Most vitamins are useless, but here are the ones you should take

It seems like simple, obvious advice: Eat your vegetables, get some exercise, and — of course — take your vitamins.

Or not.

Decades of research has failed to find any substantial evidence that vitamins and supplements do any significant good. In fact, recent studies skew in the opposite direction, having found that certain vitamins may be bad for you.

Several supplements have been linked with an increase in certain cancers, for example, while others have been associated with a rise in the risk of kidney stones. Still others have been linked with an overall higher risk of death from any cause.

So here are the vitamins and supplements you should take — and the ones you should avoid:

Vitamin B3: Skip it and eat salmon, tuna, or beets instead.

For years, Vitamin B3 was promoted to treat everything from Alzheimer's to heart disease. But recent studies have called for an end to the over-prescription of the nutrient.

A large 2014 study of more than 25,000 people with heart disease found that putting people on long-acting doses of Vitamin B3 to raise their levels of 'good,' or HDL, cholesterol didn't reduce the incidence of heart attacks, strokes, or deaths.

Plus, people in the study who took the B3 supplements were more likely than those taking a placebo to develop infections, liver problems, and internal bleeding.

Folic acid: Take it if you're pregnant or if you might want to get pregnant.

Folic acid is a B vitamin which our bodies use to make new cells. The National Institutes of Health recommends that women who are currently pregnant or who want to get pregnant take 400 micrograms of folic acid daily because their bodies demand more of this key nutrient when they are carrying a growing foetus.

Additionally, several large studies have linked folic acid supplementation before and during pregnancy with decreased rates of neural-tube defects, serious and life-threatening birth defects of the baby's brain, spine, or spinal cord.

NOW WATCH: Briefing videos

Business Insider Emails & Alerts

Site highlights each day to your inbox.

Follow Business Insider Australia on Facebook, Twitter, LinkedIn, and Instagram.