Field Notes

‘Junk Food’ Diet May Predict Future Depression Symptoms in Teens

An innovative study finds that sodium and potassium levels—reflections of a person’s typical diet—may be predictors of future depression in teens. The first-of-its-kind study is published in Physiological Reports.

The number of adolescents with depression has increased an estimated 30% in the past 10 years. Studies have shown a link between a healthful diet and improved mood in adults, but there’s little research on the effect of diet on the development of depression in teens.

Researchers followed 84 middle school students—primarily from low-income families—for a year and a half. The study focused on “urban African American youth who are at a higher risk of both poor diet and depression,” the research team explains.

At the start and end of the study, the researchers collected the participants’ urine for sodium and potassium and administered a commonly used screening test for depression. Sodium in the urine has been found to be a reliable marker of how much salt a person regularly eats and “may reflect the consumption of processed, unhealthful foods,” the researchers wrote.

Urinary potassium level is also “a marker of overall diet quality, with higher potassium excretion positively correlated with greater intake of vegetables, fruits, whole grains, fish, and poultry,” they added. Low urinary potassium levels—similar to high sodium levels—are associated with eating fast food and other processed items.

Higher sodium and lower potassium levels weren’t related to symptoms of depression at the baseline reading at the start of the trial but predicted increased depression at follow-up at the end of the study. This may mean that the effects of an unhealthful diet on mood build up over time.

“These results suggest that reducing the consumption of sodium-rich foods and increasing the consumption of potassium-rich foods (eg, fruits, vegetables, and whole grains) may help reduce the prevalence of depression in adolescents,” the researchers wrote.

— Source: American Physiological Society


Diet’s Effect on Gut Bacteria Could Help Reduce Alzheimer’s Risk

Could following a certain type of diet affect the gut microbiome in ways that decrease the risk of Alzheimer’s disease?

According to researchers at Wake Forest School of Medicine in Winston-Salem, North Carolina, that’s a fair possibility.

In a small pilot study, the researchers identified several distinct gut microbiome signatures—the chemicals produced by bacteria—in study participants with mild cognitive impairment (MCI) but not in their counterparts with normal cognition, and found that these bacterial signatures correlated with higher levels of markers of Alzheimer’s disease in the cerebrospinal fluid of the participants with MCI.

Through cross-group dietary intervention, the study also showed that a modified Mediterranean-ketogenic diet produced changes in the gut microbiome and its metabolites that correlated with reduced levels of Alzheimer’s markers in the members of both study groups.

The study appears in the current issue of EBioMedicine, a journal published by The Lancet.

“The relationship of the gut microbiome and diet to neurodegenerative diseases has recently received considerable attention, and this study suggests that Alzheimer’s disease is associated with specific changes in gut bacteria and that a type of ketogenic Mediterranean diet can affect the microbiome in ways that could impact the development of dementia,” says Hariom Yadav, PhD, an assistant professor of molecular medicine at Wake Forest School of Medicine, who coauthored the study with Suzanne Craft, PhD, a professor of gerontology and geriatric medicine at the medical school and director of Wake Forest Baptist Health’s Alzheimer’s Disease Research Center.

The randomized, double-blinded, single-site study involved 17 older adults—11 with diagnosed MCI and six with normal cognition. These participants were randomly assigned to follow either the low-carbohydrate modified Mediterranean-ketogenic diet or a low-fat, higher-carbohydrate diet for six weeks—then, after a six-week “washout” period, to switch to the other diet. Gut microbiome, fecal short-chain fatty acids, and markers of Alzheimer’s, including amyloid and tau proteins, in cerebrospinal fluid were measured before and after each dieting period.

The study’s limitations include the subject group’s size, which also accounts for the lack of diversity in terms of gender, ethnicity, and age.

“Our findings provide important information that future interventional and clinical studies can be based on,” Yadav says. “Determining the specific role these gut microbiome signatures have in the progression of Alzheimer’s disease could lead to novel nutritional and therapeutic approaches that would be effective against the disease.”

— Source: Wake Forest Baptist Health