Taking prenatal vitamins may not be the best option if you aren’t pregnant or nursing. In some cases, doing so may cause unwanted side effects, like constipation and diarrhea.

The famous saying about pregnancy is that you’re eating for two. And while you might not actually need that many more calories when you’re expecting, your nutritional needs do increase.

To ensure that expectant moms are getting enough vitamins and minerals, they’ll often take a prenatal vitamin. Prenatal vitamins are associated with reducing risks for pregnancy complications like neural tube defects and anemia.

With so many benefits, it’s easy to wonder if you should take them even if you aren’t expecting or trying to get pregnant. But for the most part, if you aren’t thinking about bringing a little one into the world, the majority of your nutrients should come from your diet — not a vitamin.

Here’s a look at the risks and benefits of taking prenatal vitamins.

The vitamin aisle at your local pharmacy contains a huge assortment of vitamins for different genders and ages. Prenatal vitamins are specifically geared toward women thinking about becoming pregnant or who are pregnant.

The concept behind prenatal vitamins is that some of a women’s nutritional and vitamin needs increase with pregnancy. A baby especially needs certain nutrients to develop. Expectant moms don’t always take in enough nutrients in their daily diets. Prenatal vitamins are meant to bridge the nutritional gap.

It’s important to remember that prenatal vitamins are a supplement to a healthy diet for expectant moms. They aren’t a replacement for a healthy diet.

Lots of different prenatal vitamin types are available on the market. While there’s not a specific formulation for all prenatal vitamins, you’ll likely find that prenatal vitamins contain at least these key nutrients:

Calcium. According to the Mayo Clinic, pregnant and adult women need 1,000 milligrams (mg) of calcium daily. Prenatal vitamins typically have between 200 and 300 mg of calcium. This contributes to a woman’s calcium requirements but doesn’t account for all of her daily calcium needs. Calcium is important for all women because it keeps their bones strong.

Folic acid. Taking in enough folic acid is linked with reducing neural tube defects like spina bifida. The American College of Obstetricians and Gynecologists recommends that pregnant women (and those trying to get pregnant) take in 600 micrograms (mcg) of folic acid every day from all sources. Since it may be difficult to get this much folic acid from foods alone, a supplement is recommended.

Foods that have folic acid (also known as folate) include beans, leafy green vegetables, asparagus, and broccoli. Many fortified foods including cereal, bread, and pasta have folate too.

Iron. This mineral is necessary to create new red blood cells in the body. Because a woman increases her blood volume during pregnancy, iron is a must-have. According to the Mayo Clinic, pregnant women need 27 mg of iron a day. This is 8 mg more than women who aren’t pregnant.

Prenatal vitamins often contain other vitamins and minerals. These could include:

Always talk with your doctor before starting to take prenatal vitamins. If you’re trying to conceive or are pregnant, your doctor will likely recommend that you take them.

While you can buy prenatal vitamins over the counter, doctors can prescribe them too. Women who are carrying multiples, pregnant teenagers, and pregnant women with a history of substance abuse have a higher risk of vitamin and mineral deficiencies. Prenatal vitamins are particularly important for these women.

Doctors often recommend that women who are breastfeeding also continue taking prenatal vitamins after delivery. Prenatal vitamins can serve as a further supplement to lactating women who need plenty of nutrients to make breast milk.

Even if you aren’t trying to get pregnant, you still might want to take a folic acid supplement. That’s because half of the pregnancies in the United States aren’t planned. Because the brain and spinal cord are already forming at the early stages of pregnancy, folic acid is vital. Women of childbearing age could also eat more folate-rich foods as an alternative to taking a supplement.

Prenatal vitamins are specific to the needs of pregnant and breastfeeding women. They’re geared to make up the common nutritional deficiencies a pregnant woman could have. But they aren’t really intended for women (or men) who aren’t expecting or lactating.

Taking too much folic acid each day can have the adverse side effect of masking a vitamin B-12 deficiency. Excess iron can be a problem, too. Getting too much iron is associated with health problems like constipation, nausea, and diarrhea.

Excess amounts of nutrients like vitamin A taken from synthetic vitamins could be toxic to a person’s liver.

Again, it’s better if you get these nutrients through your diet instead of a pill. For these reasons, most women should skip prenatal vitamins unless their doctors tell them otherwise.

Many women claim that prenatal vitamins affect hair and nail growth. Some claim that taking prenatal vitamins makes hair grow thicker or faster, and that nails could grow faster or stronger too.

But according to the Mayo Clinic, these claims haven’t been proven. Taking prenatal vitamins for better hair or nails likely won’t bring the desired results. They could also have adverse side effects.

If you’re considering taking prenatal vitamins and aren’t pregnant, breastfeeding, or trying to conceive, evaluate your diet first. Most people who eat a balanced diet don’t need to take a multivitamin. A balanced diet includes lean proteins, low-fat dairy sources, whole grains, and plenty of fruits and veggies.

But keep in mind that there are always exceptions to why you may need to take a vitamin or mineral supplement. Maybe your doctor found specific nutrition deficiencies in your diet. In this case, it’s usually better to take a supplement designed to treat your specific deficiency.

Being aware of potentially adverse symptoms can help you determine if you’re experiencing the side effects of excess vitamins or minerals.

Rachel Nall is a Tennessee-based critical care nurse and freelance writer. She began her writing career with the Associated Press in Brussels, Belgium. Although she enjoys writing about a variety of topics, healthcare is her practice and passion. Nall is a full-time nurse at a 20-bed intensive care unit focusing primarily on cardiac care. She enjoys educating her patients and readers on how to live healthier and happier lives.