Observations on multivitamins.
Multivitamins (Chemical properties)
Dietary supplements (Health aspects)
Dietary supplements (Chemical properties)
|Publication:||Name: Townsend Letter Publisher: The Townsend Letter Group Audience: General; Professional Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2009 The Townsend Letter Group ISSN: 1940-5464|
|Issue:||Date: Feb-March, 2009 Source Issue: 307-308|
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|Geographic:||Geographic Scope: United States Geographic Code: 1USA United States|
This is the first of a series of columns to assist healthcare practitioners and a growing number of interested consumers in understanding the basic concepts of the use of dietary supplements, or "nutraceuticals." In the title of these teaching columns, the word "therapeutics" is an oxymoron, given the US Dietary Supplement and Health Education Act of 1994 (DSHEA). This legislation requires that all dietary supplements carry the disclaimer "These statements have not been approved by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease."
This disclaimer represents a major enigma in modern medicine. Many health-care practitioners or recipients increasingly use nutritional supplements, botanicals, and herbs to prevent or treat disease. In fact, the mainstay of several increasingly popular traditional medical treatments, such as naturopathic medicine or Ayurveda, is the use of natural medicine and, often, the avoidance of pharmaceuticals. In essence, these "traditional" methodologies may not be perceived as conforming to "usual and customary" standards of medical care in the US.
Surveys have indicated that consumers often purchase dietary supplements with a view to wellness promotion or disease management. This circumstance highlights the problems associated with the 'legislation" of medical practice. This kind of legislation has been identified as interfering with freedom of health care, and it affects the increasing self-reliance among patients in taking control of their own health-care needs. In fact, the modern concept of the Patients' Bill of Rights emphasizes the patient's ownership of wellness promotion and the patient's importance as the decision-maker in a well-developed healer/client relationship.
The past two decades have witnessed a major shift in medical treatment paradigms, where consumer lobbies have demanded simpler and gentler ways of health promotion. This situation is perceived by many as a potential, viable alternative to allopathic interventions, despite arguments to the contrary. Of course, these circumstances have led to a residual dichotomy in medical practice. There has been the modern emergence of alternative medicine on the one hand, somewhat pitched against conventional medicine on the other.
This harsh interface of differing opinion between the alternative and the conventional has softened over the past decade. This has resulted in attempts to take a "politically correct" position under the umbrella of "integrative medicine." There seems to be a raging debate on the evidence base, or lack thereof, that supports nonconventional medical practice, but patients own their own treatment decisions. This responsibility must be complemented by education, in order that the patient may make an informed judgment about his own disease management or prevention strategies.
In medical emergencies, natural medicine may have relatively little to offer. However, natural therapeutics may star in the realm of prevention and the management of common "functional disease" or "disorders." Therefore, the author of this column does not turn his back on allopathic medicine, but some conventional medical strategies have been shown to possess disadvantages or limitations. Most notable is the observation that US citizens are the most medicated individuals in the world per capita, but their general level of health is ranked below that of more than 40 other countries.
The objective of these columns on natural medicine is to provide basic information on how dietary supplements could be applied as complementary adjuncts in disease prevention or management. However, all of the author's comments in these writings must recruit the protection of "freedom of speech," because only pharmaceuticals and accepted surgical interventions are considered usual and customary standards of medical care in the US. (1) Many US citizens are appealing for greater freedom in health-care choices. This preamble is relevant to all subsequent columns where the therapeutic potential of natural substances may be discussed to a variable degree. Manufacturers and purveyors of dietary supplements are governed by strict regulations that do not permit "treatment claims." (1)
"Vitamin Therapies": Assessing Vitamin Needs
Food scientists are correct in their assertion that vitamins and minerals are best obtained from the diet. However, much processed food in Western societies, and in urban areas in third-world countries, has been manipulated to a degree that it has been robbed of many vitamins and minerals. There is a new problem emerging in potential vitamin and mineral deficiencies. This problem is related to the modern global epidemic of obesity. (2) Individuals who are trying to control their weight may often reduce the amount of food they eat. If they are reducing the intake of processed food, which may already be deficient in vitamins, they are putting themselves at risk of deficiencies. (3)
It is known that excessive calorie intake in the diet is one major cause for obesity, but much food is manufactured to be inexpensive with high calorie content. I am not suggesting that people are walking around with obvious signs of vitamin deficiency, but it must be clearly understood that marginal deficiency of several vitamins or minerals is quite common, especially in the elderly or in the large segment of the population that relies heavily upon "fast," processed, or "junk" foods.
