products.’’ The American Cancer Society does not
endorse taking megadoses of folic acid to prevent
cancer.
Clinical trials are underway to determine safety
and effectiveness of folate/folic acid both alone and in
combination with other vitamins in preventing cancer,
cardiovascular disease, and dementias such as
Alzheimer’s disease. Cognitive decline and some
forms of dementia, including Alzheimer’s disease,
are associated with lower folate levels, which is
common amongst older people in some countries.
Individuals interested in participating in a clinical
trial at no charge can find a list of open trials at
http://www.clinicaltrials.gov.
Normal folate requirements
The United States Institute of Medicine (IOM) of
the National Academy of Sciences has developed val-
ues calledDietary Reference Intakes(DRIs) for vita-
mins andminerals. The DRIs consist of three sets of
numbers. 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.
The IOM has not set RDAs for folate in children
under one year old because of incomplete scientific
information. Instead, it has set AI levels for this age
group. RDAs and ULs for folate are measured in
micrograms (mcg). Unlike the UL for many vitamins,
the UL for folate/folic acid refers only to folic acid that
comes from fortified food or that is in folic acid dietary
supplements, multivitamins, or B-complex vitamins.
There is no UL for folate found in natural plant and
animal foods. Dietary supplements containing more
than 1,000 mcg (1 mg) of folic acid require a prescrip-
tion. 1 mcg of folate from natural food sources is equal
in biological activity in humans to 0.6 mcg of folic acid
from supplements or fortified food.
The following are the daily RDAs and IAs and
ULs for folic aside for healthy individuals:
children birth–6 months: AI 65 mcg; UL not
established
children 7–12 months: AI 89 mcg; UL not established
children 1–3 years: RDA 150 mcg; UL 300 mcg
children 4–8 years: RDA 200 mcg; UL 400 mcg
children 9–13 years: RDA 300 mcg; UL 600 mcg
children 14–18 years: 400 RDA mcg; UL 800 mcg
adults age 19 and older: RDA 400 mcg; UL 1,000 mcg
pregnant women: RDA 600 mcg; UL 1,000 mcg
breastfeeding women: RDA 500 mcg; 1,000 mcgSources of folate
People need a continuous supply of folate from
their diet because of the role it plays in creating new
blood cells. Because folate is water-soluble, little is
stored in the body; any excess is excreted in urine.
Since the folic acid fortification program began in
1998, most healthy Americans get enough folate
from their diet. The exception is pregnant women
who should, under medical supervision, take a folicKEY TERMS
Alzheimer’s disease—an incurable disease of older
individuals that results in the destruction of nerve
cells in the brain and causes gradual loss of mental
and physical functions
Amino acid—molecules that are the basic building
blocks of proteins
B-complex vitamins—a group of water-soluble
vitamins that often work together in the body.
These include thiamine (B 1 ), riboflavin (B 2 ), niacin
(B 3 ), pantothenic acid (B 5 ), pyridoxine (B 6 ), biotin
(B 7 or vitamin H), folate/folic acid (B 9 ), and coba-
lamin (B 12 ).
Dietary supplement—a product, such as a vitamin,
mineral, herb, amino acid, or enzyme, that is
intended to be consumed in addition to an individ-
ual’s diet with the expectation that it will improve
health
Diuretic—a substance that removes water from the
body by increasing urine production
Enzyme—a protein that change the rate of a chem-
ical reaction within the body without themselves
being used up in the reaction
Ribonucleic acid (RNA)—A molecule that helps
decode genetic information (DNA) and is neces-
sary for protein synthesis
Vitamin—a nutrient that the body needs in small
amounts to remain healthy but that the body cannot
manufacture for itself and must acquire through
diet
Water-soluble vitamin—a vitamin that dissolves in
water and can be removed from the body in urineFolate