
  • Fiber, garlic, milk and calcium are associated
    with decreased risk.

92
Colon Carcinogenesis
  • involves inactivation of various tumor
    suppressing genes.
  • activation of mutations.
  • loss of function in DNA repair genes
  • Metabolic activity of microflora.

93
Role of the Gut Flora in Cancer
  • Once the microbiota is established, little
    qualitative variation in the composition occurs
    over time, although there is extensive evidence
    that the metabolic activity of the microbiota can
    be modulated by diet.
  • Evidence from a wide range of sources supports
    the view that colonic microbiota is involved in
    the aetiology of cancer.

94
  • The main pieces of evidence are
  • Human feces have been shown to be mutagenic and
    exert tumor promoting activity in vitro and
    genotoxic substances of bacterial origin have
    been isolated.
  • 2. Intestinal bacteria can produce, from dietary
    components, substances with genotoxic,
    carcinogenic and tumor-promoting activity.
  • 3. Gut bacteria can activate procarcinogens to
    DNA reactive agents.

95
  • 4. Germ-free rats treated with the carcinogen
    1,2-dimethylhydrazine have a lower incidence of
    colon tumors than similarly treated rats having a
    normal microbiota.
  • 5. Germ-free rats fed human diets exhibit lower
    levels of DNA defect in tissues than conventional
    rats.

96
Evidence that probioticscan influence
carcinogenesis is derived from a variety of
sources
  • 1. Effects on bacterial enzyme activities.
  • 2. Antigenotoxic effects in vitro and in vivo.
  • 3. Effects on pre-cancerous lesions in laboratory
    animals.
  • 4. Effects on tumor incidence in laboratory
    animals.
  • 5. Epidemiological and experimental studies in
    humans.

97
  • Examples
  • metabolism of the primary bile acids to secondary
    acids, which are thought to possess
    tumor-promoting activity.
  • nitrite can be converted to N-nitroso compounds
    (mutagenic) by bacteria under neutral pH.
  • In a conventional rat study, supplementation of a
    high meat diet (72 beef) with L. acidophilus
    (1091010 organisms/day) significantly decreased
    by 4050 the activity of fecal b-glucuronidase
    and nitroreductase

98
  • consuming milk supplemented with 109 viable
    lactobacilli per day decreased activity of feacal
    enzymes.
  • LAB was able to bind the mutagens in vitro.
  • Production of SCFA, Acetate is the major SCFA
    found in human feces. In the host, it may be
    absorbed and utilized by peripheral tissues
  • SCFA, in particular butyrate, are potential
    anti-carcinogenic.

99
  • Apoptosis or programmed cell death is one of the
    primary mechanisms by which multi-cellular
    organisms control normal development. In cancer
    it is out of control.
  • Probiotics are able to balance apoptosis.

100
First Exam
  • 7-10-2013

101
Prebiotics
  • Coined by G. Gibson, non-viable food component
    that beneficially affect the host by selectively
    stimulating the growth and/or activities of one
    or a limited number of bacteria in the colon,
  • Prebiotics allow the selective growth of certain
    indigenous gut bacteria.
  • such as bifidobacteria and lactobacilli which are
    already resident in the human colon

102
To be an effective prebiotic a colonic food must
  • neither be hydrolysed nor absorbed in the upper
    part of the gastrointestinal tract.
  • have a selective fermentation such that the
    composition of the large intestinal microbiota is
    altered towards a healthier composition.

103
Commercially available prebiotics
  • fructose-containing oligosaccharides (FOSs).
  • these prebiotics are the European market leaders.
  • Bifidobacteria are able to breakdown and utilise
    fructo-oligosaccharides due to their possession
    of the ß- fructofuranosidase enzyme.
  • FOSs have proven prebiotic effects in human trials

104
  • Galacto-oligosaccharides (GOSs) are another class
    of prebiotics that are manufactured and marketed
    in Europe as well as Japan.
  • They have found application in infant formula
    foods as
  • they are naturally present (low quantity) in
    human milk.
  • Gluco-oligosaccharides can also act as
    prebiotics. or Isomalto-oligosaccharides (IMOs).
    Slowly metabolized and pass to colon.

