While high-GI foods were linked to higher risks of depression, the team said low GI-foods like vegetables and fibre lowered risks.
“The independent association between higher dietary GI intake and greater odds of depressive symptoms observed in our cohort of older adults concurs with other epidemiological studies, which suggest that high-GI diets could be a risk factor for depression,” the study explained.
Previous findings for the relationship between carbohydrate nutrition and mental health in older adults have generally been inconsistent, with one Spanish study of institutionalised older adults finding an inverse link between dietary Glycaemic Load (GL – a measure of quantity and the quality of carbohydrates) and prevalence of depression.
Meanwhile, one more study showed that higher GI and sugar intake were associated with an increased risk of incident depression.
Data collected from 2,334 participants aged 55+ years and 1952 participants aged 60+ years were analysed.
Dietary information was collected using a semi-quantitative food frequency questionnaire (FFQ) where alongside carbohydrate consumption, information about foods like fruits, vegetables and cereals were also evaluated.
Depressive symptoms were based on antidepressant use or either the 36-Item Short-Form Survey, which included the Mental Health Index (MHI), or the Center for Epidemiologic Studies Depression-10 Scale.
“Given that this is an observational study, we were not able to determine the pathways by which dietary GI could influence mental well-being; however, we can hypothesise potential mechanisms,” the study’s authors said.
“First, greater inflammation as a result of higher-GI intake has been suggested as a mechanism for depression. Second, high-GI diets could also lead to insulin resistance, which has been associated with a pattern of volumetric and neurocognitive deficits, which are very similar to that found in individuals suffering from clinical depression.
As much as inflammation had a prominent role in depression, fibre was lauded for its protective effect with the team attributing the avoidance of post meal hyperglycaemic peaks.
Repeated postprandial hyperglycaemia has been shown to lead to the overproduction of harmful free radical molecules and a greater inflammatory response.
“Older adults with higher consumption of dietary fibre are also likely to be consuming higher amounts of nutrients that are important for a healthy nervous system, which therefore has a beneficial influence on mental health status,” the authors believed.
“Moreover, vegetables have low GI and this attribute could explain its consumption being inversely associated with the prevalence of depressive symptoms in older adults.”
Source: British Journal of Nutrition
Published online ahead of print: doi.org/10.1017/S0007114516004311
“Association between carbohydrate nutrition and prevalence of depressive symptoms in older adults.”
Authors: Bamini Gopinath, Victoria Flood, George Burlutksy, Jimmy Louie, Paul Mitchell