Americans spend as much as $1.7 billion a year on vitamin and mineral supplements, but nutrition experts say much of what our bodies need to fight off infection can be found in foods.
In its latest edition, Prevention magazine says a poor diet is a top factor in making us susceptible to illness. It then lists the top five foods that give your body the best immunity: beef, sweet potatoes, mushrooms, tea and yogurt. While an all-around healthy diet is crucial, these particular foods help us best flex our immunity muscles, the magazine said.
Each of the foods should be eaten every day to boost immunity, nutritionist Heidi Skolnik told Good Morning America.
"We should eat these daily, as often as we can, especially in this weather," she said. Plenty of rest is also essential to keeping our immune systems up, she said. Health experts also advise a flu shot.
Beef It Up a Little
Of the five immunity-boosting foods, beef may be the most surprising, considering health experts recommend limiting our red meat intake. But moderation is still key.
"People should still not be eating a 24-ounce porterhouse on a daily basis," Skolnik said. "A three-ounce portion of beef — and importantly very lean beef that is low in fat — is an important source of zinc."
Zinc deficiency can greatly increase your risk of infection. Zinc helps develop white blood cells, the cells that we really need those to fight off foreign bacteria and viruses.
Vegetarians and those who do not eat red meat can look for their zinc supply in poultry, pork, fortified cereals, yogurt and milk. If you like oysters, they are also a fantastic source of zinc, Skolnik adds.
We should also be eating orange vegetables daily, especially this time of year. Sweet potatoes, or any of the orange vegetables, are a great way to add vitamin A to our diets. The reason? Vitamin A is important for our skin, which is the first line of defense for our immune systems, Skolnik said.
"Think orange, foods like sweet potatoes, and also carrots, squash, pumpkin," Skolnik said. "These are all great, especially because they are all in season this time of year. They all are great sources of beta-carotene, which the body quickly turns into vitamin A."
Although many of us eat carrots, it is often two or three days between servings, so we need to eat them more regularly, Skolnik said.
Mushrooms, Yogurt to the Rescue
To add to those 3-ounce lean burgers, mushrooms are another high-immunity food.
"Like beef, mushrooms help in the production of white blood cells in the body," Skolnik said. "Some recent studies have also found that they may make white blood cells act more aggressively against foreign bacteria."
The very best kinds of mushrooms are shiitake and maitake, which are available in most supermarkets.
In addition, the English may know something about fighting off a cold. Skolnik recommends a cup of black or green tea a day to muscle up our immune systems.
"Tea is a great source of polyphenols," Skolnik said. "Polyphenols clean up free radicals, damaging compounds that can hurt your DNA and accelerate aging."
Antioxidants take care of the free radicals, and tea has more antioxidants per part than fruits and vegetables.
Yogurt, another immunity-boosting food, is especially important to eat, particularly after you have been prescribed antibiotics. Brands that contain active cultures are a good source of healthy bacteria for your stomach.
"When we take antibiotics they destroy most of the bacteria in our body," Skolnik said. "The problem is that there are some beneficial bacteria that the antibiotics take care of as well. We need these, especially those found in our intestines, to help us break down foods."
The lack of those bacteria can make us vulnerable to germs that cause diarrhea, for instance.