105
  • Xylo-oligosaccharides (XOSs) are also used as
    prebiotics in Japan
  • XOS are much more acid stable than other
    prebiotics. For this reason, they have found
    application in soft drinks which tend to be
    acidic.
  • Lactulose.

106
Are Dietary Fibres prebiotics?
  • Dietary fibres (e.g. from wheat, maize, rice,
    soya) have always been considered to have a
    beneficial effect on gut function and colonic
    bacteria, but this is a generalised stimulatory
    effect and such polysaccharides are not
    selectively fermented in the colon.

107
Mechanisms of Prebiotic Impact on Health
  • Local and Physiological Effects of Prebiotics

Mucosal Structure
1) increase in numbers of epithelial cells, and
the intensities of their secretory functions.
2) enlarged the available area of nutrient
absorption
possibly SCFA are responsible for these adaptive
changes.
108
  • Intestinal Mucus

Made of mucin produced by goblet cells lining the
gut. Act as barrier.
Mucus is a source of nitrogen and carbon for
bacteria its continuous production by the host
makes the gut good environment for microorganisms,
1) Administration of dietary prebiotics appears
to thicken the mucus layer and increase its
secretion by goblet cells
109
  • Mineral Bioavailability

there is a strong inverse relationship between
the amount of phytic acid in the diet and iron
Ca, and Zn absorption.
1) prebiotics are known to have stimulatory
effects on iron absorption in the large bowel.
2) Addition of FOS to the diet restores zinc
absorption by enhancing zinc bioavailability
3) prebiotic consumption is associated with
enhanced breakdown of phytic acid (60), low pH
decrease its solubility
110
Colonic environment
Zn
SCFA
Phytic acid
Undigested Food (prebiotic)
Ca
Phytase enzyme
Fe
hydrolysis
fermentation
Probiotic bacteria
Ca
Zn
Fe
pH
Mineral Solubility
111
  • Modulation of the Gut Microbiota

In chronic diseases and Gastrointestinal tract
diseases it was found that decreased levels of
bifidobacteria and lactobacilli are associated
with the problem. 1) Prebiotic can increase
these levels and prevent from C D.
112
  • Immune System

prebiotics, may be particularly useful in
inflammatory conditions, or in children and the
elderly.
FOS and lactulose to the diet has been shown to
increase 1) mucosal immunoglobulin production.
2) lymph nodes number. 3) altered
pro-inflammatory compounds in the spleen and
intestinal mucosa.
113
  • Lipid Metabolism

Human studies have been small in scope, focused
on the relationship between the intake of
prebiotics and serum lipid levels. The results
have been inconsistent, and any mechanisms of
action unclear. Animal studies showed lowering
effect of prebiotics on LDL and cholesterol
(especially when fed high fat meal) May be due
to interference with hepatic lipogenesis.
114
General Mechanism
115
Prebiotics Applications
  • Infants
  • Oligosaccharides are prebiotic factors in human
    milk, causing increased levels of bifidobacteria
    in breast-fed babies compared to bottle-fed
    infants.
  • Prebiotics have been used in infant formulas in
    Japan over the last 2 decades, and in Europe for
    the last 5 years.
  • addition of 0.8 g/dl of a mixture of 10 short
    chain FOS and 90 long chain infant formulas was
    safe to add to infant formula.

116
  • Atopic Disease (allergy).
  • Allergic disease in infants is based on
    imbalanced response to food allergen and lower
    numbers of bifidobacteria are found in allergic
    infant feces.
  • By increasing the number of bifidobacteria
    prebiotics rebalance the immune response.
  • Prebiotic feeding studies in allergic infants
    have demonstrated significant reductions in the
    incidence of atopic dermatitis, and this was
    associated with increased numbers of fecal
    bifidobacteria.

117
  • Enterocolitis
  • In premature infants, bifidobacterial
    colonization is delayed in favor of high levels
    of enterobacteria and clostridia enterocolitis.
  • Breast-feeding has always been thought to protect
    against enterocolitis.
  • No human studies using prebiotics alone.

