What Are Dietary Supplements?
For decades, the Food and Drug Administration regulated dietary
supplements as foods, in most circumstances, to ensure that they were
safe and wholesome, and that their labeling was truthful and not
misleading. An important facet of ensuring safety was FDA's evaluation
of the safety of all new ingredients, including those used in dietary
supplements, under the 1958 Food Additive Amendments to the Federal
Food, Drug, and Cosmetic Act (FD&C Act). However, with passage of
the Dietary Supplements Health and Education Act of 1994 (DSHEA),
Congress amended the FD&C Act to include several provisions that
apply only to dietary supplements and dietary ingredients of dietary
supplements. As a result of these provisions, dietary ingredients used
in dietary supplements are no longer subject to the premarket safety
evaluations required of other new food ingredients or for new uses of
old food ingredients. They must, however, meet the requirements of
other safety provisions.
Signed by President Clinton on October 25, 1994, the DSHEA
acknowledges that millions of consumers believe dietary supplements may
help to augment daily diets and provide health benefits. In the
findings associated with the DSHEA, Congress stated that there may be a
positive relationship between sound dietary practice and good health,
and that, although further scientific research is needed, there may be
a connection between dietary supplement use, reduced health-care
expenses, and disease prevention.
Traditionally, dietary supplements referred to products made of one
or more of the essential nutrients, such as vitamins, minerals, and
protein. But DSHEA broadens the definition to include, with some
exceptions, any product intended for ingestion as a supplement to the
diet. This includes vitamins; minerals; herbs, botanicals, and other
plant-derived substances; and amino acids (the individual building
blocks of protein) and concentrates, metabolites, constituents and
extracts of these substances.
Dietary supplements come in many forms, including tablets, capsules,
powders, softgels, gelcaps, and liquids. Though commonly associated
with health food stores, dietary supplements also are sold in grocery,
drug and national discount chain stores, as well as through mail-order
catalogs, TV programs, the Internet, and direct sales.
One thing dietary supplements are not is drugs. A drug, which
sometimes can be derived from plants used as traditional medicines, is
an article that, among other things, is intended to diagnose, cure,
mitigate, treat, or prevent diseases. Before marketing, drugs must
undergo clinical studies to determine their effectiveness, safety,
possible interactions with other substances, and appropriate dosages,
and FDA must review these data and authorize the drugs' use before they
are marketed. FDA does not authorize or test dietary supplements.
A product sold as a dietary supplement and touted in its labeling as
a new treatment or cure for a specific disease or condition would be
considered an unauthorized--and thus illegal--drug. Labeling changes
consistent with the provisions in DSHEA would be required to maintain
the product's status as a dietary supplement.
Claims that tout a supplement's healthful benefits have always been
a controversial feature of dietary supplements. Manufacturers often
rely on them to sell their products. But consumers often wonder whether
they can trust them.
Disease claims show a link between a food or substance and a disease
or health-related condition. FDA authorizes these claims based on a
review of the scientific evidence. Or, after the agency is notified,
the claims may be based on an authoritative statement from certain
scientific bodies, such as the National Academy of Sciences, that shows
or describes a well-established diet-to-health link. As of this
writing, certain dietary supplements may be eligible to carry disease
claims, such as claims that show a link between:
Nutrition support claims can describe a link between a nutrient and
the deficiency disease that can result if the nutrient is lacking in
the diet. For example, the label of a vitamin C supplement could state
that vitamin C prevents scurvy. When these types of claims are used,
the label must mention the prevalence of the nutrient-deficiency
disease in the United States.
These claims also can refer to the supplement's effect on the body's
structure or function, including its overall effect on a person's
well-being. These are known as structure-function claims.
Examples of structure-function claims are:
If shoppers find dietary supplements whose labels state or imply
that the product can help diagnose, treat, cure, or prevent a disease
(for example, "cures cancer" or "treats arthritis"), they should
realize that the product is being marketed illegally as a drug and as
such has not been evaluated for safety or effectiveness.