In recent times, many physicians or other health-care providers may have changed their opinions about the need for vitamin or mineral supplements. There are many examples of population studies that show intakes of essential vitamins to be often below recommended daily intakes or values (RDI, RDV). Consumers must understand that the concept of the RDI was generated from assessments of vitamin intake that would prevent nutrient deficiencies. This does not necessarily mean that the RDI of a vitamin is enough for optimal health or the promotion of well-being. This has led to the suggestion that there may be optimal levels of intake of vitamins that are higher than the RDI. In addition, there are some circumstances where physicians use vitamins in higher dosages for therapeutic effects. High doses of vitamins should not be self-administered, especially if the vitamin is known to be toxic in larger amounts (A, D or K). (1)
The author believes that it is no longer possible to rely upon the average Western diet or SAD as a means of achieving optimal vitamin or mineral intake. (1) There are glaring examples of these circumstances. For example, many elderly people do not have enough vitamin D to maintain healthy bones, teeth, and other body structures, even though it can be synthesized by the body through exposure to sunlight. Furthermore, there are many references concerning the inability of individuals to receive a necessary amount of vitamins C or E from dietary sources. Many Americans are strangers to fruit and vegetables, and even daily dietary intakes of vitamin C may be inadequate in many people. (4) Only a limited segment of the population obtains the five servings of fruit and vegetables per day recommended by the obsolete USDA Food Pyramid.
There are many circumstances in which the author believes that vitamin supplementation is absolutely necessary. These include calorie-controlled dieting and acute or chronic illness, or the presence of risk factors for illness, where the need for extra vitamins may be mandatory. Excessive urination in diabetes flushes out vitamins and essential minerals (e.g., magnesium and zinc), which must be then taken in the diet in greater amounts. (1)
Western society is constantly "on the go," and so nutritional challenges are made worse by the lack of time that people have to shop for well-balanced food substances and prepare their own meals. This basic information about nutrition provides a compelling argument for every person to consider his daily needs of essential vitamins and minerals.
New Horizons for the Use of Vitamins
Many scientists and health-care providers believe in taking enough vitamins to help ensure health and well-being. (4-15) Therefore, the modern use of vitamins has more to do with the promotion of wellness than merely avoiding vitamin deficiencies. (1-15) Scientists who have proposed and modified RDIs of vitamins have been quite frank with their opinion that it is not easy to determine ideal dosages. There is a growing medical view that these dosages are likely to be much higher than the standard recommendations or values that currently prevail in medical thought.
Vitamin needs change dramatically with age, disease status, environmental conditions and health status, to name a few circumstances. (1) Adequate vitamin or mineral intake cannot be effective in promoting health without positive lifestyle changes, such as the use of a balanced, nutrient-dense diet that is somewhat restricted in saturated fat, simple sugar, and animal protein. Modern dietary recommendations for health must stress the importance of increasing dietary fiber intake (about 25 g or more/day), with a more liberal use of healthy fats, such as omega-3 fatty acids, found in fish oil. (2)
Much concern continues to be expressed about the adverse effects of taking too many vitamins. The author thinks that this fear has been somewhat overestimated, because there are relatively few reports of toxicity from the use of vitamin supplements. However, a general rule is that the fat-soluble vitamins A, D, E, and K are not to be taken in high dosages without medical supervision. (1) Consumers become confused when studies are reported that allege negative outcomes from taking larger dosages of a single vitamin. In recent times, this situation has arisen with the use of vitamin E. (12), (13)
Many studies that focus on the single use of a nutritional substance are able to be criticized by their construction, which may not result in a conclusion that can be generally applied to the population. (1) The author believes that this was the case in the recent reports of the dangers of using higher dosages of vitamin E in patients with heart disease. That said, vitamin E is an antioxidant vitamin, and the dietary supplement industry may have been overpromoting the use of antioxidants as single agents, which in high dosages may cause unwanted actions such as "pro-oxidant effects."
