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From Wikipedia, the free encyclopedia
Nutrition is a science which studies the relationship between diet and states of health and disease. Dieticians are Health professionals who are specialized in this area of expertise.
They are also the only highly trained health professionals able to
provide safe, evidence-based and accurate dietary advice and
interventions.
Between the extremes of optimal health and death from starvation or malnutrition,
there is an array of disease states that can be caused or alleviated by
changes in diet. Deficiencies, excesses and imbalances in diet can
produce negative impacts on health, which may lead to diseases such as scurvy, obesity or osteoporosis,
as well as psychological and behavioral problems. Moreover, excessive
ingestion of elements that have no apparent role in health, (e.g. lead, mercury, PCBs, dioxins), may incur toxic
and potentially lethal effects, depending on the dose. The science of
nutrition attempts to understand how and why specific dietary aspects
influence health.
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Overview
Nutrition is the body of science that seeks to explain metabolic and
physiologic responses to diet. With advances in molecular biology,
biochemistry, and genetics, nutrition is additionally developing into
the study of integrative metabolism, which seeks to connect diet and
health through the lens of biochemical processes.
The human body comprises chemical compounds such as water, amino acids (proteins), fatty acids (lipids), nucleic acids (DNA/RNA), and carbohydrates (e.g. sugars). These compounds in turn consist of elements such as carbon, hydrogen, oxygen, nitrogen, and phosphorus, and may or may not contain minerals such as calcium, iron, or zinc. Minerals ubiquitously occur in the form of salts and electrolytes. All of these chemical compounds and elements occur in various forms and combinations (e.g. hormones/vitamins, phospholipids, hydroxyapatite), both in the human body and in organisms (e.g. plants, animals) that humans eat.
The human body necessarily comprises the elements that it eats and absorbs into the bloodstream. The digestive system,
except in the unborn fetus, participates in the first step which makes
the different chemical compounds and elements in food available for the
trillions of cells
of the body. In the digestive process of an average adult, about seven
litres of liquid, known as digestive juices, exit the internal body and
enter the lumen of the digestive tract. The digestive juices help break chemical bonds between ingested compounds as well as modulate the conformation
and/or energetic state of the compounds/elements. However, many
compounds/elements are absorbed into the bloodstream unchanged, though
the digestive process helps to release them from the matrix of the
foods where they occur. Any unabsorbed matter is excreted in the feces.
But only a minimal amount of digestive juice is eliminated by this
process; the intestines reabsorb most of it; otherwise the body would
rapidly dehydrate; (hence the devastating effects of persistent diarrhea).
Study in this field must take carefully into account the state of the body before ingestion and after digestion as well as the chemical
composition of the food and the waste. Comparing the waste to the food
can determine the specific types of compounds and elements absorbed by
the body. The effect that the absorbed matter has on the body can be
determined by finding the difference between the pre-ingestion state
and the post-digestion state. The effect may only be discernible after
an extended period of time in which all food and ingestion must be
exactly regulated and all waste must be analyzed. The number of variables (e.g. 'confounding factors') involved in this type of experimentation is very high. This makes scientifically valid nutritional study very time-consuming and expensive, and explains why a proper science of human nutrition is rather new.
In general, eating a variety of fresh, whole (unprocessed) foods has
proven hormonally and metabolically favourable compared to eating a
monotonous diet based on processed foods. In particular, fresh, whole
foods provide higher amounts and a more favourable balance of essential
and vital nutrients per unit of energy, resulting in better management
of cell growth, maintenance, and mitosis
(cell division) as well as regulation of appetite and energy balance. A
generally more regular eating pattern (e.g. eating medium-sized meals
every 3 to 4 hours) has also proven more hormonally and metabolically
favourable than infrequent, haphazard food intake.
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Nutrition and Health
Ill health can be caused by an imbalance of nutrients, producing
either an excess or deficiency, which in turn affects body functioning
cumulatively. Moreover, because most nutrients are, in some way or
another, involved in cell-to-cell signalling (e.g. as building block or
part of a hormone or signalling 'cascades'), deficiency or excess of
various nutrients affects hormonal function indirectly. Thus,
because they largely regulate the expression of genes, hormones
represent a link between nutrition and how our genes are expressed,
i.e. our phenotype.
The strength and nature of this link are continually under
investigation, but observations especially in recent years have
demonstrated a pivotal role for nutrition in hormonal activity and
function and therefore in health.
