You have likely heard about a
recent study, involving roughly 40,000 women over the age of 60, in
which daily use of a multivitamin -- and several other nutrient supplements
-- was associated with a higher rate of death. Along with the mix of shock,
consternation, and disappointment is the very practical question: could a
multivitamin kill you?
certainly not! The current study -- like others before it that have hinted
at much the same association -- is absolutely NOT cause for panic. For each
such study, there is another showing no real harm. That vial of (now
menacing) multivitamins in your medicine cabinet doesn't mean you need to
fast track the preparation of your will and testament.
the study now making headlines, and the similar studies preceding it,
are observational. A large group of people is simply followed and assessed
over time, and the associations between what they do, and what happens to
them, are analyzed.
In the current case, routine use of a
multivitamin was associated with roughly a 2 percent greater chance of dying
over a 20-year span for women over age 60. So, for starters, a 2 percent
increased risk of dying over 20 years is not exactly cause for panic --
especially when one considers that dying in our early 80s is not entirely
unexpected or untimely.
But even more important, these women were not
assigned to a multivitamin or placebo; they made up their own minds. Some
chose to take nutrient supplements, some did not. How did these two groups
differ? Like all good observational studies, this one attempted to account
for obvious differences -- in education, income, smoking status, general
dietary pattern, and so on -- but the only honest answer is: we don't know!
We can't possibly know all the ways women who opt to take nutrient
supplements differ from those who don't. (That, by the way, is why
randomized trials can be so important; they reliably correct for this
limitation of observational studies.)
So, for instance: What if women more concerned
about a family history of chronic disease were the ones to take supplements?
What if women who were less confident in their ability to eat fruits and
vegetables daily were the ones to take supplements? What if women who were
just more anxious and pessimistic about their health were the ones to take
supplements? Independent of all other factors, pessimism increases
mortality, and optimism decreases it.
We don't know that any of these "what ifs" was
true; but if any one of these, or another like them, was true, it might be
the reason for the (minimally) higher death rate among supplement users,
rather than the supplements per se.
But, the fact of the matter is that several
large studies now suggest possible harm attached to the use of multivitamins
and certain other supplements (including some B vitamins, and iron). Since
we never had any clear evidence of benefit from multivitamin use, and since
the "at least it couldn't hurt" rationale for using multis as an insurance
policy is clearly not valid -- the day of the conventional multi-nutrient
supplement is over. I used to take a multi, and no longer do; I used to
recommend them to patients, and no longer do.
How could a mix of nutrients known to be
essential cause harm? When we extract nutrients from their context in food,
we are "guessing" about preparation, dose and combination. Errors in any of
these could lead to trouble.
Imagine, for example, that you had all the
essential construction material you needed to build a house -- but in the
wrong proportion. Too many roofing shingles, but too little lumber. Or
perhaps the beams were too short for the dimensions of the roof. We use
nutrients to build cells and proteins and hormones every day, and having the
right "stuff" but in the wrong form or supply could make a mess of things.
Or, consider a musical analogy. You love a
jazz ensemble, a rock band and a symphony orchestra. Imagine the sax player
from the one, the guitarist from the other, and the cellist from the third
each playing her own music, all at the same time. Noise! Lovely on their
own, a mess when combined badly.
This could be the case with how we have
approached nutrient supplementation. Frankly, I don't know for sure --
nobody does -- but the potential for real, if modest, harm is plausible.
So what do we do now?
For one thing, we should recall that all
along, the best-case scenario was "supplement," not substitute. There is no
substitute for eating well, and that deserves our dedicated commitment.
At this point, unless you are likely to have a
serious deficiency in overall nutrient intake -- or unless you have a
specific indication for taking a multivitamin, such as pregnancy or the
intent of pregnancy -- use of a multivitamin seems ill advised. You need a
good reason to do it; "what the heck" is no longer sufficient.
Judicious use of select supplements still
makes sense. We have convincing evidence of known or likely benefit from
supplemental omega-3 oils and vitamin D for most men and women, and calcium
for most women. For the most part, other supplements should be used for a
specific reason, and with input from someone with genuine expertise. As an
example, B12 supplementation is warranted for most vegans, and for all older
adults with pernicious anemia. Let's not toss out the baby with the
Another intriguing consideration is the use of
whole food-based supplements (Juice
Plus+ for example). Such products are "humble" in the sense that they
don't presume to know how to combine nutrients -- they let nature do it.
They simply compress the nutrients from healthful foods into pill form so
that those who don't eat quite as they should -- including children -- can
fill in the gaps. We need more science to prove the benefits of such
supplements, but the approach makes sense to me, and may prove to be the
new-age answer to the multivitamin/mineral supplement.
Independent of other factors, a multivitamin
is very, very unlikely to kill anyone. If there is risk attached to the use
of such supplements, it is very small. But there may be some risk -- and
there is no reliable indication of benefit.
That's really all we need to know to conclude:
it's probably time for us to kill the multivitamin.
Dr. David L. Katz;