Some scientists have suggested that vitamin supplementation can be tailored to a patient's individual needs. Unfortunately, this commendable approach is very difficult to achieve by self-management. (1) The background presented here for vitamin usage means that there is a compromise to be achieved between the RDI of vitamins and the avoidance of adverse effects of certain types of vitamin excess.
Naturopathic physicians and other practitioners of natural medicine may in general tailor vitamin needs to their patients so that they can achieve well-being beyond simple health. This approach is not often found in conventional medicine. Many drugs are known to deplete certain vitamins or minerals, and the act of adding supplements with pharmaceutical prescriptions is often overlooked. The population must be made more aware of drug-induced nutrient depletions (e.g., vitamin B12 depletion by potent antisecretory drugs).
An Overview of the Health Benefits of Vitamins
There are many accounts of the actions of individual vitamins on body structures and functions. A brief overview of the health benefits of vitamins is given in Table 1. (16-26) All practicing clinicians must have a working knowledge of the actions of essential vitamins. Recent research has identified many previously ignored functions of vitamins.
Vitamin A is present in the body in many different chemical forms. (16), (17) There are retinoids, which are "formed-types" of vitamin A, and a series of naturally occurring compounds called carotenoids that can be converted variably into vitamin A itself. Vitamin A plays a major role in supporting eye function, body linings, normal bone growth, immune functions, and reproduction. Vitamin A or beta-carotene may reduce the risk of cancer in some circumstances, but opinions are divided. Excessive amounts of vitamin A should be avoided, especially during pregnancy (due to teratogenicity).
Vitamin D is probably best not referred to as a vitamin, because, unlike other vitamins, it can be manufactured in the body. It occurs in chemical forms called calciferols. The natural, active form is D3, which has many "hormonal actions" in the body. Vitamin D is best known for its ability to increase calcium and phosphorus absorption, and it has an important role in the formation of bones and teeth. Also, it supports the production of insulin, promotes healthy immune function, and has a role in cancer prevention. Excessive amounts are not recommended because of potential toxicity; but adverse effects are only seen at high dosages, taken continuously (> about 50,000 IU/day, depending upon the context).
Vitamin E occurs in several forms called tocopherols and tocotrienols. There is evidence that naturally originating vitamin E is more effective than synthetic vitamin E. Vitamin E is a classic antioxidant vitamin, and it plays a major role in protecting cell membranes against damage (antioxidant effects). (19), (20) It works in concert with vitamins A and C as a classic antioxidant, and it supports reproductive function. Whether or not vitamin E is toxic in high dosages remains arguable, but continuously taking more than 400 IU per day should be done only under medical supervision.
Vitamin K is the classic vitamin utilized by the body in blood clotting. It is not often deficient in the diet and can be synthesized by bacteria in the colon. (21)
The B vitamins include niacin (B3), pyridoxine (B6), cobalamin (B12), thiamin (B1), riboflavin (B2), pantothenic acid, biotin, and folic acid. (22-25) All B vitamins are water soluble, and they serve many basic functions, including blood formation, support of central nervous system (CNS) function, support of general body chemistry, genetic functions, and other important activities. (22-25) In general, B vitamins do not tend to cause adverse effects, even in relatively high doses. An exception is niacin, which can cause liver damage when used in gram amounts over a significant period of time. Crystalline niacin is less likely to damage the liver than "sustained-release" niacin. Niacin is valuable in detoxification programs that use sauna treatments and exercise.
Vitamin C requires little introduction. It is essential for the health of supporting tissues in the body, blood vessel functions, wound healing, and the production of body hormones or messenger substances. Vitamin C is a powerful antioxidant. Much evidence implies that it may protect against the common cold, prevent certain types of cancer, promote cardiovascular health, support memory, prevent cataract formation, and exert antiallergic effects. Vitamin C also has documented antiaging properties. (4)
What are the Best Vitamin Supplements?
