Does eating fermented foods help you lose weight?

Kimchi is a Korean food that traditionally consists of fermented cabbage and spices.  It is a staple in the South Korean diet, and is one of the most frequently consumed fermented foods.  The presence of bacteria in the kimchi has led many to speculate that it can exert a positive influence on the microbiome, and kimchi is believed to have anti-obesity effects.  In order to test this hypothesis researchers from South Korea conducted a clinical trial in which they put obese women on a kimchi diet.  The women were split into two groups, one of which consumed fermented kimchi, while the other consumed non-fermented kimchi.  A summary of the study was recently published by Molecular Nutrition and Food Research.

Surprisingly, fermentated kimchi did not appear to affect the women’s body measurements or specific health indicators when compared to the non-fermented version.  For example, women on both diets had similar decreases in weight, waist circumference, body fat, blood pressure, and cholesterol. There were some important differences though, fermented kimchi increased fasting insulin levels and fasting blood glucose.

The scientists also measured the two groups’ gut microbiomes and blood gene-expression in the study.  The group that ate fermented kimchi had higher abundances of Bacteroides and Prevotella in their microbiomes, and an increased Bacteroides/Firmicute ratio, which has been linked to weight loss.  Bifidobacterium longum, a major lactic acid bacterium that ferments kimchi, has also been linked to weight loss, and to this end, a significant correlation between an increase of this bacterium in the microbiome and decrease in waist circumference was observed.    In addition, a gene known as Acyl-CoA synthetase long-chain family member 1 was found to be significantly upregulated in subjects consuming fermented kimchi compared to those consuming fresh kimchi. This gene plays an important role in metabolism, and it is important in breaking down fatty acids. A second gene, aminopeptidase N (ANPEP) was also expressed more in subjects consuming fermented kimchi.  ANPEP is important for regulating inflammation, and has been associated with a healthy blood pressure.

Overall, this study showed fermented kimchi possibly has beneficial effects on metabolism and immunity when compared to the non-fermented variety. While this study is limited by its small sample size, among other factors, it still shows that the bacteria involved in the fermentation process could benefit us in more ways than we currently know.  These bacteria not only make kimchi taste good, but they may make us healthy too!

Probiotics may help fight the flu

The influenza viruses are the devastating viruses that cause the flu.  They highly communicable and can cause pneumonia, ear infections, sinus infections, asthma and even diabetes.  Basically, they are really nasty bugs that people have been suffering from, and trying to get rid of, for at least the last 2000 years.  One possible treatment, which is now being explored, is the use of probiotics to prevent flu and its virulence.  Scientists in Japan recently tested how one type of probiotic, Bifidobacterium longum, could combat the flu in mice.  They published their results in Microbiology and Immunology.

Mice were divided into two groups, one which received the B. longum for 17 consecutive days in their drinking water, and one which did not.  On day 14 of the study all the mice were infected with flu via injection.  The researchers then monitored all of the mice to see the effect of the probiotics.  Surprisingly, the mice which received the probiotics had improved clinical symptoms as compared to those that did not.  For example, the mortality rate dropped from 70% to 35% after 12 days in those mice that had been given probiotics.  In addition, the probiotics seemed to help with breathing and general activity as well as kept mice from losing as much weight as the control mice.  Beyond this, the probiotics appeared to decrease the proliferation of the influenza in the respiratory tract, which resulted in a suppression of overall inflammation as compared to the mice without probiotics.  Finally the researchers presented evidence for several possible pathways by which the probiotics were helping the mice.

This study is fascinating in that it shows a simple, yet powerful tool to alleviate the flu in mice.  It also begs for a follow-up study to see if the same type of probiotic response would be observed in mice infected with rhinoviruses, the cause of the common cold.  While we here at the AMI encourage everyone to get vaccinated for the flu, if for whatever reason you cannot, perhaps consider eating a bit more yogurt this winter.