Missing Nutrients in Your Food

Even the most conscientious eaters may have dietary deficiencies.

Medically Reviewed by Brunilda Nazario, MD on May 12, 2009
8 min read

When it comes to eating healthy, some of us focus on the negative.

"A lot of people concerned about good nutrition are just watching for what they can't eat -- whether it's fat, or sugar, or whatever," says Tara Gidus, RD, a spokesperson for the American Dietetic Association.

But that attitude can blind us to all of those foods that we really should be eating more of. It also leads to missing nutrients in our food -- and dietary deficiencies -- for even the most conscientious eaters.

According to the most recent U.S. Dietary Guidelines, there are seven important nutrients in food that most Americans aren't getting in sufficient amounts:

Before you line your bathroom cabinet with supplements to fill the gaps, there's a simpler and healthier way. A few modest changes to your diet may give you all the nutrients you need.

Back in elementary school, the basics were probably drummed into you: calcium is good for bones and teeth and it's in milk. But that might be about all you know.

Calcium does a lot more than keep your bones strong. It helps maintain your heart rhythm, muscle function, and more.

How much do you need? That depends on your age.

  • Adults up through age 50: 1,000 milligrams/day
  • Adults over age 50: 1,200 milligrams/day

However, if you have a higher risk of osteoporosis, check with your doctor, who might recommend a high dose of 1,500 milligrams.

Dairy is one of the easiest ways to get this nutrient in food. Calcium is especially well-absorbed when you take it with lactose, the sugar in milk and some milk products. But if you don't like milk -- or can't tolerate it -- don't assume that you'll have to rely on supplements. There are different ways to get this nutrient in food. Some good dairy and nondairy sources of calcium are:

  • Nonfat plain yogurt (8 ounces): 452 milligrams
  • Swiss cheese (1.5 ounces): 336 milligrams
  • Skim milk (8 ounces): 306 milligrams
  • Salmon (3 ounces): 181 milligrams
  • Cooked spinach (1 cup): 146 milligrams

Calcium is also in all sorts of fortified foods, like breakfast cereals, orange juice, and soy milk.

"People don't know much about potassium," says Gidus. "They don't know how important it is, especially for maintaining healthy blood pressure." It's also key in maintaining fluid balance and the function of your nerves and muscles.

Adults should get 4,700 milligrams of potassium a day. "Potassium theoretically should be easy to get enough of, since it's in a lot of foods," says Lucia L. Kaiser, PhD, community nutrition specialist in the department of nutrition at the University of California, Davis. "But many people still don't, because they don't eat enough fruits and vegetables."

Bananas are a familiar source, Gidus says. But there are other ways to get this nutrient in food:

  • Baked sweet potato: 694 milligrams
  • Tomato paste (1/4 cup): 664 milligrams
  • Non-fat plain yogurt (8 ounces): 579 milligrams
  • Yellowfin tuna (3 ounces): 484 milligrams

You've probably heard all about the health benefits of fiber over the years. But given all the emphasis on bowels and regularity, you might assume that you won't have to worry about fiber intake until after retirement.

"People think that fiber is just for old people," says Kaiser. "But it's really important at every age for promoting a healthy intestinal tract and guarding against diseases."

So what does fiber do? In addition to keeping your bowels working well, it reduces the risk of other intestinal problems. Good fiber intake may also help protect against heart disease, type 2 diabetes, and some forms of cancer. Since fiber is so filling and low on calories, it's often key in many successful weight loss programs.

The amount of fiber you need depends on your age and your sex.

  • Women, age 19-50: 25 grams/day
  • Women, age 51 and older: 21 grams/day
  • Men, age 19-50: 38 grams/day
  • Men, age 51 and older: 30 grams/day

Some good sources of this nutrient in food include:

  • 100% bran cereal (1/2 cup): 8.8 grams
  • Cooked black beans (1/2 cup): 7.7 grams
  • Baked sweet potato, with peel: 4.8 grams
  • Small pear: 4.4 grams
  • Whole-wheat English muffin: 4.4 grams

Magnesium is involved in all sorts of bodily processes. It strengthens bones and keeps the immune system up to snuff. Magnesium also plays a key role in the function of your heart, muscles, and nerves.

The recommended daily allowance of magnesium is:

  • Women, age 19-30: 310 milligrams/day
  • Women, age 31 and older: 320 milligrams/day
  • Men, age 19-30: 400 milligrams/day
  • Men, age 31 and older: 420 milligrams/day

Good sources of this nutrient in food are:

  • Brazil nuts (1 ounce): 107 milligrams
  • 100% bran cereal (1 ounce): 103 milligrams
  • Cooked halibut (3 ounces): 91 milligrams
  • Almonds (1 ounce): 78 milligrams

Vitamin A is crucial for a lot of reasons. It's good for vision -- that's why your mother always told you to eat your carrots. It's also important for immunity and tissue growth.

How much do you need?

  • Adult men: 900 micrograms/day
  • Adult women: 700 micrograms/day

However, there are actually two types of vitamin A: retinol and carotenoids. The latter are the ones that are missing from too many American diets. There's no official daily recommended amount of carotenoids that you need. But you should try to get some of this nutrient in your food every day.