Simply stated, one "gets what one pays for" when purchasing a vitamin supplement. Cheaper types are often presented in pressed, hard tablets that are difficult to swallow, and their contents are often poorly absorbed. (1) Some are so poorly absorbed that they may be passed in the stool in an intact form. Clearly, vitamin supplements are best administered in capsules, and vegetable capsules may be preferred because of concerns about bovine gelatin as a possible source of mad cow disease. Vegetable capsules are more expensive than regular gelatin capsules, but they are advantageous.
Many people are confused about the ideal amounts of vitamins to take on a daily basis. The amounts of several vitamins in advanced formulae often exceed RDI, but they will not produce toxic effects in average use. Superior vitamin supplements are distinguished by the addition of several other vital nutrients that are not able to be classified as vitamins per se, but have other potential health benefits by acting as cofactors. (1) Many of the benefits of these valueadded nutrients will be discussed in future columns. These include green tea extract, turmeric or curcuminoids, choline, inositol, PABA, grape seed extract, lutein, and lycopene. Small amounts of black pepper are sometimes added to multivitamin formulations for antioxidant functions and the alleged promotion of better vitamin absorption.
New Trends in Vitamin Supplementation
New trends in vitamin supplementation have been influenced by more detailed knowledge of the function of vitamins that are summarized in the following short paragraphs. Much of the information is found in quick reference sources (for example, Present Knowledge in Nutrition, Ziegler EE and Filer LJ, eds., 1996; and The Nutrient Bible, Osiecki H, 2006).
* Vitamin A (retinol, retinal, retinoic acid, precursor -beta-carotene) supports retinoid receptor pathways for vision, sensory input, attention, concentration, and language processing. It is a classic lipid antioxidant that activates B and T lymphocytes: it enhances phagocyte function and antibody production. It plays a role in steroid synthesis, bone growth, and white cell differentiation, and it may induce apoptosis. It increases iron utilization and maintains tight junctions between cells with enhanced cellular adhesion, thereby stabilizing mucosal barriers for defense. It is important for membrane integrity and structure of myelin sheath. It protects against squamous cancer and promotes the synthesis of mucopolysaccharide. It is necessary for visual purple synthesis. It is a specific stimulator of neurotrophic factor synthesis.
* Vitamin B1 (co-carboxylase, active form--thiamine pyrophosphate [TPP]) is a cofactor in two dozen enzyme systems, necessary for conversion of alpha-keto acids to acyl ions, carboxylic acid, and aldehydes. It has a role in the hexose monophosphate shunt. It mimics acetylcholine (ACh) in the CNS and cardiac muscle. It regulates sugar metabolism and ion channels in cells, and may regulate appetite.
* Vitamin B2 (riboflavin, flavin adenine dinucleotide [FAD] [active form]) is a coenzyme in respiratory systems and a component of flavoproteins with specific importance in Krebs cycle. It maintains the structure of mucosal surfaces and myelin, with a role in red cell production. It may exert a role in the reduction of brain swelling following stroke or injury and plays a pivotal role in fetal development.
* Vitamin B3 (niacin, nicotinic acid, niacinamide, nicotinamide adenine dinucleotide [NAD] [active form]--coenzyme I, nicotinamide adenine dinucleotide phosphate [NADP]--coenzyme P)--has indirect functions as an electron carrier in cellular respiratory activity, and it is involved in oxidation of fats and carbohydrates. It functions as part of biochemical complexes that act with hydrogen donation; for example, fatty acid and steroid synthesis. It has well defined antineuritic activity, lowers blood cholesterol, maintains skin and digestive structure, and has a role in energy production and stimulation of DNA repair. It plays role as nicotinamide in altering the activity of several interleukins and tumor necrosis factor alpha (TNF).
* Vitamin B5 (pantothenic acid) supports immune function and steroid hormone production, and is a constituent of coenzyme A. It has major functions in the synthesis of cholesterol, corticosteroids, antibodies and acetylcholine. It alters uric acid production.