An excellent source of articles on nutrition and health is from the
quarterly newsletter of the Nutrition for Optimal Health Association
(NOHA). We have available on-line all the articles since 1984 handily
indexed for you by subject, name, and chronologically. These are on the
NOHA website at: NOHA link
Essential and non-essential amino acids
The body requires amino acids
to produce new body protein (protein retention) and to replace damaged
proteins (maintenance) that are lost in the urine. In animals amino
acid requirements are classified in terms of essential (an animal
cannot produce them) and non-essential (the animal can produce them
from other nitrogen containing compounds) amino acids. Consuming a diet
that contains adequate amounts of essential (but also non-essential)
amino acids is particularly important for growing animals, who have a
particularly high requirement.
Vitamins
Mineral and/or vitamin (tocotrienol and tocopherol) deficiency or excess may yield symptoms of diminishing health such as goitre, scurvy, osteoporosis, weak immune system, disorders of cell metabolism, certain forms of cancer, symptoms of premature aging, and poor psychological health (including eating disorders), among many others [3].
As of 2005, twelve vitamins and about the same number of minerals
are recognized as "essential nutrients", meaning that they must be
consumed and absorbed - or, in the case of vitamin D, alternatively synthesized via UVB radiation - to prevent deficiency symptoms and death. Certain vitamin-like substances found in foods, such as carnitine,
have also been found essential to survival and health, but these are
not strictly "essential" to eat because the body can produce them from
other compounds. Moreover, thousands of different phytochemicals
have recently been discovered in food (particularly in fresh
vegetables), which have many known and yet to be explored properties
including antioxidant activity (see below). Other essential nutrients include essential amino acids, choline and the essential fatty acids.
Fatty acids
In addition to sufficient intake, an appropriate balance of essential fatty acids - omega-3 and omega-6 fatty acids - has been discovered to be crucial for maintaining health. Both of these unique "omega" long-chain polyunsaturated fatty acids are substrates for a class of eicosanoids known as prostaglandins which function as hormones. The omega-3 eicosapentaenoic acid (EPA) (which can be made in the body from the omega-3 essential fatty acid alpha-linolenic acid (LNA), or taken in through marine food sources), serves as building block for series 3 prostaglandins (e.g. weakly-inflammation
PGE3). The omega-6 dihomo-gamma-linolenic acid (DGLA) serves as
building block for series 1 prostaglandins (e.g. anti-inflammatory
PGE1), whereas arachidonic acid (AA) serves as building block for
series 2 prostaglandins (e.g. pro-inflammatory PGE 2). Both DGLA and AA
are made from the omega-6 linoleic acid
(LA) in the body, or can be taken in directly through food. An
appropriately balanced intake of omega-3 and omega-6 partly determines
the relative production of different prostaglandins, which partly
explains the importance of omega-3/omega-6 balance for cardiovascular
health. In industrialised societies, people generally consume large
amounts of processed vegetable oils that have reduced amounts of
essential fatty acids along with an excessive amount of omega-6
relative to omega-3.
The rate of conversions of omega-6 DGLA to AA largely determines the
production of the respective prostaglandins PGE1 and PGE2. Omega-3 EPA
prevents AA from being released from membranes, thereby skewing
prostaglandin balance away from pro-inflammatory PGE2 made from AA
toward anti-inflammatory PGE1 made from DGLA. Moreover, the conversion
(desaturation) of DGLA to AA is controlled by the enzyme delta-5-desaturase, which in turn is controlled by hormones such as insulin (up-regulation) and glucagon
(down-regulation). Because different types and amounts of food
eaten/absorbed affect insulin, glucagon and other hormones to varying
degrees, not only the amount of omega-3 versus omega-6 eaten but also
the general composition of the diet therefore determine health
implications in relation to essential fatty acids, inflammation (e.g. immune function) and mitosis (i.e. cell division).
Sugars
Several lines of evidence indicate lifestyle-induced hyperinsulinemia and reduced insulin function (i.e. insulin resistance)
as a decisive factor in many disease states. For example,
hyperinsulinemia and insulin resistance are strongly linked to chronic
inflammation, which in turn is strongly linked to a variety of adverse
developments such as arterial microinjuries and clot
formation (i.e. heart disease) and exaggerated cell division (i.e.
cancer). Hyperinsulinemia and insulin resistance (the so-called metabolic syndrome) are characterized by a combination of abdominal obesity, elevated blood sugar, elevated blood pressure, elevated blood triglycerides, and reduced HDL cholesterol. The negative impact of hyperinsulinemia on prostaglandin PGE1/PGE2 balance may be significant.