118
  • Infection Prevention
  • Studies in children aimed at prevention of
    infection have also had mixed results.
  • The addition of 1.1 g of oligofructose daily to
    cereal of 123 infants (424 months) was
    associated with reduced episodes of fever and
    medical visits. The control group had more sick
    days, and a higher intake of antibiotics.

119
  • 134 infants fed prebiotics (8 g/l GOS/FOS) for
    the first 6 months of life, principally looking
    at allergic disease, the subjects were followed
    up until they were 2 years of age.
  • fewer episodes of physician diagnosed infections
    , fewer episodes of fever and fewer antibiotic
    prescriptions.

120
  • 2. Gastrointestinal Effects
  • Irritable bowel syndrome (IBS) has been linked to
    intestinal bacteria in a number of different
    trials.
  • IBS is a difficult disease to investigate,
    because the symptoms are highly subjective and
    difficult to quantify.
  • Gas production discomfort and flatulence are some
    of the symptoms associated with IBS.
  • many patients have visceral hypersensitivity, so
    prebiotic fermentation and gas production may
    exacerbate their symptoms, and have adverse
    affects on health and wellbeing.

121
  • Constipation
  • Prebiotics may have Laxative effects. May be due
    to gas production and increased microbial mass.
  • There is a good relation between intestinal
    motility and bacterial composition.
  • With the exception of lactulose, the prebiotics
    studied so far in human trials have been shown to
    have little effect on managing constipation, and
    to have only mildly laxative properties.

122
  • Diarrhea Antibiotic-Associated Diarrhea.
  • travelers diarrhea (E. coli) , frequency of
    diarrhea in the prebiotic group (11.2), compared
    to the placebos (19.5).
  • Clostridium difficile infections are
    antibiotic-associated diarrhea (AAD).
  • Diarrhea associated with Clostridium difficile is
    a leading cause of hospital outbreaks of diarrhea
    and it considerably increases mortality and
    healthcare costs.
  • Prebiotics reduce episodes of AAD and C.
    difficile diarrhea relapse.

123
  • 3. The Elderly
  • As people get older they often have a greater
    susceptibility to diseases and suffer from an
    increase in gastrointestinal infections,
    malnutrition, constipation and diarrhea.
  • decrease in immune function and a reduction in
    numbers of beneficial bacteria such as
    bifidobacteria, along with an increase in
    potentially harmful microrganisms.
  • few studies on the use of prebiotics in the
    elderly.

124
  • 4. Other Areas.
  • Diabetes
  • Because prebiotics are non-digestible low energy
    bulking ingredients this makes them beneficial
    they in diabetic control.
  • The proposed mechanisms of action in diabetic
    disease involve SCFA. Since High concentrations
    of free fatty acids (mainly from food) in plasma
    lower the use of glucose in tissues, and induce
    insulin resistance.

125
  • Rheumatoid Arthritis.
  • In animal studies prebiotics showed ability to
    decrease pro-inflammatory compounds by modulating
    the gut microbiota.
  • Obesity
  • Prebiotics are excellent potential to act as
    substitutes for sucrose, and to be used as
    sweeteners.
  • GOS are stable at high temperatures and low
    metabolic value at 1.73 kcal/g, while FOS are
    similar at 1.5 kcal/g.

126
  • they promoted satiety, and reduced food intake.

127
Resistant Starches
  • Resistant starches are defined as the sum of
    starch and products of starch degradation not
    absorbed in the small intestine of healthy
    individuals.
  • There are four main groups of resistant starches
    RS1- RS4.
  • RS1 is physically inaccessible starch (i.e.,
    starch in whole grains), RS2 is granular starch
    i.e., starch in green bananas), RS3 is
    retrograded starch (i.e., starch in cooked and
    cooled potatoes) and RS4 is a chemically-modified
    starch (i.e., an esterified starch).

128
  • RS has a calorific value of 1.70 kcal/g.
  • The glycemic response for RS is approximately 10
    that of a maltodextrin control.
  • Type 3 RS was shown to be well tolerated up to
    doses as high as 45 g/d.

129
Applications
  • Applications for RS include puffed or sheeted
    snacks, chips, extruded breakfast cereals, pasta,
    muffins, cookies and biscuits, crackers, frozen
    dough, breads.
  • it can also be used in low calorie products
    reducing both calories and carbohydrates when
    replacing flour or other cereal-based
    ingredients.
  • Due to its low water holding property, it also
    does not affect height and spread management of
    biscuits, cookies or other baked goods.

