An assortment of brightly colored pills.

The Belief: You should be getting all the vitamins and minerals you need in your daily diet.

The Truth: You most likely aren't.

“If you’re consuming a well-balanced diet, you still need vitamin D and calcium,” says Sidra Yunas, MD, an obstetrician/ gynecologist affiliated with Memorial Hermann–Texas Medical Center. Not only that, but a lack of knowledge about vitamins and supplements could be dangerous not only for your health, but that of your future offspring.

If you’re consuming a well-balanced diet, you still need vitamin D and calcium.

Here are six vital vitamin facts to learn:

One. Spill Everything to Your Doctor.

Share not only herbs, supplements and over-the-counter drugs you take, but also what medicines you apply to your skin.

“The Retinol that women of reproductive age apply to prevent acne or wrinkles can cause fetal abnormalities,” Dr. Yunas says. “Talk with your doctor before using any supplement, orally or otherwise.”

Two. Bottles May Mislead.

Americans spend an estimated $8 billion-plus yearly on herbal dietary supplements, reports the American Botanical Council. But that doesn’t mean they’re safe.

“The U.S. Food and Drug Administration doesn’t regulate herbal supplements, so you have no guarantee how much, if any, of the ingredient is in bottles,” Dr. Yunas says.

The U.S. Food and Drug Administration doesn’t regulate herbal supplements.

In fact, the same herb can vary from bottle to bottle. “Natural” supplements also may interfere with prescribed drugs, rendering them ineffective or overly effective or causing side effects.

“Talk with your doctor or pharmacist before taking any herbal remedy or you risk dangerous drug interactions,” she says.

Three. Age Matters; Even Teens Need Calcium.

From age 14 to 18 – the prime time for bone building – kids should take 1,300 milligrams of calcium daily. So should women over 40, during the main years for bone loss. Between 19 and 39, women need 1,000 milligrams daily.

That’s not all. Vitamin D also is pivotal to strong bones. Women over 40 typically need 1,000 IU (International Units) to prevent the brittle-bone disease osteoporosis and its precursor, osteopenia.

Pregnant women also need that amount, to aid in the development of their fetus’ bones and teeth.

But don’t think you’re off the hook for a healthy diet, Dr. Yunas notes. You also should be consuming milk, yogurt, cheese and other dairy, which are rich in calcium. So are broccoli, dark leafy greens and sardines.

Four. Future Moms Should Take and Avoid Some Vitamins.

When you add prenatal vitamins, you might need to subtract others.

Women who can get pregnant always should be on folic acid, to prevent neural tubal defects in the fetus. They also should supplement the omega-3 fatty acid DHA, aka Docosahexaenoic Acid, throughout pregnancy and breastfeeding, as it helps babies’ brain development. It also may cut the risk of postpartum depression, according to some studies, Dr. Yunas says.

Excess vitamin A, however, should be avoided, as it may cause fetal abnormalities.

Five. Don't Insist on Monitoring All Vitamin Levels.

Such thorough blood testing is a waste of time and money for most, Dr. Yunas says. “There’s insufficient information to define what constitutes a deficiency.”

Moreover, you won’t overdo a multivitamin tablet. They have 50% to 200% of the recommended daily allowance, she says, and “the body excretes what it doesn’t use -- other than vitamins, A, D, E and K.”

Additional supplements could be a problem, though. “1,000 milligrams of vitamin C is fine and may help with colds. But taking more than that predisposes you to getting kidney stones.”

Six. Diet or Health Issues Alter Vitamin Requirements.

Most vegans and vegetarians don’t get enough vitamin B in their all-plant diet and need to supplement it.

Anyone prescribed a blood thinner (often for cardiovascular disease) should not take vitamin K because it boosts clotting. Doctors also may suggest curbing consumption of foods rich in vitamin K, including broccoli, edamame, Brussels sprouts and dark, leafy vegetables including spinach, Swiss chard and turnip, kale, collard and mustard greens.

Anyone who’s had bariatric surgery should be closely monitored by a dietitian to ensure they’re getting adequate vitamins and minerals.

Finally, black cohosh and other Chinese remedies for hot flashes and other peri-menopausal and post-menopausal symptoms cut the effectiveness of estrogen treatments.

Play it safe – and your body will thank you.

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