APPLE TREE of knowledge
We are learning more about the health benefits of apples, particularly when eaten with the peel on, Dr. Joe Schwarcz writes.
Where would you find the most famous apple tree in history? The Garden of Eden might be difficult to locate, but in any case, the biblical story makes no mention of apples. The fruit of “the tree of knowledge of good and evil,” forbidden to Adam and Eve, is not named.
Curiously, the Latin word “malum” means both “evil” and “apple” — which may well have led to the association of the renowned tree with apples by early Christians. John Milton then cemented the image in his classic Areopagitica with the lines: “It was from out the rind of one apple tasted that the knowledge of good and evil, as two twins cleaving together, leaped forth into the world.”
While the Garden of Eden is mythical, Woolsthorpe Manor in Lincolnshire, England, is as real as can be. And in the garden of that Manor stands the apple tree that can indeed be deemed the most famous in history, for it was a falling apple from that tree that led Isaac Newton to eventually formulate his classic theory of gravity. No, the apple didn’t fall on his head, as many cartoons depict, but the falling-apple story is true. Newton himself gave the account to a number of people, including William Stukeley, who wrote the first biography of Newton in 1752.
According to Stukeley, Newton described the event to him in his own words. “Why should an apple always descend to the ground, I thought, why should it not go sideways or upwards? Assuredly the reason is that the Earth draws it.”
And so began the formulation of the theory of gravity as finally stated in Newton’s classic work, Principia: “Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.”
But had it not been for the plague, Newton’s mind may never have been put into motion by the falling apple. The terrible disease struck England in 1666, forcing many institutions including Cambridge University, where Newton was studying, to be closed. He returned home to Woolsthorpe where he spent time sitting in the garden and made the chance observation that would lead him to conclude that the same physical laws that governed the falling apple also applied to the movement of the heavenly bodies. What history does not record is whether Newton ate the fallen apple. Maybe he did. And maybe he ate the fruit regularly. After all, he lived to the age of 85, stunningly long for the times.
Apples have long been associated with good health, dating back to such early medical notables as Hippocrates and Galen, who suggested eating apples after a meal to aid digestion. The world’s first medical school, the Schola Medica Salertinata, established in the 9th century, taught that cooked apples were useful for disturbances of the bowel, lungs and nervous system. Master surgeon John Gerarde in 1597 recommended apples for the treatment of “hot stomacke.” And then in 1886, a Welsh magazine offered up the proverb, “Eat an apple on going to bed and you’ll keep the doctor from earning his bread.” This was eventually shortened to the popular, oft-repeated phrase, “An apple a day keeps the doctor away.”
That, of course, is wishful thinking; no single food has such miraculous properties. But we are learning more and more about the benefits of apples, particularly when eaten with the peel on. Apple peel is particularly rich in polyphenols, compounds with significant antioxidant activity.
Antioxidants are reputed to have all sorts of health benefits because they neutralize the potentially damaging “reactive oxygen species” that are byproducts of our body’s use of oxygen. While specific antioxidants in pill form have been disappointing, there is a wealth of evidence indicating that consumption of fruits and vegetables is protective against disease. Perhaps other modes of action of plant chemicals are more important than antioxidant activity. Some studies suggest that polyphenols may alter gene expression; others indicate that they may have “prebiotic” activity, meaning that they can modify the bacterial flora in our gut, which in turn can have health benefits.
There is obviously a great deal of interest in further exploration of the link between naturally occurring chemicals in plants and our well-being. One approach is to study the effect of exposing cells cultured in the laboratory to specific food extracts, with cancer cells being of particular interest. Recent studies have shown that apple peel extracts can significantly reduce the proliferation of a variety of cancer cells, including those isolated from breast, prostate and liver tumours.
Certainly this is interesting and worthy of further research, but such experiments offer no evidence for the use of apple-peel extract in humans for the prevention or treatment of cancer. On the other hand, we do have plenty of epidemiological studies that have linked apple consumption with a reduced risk of lung cancer, cardiovascular disease, chronic obstructive pulmonary disease and even stroke.
Understandably, the antiproliferative effect of apple-peel extract on cancer cells has boosted research into its potential use as a dietary supplement. One particular extract of organic apple peel, marketed as Apple Boost, has already been shown to increase antioxidant activity in the blood of people who consumed the powder, which is easily blended into smoothies or yogurt, over a 12-week period.
What we now need are studies to see if the antioxidant activity translates into health benefits over the long term. In the meantime, the best advice is to wash apples well and eat them with the peel. The more the better — except, notably, for people with inflammatory bowel disease, whose condition may be exacerbated.
Finally, it seems that it is time to stop the current practice of discarding the large amounts of apple peel generated by industries producing apple juice, apple sauce and baked apple products. Perhaps producers should take a bite out of the fruit of the tree of current knowledge. Unlike in the Garden of Eden, ignorance is not bliss.
joe.schwarcz@mcgill.ca Joe Schwarcz is director of McGill University’s Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.