High-Fat Yogurt Reduces Depression Risk in Women

The constituents of ones diet, as well as the overall healthiness of ones diet, has long been known to play a role in cognitive function, mental acuity, and mental health. 

Unipolar depression (i.e. not that associated with manic-depressive disorder: bipolar depression) is expected to be the leading cause of disability in developing
countries by the year 2030. The etiology of depression is clearly multifactorial but diet has definitely been shown to play a role in this etiology. One avenue of impact is that ones diet affects the overall composition of the bacteria (the microbiota) within ones intestines. There is ample scientific evidence (more about the gut microbiota to come in future blog posts) demonstrating the interactions between the composition of ones intestinal microbiota and immunity, diabetes, and functions of the central nervous system. To understand a bit more about the link between what happens in the gut and how this can influence brain activity and behavior got to the Gut-Brain Interactions Page of my website:

http://themedicalbiochemistrypage.org/gut-brain.php

The food we eat can, and does, dramatically affect the composition of our gut microbiota. For example the composition of gut microbiota in an overweight or obese individual with type 2 diabetes is vastly different than that of a lean healthy individual. Indeed, numerous experiments in laboratory animals has shown that transplanting the microbiota from lean healthy mice to obese mice greatly improves the metabolic profile in the obese mice and they lose fat mass even when fed a high-fat diet.

In the realm of human microbiota most people are aware of probiotic and or prebiotic supplements. Both probiotic and prebiotic supplements are able to enhance and
maintain a healthy composition of gut microbiota in humans. Probiotics are

defined as live microorganisms, whereas prebiotics are defined as non-digestible foods (think fiber) that when consumed change the composition and/or activity
of the gut microbiota. Therefore, both prebiotics and probiotics conferring benefit upon host health. In order for probiotics to exert a positive effect on health they must survive transit through gastrointestinal tract to the colon (large intestine). Probiotics can be consumed in various forms that includes, but is certainly not limited to, functional foods such, as yogurt or fermented milk formulas, or live probiotic bacteria as encapsulated supplements. Probiotic bacteria such as Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus acidophilus, and Bifidobacterium
bifidum are the most common bacteria added to yogurts and fermented milks.

The common prebiotics include the fructans (fructo-oligosaccharides and inulin) and the galacto-oligosaccharides (GOSs). Prebiotics are easy to buy and consume as they are present in fruit, vegetables and whole grains. Prebiotics promote the intestinal growth of several beneficial gut bacteria such as the Bifidobacterium and Lactobacillus strains. These bacteria improve the function of the gut barrier and promote host immunity.

Both prebiotics and probiotics have clearly been shown to lower ones risk of becoming overweight or obesity and modulate the extent of inflammatory responses. Because gut microbiota are also involved in the regulation of the gut-brain axis, it has been speculated that one consequence of a healthy composition of gut microbiota is modulation of ones affect (e.g. their mood and behavior).

A recent report in the Journal of Nutrition presents the results of a prospectively assessment of the association between yogurt (total, whole-fat, and low-fat) and prebiotic consumption and the incidence of depression among university graduates. This study included a follow-up period, of the study participants, for greater than 9 years.

Intake of High-Fat Yogurt, but Not of Low-Fat Yogurt or Prebiotics, Is Related to Lower Risk of Depression in Women of the SUN Cohort Study

The results from this prospective study were gathered from 21,291 participants who volunteered to provide information on dietary intake using a 136-item questionnaire at the outset of the study and after a 10-year follow-up. Now it is important to appreciate that there are a wide range of variables in this study such as age, marital status, smoking behavior, etc and this is well beyond the scope of this blog post.

However, the TAKE HOME from the study is that consumption of whole-fat yogurt, but not low-fat yogurt nor foods rich in prebiotics, reduced the incidence and level of depression in the female participants. There have been other studies that have shown an inverse relationship between whole-fat yogurt consumption and depression so this study is not the first to document these benefits of whole-fat yogurt. Interestingly the inverse association between whole-fat yogurt consumption and depression risk was significant only in women. The study authors speculated that the differences they observed were, in
general, due to the fact that women are more conscious of their diet women are more likely to suffer from depression than men.

So get out there and get yourself some whole-fat yogurt!!!

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