130
  • RS enhances crispiness of cookies and crackers.
  • In fried snacks, fat uptake may be reduced by up
    to 25 when RS is used, helping to meet
    high/rich in fiber claims.
  • RS3 thermal stable as high as 150 C, it will
    retain more fiber content and structure than
    other resistant starches, which start to
    breakdown below 120 C.
  • RS act as prebiotics in the gut.
  • Sugar derived from RS can be used as sweeteners.

131
Workshop design
  • Functional foods
  • in Palestine, What do we need to know?

132
Garlic and Onion as Functional Foods
  • Historically garlic and onion were used to
    preserve food from microbial spoilage.
  • Garlic has been eaten more than 4000 years and
    onion was cultivated in middle east before 5000
    years.
  • They were used for their medicinal properties.
  • Garlic on the top of vegetable-pyramid
    representing potency in cancer prevention (NIC).

133
GENERAL COMPOSITION AND SULFURCOMPOUNDS OF
GARLIC AND ONION
134
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135
  • The general composition is, of course, important
    to the nourishment of both garlic or onion
    eaters, however, in respect to the food function,
    the extraordinary high content of sulfur
    compounds in these vegetables should be much more
    important.
  • These compounds are present as a group of
    sulfur-containing amino acids.
  • When injured or damaged by slicing, the
    sulfur-containing amino acids in these plants are
    transformed immediately into volatile
    organosulfur compounds.

136
  • These compounds are called Alliins.
  • Alliin is degraded by alliinase into pyruvic acid
    and ammonia.
  • Alliinase is heat labile, and irreversibly
    inactivated at pH 3.8 or lower.
  • Oxidation of Alliins produces Allicin which has
    bactericidal and fungicidal effect.
  • in water it is active up to 40 days.
  • at -70C up to 2 years.

137
  • Organoselenium Compounds in Garlic and Onion.
  • Allium plants, especially garlic and onion, is
    their strong potential to uptake inorganic
    selenium, either selenate or selenite, from the
    soil or water culture medium, and synthesize
    organoselenium compounds.
  • Se-containing peptides, has been determined, and
    from this peptide a potent agent for cancer
    prevention was derived.

138
PHYSIOLOGICAL AND NUTRITIONAL FUNCTIONS OF GARLIC
AND ONION, AND THEIR HEALTH BENEFITS
  • Garlic and onion use sulfur compounds to protect
    themselves, Even in our bodies, sulfur-containing
    compounds play a defensive mechanism.
  • Onion has a lesser amount of sulfur compounds as
    compared with garlic. However, because people
    consume onion much more than garlic, the amount
    of sulfur compounds taken from onion per person
    may be comparable to or more than that from
    garlic.

139
  • Antibiotic Effect.
  • growth inhibition by an aqueous garlic extract.
    Which was diluted 100 times with water (about 10
    ng/ml allicin) showed a clear inhibition zone,
    and some fungus did not grow inside of the zone
    for up to 7 days.
  • Alkyl thiosulfinates are recognized as the most
    effective compounds exhibiting antimicrobial
    activity.

140
  • Antithrombotic Effect.
  • Suppression of platelet aggregation is the most
    beneficial effect of garlic intake.
  • vascular dilation have been observed primarily
    with garlic oil in human and animal studies.
  • Thus, garlic may prevent thrombus formation
    through many mechanisms involving antithrombotic,
    vasodilative effects.

141
  • Lipid-Lowering Effect.
  • several garlic compounds have been reported to be
    effective.
  • The lipid-lowering effects appear to be due to
    their degradation products, those that may be
    produced from the compounds soon after the
    absorption from the intestine.
  • And from the reduced gene expression may be an
    important factor in the lipid-lowering effects of
    garlic.

142
  • Hypoglycemic Effects.
  • It has been proposed that garlic compounds
    stimulate insulin production and prolong insulin
    turnover.
  • Especially, sulfur compounds from garlic were
    considered to protect insulin from its
    inactivation.
  • alliin (200 mg/kg) is known to reduce the plasma
    glucose level in diabetics.

