Older Americans are hooked on
despite scarce evidence they work
6, 2018 by Liz Szabo, Kaiser Health News
There's no conclusive evidence that dietary
supplements prevent chronic disease.
There’s no solid evidence that taking multi- or any other kind of vitamin is
beneficial to your health unless
||May 2018: Multivitamins, vitamin D,
calcium and vitamin C, — the most common supplements, — showed no advantage
in the prevention of cardiovascular disease, heart attack, stroke or
The multivitamins included A, B1, B2, B3 (niacin), B6, B9 (folic acid), C, D
and E; and ß-carotene; calcium; iron; zinc; magnesium; and selenium.
It's most beneficial to rely on a healthy diet to get your fill of vitamins
and minerals," Dr. Jenkins said
From a systematic review of existing data and single randomized control
trials published from 2012 to 2017.
- Rigorous studies have failed to show
that fish oil supplements prevent heart attacks.
Fish Oil Pills Don't Prevent Heart Attacks, a
Study of Studies Finds
- Neither vitamin E nor
folic acid supplements did anything to protect the heart. Even worse, studies linked high-dose
vitamin E to a higher risk of
heart failure, prostate cancer and death from any cause.
Vitamin E, also an antioxidant, increased the risk of prostate cancer in men
- folic acid pills had no overall benefit for heart disease
- beta carotene pills actually increased lung cancer rates
- calcium supplement doesn't
protect against bone fractures but increase the risk of kidney stones and
- The "90+ Study"
on AGING -- Anti-Oxidants & some
Vitamins DON'T make you live longer, including
E, A, C & Calcium
If you're taking vitamin D you're probably
taking too much.
When she was a young physician, Dr.
Martha Gulati noticed that many of her mentors were prescribing
vitamin E and folic acid to patients. Preliminary studies in the
early 1990s had linked both supplements to a lower risk of heart disease.
She urged her father to pop the pills as well: "Dad, you should be on these
vitamins, because every cardiologist is taking them or putting their patients on
(them)," recalled Gulati, now chief of cardiology for the
University of Arizona College of Medicine-Phoenix.
But just a few years later, she found herself reversing course, after
rigorous clinical trials found neither vitamin E nor
folic acid supplements did
anything to protect the heart. Even
worse, studies linked high-dose
vitamin E to a
higher risk of heart failure, prostate
cancer and death from any cause.
"'You might want to stop taking (these),'" Gulati told her father.
More than half of Americans take vitamin supplements,
including 68 percent of those age 65 and older, according to a 2013 Gallup poll.
Among older adults, 29 percent take four or more supplements of any
kind, according to a Journal of Nutrition study published in 2017.
Often, preliminary studies fuel irrational exuberance about a promising
dietary supplement, leading millions of people to buy in to the
trend. Many never stop. They continue even though more rigorous studies—which
can take many years to complete—almost never find that vitamins prevent
disease, and in some cases cause harm.
"The enthusiasm does tend to outpace the evidence," said Dr. JoAnn Manson, chief
of preventive medicine at Boston's Brigham and Women's Hospital.
There's no conclusive evidence
that dietary supplements prevent chronic disease in the average American, Manson said. And while a
handful of vitamin and
mineral studies have had positive
results, those findings haven't been strong enough to recommend supplements to
the general U.S. public, she said.
The National Institutes of Health has spent more than $2.4 billion since 1999
studying vitamins and
minerals. Yet for "all the research
we've done, we don't have much to show for it," said Dr. Barnett Kramer,
director of cancer prevention at the National Cancer Institute.
A big part of the problem, Kramer said, could be that much nutrition research
has been based on faulty assumptions, including the notion that people need
more vitamins and minerals than a typical diet provides; that megadoses are
always safe; and that scientists can boil down the benefits of vegetables like
broccoli into a daily pill.
Vitamin-rich foods can cure diseases related to vitamin deficiency. Oranges and
limes were famously shown to prevent scurvy in vitamin-deprived 18th-century
sailors. And research has long shown that populations that eat a lot of fruits
and vegetables tend to be healthier than others. But when researchers tried to
deliver the key ingredients of a healthy diet in a capsule, Kramer said,
those efforts nearly always failed.
It's possible that the chemicals in the fruits and vegetables on your plate work
together in ways that scientists don't fully understand—and which can't
be replicated in a tablet, said Marjorie McCullough, strategic director of
nutritional epidemiology for the American Cancer Society.
More important, perhaps, is that most Americans get plenty of the essentials,
anyway. Although the Western diet has a lot of problems—too much
sodium, sugar, saturated fat and calories, in general—it's not short on
vitamins, said Alice Lichtenstein, a professor at the Friedman School of
Nutrition Science and Policy at Tufts University.
