Depression is one of the most common and potentially serious mental health disorders, with up to 800,000 suicides per year. Risk factors for depression have therefore received much investigation.
A recent study published online at Nutrients deals with interactions between depression and diet, combined with exercise.
Study: The role of gut microbiota, diet and physical activity in depression and obesity—Interdependent mechanisms/co-occurrence. Image credit: Bits And Splits/Shutterstock.com
About depression
Depressive disorders include several categories, such as persistent depressive disorder (dysthymia), premenstrual dysphoric disorder, as well as depression caused by addictive drugs or medications, or by medical conditions.
All are characterized by sadness and irritability, with physical and mental changes. The result is reduced quality of life and reduced functionality.
In addition, depression is known to increase the risk for a number of metabolic diseases, including diabetes, obesity, and ischemic heart disease.
In contrast, dietary patterns are associated with mental health as well as malnutrition. For example, excessive fat intake leads to chronic inflammation and obesity.
Portliness
Obesity is defined as the accumulation of excess body fat, as measured by body mass index (BMI) and body fat percentage. It is associated with a higher risk of cardiovascular disease (CVD), insulin resistance, cancer and nerve damage.
Risk factors for obesity are known and include gender, age, smoking, in addition to eating too much fat and processed foods, which are typical of the Western diet.
Obesity and depression often affect the same person, along with anxiety disorders. They have a common mechanism of action, as shown by their bidirectional association.
People suffering from depression often indulge in comfort eating, which can increase body weight, especially if the person is also inactive. The risk of obesity in people under emotional stress is almost 40% higher.
Similarly, obese people are almost 20% more likely to become anxious or depressed due to negative self-image as well as negative social perception that they are too lazy or undisciplined to regulate their diet and weight. Treating depression with antidepressants is effective but can cause weight gain.
Unfortunately, both obesity and depression are among the most prevalent disorders worldwide and have a high mortality rate, leading to strong scientific interest in their interactions.
Gut microbiota
Gut microbiota is essential for proper energy storage and metabolism, but shows marked variability in obese compared to lean individuals. This includes lower diversity and fewer common bacteria but more pathogenic microbes in the obese. The resulting deviation in metabolism can contribute to obesity.
The need for a rational diet along with treatments such as psychotherapy and medication to treat patients with depression is emphasized by some scientists.
In addition, probiotics and prebiotics may be required, along with nutritional supplements, to correct dysbiosis and vitamin deficiencies.
Probiotics and gut microflora
Researchers sought to understand how gut microbes might be useful in treating both obesity and depression and the role of probiotics and prebiotics in such treatment.
The review suggests that approximately 57% of gut microbiota composition meets dietary patterns.
Probiotics strengthen the gut barrier and regulate the immune system. Their use is associated with improvement in depression symptoms, perhaps by providing vitamin D and short-chain fatty acids (SCFAs), which fight inflammation.
Certain strains of probiotic bacteria directly affect neural pathways. They inhibit the depression-causing hypothalamic-pituitary-adrenal axis (HPA axis) and promote the release of the anti-stress neurotransmitter GABA, also known as gamma-aminobutyric acid.
Others produce gut neurotransmitters that also affect the brain, influencing mood for the better.
Some human clinical trials suggest a positive effect of probiotics on depressive disorders as well as obesity and related metabolic conditions such as insulin resistance, type 2 diabetes and non-alcoholic fatty liver disease (NAFLD).
Further research is needed to validate these results, especially as probiotics work well in gut health and overall disease control only as part of a holistic management strategy including proper diet, exercise, stress management and adequate sleep.
Bacterial strains associated with improved neural pathways, sometimes called psychobiotics, include multiple Lactobacillus executives such as Lactobacillus casei Shirota, Lactobacillus fermentum NS8 and NS9and Lactobacillus rhamnosus JB-1as Bifidobacterium executives such as Bifidobacterium longum Rosell-175, Bifidobacterium longum 1714and Bifidobacterium longum NCC3001.
Nutrition and mental health
The brain receives a large share of the absorbed nutrients and uses them to keep itself healthy. For example, regeneration, neuroplasticity and an adequate supply of antioxidants depend on an adequate supply of nutrients to the brain.
Supplementation with fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), magnesium, folate, and vitamins E and D have been suggested to be beneficial in treating or alleviating major depression and reducing neuroinflammation.
Specific diets such as the Mediterranean diet (MD), DASH (Dietary Approaches to Stop Hypertension) or vegetarian diets have often been evaluated for their relationship to physical and mental health.
The authors of the current study found a reduced risk of depression and obesity with both DASH and MD, but conflicting data with vegetarian and vegan diets. However, high-quality vegetarian diets were protective against depression, highlighting the central role of diet quality in the type of diet chosen.
Physical activity and obesity/mood disorders
There is ample evidence that weight management is aided by increased overall energy expenditure and improved mood, with reduced anxiety and depression. Aerobic exercise has been touted for its ability to build fitness and aid in weight loss.
Physical exercise is associated with telomere lengthening, a biomarker of metabolic health. It is also associated with better brain health, sleep quality and reduced symptoms of depression.
Physical exercise is also associated with better gut microbiota composition, stronger combinations and more anti-inflammatory bacteria.
Exercise in early life can promote the growth of bacteria that can help the host adapt to changing conditions and promote healthy brain development.
The wider impact of obesity and depression
Depression is associated with increased mortality and morbidity, absenteeism, severe reductions in quality of life, and reduced productivity.
Obesity, now estimated to have a prevalence of 30% in the US, also has profound effects on personal and societal health. It reduces female fertility, promotes cognitive decline, shortens lifespan, and may increase difficulty in employment.
conclusions
Obesity and depression have a common origin and exacerbate each other. This interaction significantly affects quality of life. A possible explanation for their connections may be through gut dysbiosis.
This has stimulated many studies on the potential use of probiotics and prebiotics in depression and anxiety, as well as obesity.
“Encouraging findings from existing research highlight the need for robust clinical trials to assess the therapeutic potential of microbiota modification.”
