Pop: When pregnant (or trying to be)
Folate or folic acid (what it's called when it's man- made) is essential for any woman pre-pregnancy, as low levels increase the risk of birth defects. So pop 400 mcg of folic acid daily when you're trying for a baby and during the first three months of pregnancy.
Don't Pop: When you're in an awful mood
Rather than resorting to wine or ice-cream, a lot of people tackle a low mood with herbal supplements. The problem is it also interacts with more than half of all prescription drugs—like the Pill. So unless your GP has confirmed that it won't interfere with any medication you might be on, make Brazil nuts part of your daily diet—just three a day provide your recommended allowance of selenium, a deficiency of which has been linked to depression and anxiety.
Pop: If you're Vegetarian
When you include meat, fish, and dairy in your diet regularly, Vitamin B12 and iron aren't really things you need to worry about—your diet supplies more than enough. But for those people who eat very few (or no) animal products, like vegans or vegetarians, it's a completely different story; they often do need to take Vitamin B12 and iron tablets, as these are the nutrients that keep your cells healthy. "Consider iron supplements if you have heavy periods," advises Price.
Don't Pop: When you're feeling under the weather
Do you stock up on Vitamin C pills at the first sign of a cold? Sorry, you're wasting your time (and cash). In fact, "Vitamin C supplements are not dangerous, but they have not been shown to prevent colds," says Price. "The truth is, most of us get plenty of Vitamin C naturally from our diets alone if we regularly consume foods like oranges, lemons, broccoli, kiwifruit, and tomatoes."
Pop: When missing the Sun
Studies link low Vitamin D levels with Seasonal Affective Disorder (SAD), plus it's so vital for healthy bones. The best source is sunlight, so during the cold months when you're stuck indoors, you may benefit from a supplement of no more than 25 mcg a day.