The state of obesity clearly contributes to insulin resistance, which in turn can cause type 2 diabetes.
Virtually all obese and most type 2 diabetic individuals have marked
insulin resistance. Although the association between overfatness and
insulin resistance is clear, the exact (likely multifarious) causes of
insulin resistance remain less clear. Importantly, it has been
demonstrated that appropriate exercise, more regular food intake and
reducing glycemic load
(see below) all can reverse insulin resistance in overfat individuals
(and thereby lower blood sugar levels in those who have type 2
diabetes).
Obesity can unfavourably alter hormonal and metabolic status via resistance to the hormone leptin,
and a vicious cycle may occur in which insulin/leptin resistance and
obesity aggravate one another. The vicious cycle is putatively fuelled
by continuously high insulin/leptin stimulation and fat storage, as a
result of high intake of strongly insulin/leptin stimulating foods and
energy. Both insulin and leptin normally function as satiety signals to
the hypothalamus
in the brain; however, insulin/leptin resistance may reduce this signal
and therefore allow continued overfeeding despite large body fat
stores. In addition, reduced leptin signalling to the brain may reduce
leptin's normal effect to maintain an appropriately high metabolic rate.
There is debate about how and to what extent different dietary
factors -- e.g. intake of processed carbohydrates, total protein, fat,
and carbohydrate intake, intake of saturated and trans fatty acids, and
low intake of vitamins/minerals -- contribute to the development of
insulin- and leptin resistance. In any case, analogous to the way
modern man-made pollution may potentially overwhelm the environment's
ability to maintain 'homeostasis', the recent explosive introduction of high Glycemic Index-
and processed foods into the human diet may potentially overwhelm the
body's ability to maintain homeostasis and health (as evidenced by the
metabolic syndrome epidemic).
Antioxidants are another recent discovery. As cellular metabolism/energy production requires oxygen, potentially damaging (e.g. mutation causing) compounds known as radical oxygen species or free radicals
form as a result. For normal cellular maintenance, growth, and
division, these free radicals must be sufficiently neutralized by
antioxidant compounds, some produced by the body with adequate precursors (glutathione, Vitamin C
in most animals) and those that the body cannot produce may only be
obtained through the diet through direct sources (Vitamin C in humans, Vitamin A, Vitamin K) or produced by the body from other compounds (Beta-carotene converted to Vitamin A by the body, Vitamin D synthesized from cholesterol by sunlight).
Different antioxidants are now known to function in a cooperative
network, e.g. vitamin C can reactivate free radical-containing glutathione
or vitamin E by accepting the free radical itself, and so on. Some
antioxidants are more effective than others at neutralizing different
free radicals. Some cannot neutralize certain free radicals. Some
cannot be present in certain areas of free radical development (Vitamin
A is fat-soluble and protects fat areas, Vitamin C is water
soluble and protects those areas). When interacting with a free
radical, some antioxidants produce a different free radical compound
that is less dangerous or more dangerous than the previous compound.
Having a variety of antioxidants allows any byproducts to be safely
dealt with by more efficient antioxidants in neutralizing a free
radical's butterfly effect.
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Nutrition and sports
Nutrition is very important for improving sports performance.
Contrary to popular belief, athletes need only slightly more protein
than an average person.[citation needed]
These needs are easily met by a balanced diet, and the recommended
daily servings are generous enough to meet these needs. Additional
protein intake is broken-down to be used as energy or stored as fat.
Excess protein or grain consumption in the absence of alkalizing
mineral intake (from fruits and vegetables) leads to chonic low grade
acididosis in which calcium and glutamine are leached from bone and
muscle respectively to keep the blood pH steady.
Endurance, strength and sprint athletes have different needs. Many athletes may require an increased caloric intake.
Maintaining hydration during periods of physical exertion is key to
good performance. While drinking too much water during activities can
lead to physical discomfort, dehydration hinders an athlete’s ability.
