Which vitamins and supplements actually work?

By Julia Belluz - Thursday, December 6, 2012 at 12:02 PM - 0 Comments

Jon Feingersh/Blend Images/Getty

There’s a tendency to divide the world of pills in two: evil pharmaceuticals and nice supplements. When we’re looking at the outrageous claims on the labels of supplements—that they’ll help us lose weight, clear-up acne, live long lives—we somehow forgot that the natural-health business is a business like any other, and that in Canada, while there are loose regulations around these products, they are not necessarily safe or effective.

Unlike pharmaceuticals—which admittedly have their own evidence problems—”natural” pills don’t undergo rigorous testing before they reach the market. So some of the claims about them are simply lies or not based in good science. As Dr. Edzard Ernst, one of the world’s foremost experts on the evidence for alternative complementary medicine, told Science-ish: “It is a myth to assume that the supplement industry behaves any differently from any other industry. It is about making money, and all too often people are less than responsible in the pursuit of this aim.”

The good news is that there is strong evidence to either back or refute some common notions about supplements. Science-ish sifted through the research to identify indications for capsules that have compelling science behind them. Here’s the Science-ish guide to supplements:

Antioxidants for preventative health
Don’t mean to be alarmist here but the evidence suggests antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) may actually kill you quicker.

Vitamin C for colds
This is a myth. As Science-ish has explained in the past, this regularly updated Cochrane review on vitamin C and the common cold shows that popping these pills every day does nothing to prevent colds and only maybe shortens their duration.

Vitamin D for a range of indications
From combating chronic pain to staving off cancer, this celebrated supplement seems to be recommended for everything. Unfortunately, the evidence for most vitamin D-related claims is weak. It doesn’t help reduce the risk of a range of cancers. There’s little evidence that these pills can alleviate chronic pain. As well, no link has been found between vitamin D and reductions in blood pressure, improved cardiovascular outcomes, and the prevention of fractures in older women. People whom vitamin D can help: those who have tested positive for a deficiency.

Evening primrose oil for a range of indications
In a word: useless. Read here about uses for menopausal symptoms, here about eczema, and here about premenstrual syndrome.

Glucosamine for osteoarthritis
According to high-quality studies, these supplements appear to help manage pain and improve physical function in people suffering with this joint disorder.

Melatonin for jet lag
Melatonin supplements are the closest thing we have to a cure for jet lag. As a 2009 systematic review pointed out, “Melatonin is remarkably effective in preventing or reducing jet lag, and occasional short-term use appears to be safe.” What’s more, melatonin may also be effective for treating a number of sleeping problems, as well as cluster headaches.

Probiotics for gut health
For some very specific indications—managing diarrhea in hospital settings or antibiotic-induced diarrhea—probiotics seem to be helpful. But despite their popularity for improving gut health, the jury is still out.

St. John’s wort for depression
The use of this stuff to manage depression is actually backed by strong evidence. A synthesis of 29 studies in over 5,000 patients from several countries found that those who took the plant extract in the trials “were superior to placebo, similarly effective as standard antidepressants, and had fewer side effects than standard antidepressants.”

Weight loss supplements
Lies, damned lies. Raspberry ketones, green coffee beans: don’t waste your money! If there was a tablet that could help with weight loss, we would not be in the midst of an obesity epidemic. In fact, Science-ish has yet to come across claims about a weight-loss supplement that are backed by good evidence. As a general rule, when a study about one of these “fat busters” suggests it’s effective, that’s probably because the experiment was poorly designed or it was done in animals or cells but not in people.

Your supplement of choice isn’t listed here?
Check out this user-friendly, science-based website for more information about a range of supplements.

Science-ish is a joint project of Maclean’s, the Medical Post and the McMaster Health Forum. Julia Belluz is the associate editor at the Medical Post. Got a tip? Seen something that’s Science-ish? Message her at julia.belluz@medicalpost.rogers.com or on Twitter @juliaoftoronto

Antioxidants: Can they save you or kill you quicker?

