As scientists continue to explore the link between gut bacteria and mental health, Canadian researchers recently discovered that stress in the early stages of life can alter the bacterial population in the gut—which may have lasting implications when it comes to a healthy brain and mood in adulthood.
In a study published online last month in the journal Nature Communications, experts from the Family Digestive Health Research Institute at McMaster University in Ontario revealed that stress in infancy may trigger changes in the developing microbiome, which in turn may increase the risk of developing anxiety and depression later in life.
For the purpose of the study, researchers used two groups of newborn mice: one with normal gut bacteria and one with no gut bacteria. To analyze the effects of early life stress, the mice in both groups were separated from their mothers for a few hours each day for nearly three weeks.
Interestingly, while both groups of mice exhibited elevated stress hormone levels, those with normal gut bacteria displayed anxious or depressed behavior as well as impaired digestive function—symptoms not seen in the mice with no gut bacteria. Lead author Dr. Premysl Bercik and his colleagues believe even small changes in gut bacteria during a child’s early years may have “profound effects” on mood and behavior as an adult.
Researchers from Columbia University Medical Center in New York recently determined that a diet high in refined carbohydrates increases the risk of depression in postmenopausal women by 22 percent—and 23 percent if you factor in added sugars.
Dr. James Gangwisch and his colleagues examined the health data for roughly 70,000 women between the ages of 50 and 79, compiled as part of the National Institutes of Health Women’s Health Initiative Observational Study. By focusing on glycemic index scores and comparing them to diet as well as rates of depression, they discovered that eating a lot of highly refined carbs and added sugars (like those found in white bread, white rice, snack foods, and sugary drinks) increases the risk for depression later in life.
Glycemic index, or GI, measures the amount of sugar in the bloodstream after eating. Study authors explain that in addition to triggering a sharp rise in blood sugar (and, as a result, elevated GI scores) highly refined carbohydrates cause a hormonal response in the body that results in mood changes, fatigue, and other symptoms of depression. In previous studies, a diet high in refined carbs and sugars has been linked to increased inflammation, which is also a risk factor for depression.
On a positive note, researchers observed that women who ate more dietary fiber—especially in the form of vegetables, fruits, and whole grains—and who avoided sugary beverages were less likely to develop depression after menopause, suggesting that dietary changes may play an important role in the prevention and treatment of depressive disorders.