It is recommended that an athlete drink about 400-600mL 2-3 hours
before activity, during exercise he or she should drink 150-350mL every
15 to 20 minutes and after exercise that he or she replace sweat loss
by drinking 450-675 mL for every .5 Kg body weight loss during activity.[citation needed]
Studies have shown that an athlete that drinks before they feel thirsty
stays cooler and performs better than one who drinks on thirst cues.[citation needed]
Additional carbohydrates and protein before, during, and after exercise
increase time to exhuastion as well as speed recovery. Dosage is based
on work performed, lean body mass, and environmental factors (heat)
The main fuel used by the body during exercise is carbohydrates,
which is stored in muscle as glycogen- a form of sugar. During
exercise, muscle glycogen reserves can be used up, especially when
activities last longer than 90 min.[citation needed]
When glycogen is not present in muscles, the muscle cells perform
anaerobic respiration producing lactic acid, which is responsible for
fatigue and burning sensation, and post exercise stiffness in muscles.[citation needed]
Because the amount of glycogen stored in the body is limited, it is
important for athletes to replace glycogen by consuming a diet high in
carbohydrates. Meeting energy needs can help improve performance during
the sport, as well as improve overall strength and endurance.
Nutrition and longevity
Calorie restriction
Lifespan may be somehow related to the amount of food energy consumed[8]. A pursuit of this principle of caloric restriction followed, involving research into longevity
of those who reduced their food energy intake while attempting to
optimize their micronutrient intake. Perhaps not surprisingly, some
people found that cutting down on food reduced their quality of life so
considerably as to negate any possible advantages of lengthening their
lives. However, a small set of individuals persists in the lifestyle,
going so far as to monitor blood lipid levels and glucose response
every few months. See Calorie Restriction Society.
Underlying this research was the hypothesis that oxidative damage
was the agent which accelerated aging, and that aging was retarded when
the amount of carbohydrates (and thereby insulin release) was reduced
through dietary restriction.
However, recent research has produced increased longevity in animals
(and shows promise for increased human longevity) through the use of
insulin uptake retardation. This was done through altering an animal’s
metabolism to allow it to consume similar food-energy levels to other
animals, but without building up fatty tissue[9].
This has set researchers off on a line of study which presumes that
it is not low food energy consumption which increases longevity.
Instead, longevity may depend on an efficient fat processing
metabolism, and the consequent long term efficient functioning of our
organs free from the encumbrance of accumulating fatty deposits[10].
Thus, longevity may be related to maintained insulin sensitivity.
However, several other factors including low body temperature seem to
promote longevity also and it is unclear to what extent each of them
contribute.
Antioxidants have recently come to the forefront of longevity studies which have included the Food and Drug Administration and Brunswick labs.
Whole Plant Food Diet
In China “some areas have essentially no cancer or heart disease,
while in other areas, they reflect up to a 100-fold increase.” (this
and all quotes from The China Study, by T. Colin Campbell PhD)
Coincidentally, diets in China range from entirely plant-based to
heavily animal-based, depending on the location. In contrast, diseases
of affluence like cancer and heart disease are common throughout the
United States. Most Americans eat an animal protein based diet, with
relatively few calories coming from plant foods. China's homogeneous
gene pool, low rates of migration, and large localized variations in
diet and disease incidence provide an ideal study basis leading to
reliable data.
The research makes a good case that animal protein is "one of the
most toxic agents" in our diets. Evidently, it's better for our bodies
to break plant proteins down into amino acids and then piece them
together slowly to form human proteins, versus quickly as when one eats
animal proteins containing amino acids very closely matching our own
needs. Also, “the richer the diet is in the kinds and amounts of
nutrients and antioxidants provided by foods of plant origin, the lower
the risk of chronic degenerative diseases.”
The cover article of the November 2005 issue of National Geographic is titled The Secrets of LIVING LONGER.
The article starts out with the sentence "What if I said you could
add up to ten years to your life?" It's basically a lifestyle survey of
three populations ... Sardinians, Okinawans, and Adventists (right here in America)
... who generally display longevity and "suffer a fraction of the
diseases that commonly kill people in other parts of the developed
world, and enjoy more healthy years of life. In sum, they offer three
sets of "best practices" to emulate. The rest is up to you."
In common with all three groups is to "Eat fruits, vegetables, and whole grains."
The article noted that a NIH funded study of 34,000 Seventh-Day
Adventists between 1976 and 1988 "...found that the Adventists' habit
of consuming beans, soy milk, tomatoes, and other fruits lowered their
risk of developing certain cancers. It also suggested that eating whole
wheat bread, drinking five glasses of water a day, and, most
surprisingly, consuming four servings of nuts a week reduced their risk
of heart disease. And it found that not eating red meat had been
helpful to avoid both cancer and heart disease." Searching “34,000
Seventh-Day Adventists” will take you to several interesting study
related sites.