* Vitamin B6 (pyridoxine, co-decarboxylase hydrochloride, pyridoxal-5-phosphate [P-5-P] [active form] and pyridoxamine phosphate) has anti-aging potential by inhibiting the production of advanced glycation end products (AGEs). It plays a significant role in carbohydrate and lipid metabolism. It facilitates neurotransmitter synthesis and assists in synthesis of eicosanoids and prostaglandins. It supports nervous system function and alters transcription responses that control the actions of sex hormones. Pyridoxyl 5 phosphate is a natural angiogenesis inhibitor that downregulates RNA and DNA polymerase activity.
* Vitamin B12 (cobalamin, cyanocobalamin, methylcobalamin, adenosyl-cobalamin) supports structure and function of bone marrow and epithelial tissues. Principal role in synthesis of nucleic acids, proteins and major activity in blood cell formation. Important in methyl group transfer and required for support of myelination of nervous tissue. Methylcobalamin assists in the synthesis of choline containing phospholipids and it is an obligatory factor in folate metabolism. The formation of succinyl coenzyme A is dependent on adenosylcobalamin, a factor in lipid formation in the CNS. Clear metabolic roles in the biochemistry of fats, proteins, and carbohydrates.
* Beta-carotene (belongs to a family of compounds known as carotenoids) is a vitamin A precursor with antioxidant function and immune-stimulating activity. It quenches singlet oxygen and supports structure and functions of mucus membranes and the respiratory tract.
* Biotin (also called vitamin H, co-enzyme R) is involved in carbon dioxide transfer; that is, carboxylation reactions with effects on deamination. It maintains cutaneous health, bone marrow, and gonadal structure and function. It may reduce atherosclerotic lesions; and it modifies genomic expressions, for example, glucokinase. It is an important cofactor to several enzymes, including acetyl CoA carboxylase and other carboxylases. It increases intracellular GMP.
Folic Acid (folacin, pteroyl-mono-glutamic acid, vitamin B9) has a major role in DNA repair, nitric oxide production, purine and pyrimidine metabolism, and metabolic conversion of tyrosine and histidine. It may inhibit genomic expression of chromosomal mutations and has a specific role in synthesis of choline and neurotransmitters, for example, serotonin. It is best recognized as pivotal in maturation of blood cells. It has important effects in the differentiation of the CNS during embryonic development (role in prevention of neural tube defects).
* Vitamin C (ascorbic acid) is a classic antioxidant required to support connective tissue, bone, and teeth. It has a role in detoxification and possesses "antihistaminic" properties. It facilitates excretion of heavy metals, inhibits phosphodiesterase, and promotes wound healing. It protects against nitrosamine formation in the stomach and inhibits carcinogens, such as benzopyrene. It may reduce metastatic malignancy. It is involved in hydroxylation of cholesterol and improves specific aspects of immune function. Putative cancer protective effects remain underexplored.
* Vitamin D (1,25-dihydroxycholecalciferol [1,25-(OH)2D3]) [calcitrol or vitamin D hormone], vitamin D2 [ergocalciferol], vitamin D3 [cholecalciferol] [prohormone] is recognized as pivotal factor in calcium and phosphate regulation. It is distinguished by antiproliferative effects, recorded in several cancers, such as breast, colon, melanoma, and osteosarcoma. It is an apoptosis-inducer. It is involved in blood clotting, muscle function, differentiation of immune cells, and promotion of neurotrophic factor synthesis, and promotes mineralization of bone and teeth. It is neuroprotective in states of ischemia. Complex immune functions include inhibition of cell-mediated immunity, reduction of specific interleukin levels, and assistance in the conversion of monocytes to macrophages.
