Vitamin A and Hip Fractures in Postmenopausal Women
by Wyn Snow, Managing Editor
fractures in elderly women often lead to significant declines in
health and mobility. Recent research finds that high intakes of
vitamin A in postmenopausal women are associated with the highest
risk of hip fractures. Does this mean that such women should stop
taking vitamin A?
research analyzed data from 72,000 nurses
analysis of data from the Nurses' Health Study was published in
the January 2 issue of the Journal of the American Medical Association
(JAMA 287,1:47-54,2002). The study collected a wide range of dietary
and health information from nurses in 11 states over two decades.
The analysis looked at 72,337 postmenopausal women aged 34 to 77.
risk of fractures was found with both dietary and supplemental intake
of retinol (the technical name for vitamin A). Women with the highest
levels of intake experienced approximately 50% more hip fractures
than those with the least intake. However, no correlation between
intake and fractures was found with beta-carotene, which the
body converts into vitamin A. Also, for women taking estrogen replacement
therapy, the increase in risk was not as great.
of other research in humans and animals
contrast to this NHS research, the National Health and Nutrition
Examination Survey III (which surveyed hundreds of thousands of
people) found no association between vitamin A intake and bone density.
A study of postmenopausal women in Iowa also found no correlation
between vitamin A supplementation and either bone loss or fractures.
However, animal studies have found a relationship between very high
levels of vitamin A intake and loss of bone mineral density.
from dietary supplement trade organizations
Consumer Healthcare Products Association (CHPA)
and the Council for Responsible Nutrition (CRN)
both responded that scientific conclusions are based on the totality
of the evidence. The Institute of Medicine's current tolerable
upper intake level (more familiarly known as a safe upper limit)
is set at 3,000 mcg (equivalent to 10,000 IU). The highest level
of intake in the NHS study was roughly 4,000 mcg from food and supplements
combined. If the Institute of Medicine decides the upper intake
level should be lowered, CHPA and CRN said that supplement manufacturers
would follow the new guideline for maximum dosage levels.
A is an important nutrient
its place in the vitamin alphabet suggests, vitamin A was the first
to be named and one of the first to be discovered. Research has
established that vitamin A is essential for growth, immune function,
reproduction and vision, and may also reduce the risk of some cancers.
A occurs in two forms:
the "already formed" variety, is a fat soluble vitamin. Good
sources include liver, fish liver oil, egg yolks and milk products.
is the main form of provitamin A (the body converts beta-carotene
into vitamin A). Beta-carotene is found in a wide variety of
yellow- and orange-colored fruits and vegetables, as well as
leafy green vegetables.
much vitamin A do people need?
is no simple answer to this question. The Institute of Medicine
set the recommended dietary allowance (RDA) at 900 mcg for men and
700 for women (equivalent to 3,000 IU for men and 2,333 for women).
RDAs are a minimalist approach to nutritional needs. They are designed
to prevent deficiency diseases in 95% of the healthy population.
some doctors believe the official RDA may not be enough to maintain
optimal health. Dr. Elson Haas (medical director of the Preventative
Medical Center of Marin in San Rafael CA, author of many books and
a leading practitioner of integrative medicine) says, "Vitamin A
is needed at a level of at least 5,000 IUs per day, though this
may vary due to many factors. . . . Analysis of the
average American diet reveals that it provides only about 4,000
units of vitamin A daily, so the many problems of vitamin A deficiency,
such as visual changes, skin dryness, and increased infections,
are more common than most people realize."
pointed out in SupplementQuality.com's article on RDAs
and Safe Upper Limits: Solid Science Versus Bureaucratic Bias,
the data used to establish RDAs are not always solid or extensive.
Also, the recommended dietary allowance (RDA) is designed to meet
the needs of 95% of healthy people -- and does not apply to anyone
who is ill. In that article, Dr. Jonathan Wright (Medical Director
of the Tahoma Clinic in Kent WA, author of many books and a leading
practitioner of nutritional medicine) describes the case of a woman
who needed ten times the tolerable upper intake level of vitamin
A -- and suffered ulcerating corneas when she didn't get it.
hip fractures and ensuring an optimal intake of vitamin A are both
vitally important to maintaining wellness. Also, vitamin A (as retinol)
is a fat soluble vitamin and can be toxic at high levels in other
ways as well. The human body stores any "extra" that it receives,
so a diet with too much retinol -- whether from foods or supplements
or both -- can create a toxic buildup over time.
does this mean for consumers who are watching their vitamin intake?
Since beta-carotene does not pose any heightened risk of bone density
problems or hip fractures (or other negative side effects), people
who supplement their diets with vitamin A would be wise to choose
in vitamin A as in shoes, one size does not fit all. To be sure
of getting both enough and not too much, the most prudent course
is to consult a doctor who is knowledgeable about nutrition and
can assess individual needs.
Feskanich, ScD, et al. "Vitamin A Intake and Hip Fractures Among
Postmenopausal Women." Journal of the American Medical Association,
Vol 287, No 1, pages 47-54, 2002. ama.ama-assn.org/cgi/content/abstract/287/1/47
(abstract available to public; full text subscribers only).
M. Haas, MD. "Vitamin A -- Betacarotene." Excerpted from Staying
Healthy with Nutrition: The Complete Guide to Diet and Nutritional
Products Industry Insider. "Dietary Vitamin A May Increase Postmenopausal
Fracture Risk." News story posted 2 January 2002. www.naturalproductsinsider.com/hotnews/21h21339.html.
Health. "Too Much Vitamin A Can Up Risk of Hip Fracture." Yahoo
health news, 2 January 2002.
Webber. "Study: Vitamin Linked to Fractures." Associated Press health
news on Yahoo.com, 2 January 2002.