Zinc is a mineral your body needs in trace amounts for a variety of functions, especially for immune function and fat metabolism. Zinc deficiency has traditionally been a problem limited to third-world countries, although soil depletion and changing dietary habits have lead to increased rates within industrialized countries, such as the United States, according to "Nutrition Concepts & Controversies" by Frances Sizer. Zinc content in bananas fluctuates according to the mineral content of the soil, but varieties sold in U.S. supermarkets are generally considered a fairly good source.
Zinc
Zinc deficient soil contribute to deficiency symptoms, but so do intestinal malabsorption problems, liver and kidney disease and vegetarian diets, as the richest sources of zinc are animal and seafood products. Initial zinc deficiency symptoms include noticeable problems with your skin, hair and fingernails. You may develop more blemishes or scaly skin, notice white marks on your fingernails or see abnormal hair loss in the shower or on your pillow. Long-term problems include compromised immune response, organ failure and reduced visual acuity. To avoid deficiency symptoms, the National Institutes of Health recommend that you consume between 8 and 13 mg of zinc each day depending on your age and gender, either from food sources or supplements. Bananas are not known as an excellent source of zinc, but they do contain fairly reliable amounts.
Bananas
Bananas are a commonly available and affordable fruit throughout the U.S. They are known as a high source of carbohydrates that are readily absorbed and metabolized to supply energy. Bananas can impact insulin levels fairly dramatically, which is why diabetics are warned about their consumption. Bananas are also a very good source of potassium and magnesium, although they do contain some zinc. According to the "American Dietetic Association Complete Food and Nutrition Guide," a medium-sized banana weighing 120 g contains about 0.18 mg of zinc, which is approximately 2 percent of your daily RDA depending on your age and gender. By comparison, the same banana contains about 420 mg of potassium and 32 mg of magnesium.
Other Fruit Sources of Zinc
Bananas are not the only fruit that contains zinc, nor are they the best source. A much better source is avocado, which contain about 1.3 mg of zinc in medium-sized examples, according to Carolyn Berdanier's "CRC Desk Reference for Nutrition." A medium-sized pomegranate contains nearly 1 g of zinc, while a cup of blackberries contains about 0.75 mg. In general, berries contain much more zinc than bananas do.
Rich Sources of Zinc
The best sources of zinc are not fruit at all, but meats, seafoods, cereals and nuts, especially liver, red meat, raw oysters, crab, lobster, bran and peanuts, according to the "American Dietetic Association Complete Food and Nutrition Guide." For example, 1 cup of raw oysters can contain over 250 mg of zinc, while 1 cup of enriched bran flakes contains nearly 55 mg. Dairy products, such as milk and cheese, are other good sources.
References
- "Nutrition Concepts & Controversies," 12th Edition; Frances S. Sizer, et al.; 2011
- National Institutes of Health: Zinc Fact Sheet
- "American Dietetic Association Complete Food and Nutrition Guide," 3rd Edition; Roberta Larson Duyff; 2006
- "CRC Desk Reference for Nutrition," 2nd Edition; Carolyn D. Berdanier; 2005
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