Vitamin D Supplements Found Inconsistent
From ScienceDaily (2/13) Vitamin D Potency Varies Widely in Dietary Supplements, Analysis Finds
Vitamin D supplement potency varies widely, and the amount of vitamin D in
over-the-counter and compounded supplements does not necessarily match the
amount listed on the label, according to a research letter published in the
journal JAMA Internal Medicine.
The analysis showed that the amount of vitamin D in these supplements ranged
from 9 percent to 146 percent of the amount listed on the label. Not only was
there variation among different brands and manufacturers, but also among
different pills from the same bottle. "We were surprised by the variation in
potency among these vitamin D pills," says Erin S. LeBlanc, MD, MPH, lead
author and investigator with the Kaiser Permanente Center for Health Research
in Portland, Ore. "The biggest worry is for someone who has low levels of
vitamin D in their blood. If they are consistently taking a supplement with
little vitamin D in it, they could face health risks."
According to a recent editorial in the New England Journal of Medicine, more
than 100 million Americans spend a combined $28 billion on vitamins, herbs and
supplements each year. The U.S. Food and Drug Administration is considering new
safety guidelines for some supplements but, for the most part, the industry
Some manufacturers participate in a voluntary quality verification program
operated by the U.S. Pharmacopeial Convention -- an independent, nonprofit
organization that sets public standards for the quality of dietary supplements.
In order to receive the USP verification mark, manufacturers' facilities
undergo annual good manufacturing-practice audits, and their products are
tested for quality, potency and purity. Dr. LeBlanc and her colleagues included
one supplement from a USP Verified manufacturer in their sample. They found the
amount of vitamin D in pills from that bottle was generally more accurate than
the other bottles tested. "The USP verification mark may give consumers some
reassurance that the amount of vitamin D in those pills is close to the amount
listed on the label," said Dr. LeBlanc. "There are not many manufacturers that
have the USP mark, but it may be worth the extra effort to look for it."
The researchers tested 55 bottles of over-the-counter vitamin D from 12
different manufacturers. The over-the-counter vitamin D pills used in the
analysis were purchased at five different stores in Portland, Ore. The
compounded vitamin D was made by a compounding pharmacy in Portland. The
analysis was conducted by an independent lab in Houston.
Authors of the letter include Erin S. LeBlanc, MD, MPH, Nancy Perrin, PhD, and
Teresa Hillier, MD, from the Kaiser Permanente Center for Health Research in
Portland, Ore.; and Jeffery D. Johnson, Jr., PhD, and Annie Ballatore, from
Eagle Analytical Services in Houston.
Practical Vitamin D Recommendations from Ray Sahelian, M.D.:
Practical vitamin D recommendations based on what I know thus far (your personal
doctor is likely to have a different viewpoint): Some people may not need to
supplement since their diet includes plenty of the vitamin and they get a lot
of sun exposure. Most people may benefit from taking 400 units to 1000 iu a day
either as a separate pill or as part of their multivitamin product (in addition
to their diet and some sun exposure which could be several hundred units a
A few people -- those who do not consume much of this vitamin in their diet,
live in Northern latitudes, or some elderly who get little sun -- may benefit
from taking 600 to 2000 units daily. More is needed in the winter season and
less in the summer season.
Those who have hardly any sun exposure, or have certain chronic medical
conditions, may need 2000 to 3000 units a day for a few weeks or months and
then down to 1000 to 2000 units daily. The vast majority of people do not need
to be monitored by blood tests. Just take 1000 units a day if you are not sure
if you are getting enough and don't waste time and money on regular blood
tests. There is no need for the vast majority of Americans to take more than
2,000 units a day for the long run. There could be a detriment to taking 5,000
or 10,000 units a day. Many people are taking an unnecessary gamble taking
these very high amounts.
From the Newsletter- Supplement Research- Ray Sahelian, M.D. Nutrition Expert and Best Selling Author