The Incredible Edible Apple

Have you ever noticed that every month seems to bring a trendy new diet? And yet obesity rates continue to rise and with it a growing number of health problems. That’s why I wrote my new book How Not to Diet. Check it out at your local public library. Welcome to the Nutrition Facts Podcast. I’m your host Dr. Michael Greger.

Today, we examine the merits of an almost biblical fruit.  The apple.  In our first story, we ask which would save more lives: a prescription to eat an apple a day, or statin drugs?

Does an apple a day really keep the doctor away? That’s “a public health message” that’s been around since 1866, but is it true? You don’t know, until you put it to the test: “The association between apple consumption and physician visits,” published in the AMA’s internal medicine journal. “Objective: To examine the relationship between eating an apple a day and keeping the doctor away.”

“Promoted by the lay media and powerful special interest groups including the US Apple Association” so powerful that Big Apple recently spent a whopping $7,000 lobbying politicians  “the beneficial effects of apple consumption” may include a facilitation of “weight loss,” protection of the brain, “cancer suppression, a reduction in asthma symptoms, and improved cardiovascular health.” So, apple consumers ought to require less medical care, right? “Although some may jest, considering the relatively low cost of apples, a prescription for apple consumption could potentially reduce national health care spending if the aphorism holds true.”

So, they compared daily apple-eaters to non-apple-eaters, and asked if they had been to the doctor in the last year, been hospitalized, seen a shrink, or took a prescription medication within the last month. 8,000 individuals surveyed, and only about one out of ten reported eating an apple over the last 24 hours. And, the “evidence does not support that an apple a day keeps the doctor away.” So, maybe it takes more than an apple a day. Maybe we need to center our whole diet around plant foods. “However, the small fraction of US adults who eat an apple a day do appear to use fewer prescription medications.” So, maybe the proverb should be updated to clarify that, if anything, “apple eating may help keep the pharmacist away.”

But, hey, based on the average medical prescription cost, the difference in “annual prescription medication cost per capita between apple eaters and non-apple eaters” could be hundreds of dollars. So, “if all US adults were apple eaters,” we could save nearly $50 billion. Of course, if you factor in the cost of the apples themselves, we’d only get a net savings of like $19 billion. If this all seems like a bit of tongue-in-cheek-apple-polishing, you’ll note this was published suspiciously close to April Fool’s day. And, indeed, this was in the tradition of the British Medical Journal’s annual Christmas issue that features scientifically rigorous yet light-hearted research, which itself took on the apple issue “to model the effects on stroke and heart attack mortality of all older adults being prescribed either a cholesterol-lowering statin drug or an apple a day.

Basically, they took studies like this, where you see this nice dose response where the more fruit you eat, the lower your stroke risk appears to fall. And, similar data for heart disease, compared to the known drug effects, and concluded that “prescribing an apple a day is likely to have a similar effect on population stroke and heart attack mortality” as giving everyone statin drugs instead. And, hey, apples only have good side effects. “Choosing apples rather than statins may avoid more than a thousand excess cases of muscle damage and more than 12 000 excess diabetes diagnoses,” because statins increase the risk of diabetes, and this was in the UK. Here in the U.S., one would expect five times those numbers though, ironically, “the cost of apples is likely to be greater than those of statin drugs.” Generic Lipitor is only like 20 cents a day.

So, yes: “With similar reductions in mortality, the 150 year old health promotion message of an apple a day is able to match modern medicine and is likely to have fewer side effects.” But, apples are a few pennies a day more expensive, not to mention the increased time and difficulty associated with consuming an apple compared to a statin. I mean just one gulp with the drug, compared to all that “time consuming” chewing.

In our next story, we look at how peeled apples are pitted head-to-head against unpeeled apples and spinach in a test of artery function.

Regular apple consumption may contribute to a lower risk of dying prematurely. Moderate apple consumption, meaning like an apple or two a week, was associated with a 20 percent lower risk of dying from all causes put together, whereas those who ate an apple a day had a 35 percent lower risk.

You’ll often hear me talking about a lower or higher risk of mortality, but what does that mean? Isn’t the risk of dying 100 percent for everyone, eventually? Let’s look at some survival curves. If you follow thousands of older women over time, for example, you might see a survival curve. They all start out alive, but over a period of 15 years, nearly half succumb. Okay, but this is the survival curve of those who rarely, if ever, ate apples less than 20 a year. Those averaging more like half a small apple a day instead fall off  closer to only about 40 percent died. And those who ate an apple a day, one small apple or about a quarter of a large apple, did even better survived even longer.

Why is that the case? It seems to be less the apple of one’s eye than the apple of one’s arteries. Even a fraction of an apple a day is associated with 24 percent lower odds of having severe major artery calcifications, a marker of vascular disease. And if you’re like, duh, it’s a fruit, of course it’s healthy, the effect was not found for pears, oranges, or bananas.

Both these studies were done on women, but a similar effect was found for men, for apples and onions; we think because of the flavonoids, naturally-occurring phytonutrients concentrated in apples, thought to improve artery function and lower blood pressure, leading to improvements in blood flow throughout your body and brain thereby decreasing the risk of heart disease and strokes. But you don’t know until you put it to the test.