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Nutrition, industry and food processing
Since the Industrial Revolution some two hundred years ago, the food processing industry has invented many technologies
that both help keep foods fresh longer and alter the fresh state of
food as they appear in nature. Cooling is the primary technology that
can help maintain freshness, whereas many more technologies have been
invented to allow foods to last longer without becoming spoiled. These
latter technologies include pasteurisation, autoclavation, drying, salting,
and separation of various components, and all appear to alter the
original nutritional contents of food. Pasteurisation and autoclavation
(heating techniques) have no doubt improved the safety of many common
foods, preventing epidemics of bacterial infection. But some of the
(new) food processing technologies undoubtedly have downfalls as well.
Modern separation techniques such as milling, centrifugation, and pressing
have enabled upconcentration of particular components of food, yielding
flour, oils, juices and so on, and even separate fatty acids, amino
acids, vitamins, and minerals. Inevitably, such large scale
upconcentration changes the nutritional content of food, saving certain
nutrients while removing others. Heating techniques may also reduce
food's content of many heat-labile nutrients such as certain vitamins
and phytochemicals, and possibly other yet to be discovered substances.
Because of reduced nutritional value, processed foods are often
'enriched' or 'fortified' with some of the most critical nutrients
(usually certain vitamins) that were lost during processing.
Nonetheless, processed foods tend to have an inferior nutritional
profile than do whole, fresh foods, regarding content of both sugar and
high GI starches, potassium/sodium,
vitamins, fibre, and of intact, unoxidized (essential) fatty acids. In
addition, processed foods often contain potentially harmful substances
such as oxidized fats and trans fatty acids.
A dramatic example of the effect of food processing on a population's health is the history of epidemics of beri-beri in people subsisting on polished rice. Removing the outer layer of rice by polishing it removes with it the essential vitamin thiamine, causing beri-beri. Another example is the development of scurvy
among infants in the late 1800's in the United States. It turned out
that the vast majority of sufferers were being fed milk that had been
heat-treated (as suggested by Pasteur) to control bacterial disease. Pasteurisation was effective against bacteria, but it destroyed the vitamin C.
As mentioned, lifestyle- and obesity-related diseases are becoming
increasingly prevalent all around the world. There is little doubt that
the increasingly widespread application of some modern food processing
technologies has contributed to this development. The food processing
industry is a major part of modern economy, and as such it is
influential in political decisions (e.g. nutritional recommendations,
agricultural subsidising). In any known profit-driven economy, health
considerations are hardly a priority; effective production of cheap
foods with a long shelf-life is more the trend. In general, whole,
fresh foods have a relatively short shelf-life and are less profitable
to produce and sell than are more processed foods. Thus the consumer is
left with the choice between more expensive but nutritionally superior
whole, fresh foods, and cheap, usually nutritionally inferior processed
foods. Because processed foods are often cheaper, more convenient (in
both purchasing, storage, and preparation), and more available, the
consumption of nutritionally inferior foods has been increasing
throughout the world along with many nutrition-related health
complications.
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Advice and guidance on nutrition
Governmental policies
Most Governments provide guidance on good nutrition, and some also impose mandatory labeling
requirements upon processed food manufacturers to  Assist consumers in
complying with such guidance. Current dietary guidelines in the United
States are presented in the concept of a food pyramid. There is no apparent consistency in science-based nutritional recommendations between countries, indicating the role of politics as well as cultural bias in research emphasis and interpretation.
Teaching
Nutrition is taught in schools in many countries. In England and Wales the Personal and Social Education
and Food Technology curriculums nutrition included, stressing the
importance of a balanced diet and teaching how to read nutrition labels
on packaging.
Issues
Challenging issues in modern nutrition include:
"Artificial" interventions in food production and supply:
Sociological issues:
- Is it possible to eat right on a low-income? Is proper nutrition
economically skewed? How do we increase access to whole foods in
impoverished neighborhoods?
- How do we minimise the current disparity in food availability between first and third world populations (see famine and poverty)?
- How can public advice agencies, policy making and food supply
companies be coordinated to promote healthy eating and make wholesome
foods more convenient and available?
- Do we need nutritional supplements in the form of pills, powders, liquids, etc.?
- How can the developed world promote good worldwide nutrition
through minimising import tariffs and export subsidies on food
transfers?
Research Issues:
- How do different nutrients affect appetite and metabolism, and what are the molecular mechanisms?
- What yet to be discovered important roles do vitamins, minerals, and other nutrients play in metabolism and health?
- Are the current recommendations for intake of vitamins and minerals appropriate?