Consumers need to be on the lookout for fraudulent products. These
are products that don't do what they say they can or don't contain what
they say they contain. At the very least, they waste consumers' money,
and they may cause physical harm.
Nutrition experts agree that the Food Guide Pyramid offers a
reliable and easy-to-follow plan for healthful eating. Eating the
"pyramid way" means choosing the appropriate number of servings and a
variety of foods from each of the five Food Guide Pyramid food groups.
This is generally the best way to get all the vitamins, minerals, and
other nutrients you need.
However, even people with the best intentions sometimes fall short
on their nutrient intake. For some people a vitamin/mineral supplement
offers benefits that are both safe and effective. A vitamin/mineral
supplement may help when
To help prevent birth defects of the brain and spine, known as
neural tube birth defects, health authorities recommend that women who
are planning to become pregnant consume 400 micrograms of folic acid
daily at least one month prior to conception.
Determination of the presence or absence of a deficiency of one or
more of the micronutrient minerals (usually described as trace
elements) can be a complex problem, frequently requiring the
integration of clinical, nutritional and biochemical data. Almost
invariably, laboratory investigations are required and this short
review describes the more common techniques applied for the various
essential trace elements. Using a combination of techniques it is
usually possible to determine, with confidence, whether an individual
subject or small groups of subjects have a deficiency of a specific
trace elements, but simple reliable tests which can be used in
population studies are still lacking for several key elements. This
problem appears most acute for studies of chromium, copper and zinc,
deficiencies of which may have important roles in the pathogenesis of a
variety of human disorders.
Vitamin supplements are increasingly being used to prevent diseases
such as neural tube birth defects, heart attacks, and certain cancers.
The amount of vitamin supplements used for disease prevention is often
much higher than the RDA levels. A classic example is the use of
vitamin nicotinic acid (also called Niacin) in high doses to increase
the good HDL cholesterol and lower triglycerides in the blood. In order
to consume these higher levels of vitamins, diet alone may not be
enough, and vitamin supplements are necessary.
A nutrition intervention trial involving > 3000 participants was
conducted in Linxian, China, where the esophageal and stomach cancer
mortality rates are among the highest in the world and suspicion exists
that chronic deficiencies of multiple nutrients are etiologically
involved. The trial was randomized, double-blind, and
placebo-controlled and tested the effect of multivitamin and
multimineral supplements in reducing cancer incidence and mortality in
adults with cytologically detected esophageal dysplasia. Endoscopic and
cytologic examinations of samples of trial participants during the
intervention allowed evaluation of intermediate endpoints in esophageal
and gastric carcinogenesis, including asymptomatic histologic
precancerous lesions and early invasive cancer, epithelial
proliferation, and cytologic abnormalities. Results from these
ancillary studies suggest that multivitamin and multimineral
supplementation may decrease proliferation and enhance cytologic
reversion to non-dysplasia.
The coexistence of multiple micronutrient deficiencies is a
widespread public health problem in many regions of the world.
Interactions between zinc deficiency and vitamin A metabolism have been
reported but no longitudinal studies have evaluated the effect of iron
deficiency on vitamin A.
The objective of this study was to investigate the effect of
supplementation with iron, zinc, or both on vitamin A and its
metabolically related proteins retinol binding protein (RBP) and
transthyretin.
The study was a longitudinal, double-blind, placebo-controlled trial
in which 219 rural Mexican children aged 18?36 mo were randomly
assigned to receive 20 mg Zn/d, 20 mg Fe/d, 20 mg Zn/d plus 20 mg Fe/d,
or placebo.
Six months after supplementation, plasma retinol increased in all
supplemented groups. Compared with placebo, zinc supplementation was
associated with significantly higher plasma retinol and transthyretin
but the increase in RBP was not significant. Iron supplementation
significantly increased plasma retinol, RBP, and transthyretin.