Foods that have carotenoids include:

  • Baked sweet potato, with skin: 1,096 micrograms
  • Cooked fresh carrots (1/2 cup): 671 micrograms
  • Cooked spinach (1/2 cup): 573 micrograms
  • Cooked winter squash (1/2 cup): 260 micrograms

Vitamin A is also in many fortified cereals and oatmeal.

Vitamin C actually has several important roles in keeping you healthy. In addition to boosting the immune system, vitamin C is a powerful antioxidant that can prevent cell damage. It also helps make collagen, an important part of bone and cartilage.

How much do you need?

  • Adult men: 90 milligrams/day
  • Adult women: 75 milligrams/day

Good sources of this nutrient in food are:

  • Cooked sweet red pepper, 1/2 cup: 116 milligrams
  • Orange: 70 milligrams
  • Strawberries (1/2 cup): 49 milligrams
  • Cantaloupe (1/4 medium): 47 milligrams
  • Cooked broccoli (1/2 cup): 51 milligrams

"I think a lot of people don't get enough vitamin E," says Gidus. The reason can be ironic: they're trying too hard to eat healthy.

Vitamin E tends to appear in foods with high fat content, like nuts, seeds, and oils. So in a quest to eat low-fat and slim down, many people cut out the foods that are important sources of vitamin E. That's a mistake. Vitamin E is a powerful antioxidant that helps protect your cells from damage.

So despite the fat, you should try to include some of these foods in your diet. While Kaiser stresses that a low-fat diet is still very important for good health, you need to distinguish between the so-called bad fats (saturated and trans fats) and the good ones (monounsaturated and polyunsaturated fats) which are in these foods. Keep in mind that even the good fats are still high in calories, so you need to eat them moderately.

The form of vitamin E that is most beneficial is called alpha-tocopherol vitamin E (AT). Adults need about 15 milligrams of AT a day.

Some good sources of vitamin E are:

  • Roasted sunflower seeds (1 ounce): 7.4 milligrams
  • Almonds (1 ounce): 7.3 milligrams
  • Peanut butter (2 tbsp): 2.5 milligrams
  • Tomato sauce (1/2 cup): 2.5 milligrams

Specific groups of people may need more of these important nutrients as well.

  • Vitamin D plays a crucial role in allowing your body to use calcium. Since vitamin D is manufactured in your body when you're exposed to sunlight, people who don't get outside much -- or who have darker skin, or never go out without sunscreen -- are at risk. Vitamin D doesn't occur in high quantities in foods naturally. So you may need to rely on fortified foods and supplements -- or just get some more sun every day.
  • Folic acid is key for women during pregnancy, since it can reduce the risk of birth defects. Good sources are lentils, spinach, and broccoli. Pregnant women generally need to take 600 micrograms/day of folic acid supplements.
  • Iron is important for younger women and pregnant women especially, Kaiser says. Good sources are meats -- like beef, turkey, and chicken -- as well as spinach, kidney beans, soy beans, and many fortified foods.
  • Vitamin B12 is key in the formation of red blood cells. As people age, it's harder for them to absorb it from food. So all people over 50 should seek out foods fortified with B12 -- like many cereals -- or to take B12 supplements, says Kaiser. The recommended daily amount is 2.4 micrograms/day.

It might seem a lot simpler to take supplements and avoid the hassle of hunting down nutrients in natural food. But experts feel that supplements should generally be a last resort.

"I always tell people to try to get nutrients from food first," says Gidus. As the name suggests, supplements are supposed to supplement a healthy diet -- not replace important nutrients. Besides, many studies of supplements have found that they don't offer as many health benefits as nutrients found naturally in food.

There are cases where your doctor might recommend a supplement. For instance, if you're at risk of osteoporosis, your doctor might want you to take calcium and vitamin D to keep your bones strong.

Gidus still doesn't have a problem with taking a daily multivitamin. "I tell people it's OK to use a multivitamin as a cheap insurance policy," she tells WebMD.

However, you should be careful not to get too much of some nutrients. More isn't always better. Some nutrients can become toxic in high doses. And since so many foods are fortified these days, it's easier to get too much of some nutrients than it used to be.

Whatever you do, don't take supplements willy-nilly. Take a look at your diet first to see if you really need them and then talk with your doctor.

It's not easy to know if you're getting enough of the important nutrients lacking in the traditional American diet. You can look for some -- like fiber and vitamin C-- on nutrition labels. But you're not going to find all of them listed -- like magnesium and potassium, for instance.

What's the solution? Should you keep detailed records of your diet, and eat all meals with a scale and a calculator to tabulate your mineral intake? No, the experts say. "Don't get too worried about the exact amounts," says Gidus.

Instead, just try to eat a wide variety of foods, focusing on fruits, vegetables, and whole grains especially. It's the best way to cover your bases and get all these nutrients in food. Again, try not to get too focused on what you shouldn't eat. Don't scan the label looking for a reason to reject a food. Instead, look for reasons to include it.

"So what if a food has a little fat or a little sugar?" Gidus says. "It might have important nutrients that you really need too."