The vitamin and supplement industry is a $30 billion a year industry.  There are literally thousands of them to choose from, but how do you know which supplements actually work? Here are some of the most beneficial:

First is vitamin D. A 2013 meta-analysis of 42 studies found daily vitamin D use actually decreased mortality rates. It can also strengthen bones and protect against colds.

However, the best remedy against a cold is zinc. A 2011 study showed zinc supplements shortened the length of a cold and made symptoms less severe.

Next are garlic supplements. A review of 11 controlled trials found garlic supplements can actually help lower blood pressure.

Another supplement is niacin, also known as vitamin B3. Over-the-counter versions of this supplement have been shown to reduce the risk of heart attack or stroke in people with heart disease in a 2010 study.

Click here for Dr. Oz's Ultimate Supplement Checklist