He understood what we now know: Deficiencies of vitamins and other vital nutrients can cause us to fall prey to illness.
Specific nutrients in foods have been shown to enhance the body's ability to keep us well. Here are some tips from the Academy of Nutrition and Dietetics and other nutrition experts:
Protein: It's what immune cells are made of. Sources of immune-building protein include lean beef, pork and poultry, fish, eggs, beans and soy-based foods.
Vitamin A: Ever wonder why moms used to dose their darlings with cod liver oil to keep them healthy? Among other components, cod liver oil is a good source of vitamin A -- a nutrient that helps maintain the cells that line our intestines and lungs.
These "mucosal" cells are the sentries that guard our body from foreign invaders.
Carrots, kale, spinach, sweet potatoes and red bell peppers are good sources of vitamin A (or beta-carotene which safely converts to vitamin A in the body.)
Vitamin C: Although scientists still don't understand the exact way that vitamin C works to boost immune function, we do know this essential vitamin plays an important role in healing wounds and strengthening our resistance to disease. Vitamin C also helps form antibodies that fight off infection.
Since this essential nutrient is easily destroyed by air, heat and prolonged storage, we are smart to eat at least one high vitamin C food each day.
Sources include oranges, grapefruit, strawberries, tomatoes, peppers, kiwifruit, broccoli and Brussels sprouts.
Zinc: Like an army that relies on a continual renewal of supplies and soldiers, our immune system relies on zinc to consistently renew disease-fighting cells. And since zinc in food is bound to protein, it makes sense that good sources include oysters, beef, pork, and liver as well as whole grains, beans, nuts and seeds.
Interestingly, zinc has been called "the essential toxin" because -- although it is required for optimal health -- excessive intake can actually impair immune function.
Vitamin E: Given its antioxidant ability to neutralize free radicals, vitamin E keeps the machinery of the immune system functioning at capacity.
Good sources include nuts, seeds, and whole grains. Wheat germ is an especially good source of vitamin E.
What about supplements of vitamins and minerals? If we don't happen to eat a varied diet, we could be missing out on essential vitamins and trace minerals.
It's a discussion worth having with your health provider.
Barbara Quinn is a registered dietitian Email her at bquinnchomp.org.
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