By Julia Belluz - Thursday, July 28, 2011 at 1:35 PM - 10 Comments

Photo by gabster_ro c/o Flickr Creative Commons

The Statement: Antioxidants for “building strong bones and teeth” and  “protection and healing while improving memory function.”— Cafeteria signage, 07/28/2011

Like many of you, dear readers, on my way to lunch every day I am met with a barrage of well-intentioned signs in my workplace cafeteria that extol the benefits of antioxidants. According to these colourful posters, antioxidants do everything from build strong bones and teeth to protect and heal the body (whatever that means) while also improving memory function.

These signs ring bells: naturally, Science-ish is skeptical of any life-preserving miracle cures. So we asked: what are antioxidants and what do they really do for the body?

First, we must begin with free radicals, which are molecules that have at least one unpaired electron and therefore can be unstable and highly reactive. The theory goes oxidation (or oxygen metabolism), which is a natural process needed to sustain life, also causes the formation of free radicals, and the free radicals can age and damage your cells, leading to diseases such as cancer.

That’s where antioxidants come in. Found in many foods—from fruits and vegetables to wine, chocolate, and tea—antioxidants are thought to interact with the free radicals, stabilize them, and prevent some of the damage they would otherwise cause. In other words, they protect the body’s cells from the sometimes harmful effects of those wild free radicals.

So it would seem to make sense that consuming more antioxidants—drinking pomegranate juice and eating carrots at lunch, topping up with vitamin supplements C and E—leads to more health benefits, which is probably why the thinkers behind the lunchroom signage encourage cafeteria-dwellers to dive in.

But the science shows that more antioxidants, particularly those derived from vitamin supplements, have no health benefits and, what’s worse: they can kill you early.

A 2008 systematic review of the literature on antioxidants found no evidence to support the seemingly widely accepted use of antioxidant supplements, such as vitamins A and E, and beta-carotene. Instead, the researchers concluded, these substances may increase mortality. “Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing,” they wrote.

Similarly, a comprehensive evidence report out of Johns Hopkins University stated: “With few exceptions, neither beta-carotene nor vitamin E had benefits for preventing cancer, cardiovascular disease, cataract, and age-related macular degeneration.” Beta-carotene supplements actually increased the risk of lung cancer in people at risk (smokers and those exposed to asbestos).

Though I’ve pointed to some of the newer and more comprehensive evidence, it by no means tells a different story from what the scientific community has known for years about antioxidants.

As science writer Ben Goldacre outlines in his book Bad Science, a large 1994 study—published in the New England Journal of Medicine—investigated the then-promising notion that diets rich in carotenoid-rich fruits and vegetables, as well vitamin E and beta carotene, were associated with a reduced risk of lung cancer. Nearly 30,000 Finnish people with a high risk of lung cancer were recruited for the study, and the findings dashed the hopes of researchers when it was revealed that those who received beta-carotene supplements had more deaths overall—from lung cancer and heart disease—compared to those who received a placebo.

The well-documented Beta-Carotene and Retinol Efficacy Trial (CARET) was similarly alarming: it looked at the effect of daily beta-carotene and vitamin A on the incidence of lung cancer, other cancers, and death in over 18,000 people at risk for lung cancer, and had to be stopped ahead of schedule in 1996. The reason? Those assigned to receive the vitamins were found to have a 28% increase in incidence of lung cancer, a 17% increase in incidence of death, and a higher rate of cardiovascular disease mortality compared with the control group.

Where does this leave us? Since there’s no scientific evidence to back the use of supplemental antioxidants, sticking to the old commonsensical balanced diet plan with fruits and vegetables should do the trick.

*Thank you to reader @helenspitzer for requesting a post on antioxidants.

Science-ish is a joint project of Maclean’s, The Medical Post, and the McMaster Health Forum. Julia Belluz is the associate editor at The Medical Post. Got a tip? Seen something that’s Science-ish? Message her at julia.belluz@medicalpost.rogers.com or on Twitter @juliaoftoronto