When I first saw this paper on testing flavonoid-rich apples, I assumed they had like selectively bred or genetically engineered some special apple, but no, the high-flavonoid apple was just an apple with its peel on, compared to the low-flavonoid apple, which was just the exact same apple but with the peel removed.

Over the next three hours, flavonoid levels in the bloodstream shot up in the unpeeled apple group, compared to the peeled apple group, which coincided with significantly improved artery function peeled versus unpeeled. They conclude that the lower risk of cardiovascular disease with higher apple consumption is most likely due to the high concentration of flavonoids in the skin, which improve artery function, though it could be anything in the peel. All we know is that apple peels are particularly good for us, improving artery function and lowering blood pressure.

Even compared to spinach? Give someone about three-quarters of a cup of cooked spinach, and within two to three hours, their blood pressure drops. Instead, eat an apple with some extra peel thrown in, and you get a similar effect.

The researchers conclude that apples and spinach almost immediately improve artery function and lower blood pressure. What’s nice about these results is that we’re talking about whole foods, not some supplement or extract; so, this could easily translate “into a natural and low-cost method of reducing the cardiovascular risk profile of the general population.”

Finally today, we look at the health benefits associated with apple consumption.

Regular apple intake is associated with all sorts of good things, like living longer particularly a lower risk of dying from cancer. Here’s the survival curve of elderly women who don’t eat an apple a day. Ten years out, nearly a quarter had died, and 15 years out, nearly half were gone. But, those who average like a half an apple a day didn’t drop off as fast, and those eating an apple a day, more than three and a half ounces of apples a day, like a cup of apple slices stayed around even longer. Yeah, but maybe people who eat apples every day just happen to practice other healthy behaviors, like exercising more, or not smoking, and that’s really why they’re living longer. Well, they controlled for most of that obesity, smoking status, poverty, diseases, exercise so as to compare apples to apples (so to speak!).

But, what they didn’t control for was an otherwise healthier diet. Studies show that those who regularly eat apples have higher intakes of not just nutrients like fiber, found in the apples, but they’re eating less added sugar, less saturated fat. In other words, they’re eating overall healthier diets. So, no wonder apple eaters live longer, but is apple eating just a marker for healthy eating, or is there something about the apples themselves that’s beneficial? You don’t know, until you put it to the test.

There are all sorts of fun studies like this, where subjects were randomly assigned in the morning to nothing, a caffeinated energy drink, black coffee, or an apple given that athletes use a variety of common strategies to stimulate arousal, cognition, and performance before their morning training. Did the apple hold its weight? Yes, appearing to work just as well as the caffeinated beverages. The problem with these kinds of studies, though, is that they’re not blinded. Those in the apple group knew they were eating an apple. So, there may have been an expectation bias, placebo effect, that made them unconsciously give that extra bit of effort in the testing, and skew the results. You just can’t stuff a whole apple into a pill.

That’s why researchers, instead, test specific extracted apple components. So, they can perform a double-blind, placebo-controlled study, where half get the fruit elements, half get a sugar pill, and you don’t know until the end who got which. The problem there, though, is that you’re no longer dealing with a whole food removing the symphony of interactions between the thousands of phytonutrients in the whole apple.

Most of these special nutrients are concentrated in the peel, though. Instead of just dumping millions of pounds of nutrition in the trash, why couldn’t researchers just dry and powder the peels into opaque capsules to disguise them, and then run blinded studies with that? Even just “a small amount could greatly increase phytochemical content and antioxidant activity.”

The meat industry got the memo: “Dried apple peel powder decreases microbial expansion in meat and protects against carcinogen production” when you cook it. And, “one of the carcinogens formed during the grilling of meat is a beta-carboline” alkaloid, a neurotoxin, which may be contributing to the development of neurological diseases, like Parkinson’s. Uncooked meat doesn’t have any; the neurotoxin is formed when you cook it. But, you can cut the levels in half by first marinating the meat with dried apple peel powder.

And, it also cuts down on the amount of fecal contamination bacteria in the meat. Fecal bacteria growing before and after the addition of dried apple peel powder, in pork, beef, and turkey. Apple peels can also inhibit the formation of genotoxic, DNA-damaging, heterocyclic amines, cutting the effects of these cooked meat carcinogens by up to more than half. “In view of the risks associated with consuming these cancer-causing compounds in meat, there is a need to reduce exposure by blocking HCA formation such as adding apple peel powder during the cooking of meats to help prevent their production.” I can’t think of any other way to reduce exposure.

What about consuming apple peels directly? Dried apple peel powder was found to exhibit “powerful anti-inflammatory and antioxidant action.” But, this was in mice. Does it have anti-inflammatory properties in people? You don’t know, until you put it to the test.

A dozen folks “with moderate loss of joint range of motion and associated chronic pain” were given a spoonful of dried apple peels a day for 12 weeks, and pain scores dropped month after month, and the range of motion improved in their neck, shoulders, back, and hips. Conclusion: “Consumption of dried apple peel powder was associated with improved joint function and pain reduction.” Why just “associated”? Because there was no control group; so, they might have all been just getting better on their own, or it could have been a placebo effect. But hey, why not give apple peels a try by eating more apples?

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