143
  • ANTICANCER EFFECTS OF GARLIC AND ONION
  • A number of epidemiological and experimental
    studies indicated that garlic and onion can be
    considered as important functional foods for
    cancer prevention.
  • study in northeast China found that the
    consumption of onion was inversely related to the
    risk of developing brain cancer.
  • Similar studies reported that garlic intake
    significantly reduced the risk of prostate and
    breast cancers, and increased protective power
    against stomach and colorectal cancers.

144
  • 3. Site-specific case-control studies on stomach
    and colorectal cancers suggest a protective
    effect of high intake of raw and/or cooked
    garlic.
  • 4. The overall anticancer effects that have been
    reported for garlic and onion by some hundreds of
    researchers can be collected largely into three
    groups
  • Antimutagenic and anticarcinogenic effects.
  • Antiproliferative effects.
  • Differentiation effects involving the apoptotic
    effect.

145
  • Other Effects.
  • blood pressure-lowering.
  • Diuretic.
  • anti-inflammatory, immunomodulatory.
  • Enhancing effect on vitamin B1 absorption.
  • stimulate both noradrenaline secretion from
    nervous systems and testosterone from testis.

146
Garlic processing
  • Cutting, slicing, crushing.
  • Allicin from damaged garlic turned to sulfides.
  • Allicin may collected when slicing garlic in
    water, but sulfides better collected in cooking
    oil.
  • Boiling and heating
  • If an intact bulb is heated, alliin stays
    unchanged inside the bulb.
  • if the heating is not quite sufficient to
    denature the alliinase, a large amount of alliin
    is transformed into allicin and sulfides while
    cooking or eating the bulb.

147
  • Heating the chopped garlic in cooking oils,
    allicin, sulfides as well as alliin must be
    present, in the oils or within the pieces. Hence,
    people prefer to cook garlic with cooking oils or
    fatty meats.
  • Pickling
  • The pickled clove in any medium loses alliinase
    activity more or less, depending on the period of
    its preservation. It takes at least a month to
    penetrate a medium into the clove with a gradual
    decrease in alliinase activity.

148
  • Garlic Oil
  • Garlic Powder
  • Dehydrated Onion Pieces
  • Onion Powder
  • Onion Oil
  • Onion Salt
  • Pickled Onion

149
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150
Quiz
  • Discuss briefly how probiotics and /or prebiotics
    may prevent from cancer?

151
Green and Black Tea
  • Tea (Camellia sinensis) has been discovered and
    utilized for its unique flavor and medicinal
    properties by man for a long time, which may be
    traced back to 50006000 years ago in China.
  • Tea beverages are now the second most popular
    drinks and only next to water in terms of
    worldwide consumption.
  • Scientific research on the chemical components
    and functionalities of tea is relatively recent.

152
  • Through research, tea has been linked with health
    benefits including protection of oxidative DNA
    damage, lowering the atherosclerotic index and
    improving blood flow, liver function, and oral
    health.
  • Nowadays, the utilization of tea has been
    extended not only to pharmaceutical products but
    also to toiletry, cosmetic, and food products.

153
  • Commercial tea leaf products can be classified
    into three major types green tea, black tea, and
    oolong tea.
  • Green tea is nonfermented processed tea, in which
    polyphenols in fresh tea leaves are less
    oxidized.
  • Black tea and oolong tea are enzymatically
    fermented tea, with black tea being the most
    fermented and oolong tea partially fermented (or
    so called semifermented).

154
Tea polyphenols
  • The functional properties of tea are believed to
    be due to tea polyphenols. The principal tea
    polyphenols are tea catechins.
  • Catechin has been accepted as a quality indicator
    of green tea products.
  • There are some 830 of total catechins in dry
    green tea leaves.
  • The estimated daily intake of tea catechins based
    on 3 cups (600 mL) of green tea (1 4 g), which
    is brewed traditionally (15 min in boiling
    water), is in the range of 5382594 mg of total
    catechins.

155
  • the antioxidative activity/free radical
    scavenging ability of tea catechin varies with
    the type of radical species, ionization state,
    pH, polarity, and enzyme in the designated
    studies.

