Christopher
Labos is a Montreal doctor (Division of Epidemiology,
Biostatistics and Occupational Health McGill University
who writes about medicine and health issues. He also co-hosts
a podcast called The Body of Evidence.
Many people
see vitamins as an inexpensive and risk-free way to prevent
disease. But just as the Holy Roman Empire was neither holy,
nor Roman, nor an empire, vitamins are neither inexpensive
nor risk free, and they do not actually prevent disease.
In fact, they may make things worse.
Last week, the
United States Preventive Services Task Force published its
recommendations about whether vitamins, minerals and nutritional
supplements should be taken to prevent cardiovascular disease
and cancer. Much as it did in 2014 when it last reviewed
the evidence, it explicitly recommends against taking beta-carotene
or vitamin E, and says there is insufficient evidence to
support the use of any other vitamins.
In short, vitamins
don’t work. In fact, beta-carotene increases the risk
of cancer and vitamin E the risk of hemorrhagic strokes.
So why do people
keep taking them?
Amazingly, negative
vitamin studies don’t seem to dent sales, which amount
to billions of dollars globally. When asked, most people
say they take vitamins to improve their health, but, paradoxically,
when you look at data from the National Health and Nutrition
Examination Survey the people who take vitamins are more
likely to be in good health to begin with. They smoke less,
exercise more and have lower rates of obesity. Also, when
you survey people about their vitamin use, you unveil surprisingly
contradictory beliefs. Almost 90 per cent of people surveyed
agree or strongly agree that vitamins can help people meet
their nutritional requirements. But 80 per cent of them
also agree or strongly agree that vitamins shouldn’t
be used as a substitute for an unhealthy diet, and 75 per
cent agree or strongly agree that vitamins are not meant
to cure disease.
When you drill
down in people’s perceptions, they at once acknowledge
that vitamins do not cure disease and yet simultaneously
see them as boosting health.
Some people
do have valid medical reasons to take vitamins; vitamin
deficiencies do happen. But vitamin deficiencies are extremely
rare.
That leaves
many people taking vitamins for reasons that are not medically
justifiable. A survey of Italian students found that those
taking supplements were not taking them because they were
worried about not getting enough vitamin D, iron or omega-3.
The most common reason given was to boost athletic performance,
even though there is little evidence to support this idea.
This belief
system is incredibly difficult to dislodge. The editorial
accompanying the USPSTF recommendations discusses why this
may be the case. Rather successful marketing continues to
convince the public that vitamin supplementation has value,
when it largely does not. Vitamins are seen as natural and
people who abhor “Big Pharma” and taking medication
happily take a vitamin supplement while being blissfully
unaware that prescription drugs and vitamins are often made
by the same company. Also, people often prefer to do “something”
even when that something is contrary to their self interest.
Statistically, a soccer goalie’s best strategy is
to stay in the centre of the net during a penalty kick.
And yet goalies feel compelled to dive one way or the other
because in that setting inaction is unacceptable. The term
has a name: action bias. It is what compels some of us to
honk our car horns in traffic when we know it will have
little effect.
Humorous examples
aside, the problem with our vitamin fascination is that
only one-quarter of people who take vitamins would stop
taking them if advised to do so by public health. While
it is understandable to want to take your health in hand,
there are better, cheaper things you can do. Quit smoking,
exercise regularly, eat plenty of fruits of vegetables,
avoid junk food, and you will drastically reduce your risk
of both cancer and heart disease. Simply take vitamins,
and you will not.
COMMENTS
TheVitaminWhiz
Come on, that's yet another flimsy anti-vitamin article
that exaggerates risks and downplays benefits. It also contains
outright lies about the amount of people with vitamin deficiencies
and the safety of them. Finally, the design of the website
combined with the complete lack of sources shows that this
isn't at all trustworthy.
Anyways, hope this helps!
also by Christopher Labos:
Coffee
and Cancer
Fit
and Fat?
Zika
Bites That Kill
Genetically
Modified Salmon
