You need 5 to 9 servings of fruits and vegetables every day. Try to incorporate them into every meal—and snack. (One serving is one half a cup or one medium fruit/veggie.)

Nothing could be truer than that old saying, "You are what you eat". When you eat a healthy diet—rich in fruits and vegetables, whole grains, beans, olive oil and other healthy fats, fish, lean meat, and plenty of water—you're healthier and have more energy. Your skin looks radiant and more youthful as well.

But a question I commonly get in my practice is: "What are the most important nutrients that I need?" This is a hard question to answer as your body really needs a balance of all key nutrients. I'm going to focus here, though, on three critical antioxidant nutrients your body needs—and why.

Magnesium: This mineral is essential to more than 300 enzyme systems that regulate things like muscle and nerve function, blood glucose levels, the production of the key sleep hormone melatonin, and blood pressure (to name just a few!).

Low magnesium levels (which can be triggered by many things including stress and medications like antibiotics, diuretics, and beta blockers) can lead to exhaustion, irritation, and sleeplessness, as well as to stress and anxiety. Your primary care doctor can test your magnesium levels with a red blood cell magnesium test (which can be added to a routine blood test).

"Magnesium helps regulate cortisol — too much of which can lead to anxiety — as well as melatonin, which is essential for sleep."

Magnesium-rich foods include green leafy vegetables like spinach, legumes, nuts like almonds, seeds, and whole grains, as well as dark chocolate (a good reason to indulge every once in a while, in moderation!).

How much you need: Take a look at this helpful chart from the National Institutes of Health Office of Dietary Supplements.

Vitamin C: This powerful antioxidant vitamin—also known as ascorbic acid—helps the immune system work efficiently to protect the body, improves the absorption of iron from plant-based foods, and is essential for the production of collagen (a structural protein required for wound healing and also critical in keeping the skin youthful looking).

Not getting enough vitamin C can result in fatigue, inflammation of the gums (indicated by swollen, bleeding gums), joint pain, poor wound healing and, in some people, even depression. Again, if you or your doctor suspects you may be deficient in vitamin C, he or she can order a blood test.

Vitamin C-rich foods include citrus fruits, red and green peppers, kiwifruit, broccoli, strawberries, and tomatoes.

"The vitamin C content of foods can be reduced by prolonged storage and cooking. If you can, eat vitamin C-rich foods raw — or cook for a very short time — to maintain the vitamin C levels."

How much you need: Take a look at this helpful chart from the National Institutes of Health Office of Dietary Supplements.

Zinc: This antioxidant mineral is involved in all aspects of metabolism, immune function, wound healing, and cell division, as well as normal growth and development. It's also essential for maintaining a normal sense of taste and smell. A deficiency of zinc can trigger hair loss, loss of appetite, and impaired immune function—to name just a few. Talk to your doctor if you suspect you may be deficient; a simple blood test can determine your levels.

"A daily intake of zinc is critical as the body is unable to produce, or store, zinc."

Zinc-rich foods include oysters (which contain more zinc per serving than any other food), liver, crimini mushrooms, spinach, pumpkin seeds, crab, and beef.

How much do you need: Take a look at this chart from the National Institutes of Health Office of Dietary Supplements.

I always recommend getting as much of the key nutrients you need from healthy food. If you can't, thensupplement.

Be healthy, be well,