156
GREEN TEA ANTIOXIDANTS AND HEALTH BENEFITS
  • Green Tea and Neurodegenerative Diseases
  • Catechins chelate metal ions such as copper(II)
    and iron(III) to form inactive complexes and
    prevent the generation of potentially damaging
    free radicals.
  • In the rat brain tissue, green tea and black tea
    extracts were shown to inhibit lipid peroxidation
    promoted by iron.
  • As well decrease neurons death (Alzheimer's)

157
  • Green Tea and Obesity
  • Polyphenols interact to alter the energy balance.
  • the redox status or potential.
  • the activities of obesity-related cells.
  • Green Tea and Cardiovascular Disease.
  • cardiovascular diseases is multifactorial and
    comprises processes, which appear to be affected
    by tea ingredients
  • endothelial dysfunction.
  • inflammation. And thrombus formation

158
  • Green Tea and Cancer
  • inhibition of oxidative stress.
  • inhibition of carcinogen.
  • induction of apoptosis.
  • Inhibition of angiogenesis.
  • Type of cancers
  • Skin cancer Studies have suggested that green
    tea polyphenols may afford protection against
    inflammatory responses and the risk of skin
    cancer.

159
  • Lung Cancer Ingestion of green tea (2 of diet)
    decreased the number of lung induced tumors in
    mice.
  • consumption of green tea was associated with a
    reduced risk of lung cancer among nonsmoking
    women and the risks decreased with increasing
    consumption.
  • Liver Cancer In a study in China it was found
    that Green tea drinking decreased the risk for
    the development of liver cancer by 78 among
    alcohol drinkers and 43 among cigarette smokers.

160
  • Breast Cancer green tea consumption was
    associated with a reduction in breast cancer
    risk.
  • Prostrate Cancer Green tea
  • inhibits the growth and progression of prostate
    cancer in model mice.
  • ANTIBACTERIAL AND ANTIVIRAL ACTIVITY
  • Antimicrobial activity against cariogenic and
    periodontal bacteria has been reported.
  • Tea extracts inhibit enteric pathogens such as
    Staphylococcus aureus, Salmonella typhi,
    Shigella, V. cholerae, Cam. jejuni,

161
  • Tea polyphenols also inhibit bacteria responsible
    for tooth decay.
  • black and green tea extracts can kill
    Helicobacter pylori associated with gastric,
    peptic, and duodenal ulcer diseases.
  • but are not effective against Escherichia coli,
    Pseudomonas aeruginosa.
  • Some results indicate that tea catechins are
    potentially antiviral and antiprotozoiac agents

162
Polyphenols stability
  • The stability of tea catechins is dependent on pH
    and temperature. In acidic systems (pH lt 4), tea
    catechins are fairly stable.
  • in systems of pH gt 5, that is, near neutral or
    alkaline systems, they degrade rapidly.
  • On the contrary, tea catechins become less stable
    when processing temperature increases, where
    thermal degradation, oxidation could occur.
  • 82C was reported as a turning point in thermal
    reactions of tea catechins

163
  • Ascorbic acid showed a significantly protective
    effect on the stability of tea catechins.
  • Functional food containing Green tea.
  • green tea beverage products.
  • Sport beverages.
  • cereal, confectionary, dairy, edible oil.
  • ice cream and noodle products containing green
    tea.
  • Green tea extracts have also been incorporated in
    chocolates and chewing gums.

