BY MEN’S HEALTH + GNC

With so many supplements available, it can be tough to separate the muscle-building, brain-boosting, highly beneficial brands from the ineffective—and even harmful—ones.

That’s where we come in. Here are the six nutrients your body needs most, and the best way to find them naturally and in supplements.

Choline
Choline repairs DNA and supports brain function. A deficiency can raise your risk of liver damage and even liver cancer, says Steven Zeisel, M.D., Ph.D., director of the UNC Nutrition Research Institute.

In one study, people who ate the most choline cut their pancreatic cancer risk by a third.

Related: Lift Weights? Here’s What You Need to Know About BCAAs

Get it naturally: Eggs are loaded. If you ate six pork ribs, you’d still be just shy of your day’s quota (550 milligrams), but a three-egg omelet provides more than 80 percent of that amount. (See the 14 Best Ways to Eat an Egg.)

How to supplement: Pick a pill that has less than 100 percent of your daily value—you want just enough to top off your tank. Gut bacteria transform excess choline into trimethylamine, which causes fishy-smelling BO.

Magnesium
It’s brain food. It may help fight headaches and muscle cramping and improve your mood, says Emily Tarleton, R.D., of the University of Vermont College of Medicine. Shoot for about 400 to 420 milligrams a day.

Get it naturally: Plants suck up magnesium in soil through their roots; seeds harbor the bulk of it. Top sources: sesame seeds (126 milligrams per ¼ cup), raw cashews (100), and almonds (97). Black beans, technically a seed, have 84 milligrams per full cup.

Related: The Top 10 Sources of Magnesium

How to supplement: Nearly half of Americans fall short on magnesium in their diet. The Institute of Medicine recommends taking up to 350 milligrams a day from a supplement. Your body absorbs magnesium citrate best.

Vitamin B12
It keeps your brain’s spark plugs (the neurotransmitters) firing so information can be relayed. Even a mild B12 deficiency can speed cognitive decline with aging. B12 is also required for proper red blood cell formation.

Get it naturally: Eat more steak! Meat and seafood are the main sources of B12, and carnivores can easily reach their daily 2.4 micrograms by enjoying a 6-ounce serving of top sirloin (2.8 micrograms) or canned tuna (2.5).

How to supplement: If your diet is light on meat and fish, ask to have your B12 levels checked the next time you have blood work done. If you’re low, then yes, a supplement can help protect your brain and blood.

Vitamin K
Vitamin K keeps your heart healthy. People with low K intake are nearly three times as likely to have heart problems as those who get the most.

Related: 30 Easy Ways to Save Your Heart Today

Get it naturally: Never skimp on the salad course. A mere cup of raw kale provides 113 micrograms of vitamin K­­­– that’s 94 percent of your daily requirement. Spinach and collard greens are also great sources.

How to supplement: Adults need 120 micrograms a day, but the average man falls short with just 85. So supplement with at least 45 micrograms of K2, the type your body absorbs best, says Cees Vermeer, Ph.D., founder of the R&D Group Vita K at Maastricht University in the Netherlands.

Vitamin D
The sunshine vitamin improves your mood and lowers your risk of heart disease, cancer (especially prostate), diabetes, and Alzheimer’s, says Michael Holick, Ph.D., M.D., of Boston University Medical Center Hospital, author of The Vitamin D Solution.

Related: The Vitamin You Need So Your Penis Can Perform

Get it naturally: Unless you’re routinely outside and shirtless between 10 a.m. and 3 p.m., you’re probably falling short, says Dr. Holick. Add D-rich foods like fortified dairy and fatty fish (e.g., salmon) to your diet.

How to supplement: Technically, fortified dairy is a supplement: Milk has about 100 IU of vitamin D per cup. But that’s far below the 1,500 to 2,000 IU a day the Endocrine Society recommends. Popping extra D can help.

Zinc
As antioxidants go, zinc is powerful stuff. It’s found in every cell, assists in healing wounds, and helps beat sneaky viruses. And if you want kids, know this: Zinc also improves sperm quality.

Get it naturally: Aim for 11 milligrams of zinc daily; six oysters have about triple that. Bonus: Your body can bank some of the excess, says David Killilea, Ph.D., who studies nutritional metals.

How to supplement: If you’ve noticed your energy and sex drive flagging, turn to foods or supplements that contain both zinc and copper to help support cells in your reproductive and central nervous systems. The two work in concert; supplementing with high levels of zinc alone can result in a copper deficiency.