Published in The British Journal of Nutrition, the study analysed the effects of inulin supplementation on inflammation and clinical symptoms of women with obesity and depression and noted lower intake of protein and dietary fibre in the intervention group and following a calorie-restricted diet.
Calorie and protein intake can impact inflammatory biomarkers and consequently affect depression and mood, according to researchers from Tabriz University of Medical Sciences in Iran.
“This finding might add to the evidence that inulin may promote satiety and lower energy intakes, which in turn could potentially improve weight loss maintenance and hence psychological outcomes over a longer-time period.”
Major depressive disorder (MDD) is an inflammatory condition that is exacerbated by gut microbiota dysbiosis, also observed in individuals with obesity. However, experts believe prebiotic treatment, to alter gut microbiota, could help alleviate symptoms.
There is a “bidirectional association” between depression and obesity. Patients with depression are 58% more likely to become obese, while obese individuals have a 55% greater risk of developing depression and also demonstrate poor responses to anti-depressants, the authors explained.
One proposed mechanism affecting depression is the downregulation of brain-derived neurotrophic factor (BDNF), while higher levels of circulating zonulin, endotoxin, and pro-inflammatory cytokines are implicated in both obesity and depression, they said.
“Moreover, prevention of cardiovascular complications very much depends on management of both obesity and depression in patients suffering from both disorders.”
Studies suggest prebiotics could facilitate weight loss and improve gut barrier function, endotoxemia, and inflammation, and mitigate depression.
Depression is often accentuated by long-term calorie restrictions but there are very few studies investigating the anti-depressant and anti-inflammatory effects of calorie restrictions and prebiotic supplementation on subjects with obesity and depression.
The current random, double-blind study assessed the effects of a calorie-restricted diet and inulin intake on depression, serum brain-derived neurotrophic factor (BDNF), gut permeability, endotoxemia, and inflammatory biomarkers of 45 obese women (with a body mass index between 30-40kg/m2) and suffering from MDD (based on DSM-5 criteria).
Subjects consumed 10g/day of either inulin (Frutafit IQ supplied by Sensus) or maltodextrin (control) for eight weeks and followed a healthy calorie restricted diet.
A demographic questionnaire was completed at baseline to assess physical activity levels and subjects were asked to maintain usual activity throughout the study. Three food records were also supplied before starting the calorie-restricted diet and a further three at the endpoint.
Anthropometric measures, depression, and serum levels of zonulin, lipopolysaccharide (LPS), inflammatory biomarkers, and BDNF were also assessed at baseline and end of the study.
There were no significant benefits identified in relation to body weight, depression rating score (HDRS), BDNF and biomarkers of endotoxemia, gut permeability, and inflammation, compared to placebo.
After adjusting for baseline values, calories and protein intake was lower following supplementation, compared to the placebo group, although there was no significant difference between the two groups for calorie percent from proteins and dietary fibre per 1,000 calories of energy intake at eight weeks.
Prebiotic intake did not alter subjects’ weight and there was no significant impact on psychological outcomes. Twelve subjects in each group experienced similar improvements in HDRS.
Five patients in the prebiotic group experienced gastrointestinal discomfort (flatulence and soft stool), but symptoms disappeared after two weeks.
The authors maintained that non-significant outcomes could be attributed to the regular visits and same dietary advice for all patients, who talked freely about their personal life and problems, which may have influenced mood states.
Future studies should focus on optimal type and dosage of prebiotics as well as supplementation duration for patients suffering from both depression and obesity, the suggest.
Source: The British Journal of Nutrition
Published online: doi: 10.1017/S000711452200232X
‘Effects of inulin supplementation on inflammatory biomarkers and clinical symptoms of women with obesity and depression on a calorie-restricted diet: a randomized controlled clinical trial’
Authors: E. Vaghef-Mehrabani, et al.