Which vitamins and supplements actually work?

St. John’s wort makes the cut, but stop wasting your money on raspberry ketones
Overweight man eating plate full of pills
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 [email protected] or on Twitter @juliaoftoronto