The truth about the vitamins you actually need

“How can I make sure I’m getting my vitamins?” . . . is actually a very loaded question. The answer? It depends on whom you ask.

If you’re talking to someone “hawking” supplements, they’re going to tell you about the latest nutritional “miracle,” and may not even answer your question. A conventional MD might simply direct you to buy a bottle of multivitamins and quit worrying about it, while a registered dietician might start listing from their encyclopedic vegetable knowledge, confusing you in the process.

It’s hard to get a straight answer. This is partly because experts don’t know the exact answer, and the science of nutrition is constantly changing as researchers try to figure it all out.

What we do know, however, is that there are 13 essential vitamins, so named because your body truly could not function without them. These compounds keep your heart pumping, your cells growing and your food digesting. Without them, people develop old-timey-sounding conditions including scurvy (Vitamin C deficiency), anemia (iron deficiency) and rickets (Vitamin D deficiency).

We also know quite a bit about each one of the vitamins’ basic properties. Some vitamins, such as Vitamin D, are fat soluble, meaning your body can store excess amounts of them. But others, such as the B Vitamins, are water soluble, meaning that you’ll just “pee-out” the excess, rather than “stocking up.” Luckily (as you’ll see in this article), it’s pretty easy to get everything you need just by eating a balanced, healthy diet and going outside of it every once in a while.

That’s why most Americans don’t need to take vitamin supplements at all. You also don’t need to be taking extra amounts of these compounds. For instance, despite the hype, a mega-dose of Vitamin C will not prevent a cold. In fact, if you consistently take too much, you can actually overdose on vitamins, and have a dangerous reaction to some.

That said, there are instances when certain supplements become necessary. Here are a few of your essential vitamins:

Vitamin A (Retinol) Why you need it: Vitamin A helps keep many of your organs working properly, including your kidneys, heart and lungs. It’s also necessary for maintaining healthy teeth and skin. It’s especially important for vision. People with Vitamin A deficiencies have trouble seeing in low light. And Vitamin A deficiency is the leading cause of preventable blindness worldwide.

Where you’ll find it: Many animal products have Vitamin A, including cheese, eggs and meat. But because these also come with high levels of saturated fat and cholesterol, they shouldn’t be your main sources of the vitamin. Instead, focus on eating your leafy greens as well as red and yellow fruits and vegetables (e.g., mangoes and carrots). Read more.

Vitamin C (Ascorbic Acid) Why you need it: Your body needs Vitamin C in order to repair itself. That includes making collagen, a protein needed in order to heal wounds, as well as keeping your teeth, bones, and cartilage in good shape. Plus, Vitamin C can help your body absorb iron from other foods.

Where you’ll find it: We often think of citrus fruits as the ultimate Vitamin C sources — and they’re definitely good choices. But other foods (including potatoes, tomatoes, and broccoli) pack a big Vitamin C punch, as well. Some cereals are also fortified with extra Vitamin C, so be sure to check the label.

Vitamin D Why you need it: Vitamin D helps your body absorb calcium, and you need both to keep your bones healthy. As a kid, Vitamin D was especially important to make sure your skeleton grew with you properly. But you still need it as an adult. Vitamin D deficiency can make you feel especially fatigued and lead to conditions like Osteoporosis, as you get older.

Where you’ll find it: Very few foods contain Vitamin D, and those that do, such as milk and orange juice, are fortified, (meaning Vitamin D was added). Humans get most of their Vitamin D from sun exposure, the original source. When you’re exposed to UV rays, your skin converts a hormone into D3, a form of Vitamin D that we can’t readily use. That then gets sent to your liver and kidneys, which turn it into the active form of Vitamin D.

Vitamin E Why you need it: Your immune system needs Vitamin E in order to keep you safe from viruses and bacteria. It also helps you use Vitamin K (more on that later). Vitamin E is also an antioxidant, which means it helps protect the body from damage to tissues and organs caused by free radicals. These are molecules that are thought to play a role in the aging process. However, researchers are still figuring out exactly how helpful antioxidants are, if at all.

Where you’ll find it: There are actually several different antioxidant compounds all referred to collectively as “Vitamin E.” You’ll find them in the highest amounts in seeds, nuts and vegetable oils. But they’re also in avocado and dark-green veggies.

Vitamin K Why you need it: Vitamin K’s role is simple and vital. Without it, your blood wouldn’t clot. People who have a condition in which the blood doesn’t clot properly, such as Hemophilia, bleed longer after an injury than others and may suffer from internal bleeding. That can damage your organs and even be life threatening.

Where you’ll find it: Dark, leafy greens are your best bet for getting Vitamin K. However, soybeans, pumpkin, eggs, and meats also are good options.

Vitamin B1 (Thiamine) Why you need it: Thiamine is especially helpful for converting carbohydrates into usable energy — glucose. Your body, brain and nerves need that to function normally. Where you’ll find it: Get your hands on some whole grains, legumes, eggs, nuts and seeds, and you’ll be all set. A hearty grain bowl is the perfect way to get all of them in one meal.

Vitamin B2 (Riboflavin) Why you need it: Like all B Vitamins, Riboflavin helps your body convert carbs, proteins, and fats into energy you can use. But riboflavin deficiency has also been linked to vision problems and migraines. Researchers are still figuring out exactly what that association means.

Where you’ll find it: The best sources of Riboflavin are lean meats, dairy (including milk) and eggs. But you can also get it from leafy veggies, legumes, and nuts.