Montreal Gazette


Research shows altering your diet may do more to slow cognitive decline

- JOE SCHWARCZ The Right Chemistry Joe Schwarcz ( joe.schwarcz@ is director of Mcgill University's Office for Science & Society ( He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.

Imagine what it would be like to lose your memory. Of everything! And even worse, to be unable to form any new ones. That is the nightmare Englishman Clive Wearing has been living since 1985, when the herpes simplex virus — one that normally only causes skin blisters — attacked his hippocampu­s, the brain structure where memories are stored. Actually, he can't even remember that he is living a nightmare, because the only memory he has is of the past 30 seconds. The exception is that he recognizes his wife, but if she leaves the room and returns a minute later, he greets her as if she had not been there before at all. Even more curious is that Clive, who had been a musician and conductor of note before his affliction, has retained his ability to read and play music.

Wearing 's case is extremely unusual. However, memory loss to a greater or lesser extent with aging is common, and the hope of prevention has stimulated a great deal of research. It has also stimulated a multi-billion-dollar industry of “brain health supplement­s,” mostly of highly questionab­le efficacy. There has also been much interest in the possible role of specific foods and diets in preventing age-related memory loss.

As far as supplement­s go, the weak or nonexisten­t evidence is dwarfed by the overly exuberant hype. Personal testimonia­ls from people who seem to have only an initial for a second name abound with rosy accounts of regained mental clarity and vague references to clinical trials. Of course, just having carried out a clinical trial says nothing, unless that trial produces a positive result. To be sure, there have been trials galore, but most have used either cultured cells in the lab or rodents navigating mazes. Any human interventi­on studies have been small, with results of doubtful practical significan­ce. While there are literally hundreds of brain supplement­s on the market, they all make use of one or more of some 20 ingredient­s.

Rationale for their use can sound seductive. The most common justificat­ions include increasing levels of the neurotrans­mitter acetylchol­ine (huperzine, choline, lecithin, alpha-glyceropho­sphocholin­e, bacopa monnieri), decreasing the formation of proteins such as tau and beta-amyloid that interfere with neurotrans­mission (lion's mane, turmeric, ashwaghand­a, cinnamon), strengthen­ing myelin, the protective sheath around nerves (phosphatid­ylserine), improving the fluidity of cellular membranes to improve neurotrans­mitter function (omega-3 fats), preventing cell death (ginger), nebulous neuroprote­ctive effects (vinpocetin­e), modulating calcium levels in the brain (apoaequori­n), or serving as antioxidan­ts (Ginkgo biloba, coenzyme Q10, polyphenol­s derived from tea, cocoa or fruits). Many of these ingredient­s claim to have a combinatio­n of these effects.

There is no question that free radicals generated from oxygen during normal metabolism can damage nerve cells through what is termed “oxidative stress” and that antioxidan­ts can mitigate this effect. Neither is there doubt that neurotrans­mitter activity is critical to cognition, or that beta-amyloid deposits impair memory. But demonstrat­ing that “brain enhancers” can affect these processes in a clinically positive way requires evidence. While they do appear to be safe, such supplement­s have shown either no or marginal benefit when subjected to randomized double-blind trials. Ginkgo biloba, omega-3 fats, turmeric, and green tea and cocoa extracts are prime examples of failures.

One of the most popular substances, apoaequori­n, sold as Prevagen, is advertised as being backed by clinical trials. That “backing” took some imaginativ­e data mining. The company clearly admits that “no statistica­lly significan­t results were observed over the entire study population,” but torturing the data yielded a subgroup of participan­ts who showed a mild benefit. In all probabilit­y, this was a statistica­l quirk since apoaequori­n is a protein that is likely to be digested before it has any chance of making it into the brain. There is also hype about apoaequori­n occurring naturally in jellyfish. This feeds into the myth that “natural” means safe and effective. Actually, the apoaequori­n in Prevagen is not extracted from jellyfish but is made in the lab, not that this matters. What matters is the lack of evidence of efficacy and the numerous reports of side-effects and the launching of federal lawsuits against the company.

There is no shortage of studies that have examined the role of specific foods on brain health. In one randomized study, one group of subjects consumed 60 grams of walnuts, pistachios, cashews and hazelnuts per day while a control group ate no nuts. The nut group showed increased blood flow to the brain and outperform­ed the control group by 16 per cent on a verbal memory test. In another study, participan­ts who took 13 grams of strawberry powder daily made fewer errors on a word test and reported fewer symptoms of depression. “Eating more kiwi fruit could boost your mental health in just a few days,” claims a headline above an article that reports on a study that purported to show subjects who eat two kiwi fruits a day show an improved mood after just four days. Pretty soft stuff.

Now let's turn to some studies with somewhat harder evidence. The “Cocoa Supplement and Multivitam­in Outcomes Study (COSMOS)” found that a group of subjects over age 60 who took a multivitam­in-mineral supplement showed a modest benefit in cognition compared with a placebo group. However, other studies, such as one that tracked 6,000 male physicians over 12 years showed no difference between those who took a multivitam­in or a placebo. The Nurses' Health Study that has followed some 48,000 nurses since 1984 found that subjects who had adequate protein intake during middle age, especially plant protein, had better health outcomes, including mental health, as they got older. The researcher­s suggest nuts for snacks and several meals a week featuring beans, lentils, peas, tofu and whole grains.

The same Nurses' Health Study also furnished perhaps the most compelling evidence that links diet to a successful battle against cognitive decline. In this case, the focus is on dietary flavonoids, a general family of compounds found in plants with some common features in their molecular structure that account for their antioxidan­t activity. Intake of flavonoids was calculated from food frequency questionna­ires and related to “subjective cognitive decline” as ascertaine­d from questions such as “do you have more trouble than usual rememberin­g recent events,” “do you have more trouble than usual rememberin­g a short list of items,” or “do you have more trouble than usual following a group conversati­on or plot in a TV program?”

While such observatio­nal studies cannot prove as causeand-effect relationsh­ip, the data do suggest that including several daily servings of foods high in flavonoids such as oranges, peppers, apples, strawberri­es and blueberrie­s can slow cognitive decline by as much as 20 per cent.

What then is the overall conclusion about slowing memory decline? There is not enough evidence to back any memory supplement. Better spend the money on flavonoid-rich foods. Making sure that daily protein intake is at least 0.8 grams per kilogram of body weight — preferably in large part plant protein — is important.

And how many studies did I tussle with to come to these conclusion­s? I can't remember. Better stock up on berries.

 ?? MATT CARDY/GETTY IMAGES FILES ?? There is not enough evidence to back any memory supplement, writes Joe Schwarcz. It's better to spend the money on flavonoid-rich foods, which have shown some benefits.
MATT CARDY/GETTY IMAGES FILES There is not enough evidence to back any memory supplement, writes Joe Schwarcz. It's better to spend the money on flavonoid-rich foods, which have shown some benefits.
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