And although there are more than 90,000 dietary supplements from
which to choose, federal health agencies and advisers still recommend that
Americans meet their nutritional needs with food, especially fruits and
vegetables. Also, American food is highly fortified—with
vitamin D in milk, iodine in salt, B vitamins in flour,
even calcium in some brands of orange juice. Without even
realizing it, someone who eats a typical lunch or breakfast "is essentially
eating a multivitamin," said journalist Catherine Price, author of "Vitamania:
How Vitamins Revolutionized the Way We Think About Food."
That can make studying vitamins even more complicated, Price said. Researchers
may have trouble finding a true control group, with no exposure to supplemental
vitamins. If everyone in a study is consuming fortified food,
vitamins may appear less effective.
The body naturally regulates the levels of many nutrients, such as
vitamin C and many B vitamins, Kramer said, by excreting what it doesn't need
in urine. He added: "It's hard to avoid getting the full range of
Not all experts agree. Dr. Walter Willett, a professor at the Harvard T.H. Chan
School of Public Health, says it's reasonable to take a daily
multivitamin "for insurance." Willett said that clinical trials underestimate
supplements' true benefits because they aren't long enough,
often lasting five to 10 years. It could take decades to notice a lower rate of
cancer or heart disease in vitamin takers, he said.
For Charlsa Bentley, 67, keeping up with the latest nutrition research can be
frustrating. She stopped taking
calcium, for example, after studies
found it doesn't protect against bone
fractures. Additional studies suggest
that calcium supplements increase the risk of kidney stones and heart disease. "I faithfully chewed those
calcium supplements, and then a study said they didn't do any good at
all," said Bentley, from Austin, Texas. "It's hard to know what's effective and
Bentley still takes five supplements a day: a multivitamin to
prevent dry eyes, magnesium to prevent cramps while exercising,
red yeast rice to prevent diabetes,
coenzyme Q10 for overall health and
vitamin D based on her doctor's recommendation.
Like many people who take dietary
supplements, Bentley also exercises
regularly—playing tennis three to four times a week—and watches what she eats.
People who take vitamins tend to be healthier, wealthier and
better educated than those who don't, Kramer said. They are probably less
likely to succumb to heart disease or cancer, whether they take
supplements or not. That can skew research results, making
vitamin pills seem more effective than they really are.
Preliminary findings can also lead researchers to the wrong conclusions.
For example, scientists have long observed that people with high levels of an
amino acid called homocysteine are more likely to have heart attacks. Because
folic acid can lower homocysteine levels, researchers once
hoped that folic acid supplements would prevent heart attacks and strokes. In a
series of clinical trials, folic acid pills lowered homocysteine levels but had
no overall benefit for heart disease, Lichtenstein said.
Studies of fish oil
also may have led researchers astray. When
studies of large populations showed that people who eat lots of seafood had
fewer heart attacks, many assumed that the benefits came from the
omega-3 fatty acids in fish oil, Lichtenstein said.
Rigorous studies have failed to
show that fish oil supplements prevent heart attacks. A clinical trial of fish oil pills and
vitamin D, whose results are expected to be released within
the year, may provide clearer questions about whether they prevent disease.
But it's possible the benefits of sardines and salmon have nothing to do with
fish oil, Lichtenstein said. People who have fish for dinner may be
healthier due to what they don't eat, such as meatloaf and cheeseburgers.
"Eating fish is probably a good thing, but we haven't been able to show that
taking fish oil (supplements) does anything for you," said Dr. Steven Nissen,
chairman of cardiovascular medicine at the Cleveland Clinic Foundation.
Taking megadoses of vitamins and minerals, using amounts that people could never
consume through food alone, could be even more problematic. "There's something
appealing about taking a natural product, even if you're taking it in a way that
is totally unnatural," Price said. Early studies, for example, suggested that
beta carotene, a substance found in carrots, might help prevent
In the tiny amounts provided by fruits and vegetables,
beta carotene and similar substances appear to protect the body from a process
called oxidation, which damages healthy cells, said Dr. Edgar Miller, a
professor of medicine at Johns Hopkins School of Medicine.
Experts were shocked when two large, well-designed studies in the 1990s found
that beta carotene pills actually increased lung cancer rates.
Likewise, a clinical trial published in
2011 found that vitamin E, also an antioxidant, increased the risk of prostate cancer in men by 17 percent. Such studies reminded
researchers that oxidation isn't all bad; it helps kill bacteria and malignant
cells, wiping them out before they can grow into tumors, Miller said.
"Vitamins are not inert," said Dr. Eric Klein, a prostate
cancer expert at the Cleveland Clinic who led the vitamin E study.
"They are biologically active agents. We have to think of them in the same way
as drugs. If you take too high a dose of them, they cause side effects."
Gulati, the physician in Phoenix, said her early experience with recommending
supplements to her father taught her to be more cautious. She
said she's waiting for the results of large studies—such as the trial of
fish oil and vitamin D—to guide her advice on
vitamins and supplements. "We should be responsible physicians," she said,
"and wait for the data."