* Vitamin E (tocopherols--there are eight naturally occurring compounds that can be divided into two classes--tocopherols and tocotrienols) is a classic lipophylic cellular antioxidant with notable effects on fertility and gestation. It has defined actions on retention of cognitive function in the elderly and is obligatory for actions of superoxide dismutase (SOD). It has specific effects on immunity including enhanced T-helper cell function. It inhibits platelet aggregation and adhesion of monocytes. It has a principal role in maintaining integrity of lipid membranes by direct trapping of peroxyl radicals. It has an important role in modulation of phospholipase, lipooxygenase, and cyclo-oxygenase with major effects on the expression of inflammation. Tocopherols have other defined effects on gene expression, angiogenesis, growth factor signaling, mitochondrial function, inflammation, etc. Tocotreinols inhibit lipid peroxidation, decrease blood cholesterol, and are antiangiogenic, antioxidant, etc.
* Vitamin K ([phylloquinoneK 1], menadione [[kappa]3], menaquinone [[kappa]2], phylloquinone [2-Me-3 phytyl-1-4 napthoquinone] sourced from plants, menaquinone [2-M3-3-polyisoprenyl-1-4-naptoquinone] bacterial source) plays a major role in calcium metabolism, blood clotting, and sphingolipid metabolism, but is best known for its role in blood clotting. It inhibits apoptosis in neurons. It is important in the synthesis of surfactants in the lung. It promotes the synthesis of proteins C and S, which inhibit clot formation, and promotes production of prothrombin with Factors II, IX, VII and X, involved in clot lysis.
The trend of using large doses of vitamins continues. Megadosages are generally defined as more than ten times the RDA. While some indications for the use of large doses of vitamins appear to have been defined, opinions differ on the value of such treatments. In general, the author reiterates that it is prudent to have a health-care practitioner supervise the use of high dosages of vitamins. (1)
Examples of the therapeutic use of certain vitamins in high dosage includes treatment of acne and other skin disorders with vitamin A and its derivatives; but toxicity, including an increased risk of birth defects, can occur. High-dosage vitamin therapy can pose special problems in individuals with underlying disease. In this context, excessive vitamin A administration in individuals with renal failure may cause bone resorption with hypercalcemia. (17) In general, fat-soluble vitamins tend to have greater toxicity than water-soluble vitamins.
However, megadosages of water-soluble vitamins are not devoid of side effect profiles. For example, in the B vitamins, large doses of nicotinic acid used in the management of lowering blood cholesterol may cause flushing with skin irritation and significant metabolic consequences, including a decrease in glucose tolerance and hyperuricemia. Abnormal liver function with clinical consequences similar to hepatitis and aggravation of acid peptic disease may also occur. Toxicity appears to be more overt when controlled-release preparations with niacin are used. In another case, administration of folic acid to an individual who is deficient in vitamin B12 may precipitate serious CNS side effects. (27)
In brief, one may see a clear distinction between the physiological and the pharmaceutical effects of vitamin intake, where the dosage appears to be critical in the clinical outcome. It seems clear that the harmony of body chemistry works is complex and requires a well-balanced interaction of many vital nutrients. All nutritional agents require ancillary help by others. This means that vitamins and other vital nutrients act in concert or as dependent cofactors in biochemical reactions.
