There's some truth to the adage ‘An apple a day...’

Q: What happens to you if you eat more than one apple a day?

I realize that this question was meant to be humorous, but there is a serious answer to it. Believe it or not, there is a three-apple-a-day diet, which I'll get to later. But, first, let's discuss a single apple a day.

We have to go back in time to Wales to find the origins of “An apple a day keeps the doctor away.”

The earliest known record of the maxim is in an 1866 edition of Notes and Queries magazine:

A Pembrokeshire proverb. Eat an apple on going to bed, And you'll keep the doctor from earning his bread.

A number of variations were heard around the turn of the 20th century. In 1913, there's a record in Rustic Speech and Folk-lore of the first known mention of the version we use now:

Ait a happle avore gwain to bed, An' you'll make the doctor beg his bread; or as the more popular version runs: An apple a day keeps the doctor away.
Apples have many healthful qualities, but they don't keep the doctor away. A better rhyme today would be: You'll hit a wall if you want a house call.

So what's in an apple that makes it so good for you?

• Vitamin C, which boosts your immune system.
• Pectin, a fiber that lowers blood pressure and bad LDL cholesterol.
• Boron, a nutrient that is good for your bones and brain.
• Quercetin, a nutrient that may work against cancer and Alzheimer's disease.
• Phytonutrients, compounds that can reduce the risk of heart disease, diabetes and asthma.

Researchers in the Netherlands found that eating apples is associated with a lower risk of stroke. They don't know why, but the anti-stroke effect may be from the pectin that lowers blood pressure, and the quercetin that may have anti-inflammatory properties.

Apples help you fight obesity. They fill you up. They have lots of fiber and require that you spend time chewing. The natural sweeteners in apples level your blood sugar so you avoid cravings.

The 3-Apple-A-Day Plan is a diet that instructs you to eat an apple before every meal because the fiber in apples makes you feel full and the sweetness satisfies cravings.

Apples are brain food. Apples are thought to keep your brain sharp as you age because they boost the production of a chemical that transmits messages between nerve cells.

Apples are good for fighting tooth decay, too, because they clean your teeth when you eat them.