The old saying that an apple a day keeps the doctor away may well be true. The humble apple, it turns out, is a powerhouse of beneficial compounds that can prevent heart disease, some forms of cancer, diabetes and even ease asthma.
Apples guard against heart disease via several routes. They are an excellent source of pectin, a water soluble fiber. Pectin lowers the amount of LDL cholesterol in the blood stream. It changes the composition of VLDL cholesterol (the precursor of LDL) so that is more likely to be broken down by fat burning enzymes. Apples also enable LDL cholesterol to resist oxidation- the apple antioxidants are incorporated into the LDL and oxidize in the place of the LDL, which prevents it from causing inflammation of the blood vessel walls. Apples cause the liver to sprout more LDL receptors, which means less LDL cholesterol gets loose into the bloodstream. They prevent the return of bile acids (which your body uses to make cholesterol) to the liver- this is how the drug Questran works. Pectin inhibits the ability of cholesterol to cross from the intestine into the cells. It also makes the blood cells less sticky, which reduces both clotting and atherosclerosis, and they relax the artery walls.
Pectin also keeps blood sugars steady; a Finnish study of 10,000 people showed that people with a higher apple intake had a reduced incidence of Type 2 diabetes. Other studies showed lower diabetes rates in those who have a higher intake of quercetin, which is abundant in apple peels.
Apples are the only food that is specific to a lower lung cancer risk. High apple consumption is associated with good lung health, and a reduced incidence of asthma- both for adults eating the apples, and for the babies of women who ate large amounts of apples during pregnancy. There is also a positive association between apple intake and lung function in general and with a lower incidence of chronic obstructive pulmonary disease.
Apples, and especially apple peels, have strong antioxidant activity and have been found to inhibit the growth of liver and colon cancer cells. This has been proved to be the result of the combination of compounds found in the apples, not just vitamin C or any other single component of the fruit. They are also anti-inflammatory and boost the immune system. It has even been shown that an extract from green apples inhibited the actions of cholera toxin!
Not all apples are created equal. Different breeds have different levels of antioxidants and polyphenols (sadly, there is not one which is highest in all the different beneficial components), and the amounts they contain vary with degree of ripeness, amount of sun the fruit received, how much nitrogen fertilizer the tree received (higher nitrogen equaled lower beneficial compounds), soil calcium, and with the application of some agricultural chemicals. Non-organic apples tend to be subjected to a lot of chemical sprays, and as a lot of the good compounds are in the peel, this is a fruit that it really pays to buy organic.
Amazingly, storage does not reduce the amount of the beneficial components. When processed, almost all the good compounds stay in the pomace, making apple juice nearly void of beneficial components. The best way to reap the rewards of apples wide array of benefits is to eat a whole, organic apple a day, peel and all.
Apple phytochemicals and their health benefits by Jeanelle Boyer and Rui Hai Liu http://www.nutritionj.com/content/3/1/5
Cholesterol Down, by Janet Bond Brill, Ph.D., R.D., LDN