These circumstances are well recognized with the increasing definition of other substances that have been considered to be essential nutrients for humans. That said, the "vitamin status" of many of these other substances may not have been clearly defined or established. A large body of experimental research, most notably in animals, implies that substances such as coenzyme Q10, para-aminobezoic acid, inositol, bioflavanoids, choline, lipoic acid, and L-carnitine have "vitamin-like activity." (27)
Nature provides an abundance of phytochemicals that may act in concert with essential vitamins or other nutrients. (1) Therefore, modern concepts in integrative medicine have now started to favor the use of complex mixtures of vitamins, phytochemicals, and minerals found in powdered preparations of berries, fruits, vegetables, and green plant life. (3) This approach is considered to provide more optimal nutritional insurance than the regular notion of "popping the multivitamin pill" alone. (1), (3)
There are major constituents of the diet that are essential for human health because several nutrients are not able to be synthesized by the body. Perhaps a key example is found in fatty acids of the omega-3 and omega-6 series. Omega-3 fatty acids are found in their active form in fish and certain algae. Omega-6 fatty acids are overabundant in many Western diets, and supplementation is seldom required in general nutritional practice. There is believed to be a widespread deficiency of omega-3 fatty acids or a gross disturbance of the ratio of dietary intake of omega-6 to omega-3 fatty acids, such that many physicians in integrative medicine are routinely using omega-3 fatty acids in the same manner in which they utilize multivitamin supplements. (28)
The therapeutic benefits of omega-3 fatty acids are legion, and high dosages of active omega-3 fatty acids (eicosapentanioic acid [EPA] and docosahexanoic acid [DHA]) are often required to achieve an optimum therapeutic outcome in certain disease states--for example, chronic inflammatory disorders and depression. The notion that precursor omega-3 fatty acids are good sources of active EPA and DHA has been repeatedly challenged because the conversion of these precursors to active moieties is often impaired by disease or dietary selections, and this conversion is quite incomplete in many individuals under normal circumstances. (28)
The recognition of the need for high-dose fish oil administration to deliver high concentrations of EPA and DHA has implications for compliance with fish oil supplements. Evidence has emerged that enteric coated fish oil capsules may provide improved bioavailability of active omega-3 fatty acids (EPA/DHA) with improved patient tolerance. (1), (2), (28) These days, spontaneous decomposition of fish oil liquids and questionable absorption of EPA/DHA from standard gel capsules are seen as quite disadvantageous in a therapeutic setting.
Are Multivitamins a Health Risk?
Different opinions exist on the safety and effectiveness of dietary supplements. Airing these views can cause confusion, but it is necessary for consumers to reach an informed decision. In May 2006, the National Institutes of Health (NIH) held its "State-of-the-Science Conference on Multivitamin/Mineral Supplements and Chronic Disease Prevention." The members of this expert panel proposed that multivitamins may pose some "theoretical" health risks, especially in circumstances of self-medication.
Protests to the conclusions of the NIH panel emerged rapidly. For example, the National Nutritional Food Association (NNFA or NPA, a US body representing the dietary supplement industry) labeled the NIH panel as irresponsible and uninformed in its process of "theorizing" on the risks of multivitamins.
All medical interventions pose risks, and this is why the good practice of medicine always involves an assessment of risks versus benefits. In the case of multivitamins, it is clear that only a small proportion of the estimated 100 million users of vitamins have adverse reactions. Such reactions are infrequent and, in many cases, minor or rapidly reversible. Data produced by the American Association of Poison Control imply that only four percent of all adverse reactions to prescription or over-the-counter products can be linked to vitamin usage (NNFA, NPA 2006).
The NIH panel expressed concerns about lack of regulatory authority on supplement sales and the need for more research to assess supplement benefits, or lack thereof. One major problem is the unwillingness of some scientists to accept benefits of nutritional factors described in observational or population studies. If one waited for conclusive, clinical data on supplement usage, one might wait forever! Economic rewards in medical care rest most often with drugs. Dietary supplements do not fit the economic models of patented drugs, and there is little incentive and limited financial backing for dietary supplement research.
Some Important Therapeutic Concepts
There are several antagonists of the synthesis, metabolism, or actions of vitamins, where competitive biochemical activity occurs because of the resemblance of an "antivitamin" to the active vitamin molecule. Good examples of vitamin antagonists include isonicotinic acid hydrazide (antagonist of pyridoxine), aminopterin (folate antagonist), dicumarol (vitamin K antagonist), and avidin (interferes with biotin absorption). (27)
Arguments prevail about dietary factors that are considered arguably to be vitamins, but the presence of such nutrients provides strong support for the obligatory use of dietary supplements in certain circumstances. For example, choline is required in large amounts during growth and development, and it has demonstrable "vitamin-like" activity in experimental animals. (27), (29) While choline presents itself in the diet in phosphatide molecules, the ability of the body to synthesize choline from ethanolamine and methyl groups is sometimes subject to compromise, or it may be inadequate to meet needs.
