Food for Thought

Food for Thought periodically reports on nutrition research aimed at improving health and well-being.

Rebecca Voelker, MSJ

JAMA. Published online October 24, 2019. doi:10.1001/jama.2019.16477

The science behind food’s effects on human health is discovering some tasty benefits.Berries and Grapes Linked With Memory Boost

As the world’s elderly population races toward an estimated 2 billion by 2050, memory loss is expected to take a substantial toll. But recent research shows that polyphenols from grapes and blueberries combined may help boost declining memory among some older adults.

The study by investigators in France and Canada built not only on their own work in mice, but also on other preclinical and clinical studies showing that blueberries and grapes or their extracts may offer benefits for age-related cognitive decline. Their previous animal research also showed a synergistic effect—grape extract enhanced the absorption of polyphenols in the blueberry extract.

To determine whether an extract of both fruits may affect human cognition, the investigators enrolled 215 men and women aged 60 to 70 years in a 6-month clinical trial. They randomized the participants to receive a placebo or 600 mg per day of a polyphenol-rich grape and blueberry extract that contained 258 mg of flavonoids.

At the trial’s start, the investigators administered several cognitive ability tests. The primary outcome was results from visuospatial skills and episodic memory tests in which participants watched boxes, some that contained patterns, open on a touchscreen computer. When the patterns then appeared in the middle of the screen, participants had to match them to the appropriate box. Additional testing assessed episodic verbal memory and working memory.

Although all participants improved on the touchscreen computer test after 6 months, the investigators reported no difference in performance between the extract and placebo groups. But when they divided the participants into 4 groups according to their baseline test performance, the investigators found significant improvement among extract recipients with the greatest cognitive decline. In this group, cognitive age estimated from baseline test results improved by nearly 14 years compared with about 5½ years in the placebo group. Overall, the extract group also improved in verbal recall.

“[O]ur study confirms the need to define a recommended dietary allowance for flavonoids and revise recommendations for foods rich in these bioactives,” the authors concluded.Why Cilantro May Curb Seizures

Cilantro is an herb of many faces. It’s a staple in salsa and perfect for pickling. Not only were its seeds found in King Tut’s tomb, but it has a folk medicine history as an anticonvulsant. Now recent research explains why it’s been used to combat some seizures.

In a recent FASEB Journal study, researchers at the University of California, Irvine (UCI), reported that cilantro, or Coriandrum sativum, is a potent activator of neuronal voltage-gated potassium channel subfamily Q (KCNQ). Mutations in most of the genes that express this family of potassium channels can lead to heart disease, deafness, and severe epilepsy syndromes that are resistant to modern anticonvulsants.

By screening cilantro leaf metabolites, the researchers found that one—the long-chain fatty aldehyde (E)-2-dodecenal—activates several KCNQ channels, including the predominant neuronal and cardiac isoforms that regulate electrical activity in the brain and heart. “[D]odecenal binds to a specific part of the potassium channels to open them, reducing cellular excitability” and seizure activity, Geoff Abbott, PhD, professor of physiology and biophysics at the UCI School of Medicine, said in a statement. The metabolite also delayed some chemically induced seizures in mice.

Abbott said the finding “is important, as it may lead to more effective use of cilantro as an anticonvulsant or to modifications of dodecenal to develop safer and more effective anticonvulsant drugs.”Do Mushrooms Really Protect Against Cardiometabolic Disease?

Mushrooms may be rich in vitamins, minerals, and bioactive compounds such as polysaccharides, but recent research indicates that the fungi may not measure up to claims that they protect against cardiovascular disease and type 2 diabetes.

Investigators from Harvard Medical School and Harvard’s T.H. Chan School of Public Health noted that evidence from human studies to support mushrooms’ cardiometabolic benefits is limited. So they turned to 2 large, prospective, long-running cohort studies—the Nurses’ Health Study and the Health Professionals Follow-up Study—to examine whether eating mushrooms may reduce cardiometabolic disease risks or affect related biomarkers such as low-density lipoprotein (LDL) cholesterol.

Their analysis involved 67 139 women, 43 541 men, and more than 2 million person-years of follow-up. Based on food-frequency questionnaires, the investigators separated participants into categories according to how often they ate mushrooms. The cardiometabolic disease biomarkers they evaluated in addition to LDL cholesterol included total and high-density lipoprotein cholesterol, triglycerides, C-reactive protein, and C peptide.

Among participants who ate 5 or more servings of mushrooms per week, the investigators found no difference in risk of cardiovascular disease or type 2 diabetes compared with those who ate mushrooms less than once a month. They also found no association between mushroom consumption and disease biomarkers.

The investigators did, however, note limitations: Mushroom consumption in their study was low; about half the participants ate them less than once a week. In addition, they assessed mushroom consumption only once, at baseline. “Given the wide popularity of mushrooms and the growing interest in their potential clinical effects, more prospective cohort studies addressing the limitations of this study are warranted,” the researchers wrote.

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