You probably know the old saying about an apple a day keeps the doctor away. Most of us heard it as children, usually from a parent handing over fruit instead of candy.
Whether the saying actually holds up has turned out to be harder to pin down than you might think.
A randomized controlled trial in the American Journal of Clinical Nutrition found that adults who ate two apples a day for eight weeks saw their LDL cholesterol drop.
Because it was a crossover design, the same 40 people also spent eight weeks drinking a sugar-matched control beverage. The cholesterol dip only showed up with the fruit.
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The participants were middle-aged adults with slightly high cholesterol to begin with. Their average age was 51, and the group included men and women in roughly equal numbers.
The trial was not dramatic
The fall in LDL cholesterol was modest but statistically significant. Total cholesterol went down a similar amount. Blood triglycerides, another fat in the blood, also fell.
The researchers also measured a marker called ICAM-1, which rises in the lining of blood vessels when the vessels are irritated. That marker dropped as well.
Small blood vessels responded a little better to a test of their ability to relax, another hint that circulation improved during the apple weeks.
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Nothing in the trial was dramatic. Two apples a day did not act like a cholesterol drug. But picking up a measurable change from fruit alone, in a randomized crossover design, is unusual for a nutrition study.
Two things stand out
Two things in apples stand out in nutrition research. One is pectin, a type of soluble fiber. The other is a group of plant compounds called polyphenols, concentrated in the skin.
Harvard T.H. Chan School of Public Health describes how soluble fiber works. It binds to bile acids in the gut and carries them out with waste. The liver then pulls cholesterol out of the blood to build fresh bile, which nudges LDL downward.
The daily apple dose in the trial supplied close to a gram of polyphenols, most of them from a group called proanthocyanidins.
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Lab work has linked these compounds to lower inflammation and better blood vessel function.
Harvard Health reaches the same conclusion from a wider base of research. The site notes that eating one medium apple a day may help lower blood pressure, cholesterol, and inflammation, pointing to a 2020 review of 16 studies.
How to make the effect count at breakfast
Pectin and polyphenols sit mostly in and just under the skin.
Peeling an apple throws much of the benefit in the bin. Eating the fruit whole, skin and all, gives you both the fiber and the plant compounds in one bite.
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Apples are not the only common food shown to nudge LDL down from the inside. Oats work through the same soluble-fiber route, and avocados, beans, and barley have related effects in trials.
If your cholesterol is already high, two apples a day do not replace what your doctor has you on. They may fit alongside it.
Talk with your doctor if you plan to make food changes as part of a cholesterol plan.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.