Quick Studies: A snapshot of the latest research on diet, exercise, and more

Keeping Diabetes at Bay

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Africa Studio/stock.adobe.com.

What’s the best way to keep prediabetes from becoming type 2 diabetes?

Scientists (partly funded by the food industry) had 2,223 people with prediabetes lose at least 8 percent of their initial weight with a very-low-calorie diet for eight weeks, then randomly assigned them to one of two diets:

  • high protein, low glycemic index (GI), or
  • moderate protein, moderate GI.

(Carbohydrates with a low GI lead to a smaller spike in blood sugar.)

After three years, only 3 percent of the people in each group had been diagnosed with diabetes. The only difference: blood sugar levels in those on the high-protein, low-GI diet were less likely to drop to the normal range.

What to do: To stave off diabetes, lose excess weight.

Diabetes Obes. Metab. 2020. doi:10.1111/dom.14219.

The Eyes Don’t Need It

Monkey Business/stock.adobe.com.

Age-related macular degeneration (AMD) is a leading cause of vision loss in U.S. adults.

Researchers randomly assigned roughly 25,000 adults to take vitamin D (2,000 IU), fish oil (1,000 milligrams), both, or a placebo every day for five years. The supplements had no impact on whether AMD occurred or got worse.

What to do: Don’t rely on vitamin D or fish oil to protect your eyes.

JAMA Ophthalmol. 2020. doi:10.1001/jamaophthalmol.2020.4409.

THC Behind the Wheel

woman driving
LIGHTFIELD STUDIOS/stock.adobe.com.

THC—the intoxicating component of marijuana—impairs driving. Does CBD (the non-intoxicating component) counteract THC’s psychoactive effects, as some claim?

Scientists had 26 young adults vape (inhale) THC, CBD, THC + CBD, or a placebo on different days. Each dose of THC or CBD was 13.75 milligrams. After 40 to 100 minutes, and again after four to five hours, the volunteers drove for an hour at 60 mph. (Relax. The car had a second set of pedals for the research team.)

Compared to the placebo, lane weaving, swerving, and overcorrection during the first drive were worse after both the THC and the THC + CBD, but not after just the CBD. No differences were seen after four or five hours.

What to do: Don’t expect CBD to make THC safe for driving. And the THC in edibles—like gummies or brownies—takes longer to wear off than inhaled THC, because it takes longer to reach the bloodstream.

JAMA 324: 2163, 2177, 2020.

A Mediterranean Diet & ED

man cooking

Can a Mediterranean diet help prevent erectile dysfunction (ED)?

Researchers tracked 21,469 men aged 40 to 75 for 11 years. They calculated Mediterranean diet “scores” by adding points for vegetables, beans, fruits, nuts, grains, fish, and polyunsaturated rather than saturated fats, and by subtracting points for red meat and dairy.

Compared to men with a low Mediterranean diet score, those with a high score had a 22 percent lower risk of ED if they were under age 60 and an 18 percent lower risk if they were 60 to 69. For men aged 70 or older, the difference in ED risk wasn’t quite statistically significant.

What to do: This kind of study can’t prove that a Mediterranean diet prevents ED, but that (or a similar) diet is worth eating to protect all of your blood vessels.
JAMA Netw. Open 2020. doi:10.1001/jamanetworkopen.2020.21701.