Another example of obligatory requirements for supplements includes circumstances where vitamin loss may be excessive; for example, diabetes mellitus. (1) In this context, an important vitaminlike substance is myo-inositol. This nutrient is associated with high urinary loss in patients with diabetes, and there may be coincidental reduced levels of this form of inositol in membranes of the nervous system, perhaps providing one explanation for diabetic neuropathy. (27) These circumstances present one of many reasons why individuals with diabetes may benefit from routine vitamin supplementation, especially with water soluble-vitamins. (1)
Almost every medical practitioner believes in the benefits of vitamin supplementation of the standard American diet. Vitamins are essential substances in the diet that exert major controls over the chemistry of life. (30) Modern research demonstrates that certain vitamins have disease-prevention and even treatment capabilities when taken in the correct amounts or forms. The concept of recommended daily intakes has been challenged as it becomes clear that some nutrients assist in preventing several chronic diseases only in higher dosage ranges. Some vitamins may slow some of the physical deterioration that occurs with aging. (1), (30)
The author believes that several groups of people at risk must take daily vitamins. These include aerobic exercisers, smokers, prescription--drug users, people with diabetes mellitus, individuals with many chronic diseases, and especially the elderly. Pharmaceuticals remain an underestimated cause of nutritional depletion, which can be largely corrected by dietary supplementation with a well-formulated multivitamin product. (1)
Chev. Professor, Dr. Stephen Holt, MD, LLD (Hon.) ChB., PhD, DNM, FRCP (C), MRCP (UK), FACP, FACG, FACN, FACAM, Knight of Grace and Lieutenant Grand Hospitaller of the Holy Order of St. John, is a best-selling author, physician, and pioneer of integrative medicine. He is the founder of the Holt Institute of Medicine (www.hiom.org), which is affiliated with the World University of Natural Medicine (www.wunm.org). He holds the academic rank of Distinguished Professor of Medicine and is the chairman of the New York Department of Integrative Medicine. Therapeutic content may be found in "Conversations in Integrative Medicine," a series of ten-minute module webinars, by specific request (973-256-4660).
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by Stephen Holt, MD *
* Stephen Holt, MD, Distinguished Professor of Medicine; Chairman, New York Department of Integrative Medicine, NYCPM, NY; Founder, Holt Institute of Medicine (www.hiom.org); Lieutenant Grand Hospitaller, Holy Order of St. John.
Table 1: Actions of Vitamins "At a Glance." (All functions are not described.) Vitamin General actions Vitamin A, alpha, beta, maintains epithelial tissue, gamma-carotene critical in bone and tooth development, supports night vision, and is toxic in large dosages Vitamin D, calciferol a prohormone, essential to support teeth and bones; a major role in absorption and metabolism of calcium and phosphorous, and toxic in large dosages Vitamin E, tocopherols a principal antioxidant that supports structure of unsaturated fatty acids and vitamin A; anti-hemolytic actions with support of reproductive function, maintenance of epithelium and eicosanoid metabolism Vitamin K, phylloquinone and provides support for normal blood menaquinone clotting functions; toxic in large dosages Thiamine provides support for carbon dioxide removal from alpha-keto acids during carbohydrate oxidation, maintenance of digestive function, and nervous system function Riboflavin acts as enzyme in tissue respiration, transports hydrogen ions, coenzyme forms flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) Niacin, nicotinic acid and supports amino acid and carbohydrate nicotinamide metabolism, promotes tissue respiration and fat synthesis, part of enzyme system Vitamin B6, pyridoxine, pyridoxal supports amino acid breakdown, and pyridoxamine converts tryptophan to niacin, produces unsaturated fatty acids from essential fatty acids Folate supports red blood cell growth, promotes production of nucleic acid, acts as coenzyme tetrahydrofolic acid Vitamin B12 promotes production of nucleoproteins and nucleic acids, supports folate, nervous tissue, and single-carbon fragment metabolism Pantothenic acid part of coenzyme A, promotes metabolic function Biotin supports enzyme function, particularly breakdown of fatty acids and amino acids Vitamin C, ascorbic acid classic antioxidant with special role in maintenance of intracellular cement substances, preservation of capillary structure, wound healing, allergic reactions, and facilitation of iron absorption; important role in hydroxylation and support of immune function
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