It turns out that the old adage, "An apple a day will keep the doctor away," may actually hold some truth. This humble fruit, long a staple of fruit baskets and brown bag lunches, contains several nutrients and compounds that doctors say may help boost the immune system. The fact that the fruit is both tasty and versatile in preparation is simply the icing on the proverbial cake -- a healthy, disease-fighting fruitcake, of course.
Soluble Fiber
Apples come recommended by the University of Illinois as a immune system booster thanks to its soluble fiber. While all fiber can be beneficial for your health, soluble fiber actually "changes the personality of immune cells," says Dr. Gregory Freund of the University of Illinois. The fiber in apples causes your immune cells to switch gears into an anti-inflammatory mode, which the university reports may help you recover and overcome an illness much faster than usual.
Flavonoids
Just like other immunity-enhancing foods, such as green tea and onions, apples contain potent levels of flavonoids. This is a type of antioxidant that scours your body and helps your immune system defeat dangerous, disease-causing particles known as free radicals. In fact, the Linus Pauling Institute notes that apples provide Americans with 22 percent of their dietary intake of flavonoids. For the best results, choose dark red apples, such as Red Delicious, which the institute calls "remarkably protective against oxidation."
Vitamin C
The average medium-size apple measuring approximately 2.5 inches across packs a nice vitamin C punch: 8 mg. In a meta-analysis of dozens of research studies, the Linus Pauling Institute reports that vitamin C may help boost your immune system to ward off myriad problems, including the common cold, by stimulating virus- and bacteria-fighting white blood cells known as neutrophils.
Pectin
Apples offer up a rich source of pectin. When you eat an apple, the pectin enters your digestive tract. There, beneficial bacteria ferment the pectin. This in turn stimulates your immune system's production of white blood cells and antibodies for a potentially stronger defense against illness.
Potassium
Your immune system, and all the cells in your body, require potassium. This mineral helps conduct electrical charges in your body for proper cell functioning and communication. This is essential when your body's fighting a viral or bacterial invasion. The average apple offers up 159 mg of this critical mineral.
References
- University of Illinois; An Apple a Day? Study Shows Soluble Fiber Boosts Immune System; Gregory Freund; March 2010
- Linus Pauling Institute; Why Apples are Healthful; Silvina Lotito; November 2004
- University of Illinois Extension: Apple Nutrition
- Linus Pauling Institute; Vitamin C; Jane Higdon; November 2009
- "Daily Mail"; An Apple a Day Keeps the Doctor Away; Penny Stanway; April 2011
- University of Maryland Medical Center; Potassium; Steven Ehrlich; May 2009
