Of all the medical issues that people worry about, brain conditions that affect memory in later life are among the scariest--and with good reason.

We're at an almost epidemic level, with one in eight Baby Boomers over 60 reporting memory loss, according to the Centers for Disease Control.

A third of those, so about 4 percent overall, reported memory loss significant enough that it interfered with work, social lives, or the ability to do household chores.

That's why I think that a massive new study about how diet can affect memory loss, authored by researchers associated with the Harvard School of Public Health, will be of great interest to many people--especially because they say they've found that a certain type of diet is linked to better memory as people age.

Let's not hide the ball here: The diet they found predicted the least memory loss as people aged is one that is high in vegetables and fruit -- even fruit juice. There are three key, but related, findings:

  • Proportionality. The larger the total intake of vegetables, fruit, and fruit juice that study participants reported, especially during middle and late adulthood, the lower the likelihood of memory loss later in life.
  • Variety. Drilling down, dark orange vegetables, red vegetables, leafy greens, and berry fruits had the most pronounced links between high levels of consumption and less reported memory loss.
  • Timing. Unfortunately, it did not appear that people in later life could make up for earlier lack of fruit and vegetable consumption; it was a pattern of eating lots of these fruits and vegetables between 10 and 22 years earlier that was linked to a lower degree of poor cognitive function. More recent eating preferences didn't matter.

The study was published in the journal Neurology last month. Its authors, Changzheng Yuan, Elinor Fondell, Ambika Bhushan, Alberto Ascherio, Olivia I. Okereke, Francine Grodstein, Walter C. Willett, are all associated with the Harvard School of Public Health.

Their work involved an analysis of data on 27,842 men that they obtained from the Health Professionals Follow-Up Study, which began in 1986 and followed its participants for two decades. Besides self-reported data on fruit and vegetable consumption, the men took tests involving thinking and memory skills when they reached 73 years of age. 

As Reuters summarized: 

Based on those test results, researchers found that by the time they were in their late 70s, men who had regularly eaten the most vegetables over the previous decades were 17 percent less likely to have moderate cognitive problems and 34 percent less likely to have more extensive cognitive deficits than men whose diets contained the least produce.

We should be very clear that this study only shows correlation, not causation

Also, it's a bit amusing to see that the study authors specifically call out orange juice as a positive thing to consume, given that it's now seen as a much less healthy drink than it was in the 1980s and 1990s.

"Since fruit juice is usually high in calories from concentrated fruit sugars, it's generally best to consume no more than a small glass (four to six ounces) per day," Yuan told Reuters.

But as for the other categories--red and orange fruits and vegetables, berry fruits, along with leafy green vegetables--it is promising research, and it certainly counts as yet another reason to include lots of healthy fruits and vegetables in your diet.