breakfast cereal substantially reduced vitamin defi-
ciency diseases. Commercially manufactured vitamin
supplements also began to appear, and taking a daily
multivitamin supplement became popular. By 2007,
more than 100 million Americans regularly took some
form of vitamin supplement.
Vitamin supplements come as tablets, capsules,
and elixirs (liquids). Supplements can contain a single
vitamin, a group of related vitamins that work together
in the body (e.g. B-complex vitamins), or a mixture of
vitamins andminerals(e.g.vitamin Dandcalciumthat
work together to build bones). Vitamins are also added
to foods that can then be labeled ‘‘fortified’’ or
‘‘enriched.’’ Many so-called functional foods, or nutra-
ceuticals, have added vitamins, minerals, and herbs.
In the United States, the Food and Drug Admin-
istration (FDA) regulates dietary supplements under the
1994 Dietary Supplement Health and Education Act
(DSHEA). Under DSHEA, supplements are subject to
the same regulation as food, which is much less rigorous
than the regulation of prescription or over-the-counter
drugs. Vitamin manufacturers do not have to prove that
their products are safe or effective before they can be
sold to the public. By contrast, manufacturers of con-
ventional prescription and over-the-counter drugs must
prove both safety and effectiveness in extensive humans
before their product can be marketed.
In 2007, ConsumerLab, an independent testing
company in New York, evaluated 21 brands of multi-
vitamins. They found that only 10 of these multivita-
mins contained all the vitamins and minerals in the
quantities listed on the label. In addition, some brands
contained contaminants, including lead. To get the
most out of vitamin supplements, consumers should
read the label carefully to understand exactly what is
in the supplement
avoid megadoses of vitamins. The daily value (DV)
given on the label should be around 100% for each
vitamin.
Look for ‘‘USP’ on the label. This means that the
supplement meets the strength and purity standards
of the U.S. Pharmacopeia, a testing organization.
check the expiration date
stick with well-known brandsVitamin requirements
The United States Institute of Medicine (IOM) of
the National Academy of Sciences has developed val-
ues calledDietary Reference Intakes(DRIs) for most
vitamins and minerals. The DRIs consist of three sets
of values. The Recommended Dietary Allowance(RDA) defines the average daily amount of the
nutrient needed to meet the health needs of 97–98%
of the population. The Adequate Intake (AI) is an
estimate set when there is not enough information to
determine an RDA. The Tolerable Upper Intake Level
(UL) is the average maximum amount that can be
taken daily without risking negative side effects. The
DRIs are calculated for children, adult men, adult
women, pregnant women, andbreastfeedingwomen.
Experts agree that vitamin supplements are not a
substitute for nutrients from food. Most healthy peo-
ple in developed countries who eat a varied diet high in
fruits, vegetables, and whole grains get enough vita-
mins and do not need a vitamin supplement, although
many take a daily multivitamin as ‘‘insurance.’’ How-
ever, some groups do tend to need either general sup-
plementation with a multivitamin or supplementation
with specific vitamins to prevent vitamin deficiency
diseases. People in these groups should discuss their
vitamin requirements with their healthcare provider.
They include:
the elderly, especially those on restricted diets
vegans, because they eat no animal products
breastfed babies of vegan mothers
people with lactose intolerance or those who do not
eat dairy products
people with alcoholism
people who have had part of their stomachs or intes-
tines surgically removed
pregnant women or those who could become
pregnant
people with diseases that interfere with vitamin
metabolism
people taking drugs that interfere with vitamin
metabolismVitamin excess
Although vitamins play an undeniable role in
maintaining health, large doses of vitamins in healthy
individuals can cause adverse effects. Almost all vita-
min excess (hypervitaminosis) occurs because of sup-
plementation; it is almost impossible to get too many
vitamins from food. Although great deal of advertising,
especially on the Internet, suggests that megadoses of
certain vitamins can improve athletic performance, pre-
vent and treat chronic disease, delay aging, and increase
longevity, there is little or no evidence from independ-
ent, well-controlled human clinical trials to support
these claims. One exception is high doseniacin,which
has been used to treat high blood cholesterol levels.
Althugh niacin is very safe at normal doses, the theVitamins