Nutrients in Apples
Apples are an excellent source of vitamin C and dietary fiber. They are a good source of potassium. Apples are a rich source of the flavanoid quercetin.

Lower Cholesterol
In a study on moderately obese male and female subjects, polyphenols extracted from apples were shown to significantly lower cholesterol. Apples are also high in pectin, a soluble fiber with the ability to lower cholesterol, and it has been demonstrated that an apple a day can lower cholesterol by up to 16 percent. Quercetin found in apples prevents the oxidation of LDL cholesterol.

Cancer Prevention
Studies have shown that quercetin found in apples reduces the cancer risk of prostate cancer, ovarian cancer, breast cancer, and colon cancer.
Laboratory studies have demonstrated that quercetin treatment of prostate cancer cells results in decreased cell proliferation and viability. It was demonstrated that quercetin promotes prostate cancer cell apoptosis (cell death) by down-regulating the levels of heat shock protein (Hsp) 90. Quercetin inhibits growth in prostate cancer cells while exerting no quantifiable effect on normal prostate cells.
Results from other studies indicate that apple peels phytochemicals have potent antioxidant activities, and may be partially responsible for the cancer prevention activities of whole apples. In other research conducted at Sammons Cancer Center, Dallas, it was found that the annurca variety of apple from southern Italy was rich in polyphenols associated with cancer prevention properties. Incidences of colon cancer are lower in southern Italy than anywhere else in the western world.

Weight Loss
Regular consumption of apples can promote healthy weight loss.
Results from a clinical trial conducted involving forty-nine women indicated that energy densities of fruits could help to promote weight loss over time.In a study of overweight women, weight loss was associated with a diet supplemented with 3 apples a day.

Glycemic Index (GI)
In a study to determine the estimated GI of various foods, it was concluded that apples have a low GI of 40.

Antioxidants
Flavanoids found in apples and other fruit and vegetables are known for their antioxidant activity, antioxidants neutralize free radicals which cause cell damage.

Anti-inflammatory
In an in vitro study at the Boston University School of Medicine, it was concluded that the flavonoid quercetin, which is present in apples, has anti-inflammatory activity.

Heart Disease
The quercetin found in apples is associated with reduced risk of coronary heart disease, and apple consumption has consistently been associated with reduced heart disease.

Dietary Fiber
The high fiber content of apples is also of great benefit to the bowels. A 5-ounce apple can supply the body with more than 3 grams of fiber, 10 percent of the daily-recommended intake. The fiber in apples will be beneficial for losing weight, and the fructose will help to stabilize blood sugar levels. Apple polyphenols have demonstrated the ability to regulate fat metabolism.