Friday Favorites: For Flavonoid Benefits, Don’t Peel Apples

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

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 to help visualize. If you follow thousands of older women over time, for example, you might see a survival curve like this. 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…like this. Over the same time period, 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 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.”

I’ve got more videos coming up on other natural low-cost methods for preventing and treating our leading killers; so, keep your eyes peeled—but, keep your apples unpeeled.

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• Hodgson JM, Prince RL, Woodman RJ, et al. Apple intake is inversely associated with all-cause and disease-specific mortality in elderly women. Br J Nutr. 2016;115(5):860-7.
• Bondonno NP, Lewis JR, Prince RL, et al. Fruit Intake and Abdominal Aortic Calcification in Elderly Women: A Prospective Cohort Study. Nutrients. 2016;8(3):159.
• Knekt P, Jarvinen R, Reunanen A, Maatela J. Flavonoid intake and coronary mortality in Finland: a cohort study. BMJ. 1996;312(7029):478-81.
• Bondonno NP, Bondonno CP, Blekkenhorst LC, et al. Flavonoid-Rich Apple Improves Endothelial Function in Individuals at Risk for Cardiovascular Disease: A Randomized Controlled Clinical Trial. Mol Nutr Food Res. 2018;62(3).
• Rees A, Dodd GF, Spencer JPE. The Effects of Flavonoids on Cardiovascular Health: A Review of Human Intervention Trials and Implications for Cerebrovascular Function. Nutrients. 2018;10(12).
• Bondonno CP, Yang X, Croft KD, et al. Flavonoid-rich apples and nitrate-rich spinach augment nitric oxide status and improve endothelial function in healthy men and women: a randomized controlled trial. Free Radic Biol Med. 2012;52(1):95-102.

Image credit: Alexandra via pixabay. Image has been modified.

Motion graphics by Avocado Video