6 Vitamins and Minerals You May Not Be Getting Enough Of

Why you might be low: Your period, pregnancy and breastfeeding can all contribute to low iron levels, and if you end up depleted after a pregnancy and don't get your levels back up, the problem can become worse, says Behar.

Why you need it: Iron helps make up the protein that carries oxygen from your lungs to the rest of your body, which is why being mentally and physically tired is one of the main symptoms of low iron.

Where to find it: Meat sources like beef and chicken are your best bet, since the type of iron found in meat (called heme iron) is more bioavailable, or better absorbed, by our bodies than the type we get from plants, says Thacker. But you can also get significant amounts of iron from legumes and lentils.