Can apple a day really keep the doctor away? Studies show eating apples is linked to reduced risk of heart disease, T2 diabetes, lung cancer and asthma.
We all know that eating lots of fresh fruit and vegetables is good for our health – five servings of vegetables and two of fruit a day – but new research shows that the old adage of “an apple a day keeps the doctor away” might be true. Some 85 different studies have found apples’ high levels of powerful antioxidants help protect the eater against cell-damaging free radicals, which could contribute to various cancers, cardiovascular disease, T2 diabetes and even asthma.
Polyphenols Source of Apples’ Antioxidant Power
While apples do contain some vitamin C (an average 100 gram (3.5 ounce) apple contains about 5.7 milligrams), it’s not the main source of apples’ antioxidant power. This is due to the apple’s amazing array of phytonutrients, which brings their antioxidant activity up to a massive equivalent of about 1,500 mg of vitamin C.
Apples contain the polyphenols – quercetin, kaempferol and myricetin, catechins, anthocyanins (if the apples are red-skinned), chlorogenic acid, phloridizin, and several dozen more health-supportive polyphenol nutrients. These have been extensively researched in recent years.
Eating Apples Good for Heart Health
As well as the antioxidants preventing lipid peroxidation of blood vessels, apples offer other benefits to cardiovascular health. In addition, the water-soluble fibre (pectin) in apples helps reduce total cholesterol and LDL-cholesterol through regular eating of apples.
A review of several studies into the effect of bioflavonols on coronary heart disease,”The relation between dietary flavonol intake and coronary heart disease mortality: a meta-analysis of prospective cohort studies,” published in the European Journal of Clinical Nutrition in 2003, concluded that “high dietary intake of flavonols from a small number of fruits and vegetables… may be associated with a reduced risk from CHD mortality.”
At the same time, other research has shown that the quercetin content of apples also provides our cardiovascular system with anti-inflammatory benefits. Blood levels of C-reactive protein, or CRP (a marker for inflammatory processes) are reduced following consumption of apples and researchers believe that the quercetin content of apples is the primary reason for this drop in CRP.
Cancer-protective Properties of Apples
Although it’s been suggested that apples’ antioxidant properties may help reduce the risk of developing cancer – especially breast and colon cancers – studies into lung cancer have shown the best results.
A study published in the International Journal of Cancer in August 2008, “Dietary flavonoid intake and risk of cancer in postmenopausal women,” noted that “Flavonoids… are thought to lower cancer risk through their antioxidant, antiestrogenic and antiproliferative properties. We examined the association of intake of total flavonoids and seven flavonoid subclasses with risk of lung, colorectal, breast, pancreatic and upper aerodigestive cancer among women in a large prospective cohort study.”
The only clear result was for a reduction in the risk of lung cancer, especially among smokers and former smokers. The authors concluded that “This study provides further support for a beneficial effect of flavonoid intake on lung cancer risk, especially among current and past smokers.”
Apples Help Regulate Blood Sugar
A new area of research into the health benefits of apples, is their effect on blood sugar levels and the management of T2 diabetes. A review of studies of animal models and a limited number of human studies, published in the International Journal of Molecular Science in April 2010, “Impact of Dietary Polyphenols on Carbohydrate Metabolism” showed that “dietary polyphenols may influence carbohydrate metabolism at many levels.”
The polyphenols affect our digestion and the absorption of carbohydrates, improving regulation of blood sugar. They do this in four ways:
slowing down carbohydrate digestion. Quercetin and other flavonoids inhibit carbohydrate-digesting enzymes so carbohydrates are broken down less readily into simple sugars, and less load is placed on our bloodstream to accommodate more sugar.
reducing glucose absorption. Apples’ polyphenols have been shown to lower the rate of glucose absorption from our digestive tract.
stimulating the pancreas to produce more insulin. By telling the beta cells of our pancreas to produce more insulin, the polyphenols help us clear more sugar from our blood and keep our blood sugar level in better balance.
stimulating insulin receptors to bind onto more insulin and increase the flow of sugar out of our bloodstream and into our cells, where it’s needed for energy. Polyphenols in apples help to activate cell insulin receptors, facilitating the passage of sugar from the bloodstream into our cells.
The Best Way to Enjoy Apples
For maximum health benefits from apple’s polyphenols, vitamin C and soluble fibre, it’s recommended to eat at least one apple a day. Whole apples are a much better nutritional choice than apple juice. Not only are whole apples richer in dietary fibre, but the current processes of juice production drastically reduce the phytonutrient concentrations originally found in the whole fruit. Of course, if you juice the apples yourself, and drink the juice as soon as possible after making it, you will gain the benefits of most of the micronutrients, although not much of he soluble fibre.
Where possible, eat the apple with the skin on, as many of the phytonutrients are concentrated just under the skin. Wash the apple under running water while gently scrubbing for 10 to 15 seconds to remove pesticides, waxes and other residues. Fresh sliced or diced apple, with the skin on, is a good addition to any salad of vegetables or fruit. And slices of apple, eaten with either a strong or mild cheese, is a delicious combination.
Try to cook apples as little as possible to preserve the nutrients. In particular, avoid boiling or simmering to make applesauce. Almost all the antioxidant content will be destroyed, although you will retain the soluble fibre and apple’s small amount of B vitamins and calcium.