Supplementation with zinc plus iron significantly increased plasma
retinol but not RBP or transthyretin. Children deficient in zinc, iron,
or vitamin A (as indicated by nutrient plasma concentration) at the
beginning of the study had a significantly greater increase in retinol
than did children with adequate nutrient status.
Conclusions: Supplementation with zinc, iron, or both
improved indicators of vitamin A status. The results of this study
agree with previous observations of a metabolic interaction between
zinc and vitamin A and suggest an interaction between iron and vitamin
A metabolism.
Before taking a supplement, be aware that health risks exist for
some people. For instance, it is not recommended that pregnant women
take more than 5000 IU daily of vitamin A from retinol (a form of
vitamin A). Too much vitamin A can increase the risk of birth defects.
In addition, too much iron can increase risk of chronic disease, so it
is recommended that men and post-menopausal women not routinely take
iron supplements at levels higher than 100 percent of the Daily Value.
Check the label to be sure. Consult a registered dietitian or doctor
before taking a single supplement.
For those who choose to take a supplement, it is best to select a
product that provides no more than 100 percent of the Daily Value for
vitamins and minerals. Check the Nutrition Facts panel on the label.
For decades, the Food and Drug Administration regulated dietary
supplements as foods, in most circumstances, to ensure that they were
safe and wholesome, and that their labeling was truthful and not
misleading. An important facet of ensuring safety was FDA's evaluation
of the safety of all new ingredients, including those used in dietary
supplements, under the 1958 Food Additive Amendments to the Federal
Food, Drug, and Cosmetic Act (FD&C Act). However, with passage of
the Dietary Supplements Health and Education Act of 1994 (DSHEA),
Congress amended the FD&C Act to include several provisions that
apply only to dietary supplements and dietary ingredients of dietary
supplements. As a result of these provisions, dietary ingredients used
in dietary supplements are no longer subject to the premarket safety
evaluations required of other new food ingredients or for new uses of
old food ingredients. They must, however, meet the requirements of
other safety provisions.
Signed by President Clinton on October 25, 1994, the DSHEA
acknowledges that millions of consumers believe dietary supplements may
help to augment daily diets and provide health benefits. In the
findings associated with the DSHEA, Congress stated that there may be a
positive relationship between sound dietary practice and good health,
and that, although further scientific research is needed, there may be
a connection between dietary supplement use, reduced health-care
expenses, and disease prevention.
Traditionally, dietary supplements referred to products made of one
or more of the essential nutrients, such as vitamins, minerals, and
protein. But DSHEA broadens the definition to include, with some
exceptions, any product intended for ingestion as a supplement to the
diet. This includes vitamins; minerals; herbs, botanicals, and other
plant-derived substances; and amino acids (the individual building
blocks of protein) and concentrates, metabolites, constituents and
extracts of these substances.
Dietary supplements come in many forms, including tablets, capsules,
powders, softgels, gelcaps, and liquids. Though commonly associated
with health food stores, dietary supplements also are sold in grocery,
drug and national discount chain stores, as well as through mail-order
catalogs, TV programs, the Internet, and direct sales.
One thing dietary supplements are not is drugs. A drug, which
sometimes can be derived from plants used as traditional medicines, is
an article that, among other things, is intended to diagnose, cure,
mitigate, treat, or prevent diseases. Before marketing, drugs must
undergo clinical studies to determine their effectiveness, safety,
possible interactions with other substances, and appropriate dosages,
and FDA must review these data and authorize the drugs' use before they
are marketed. FDA does not authorize or test dietary supplements.
A product sold as a dietary supplement and touted in its labeling as
a new treatment or cure for a specific disease or condition would be
considered an unauthorized--and thus illegal--drug. Labeling changes
consistent with the provisions in DSHEA would be required to maintain
the product's status as a dietary supplement.
Claims that tout a supplement's healthful benefits have always been
a controversial feature of dietary supplements. Manufacturers often
rely on them to sell their products. But consumers often wonder whether
they can trust them.