164
Tea and iron
  • Display Settings
  • Abstract

Send to
Crit Rev Food Sci Nutr. 2000 Sep40(5)371-98. Eff
ect of tea and other dietary factors on iron
absorption. Zijp IM, Korver O, Tijburg
LB. Source Unilever Research Vlaardingen, The
Netherlands. Abstract Iron deficiency is a major
world health problem, that is, to a great extent,
caused by poor iron absorption from the diet.
Several dietary factors can influence this
absorption. Absorption enhancing factors are
ascorbic acid and meat, fish and poultry
inhibiting factors are plant components in
vegetables, tea and coffee (e.g., polyphenols,
phytates), and calcium. After identifying these
factors their individual impact on iron
absorption is described. Specific attention was
paid to the effects of tea on iron absorption. We
propose a calculation model that predicts iron
absorption from a meal. Using this model we
calculated the iron absorption from daily menus
with varying amounts of enhancers and inhibitors.
From these calculations we conclude that the
presence of sufficient amounts of iron absorption
enhancers (ascorbic acid, meat, fish, poultry, as
present in most industrialized countries)
overcomes inhibition of iron absorption from even
large amounts of tea. In individuals with low
intakes of heme iron, low intakes of enhancing
factors and/or high intakes of inhibitors, iron
absorption may be an issue. Depletion of iron
stores enhances iron absorption, but this effect
is not adequate to compensate for the inhibition
of iron absorption in such an inadequate dietary
situation. For subjects at risk of iron
deficiency, the following recommendations are
made. Increase heme-iron intake (this form of
dietary iron present in meat fish and poultry is
hardly influenced by other dietary factors with
respect to its absorption) increase meal-time
ascorbic acid intake fortify foods with iron.
Recommendations with respect to tea consumption
(when in a critical group) include consume tea
between meals instead of during the meal
simultaneously consume ascorbic acid and/or meat,
fish and poultry.
  • Crit Rev Food Sci Nutr. 2000 Sep40(5)371-98.
  • Effect of tea and other dietary factors on iron
    absorption.
  • Zijp IM, Korver O, Tijburg LB.
  • Abstract
  • Iron deficiency is a major world health problem,
    that is, to a great extent, caused by poor iron
    absorption from the diet. Several dietary factors
    can influence this absorption.
  • Absorption enhancing factors are ascorbic acid
    and meat, fish and poultry
  • inhibiting factors are plant components in
    vegetables, tea and coffee (e.g., polyphenols,
    phytates), and calcium.
  • For subjects at risk of iron deficiency, the
    following recommendations are made. Increase
    heme-iron intake (this form of dietary iron
    present in meat fish and poultry is hardly
    influenced by other dietary factors with respect
    to its absorption) increase meal-time ascorbic
    acid intake fortify foods with iron.
  • Recommendations with respect to tea consumption
    (when in a critical group) include consume tea
    between meals instead of during the meal
    simultaneously consume ascorbic acid and/or meat,
    fish and poultry.

165
  • Am J Clin Nutr. 2001 Mar73(3)607-12.
  • Green tea or rosemary extract added to foods
    reduces nonheme-iron absorption.
  • Samman S, Sandström B, Toft MB, Bukhave K, Jensen
    M, Sørensen SS, Hansen M.
  • Abstract
  • BACKGROUND
  • Phenolic compounds act as food antioxidants. One
    of the postulated mechanisms of action is
    chelation of prooxidant metals, such as iron.
    Although the antioxidative effect is desirable,
    this mechanism may impair the utilization of
    dietary iron.
  • Results
  • The presence of the phenolic-rich extracts
    resulted in decreased nonheme-iron absorption.
    Mean (/-SD) iron absorption decreased from 12.1
    /- 4.5 to 8.9 /- 5.2 (P lt 0.01) in the
    presence of green tea extract and from 7.5 /-
    4.0 to 6.4 /- 4.7 (P lt 0.05) in the presence
    of rosemary extract.
  • CONCLUSION
  • Phenolic-rich extracts used as antioxidants in
    foods reduce the utilization of dietary iron.

166
  • J Hum Nutr Diet. 2004 Feb17(1)43-54.
  • Impact of tea drinking on iron status in the UK
    a review.
  • Nelson M, Poulter J.
  • Abstract
  • BACKGROUND
  • The aims of this review are (1) to evaluate the
    literature on the likely impact of tea drinking
    on the iron status of different groups within the
    UK population
  • RESULTS
  • There is clear evidence to show that tea drinking
    limits the absorption of nonhaem iron.
  • CONCLUSION
  • From the available evidence there is no need to
    advise any restriction on tea drinking in healthy
    people with no risk of iron deficiency. In groups
    at risk of iron deficiency the advice should be
    to drink tea between meals and to wait at least 1
    h after eating before drinking tea.

167
What will happen to gut microflora if there is
more iron in the gut?
  • Good bacteria dont require iron for growth (this
    is the case in infan
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