5 Must-Haves You Are Missing from Your Diet
You need: 4,700 mg a day
You get: National survey data shows over 90 percent of Americans don't get the recommended daily allowance, says Willett, who is also the author of Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating.
Good sources: Eat a variety of fruits and vegetables that have higher levels, like broccoli, cantaloupe, winter squash, sweet potatoes and, yes, bananas (these foods should be eaten raw, steamed or baked but not boiled, since boiling depletes potassium.)
You need: 150 mcg a day; 250 mcg if pregnant (new research reveals that even a mild deficiency can have a long-term effect on brain development); 290 mcg if nursing.
You get: While iodine deficiencies are much less common than they were before the mineral was added to table salt in the 1920s, Willett says that a growing number of Americans are not getting enough. This is due, in part, to more people setting aside regular table salt in favor of non-iodized kosher or sea salt, or avoiding dairy products (iodine is often present in cow or goat feed, which is passed to us via their milk).
Good sources: If you tend to use non-iodized table salt, make sure you're eating enough seafood (seaweed, cod, shrimp, canned tuna), dairy foods, enriched grains and eggs. You could also consider taking a supplement.
You need: 600 IU a day; 800 IU if over 80.
You get: Willett says that about half of Americans, and 80 percent of those with darker skin, don't get enough (higher amounts of melanin in the skin interfere with vitamin D absorption).
Good sources: The easiest way to get vitamin D used to be from the sun, but now our risk of skin cancer is high enough that all dermatologists (and most nutritionists, including Willett) advise instead to rely on food or supplements. Your best bet is the flesh of fatty fish (such as salmon, tuna and mackerel). A tablespoon of cod liver oil has 340 times the RDA (though many folks cannot stomach it). Smaller amounts are naturally found in beef liver, cheese and egg yolks. You can also find vitamin D in fortified milk, yogurt and orange juice . (Talk to your doctor about supplements).
You need: 2.4 mcg (2.6 mcg if you're pregnant, 2.8 mcg if you're nursing).
You get: If you're a vegan or vegetarian, or you go for days without meat, fish or eggs, it's likely you're not getting enough vitamin B12. Adults over 50 also tend to have a harder time absorbing this vitamin, says Willett (a problem, especially since a deficiency accelerates cognitive decline, as do those with some intestinal and gastric conditions.
Good sources: Pescatarians, you're in luck: Clams are off the charts in B12, and rainbow trout and salmon are pretty high, too. If you don't eat any animal products at all, look for fortified cereals, nutritional yeast and supplements with 100 percent of the recommended daily value.
You need: 320 mg for women; 420 mg for men.
You get: Although we hear a lot about the importance of magnesium, studies show that more than half of us don't get enough—we're 100 mg short, on average, of the recommended amount.
Good sources: Nuts are magnesium powerhouses (almonds have the highest amount, at 80 mg per ounce, but cashews are a close second). Also look for green vegetables like spinach and okra, as well as soybeans, legumes, seeds and unrefined whole grains.
Next: Secret substitutions to make the foods you love even better