Disease claims show a link between a food or substance and a disease
or health-related condition. FDA authorizes these claims based on a
review of the scientific evidence. Or, after the agency is notified,
the claims may be based on an authoritative statement from certain
scientific bodies, such as the National Academy of Sciences, that shows
or describes a well-established diet-to-health link. As of this
writing, certain dietary supplements may be eligible to carry disease
claims, such as claims that show a link between:
- the vitamin folic acid and a decreased risk of neural tube
defect-affected pregnancy, if the supplement contains sufficient
amounts of folic acid - calcium and a lower risk of osteoporosis, if the supplement contains sufficient amounts of calcium
- psyllium
seed husk (as part of a diet low in cholesterol and saturated fat) and
coronary heart disease, if the supplement contains sufficient amounts
of psyllium seed husk.
Nutrition support claims can describe a link between a nutrient and
the deficiency disease that can result if the nutrient is lacking in
the diet. For example, the label of a vitamin C supplement could state
that vitamin C prevents scurvy. When these types of claims are used,
the label must mention the prevalence of the nutrient-deficiency
disease in the United States.
These claims also can refer to the supplement's effect on the body's
structure or function, including its overall effect on a person's
well-being. These are known as structure-function claims.
Examples of structure-function claims are:
- Calcium builds strong bones.
- Antioxidants maintain cell integrity.
- Fiber maintains bowel regularity.
If shoppers find dietary supplements whose labels state or imply
that the product can help diagnose, treat, cure, or prevent a disease
(for example, "cures cancer" or "treats arthritis"), they should
realize that the product is being marketed illegally as a drug and as
such has not been evaluated for safety or effectiveness.
Consumers need to be on the lookout for fraudulent products. These
are products that don't do what they say they can or don't contain what
they say they contain. At the very least, they waste consumers' money,
and they may cause physical harm.
Nutrition experts agree that the Food Guide Pyramid offers a
reliable and easy-to-follow plan for healthful eating. Eating the
"pyramid way" means choosing the appropriate number of servings and a
variety of foods from each of the five Food Guide Pyramid food groups.
This is generally the best way to get all the vitamins, minerals, and
other nutrients you need.
However, even people with the best intentions sometimes fall short
on their nutrient intake. For some people a vitamin/mineral supplement
offers benefits that are both safe and effective. A vitamin/mineral
supplement may help when
- your hectic lifestyle frequently keeps you from eating the recommended number of servings from the food guide pyramid,
- you are on a very low-calorie weight loss diet,
- you are elderly and not eating as much as you should,
- you are a strict vegetarian,
- you can't drink milk or eat cheese and yogurt,
- or you are a woman of child-bearing age who doesn't get enough folate from fruits, vegetables, beans, and grains.
To help prevent birth defects of the brain and spine, known as
neural tube birth defects, health authorities recommend that women who
are planning to become pregnant consume 400 micrograms of folic acid
daily at least one month prior to conception.
Determination of the presence or absence of a deficiency of one or
more of the micronutrient minerals (usually described as trace
elements) can be a complex problem, frequently requiring the
integration of clinical, nutritional and biochemical data. Almost
invariably, laboratory investigations are required and this short
review describes the more common techniques applied for the various
essential trace elements. Using a combination of techniques it is
usually possible to determine, with confidence, whether an individual
subject or small groups of subjects have a deficiency of a specific
trace elements, but simple reliable tests which can be used in
population studies are still lacking for several key elements. This
problem appears most acute for studies of chromium, copper and zinc,
deficiencies of which may have important roles in the pathogenesis of a
variety of human disorders.
Vitamin supplements are increasingly being used to prevent diseases
such as neural tube birth defects, heart attacks, and certain cancers.
The amount of vitamin supplements used for disease prevention is often
much higher than the RDA levels. A classic example is the use of
vitamin nicotinic acid (also called Niacin) in high doses to increase
the good HDL cholesterol and lower triglycerides in the blood. In order
to consume these higher levels of vitamins, diet alone may not be
enough, and vitamin supplements are necessary.
