Are There Any Fruit Juices That Can Boost Brain Health or Prevent Dementia?

Red wine can cause extra fat to spill out into your blood stream after a meal compared to dealcoholized red wine, as well as increase inflammation over the six hours after consumption. This is significantly higher than drinking a sugary beverage, which helps to explain why nonalcoholic red wine can improve artery function while regular red wine can make things worse.

What about just drinking grape juice? One shouldn’t necessarily expect the effects of grape juice and nonalcoholic wine to be similar, even when produced from the same grapes. For example, wine aged in oak barrels not only picks up compounds from the wood, the grape compounds themselves become modified. The desired taste implications have led to the addition of oak chips, blocks, or shavings to achieve a similar effect in non-barrel-aged wines. Even without the oak, the color of red wine shifts as it ages, a function of changes that occur to the pigments that may play a role in any health effects. Ironically, grape juice alone was found to be twice as effective as red wine, dealcoholized or not, in reducing cholesterol and reducing atherosclerosis, but this was in hamsters.

There was a study that found that a cup (240 ml) a day of white wine was superior to white grape juice for lowering cholesterol, but this result seems spurious, given that eight other randomized controlled trials failed to find any LDL-lowering benefit to wine. No such benefit has been found for grape juice either, but whole grapes do appear to have a small effect, lowering by six points, on average. My first instinct was to unreservedly recommend whole fruit over juice, given that fruit consumption is associated with living longer, while fruit juice consumption is not. But the Kame Project study inspired me to dig a little deeper.

In the 1990s, more than 1,500 dementia-free Japanese Americans in the Seattle area were enrolled in a study to see whether juice consumption was associated with incident Alzheimer’s disease. After controlling for a long list of lifestyle factors they found that compared to those who drank fruit or vegetable juice less than once per week, those who drank it three times or more a week were 76 percent less likely to develop Alzheimer’s in the ensuing six years. Juice drinkers appeared to wipe out nearly three-quarters of their risk! In contrast, ­­­­similar studies on fruits and vegetables only uncovered about 40 percent lower risk.

Is it possible that the high-pressure extraction methods used to make commercial juices could draw out more brain protecting polyphenols from the pulp, peel, or seeds than one might get eating the fruit directly? There was one study, entitled “Plum juice, but not dried plum powder, is effective in mitigating cognitive deficits in aged rats,” that at first glance suggested juice might have an edge, but the rats in the juice group were given nine times the dose of plum polyphenols, so it wasn’t a fair fight. Thankfully, there are human trials that put fruit juice to the test in randomized controlled trials to assess at least short-term cognitive effects.

A Harvard study that followed tens of thousands of health professionals for about 20 years found that those who drank orange juice every day only had about half the odds of developing poor cognitive function. To try to tease out cause-and-effect evidence, older adults were randomized to two months of a cup (240 ml) of OJ or orange-flavored sugar water twice a day, and cognitive function was significantly better after the juice. The investigators concluded that orange juice appears to offer “benefits for global cognitive function in healthy older adults.” There it was right there in the title “Chronic consumption of flavanone-rich orange juice is associated with cognitive benefits.” But if you look closely at the data, the OJ didn’t improve cognitive function significantly at all; instead, the orange “Kool-Aid” made brain function worse and the juice just looked good in comparison.

A similar false effect was found for pomegranate juice. A four-week pilot study with a few dozen subjects found that pomegranate juice appeared to improve verbal memory. So, the POM Wonderful company funded a trial randomizing hundreds of middle-aged and older individuals to a year of their pomegranate juice or pomegranate-flavored sugar water. They were unable to replicate the verbal memory effect, and the only significant difference was a drop in the ability to learn visual information in the “Kool-Aid” group. If you insist on drinking a sugary beverage, OJ or pomegranate juice won’t impair your brain function as much as fruit-free sugar water, but why not devote those calories to something that could actually boost your brain, like blueberries?

Older adults randomized to the equivalent of a cup (240 ml) a day of blueberries experienced an improvement in cognition within 90 days over the placebo control (though apparently not when taken with fish oil). But what about just blueberry juice? Over the same time span, a blueberry concentrate equivalent to about one and a half cups (355 ml) a day of blueberry juice showed evidence of improvement in working memory over placebo in healthy older adults. What about in older adults starting out with impaired memory? An improvement there too, but the dose used for the average participant was about two and a half cups (590 ml) a day. The placebo they used was a grape-flavored beverage. What about actual grape juice? As I’ve reviewed before, the data are rather disappointing.

Cherry juice also fails to improve cognitive performance acutely, after a single dosing, but twelve weeks drinking two cups (470 ml) a day of tart cherry juice improved cognitive function of older adults (compared to baseline and the cherry “Kool-Aid” placebo control). What about among older adults already stricken with mild‑to‑moderate dementia? Twelve weeks of Bing cherry juice significantly improved some cognitive measure from baseline, but not compared to apple juice, which was used as the control. Maybe there are benefits to apple, too?

The Apple Products Research and Education Council funded an “open-label” study (meaning no blinding, no control group) giving institutionalized patients with moderate-to-late-stage Alzheimer’s disease two half cups (590 ml) of apple juice a day for a month. Caregivers reported an improvement in behavioral symptoms like agitation, but objective measures of cognitive performance showed no effect.