- How and why do different cell types respond differently to
chronically elevated circulating levels of insulin, leptin, and other
hormones?
- What does it take for insulin resistance to develop?
- What other molecular mechanisms may explain the link between nutrition and lifestyle-related diseases?
- What role does the intestinal bacterial flora play in digestion and health?
- How essential to proper digestion are the enzymes contained in food itself, which are usually destroyed in cooking (see Living foods diet)?
- What more can we discover through what has been called the phytochemical revolution?
See also
For detailed information, see related entries in the following categories:
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Food:
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References
- The Times newspaper, January 31 2004 Could vitamins help delay the onset of Alzheimer’s? by Jerome Burne.
- The Times newspaper February 28, 2004 Autism: I can see clearly now . . . by Simon Crompton
- The Times newspaper March 10, 2004 Work up an Amish appetite by Anne-Celine Jaeger
- William Eaton et al. 2004. Coeliac disease and schizophrenia. British Medical Journal, February 21, 2004.
- Janssen I, Katzmarzyk PT, Ross R. Waist circumference and not body mass index explains obesity-related health risk. Am J Clin Nutr. 2004 Mar;79(3):379-84.
- J Mei, SSC Yeung et al. 2001. High dietary phytoestrogen intake and bone mineral density in postmenopausal women. Journal of Clinical Endocrinology and Metabolism, Vol 86, Iss 11.
- Merritt JC. 2004. Metabolic syndrome: soybean foods and serum lipids. J Natl Med Assoc. Aug;96(8):1032-41.
- Sobczak S, et al. (2004) Lower high-density lipoprotein cholesterol
and increased omega-6 polyunsaturated fatty acids in first-degree
relatives of bipolar patients Psychol Med. 2004 Jan;34(1):103-12.
- Walter C. Willett and Meir J. Stampfer. 2003. Rebuilding the Food Pyramid. Scientific American January 2003.
- Galdston, I., Human Nutrition Historic and Scientific (New York: International Universities Press, 1960)
- Mahan, L.K. and Escott-Stump, S. eds. (2000) Krause's Food, Nutrition, and Diet Therapy. 10th ed. (Phaladelphia: W.B. Saunders Harcourt Brace)
- ^ Unraveling the Enigma of Vitamin D - a paper funded by the United States National Academy of Sciences
- ^ "Can a virus make you fat?" at BBC News; "Contagious obesity? Identifying the human adenoviruses that may make us fat" at Science Blog
- ^ Shils et al. (2005) Modern Nutrition in Health and Disease, Lippincott Williams and Wilkins. ISBN 0781741335.
- ^ Seddon JM et al. JAMA. 1994; 272: 1413-1420; Schepens Eye Institute/Harvard Medical School, Nov. 11, 2003. See http://www.mdsupport.org/library/zeaxanthin.html.
- ^
Lyle, B. J., J. A. Mares-Perlman, et al. (1999). "Antioxidant intake
and risk of incident age-related nuclear cataracts in the Beaver Dam
Eye Study." Am J Epidemiol 149(9): 801-9; Yeum, K. J., A. Taylor, et
al. (1995). "Measurement of carotenoids, retinoids, and tocopherols in
human lenses." Invest Ophthalmol Vis Sci 36(13): 2756-61; Chasan-Taber,
L., W. C. Willett, et al. (1999). "A prospective study of carotenoid
and vitamin A intakes and risk of cataract extraction in US women." Am
J Clin Nutr 70(4): 509-16; Brown, L., E. B. Rimm, et al. (1999). "A
prospective study of carotenoid intake and risk of cataract extraction
in US men." Am J Clin Nutr 70(4): 517-24.
- ^ Am J Clin Nutr, Vol. 82, No. 2, 451-455, August, 2005 (inflammatory polyarthritis); Am J Epidemiology 2006 163(1).
- ^ Am J Clin Nutr, Vol. 70, No. 2, 247-251, August 1999.
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Weindruch R, et al. The retardation of aging in mice by dietary
restriction: longevity, cancer, immunity and lifetime energy intake. Journal of Nutrition, 116(4), pages 641-54.,April, 1986.
- ^ Bluher, Khan BP, Kahn CR, Extended longevity in mice lacking the insulin receptor in adipose tissue. Science 299(5606): 572-4, Jan 24, 2003.
- ^ Das M, Gabriely I, Barzilai N.Caloric restriction, body fat and aging in experimental models. Obes. Rev. 2004 Feb;5(1):13-9.
External links
Professional Dietetic Associations
Other
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