A nutrition intervention trial involving > 3000 participants was
conducted in Linxian, China, where the esophageal and stomach cancer
mortality rates are among the highest in the world and suspicion exists
that chronic deficiencies of multiple nutrients are etiologically
involved. The trial was randomized, double-blind, and
placebo-controlled and tested the effect of multivitamin and
multimineral supplements in reducing cancer incidence and mortality in
adults with cytologically detected esophageal dysplasia. Endoscopic and
cytologic examinations of samples of trial participants during the
intervention allowed evaluation of intermediate endpoints in esophageal
and gastric carcinogenesis, including asymptomatic histologic
precancerous lesions and early invasive cancer, epithelial
proliferation, and cytologic abnormalities. Results from these
ancillary studies suggest that multivitamin and multimineral
supplementation may decrease proliferation and enhance cytologic
reversion to non-dysplasia.
The coexistence of multiple micronutrient deficiencies is a
widespread public health problem in many regions of the world.
Interactions between zinc deficiency and vitamin A metabolism have been
reported but no longitudinal studies have evaluated the effect of iron
deficiency on vitamin A.
The objective of this study was to investigate the effect of
supplementation with iron, zinc, or both on vitamin A and its
metabolically related proteins retinol binding protein (RBP) and
transthyretin.
The study was a longitudinal, double-blind, placebo-controlled trial
in which 219 rural Mexican children aged 18?36 mo were randomly
assigned to receive 20 mg Zn/d, 20 mg Fe/d, 20 mg Zn/d plus 20 mg Fe/d,
or placebo.
Six months after supplementation, plasma retinol increased in all
supplemented groups. Compared with placebo, zinc supplementation was
associated with significantly higher plasma retinol and transthyretin
but the increase in RBP was not significant. Iron supplementation
significantly increased plasma retinol, RBP, and transthyretin.
Supplementation with zinc plus iron significantly increased plasma
retinol but not RBP or transthyretin. Children deficient in zinc, iron,
or vitamin A (as indicated by nutrient plasma concentration) at the
beginning of the study had a significantly greater increase in retinol
than did children with adequate nutrient status.
Conclusions: Supplementation with zinc, iron, or both
improved indicators of vitamin A status. The results of this study
agree with previous observations of a metabolic interaction between
zinc and vitamin A and suggest an interaction between iron and vitamin
A metabolism.
Before taking a supplement, be aware that health risks exist for
some people. For instance, it is not recommended that pregnant women
take more than 5000 IU daily of vitamin A from retinol (a form of
vitamin A). Too much vitamin A can increase the risk of birth defects.
In addition, too much iron can increase risk of chronic disease, so it
is recommended that men and post-menopausal women not routinely take
iron supplements at levels higher than 100 percent of the Daily Value.
Check the label to be sure. Consult a registered dietitian or doctor
before taking a single supplement.
For those who choose to take a supplement, it is best to select a
product that provides no more than 100 percent of the Daily Value for
vitamins and minerals. Check the Nutrition Facts panel on the label.
- Dietary Supplement Health And Education Act Of 1994. U. S.
Food and Drug Administration Center for Food Safety and Applied
Nutrition - Paula Kurtzweil. An FDA Guide to Dietary Supplements. Publication No. (FDA) 99-2323
- Do You Need a Multivitamin/Mineral Supplement? The American Dietetic Association/National Center for Nutrition and Dietetics
- Jackson MJ. Diagnosis and detection of deficiencies of micronutrients: minerals. Br Med Bull 1999;55(3):634-42
- PR
Taylor, GQ Wang, Et al. Effect of nutrition intervention on
intermediate endpoints in esophageal and gastric carcinogenesis. Am. J.
Clinical Nutrition 1995 62 - Elsa C Muñoz, Jorge L Rosado, Et
al. Iron and zinc supplementation improves indicators of vitamin A
status of Mexican preschoolers. Am J Clin Nutr 2000 71: 789-794
No comments:
Post a Comment