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Bioavailability of food is an important issue in nutrition. But, trying to calculate quantitatively how much
of each known nutrient you are getting out of your diet is both a waste of time and impossible to do. It is recommended
that you do not try to quantify your intake of specific Micronutrients from your diet.
Highlights of Bioavailability of Nutrients - The Nutrition of Micronutrients:
- Good nutrition from eating a healthy diet is the foundation of the biomedical model of natural health.
- Any change in your diet, however small, that improves your natural health is a step in the right direction.
- Micronutrients include vitamins, minerals and water.
- Micronutrients do not provide any energy to the body.
- You improve your nutrition and natural health by choosing to eat healthier foods than you are currently eating.
Micronutrients include vitamins, minerals and water. Macronutrients
are carbohydrates, proteins, fats and individual fatty acids. Micronutrients do not provide any energy to the body,
while Macronutrients primarily provide the body with energy.
Good nutrition from eating a healthy diet is the foundation of any wellness program. The Goal is to get an adequate
amount of Micronutrients in your diet by eating a large variety of healthy foods at a total caloric rate that will
either maintain your present body weight, or achieve your ideal body weight over a reasonably long period of time.
Nutrition is the relationship of foods to the health of the human body. The foods we consume should provide
our bodies with the nutrients necessary for good health. The basic premise of any good diet is variety,
balance and moderation[19] in what we eat,
on a regular basis. Good nutrition is obtainable without engaging in dieting extremes.
Poor nutrition is the result of consuming too little, too much, or the wrong kinds of food, on a regular basis.
Food science, a root cause of poor nutrition, transforms natural whole foods into garbage that fills the belly
while developing excessive human appetites for fat, sugar, and salt. Avoiding poor nutrition simply means refusing
to eat junk food.
You may be tempted to look up your diet in a food database, or with a computerized diet program. Analyzing your
diet is appropriate for Macronutrients, but
would be largely inaccurate for your micronutrients. You could indeed spend a considerable amount of time generating
numbers regarding how much of each nutrient you are currently getting from your diet.
But, what would your numbers really mean? Not much!
Before you could be accurate, you would need to know not only the nutrient composition of foods, but also all
sources of potential losses to those nutrients.
"Nutrients ingested but not released during the digestive process for absorption are of no nutritional
value."[1] "An assessment of the adequacy of dietary intakes of nutrients requires not only knowledge
of the nutrient content of the foods ingested but also the extent to which the nutrient present in the diet is
available for absorption and utilization."[1] Bioavailability is the technical term used to convey the
fact that you do not absorb 100% of all nutrients consumed, no matter if you take them in the form of nutritional
supplements or as food. In fact, you may absorb from food, close to none of some nutrients.
"The term 'bioavailability' attempts to include in a single concept the effect of a sequence of metabolic
events, i.e., digestibility, solubilization, absorption, organ uptake and release, enzymatic transformation, secretion
and excretion."[2]
A number of factors affect bioavailability: factors contained in the food itself, factors of human physiology,
factors specific to your health status, and factors related to the food processing.
Food Related Factors -- "The bioavailability of a nutrient can, in some cases, be significantly
influenced by the chemical form in which it appears in the diet and by the presence of other factors in food that
may enhance or depress mineral absorption and utilization."[4]
"While most vitamins are very well absorbed [from food], most essential minerals are not. Usual absorption
of minerals ranges from less than 1% to over 90%. The bioavailability of dietary minerals must be considered when
determining whether the diet contains enough, too little, or too much."[3]
Human Physiology Related Factors -- "Various nutrients and dietary components interfere with
the bioavailability of vitamins. Hence, requirements for vitamins cannot be considered independently, but must
be evaluated in relationship to other nutrients and compounds consumed by an individual."[1]
Nutrients compete with other nutrients for absorption. Some nutrients will enhance/reduce the amounts of other
nutrients being absorbed by your body.
Health Status Related Factors -- Probiotics can be used to improve your intestinal tract health in order
to enhance the bioavailability of some nutrients.[5] You may also have a genetic defect that adversely affects
the absorption of specific nutrients.
Food Processing Related Factors -- There is no best way to prepare food. Consuming fruits and vegetables
raw enhances the absorption of some nutrients, whereas soaking and fermentation will increase the absorption of
minerals in legumes and grains to the detriment of the water soluble nutrients. Cooking by breaking down fiber
generally increases digestibility of many nutrients, while all the oil soluble nutrients require the presence of
fat for best absorption.
In conclusion: Trying to calculate quantitatively how much of each known nutrient you are getting out
of your diet is both a waste of time and impossible to do There are simply too many factors evolved. It is, thus,
recommended that you do not try to quantify your intake of specific Micronutrients from your diet.
"It will therefore require major research programs before the term 'bioavailability' of a nutrient can
become a quantitative concept useful for clinical, nutritional or managerial evaluation and counseling."[2]
The best approach to optimizing your diet is to follow the simple dietary rules of thumb provided elsewhere
on this web site.
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Micronutrients by Food Groups
- Dairy:
- The primary source of calcium in your diet.
- heavy in saturated fat
- calcium, potassium, phosphorus, magnesium, and iodine [10]
- protein [13]
- Fatty Fish:
- omega-3 fatty acids (eicosapentaenoic acid [EPA] & docosahexaenoic acid [DHA]) [12]
- protein [13]
- iron
- Fruits:
- Because fruits are normally eaten raw, they are the primary source of many water soluble / living nutrients
your diet.
