More berries, apples, and tea may protect against Alzheimer’s

A study published in the American Journal of Clinical Nutrition suggests that consuming more flavonoid-rich foods, such as berries, apples, and tea, may help protect against developing Alzheimer’s disease and related dementias. The epidemiological study of 2,800 people aged 50 and older examined the long-term relationship between eating foods containing flavonoids and the risk of Alzheimer’s disease (AD) and Alzheimer’s disease and related dementias (ADRD). While many studies have looked at associations between nutrition and dementias over short periods, the new study looked at exposure over 20 years.

To measure long-term flavonoid intake, the research team used dietary questionnaires, filled out at medical exams approximately every four years by participants in the Framingham Heart Study, a largely Caucasian group of people who have been studied over several generations for heart disease risk factors.

At the start of the study, the participants were free of AD and ADRD, with a completed valid food frequency questionnaire at baseline. Flavonoid intakes were updated at each exam to represent cumulative average intake across the five exam cycles. Researchers categorized flavonoids into six types and created four intake levels based on percentiles: less than or equal to the 15th percentile, 15th–30th percentile, 30th–60th percentile, and greater than 60th percentile. They then compared flavonoid intake types and levels with new diagnoses of AD and ADRD.

Low intake (15th percentile or lower) was equal to no berries (anthocyanins) per month, roughly one-and-a-half apples per month (flavonols), and no tea (flavonoid polymers). High intake (60th percentile or higher) was equal to roughly seven-and-a-half cups of blueberries or strawberries (anthocyanins) per month, eight apples and pears per month (flavonols), and 19 cups of tea per month (flavonoid polymers).

The researchers found that low intake (15th percentile or lower) of three flavonoid types was linked to a higher risk of dementia when compared to the highest intake (greater than 60th percentile). Specifically, they found the following:

• Low intake of flavonols (apples, pears, and tea) was associated with twice the risk of developing ADRD.
• Low intake of anthocyanins (blueberries, strawberries, and red wine) was associated with a four-fold risk of developing ADRD.
• Low intake of flavonoid polymers (apples, pears, and tea) was associated with twice the risk of developing ADRD.

The results were similar for AD.

“Our study gives us a picture of how diet over time might be related to a person’s cognitive decline, as we were able to look at flavonoid intake over many years prior to participants’ dementia diagnoses,” said Paul Jacques, senior author and a nutritional epidemiologist at the Jean Mayer USDA Human Nutrition Research Center on Aging, in a press release.