- soluble dietary fiber (such as pectin) [6]
- folic acid
- 57.9% of the total vitamin C intake [7]
- 40.6% of the total beta-carotene intake [7]
- Plant families of Fruits:
- Citrus Fruits (orange, tangelos,tangerine)
- monoterpenes (inhibits carcinogen activation ) [18]
- Vitamin C
- Carotene rich fruits (raw
tomatoes, cantaloupe, mango, papaya, dried apricots & peaches)
- Whole-Grains / Cereal:
- bran, which may contain the most important bioactive nutrients.[20]
- insoluble fiber (such as cellulose) [6]
- sodium, iron, magnesium, manganese, and iodine [9],[10]
- "The long list of cereal antioxidants includes vitamin E, tocotrieonols, selenium, phenolic acids,
and phytic acid. These multifunctional antioxidants come in immediate-release to slow-release forms and thus are
available throughout the gastrointestinal tract over a long period after being consumed."[20]
- B vitamins, vitamin E, selenium, zinc, copper, and magnesium.[8]
- protein [13]
- lignans [20]
- See Health Benefits of Whole-Grains
for additional information.
- Legumes:
- soluble dietary fiber (such as pectin) [6]
- insoluble fiber (such as cellulose)
- protein [13]
- "Legumes are rich sources of slowly digestible starch promoting moderate postprandial glycernic and
insulinemic responses." [14]
- Meat:
- saturated fat
- The primary source of iron, zinc, and vitamin B-12 in your diet. [11]
- protein [13]
- copper, phosphorus, selenium, and zinc [9]
- Nuts:
- low in saturated fatty acids and high in monounsaturated and polyunsaturated fatty acids [16]
- protein, copper, magnesium [16]
- best natural source of vitamin E and are relatively concentrated repositories of magnesium, potassium, and
arginine [17]
- protein [13]
- Vegetables:
- Vegetables are normally eaten cooked in order to break down fiber and to destroy toxins. Thus, they are the
primary source of many nutrients that are improved by the cooking process.
- soluble dietary fiber (such as pectin) [6]
- insoluble fiber (such as cellulose)
- magnesium, potassium [9]
- folic acid
- 34.8% of the total beta-carotene intake [7]
- 17.3 % of the total vitamin C intake [7]
- Plant families of Vegetables:
- Brassica or Cruciferous vegetables (broccoli, cabbage, kale, Brussels sprouts, cauliflower)
- aromatic isothiocyanates (inhibits carcinogen activation ) [18]
- glucobrassicin & indoles (inhibits carcinogen activation )[18]
- Carotene rich vegetables
([dark-green leafy vegetables (kale, collard greens, spinach, greens in general) and deep-yellow-orange vegetables]
(cooked tomatoes, carrots, sweet potato, pumpkin)
- Approximately 80-90% of the carotenoids present in green, leafy vegetables such as broccoli, kale, spinach
and brussel sprouts are xanthophylls, whereas 10-20% are carotenes. Conversely, yellow and orange vegetables including
carrots, sweet potatoes and squash contain predominantly carotenes. [15]
- Allium vegetables (onion, garlic, leek, chive).
- organosulphur compounds (inhibits carcinogen activation ) [18]
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Additional information on this website on Nutrition is located at:
- The Nutrition of a Varied Diet
- The Nutrition of a Balanced Diet
- The Nutrition of Macronutrients
References
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- Bronner F. Nutrient bioavailability, with special reference to calcium. J Nutr. 1993 May;123(5):797-802. Review.
PMID: 8487089
- Turnlund JR. Bioavailability of dietary minerals to humans: the stable isotope approach. Crit Rev Food Sci
Nutr. 1991;30(4):387-96. Review. PMID: 1910521
- Dreosti IE. Recommended dietary intakes of iron, zinc, and other inorganic nutrients and their chemical form
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- Kopp-Hoolihan L. Prophylactic and therapeutic uses of probiotics: a review. J Am Diet Assoc. 2001 Feb;101(2):229-38;
quiz 239-41. Review. PMID: 11271697
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- Gascon-Vila P, Ribas L, Garcia-Closas R. [Dietary sources of vitamin A, C, E and beta-carotene in a adult Mediterranean
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- Pennington JA, Schoen SA. Contributions of food groups to estimated intakes of nutritional elements: results
from the FDA total diet studies, 1982-1991. Int J Vitam Nutr Res. 1996;66(4):342-9. PMID: 8979163
- Pennington JA, Young BE. Total diet study nutritional elements, 1982-1989. J Am Diet Assoc. 1991 Feb;91(2):179-83.
PMID: 1991931
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cooking method, and water rinsing. J Am Diet Assoc. 1992 Nov;92(11):1367-71. PMID: 1430722
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National Health and Nutrition Examination Survey, 1988-1991. J Am Diet Assoc. 1999 Jul;99(7):813-20. PMID: 10405679
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- Micozzi, M.S. et al. (1990) Carotenoid analyses of selected raw and cooked foods associated with a lower risk
for cancer. Journal of the National Cancer Institute 82:282-285. PMID: 2299676
- Kris-Etherton PM, Yu-Poth S, Sabate J. Nuts and their bioactive constituents: effects on serum lipids and other
factors that affect disease risk. Am J Clin Nutr. 1999 Sep;70(3 Suppl):504S-511S. Review. PMID: 10479223
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- Wattenberg LW. Inhibition of carcinogenesis by minor anutrient constituents of the diet. Proc Nutr Soc. 1990
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- The Natural Health Perspective™
Health Program Principle 2: The Fundamental Principle of natural health and fitness is Moderation and Balance
in all things.
- J. W Anderson. EDITORIAL: Whole grains and coronary heart disease: the whole kernel of truth. Am. J. Clinical
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