Yoghurt is an excellent source of calcium, protein, magnesium, vitamin B12, and riboflavin. It is also a good source of probiotics (health-promoting bacteria) and iodine, particularly for vulnerable people in countries without an iodine-fortified food supply, such as the United Kingdom.
Past studies show that yoghurt reduces the risk of type 2 diabetes, but the exact way it does this is unknown. Now, new research reveals that yoghurt alters gut bacteria and boosts blood and liver levels of branched-chain hydroxy acids (BCHA), compounds that improve insulin sensitivity.
“We found that lyophilised yoghurt intake (equivalent to two servings of yoghurt) reduced the development of high-fat diet-induced insulin resistance, which was linked to its effects on liver metabolism and the gut microbiota. These beneficial metabolic effects of yoghurt intake were associated with an increase of branched-chain hydroxy acids (BCHA) in the liver of these animals. We further show that BCHA are specifically present in yoghurt and generated upon milk fermentation,” the researchers wrote.
The study, “Gut microbiota and fermentation-derived branched-chain hydroxy acids mediate health benefits of yoghurt consumption in obese mice,” was published in Nature Communications.
To understand how yoghurt lowers type 2 diabetes risk, researchers fed obese mice either a Western-style high-fat, high-sugar diet or the same diet supplemented with two servings of plain yoghurt. Yoghurt-fed mice had significantly lower fasting blood glucose, insulin and insulin resistance, and less fat and inflammatory proteins in their livers after 12 weeks. These changes were related to high BCHA levels in the bloodstream and liver.
“BCHAs are found in fermented dairy products and are particularly abundant in yoghurt. Our body produces BCHA naturally, but weight gain seems to affect the process,” Hana Koutnikova, study co-author and researcher at Danone Nutricia Research said in a press release.
BCHAs are made during the breakdown of certain branched-chain amino acids (BCAAs), including leucine, isoleucine and valine. It is worth noting that BCHAs are only produced during milk fermentation. They are found in other fermented milk products but absent in milk.
“In the group that was not given yoghurt, the amount of these metabolites in the bloodstream and in the liver decreased with weight gain. In the yoghurt group, the amount of BCHA was partially maintained. We also found that an abundance of BCHA in the liver was tied to improved fasting glucose and hepatic [liver] triglycerides,” Professor Andre Marette, a researcher at the Institute of Nutrition and Functional Foods (INAF) at Laval University said.
Yoghurt-fed bacteria had higher levels of Streptococcus bacteria and lower levels of an unknown bacteria species called Peptostreptococcaceae. Notably, this change was associated with improved insulin sensitivity.
More studies are necessary to understand how BCHAs improve insulin sensitivity and liver disease in obesity. “However, our findings show that yoghurt intake over only three months can partially prevent BCHA reduction in obese animals, suggesting that nutritional interventions with yoghurts, and possibly other fermented dairy products, should be explored in clinical trials to determine whether they can supply exogenous BCHA and compensate for their impaired endogenous production, and thus alleviate insulin resistance and NAFLD (non-alcoholic fatty liver disease) in obesity,” the researchers wrote.
The Takeaway
Yoghurt is a nutrient-dense food with a high protein, calcium, magnesium, and vitamin B12 content. Because of its acidic matrix, the nutrients it contains are easier to absorb than from milk. Previous studies have found that yoghurt reduces the risk of type 2 diabetes, but researchers have not clearly understood why.
This study shows that yoghurt increases insulin sensitivity, lowers fat and inflammation in the liver and improves gut health through the action of specific compounds called BCHAs. BCHAs occur in the body naturally, but they decrease with weight gain and obesity. Fortunately, BCHAs are abundant in yoghurt and other fermented milk products but absent in milk.
With mounting evidence showing yoghurt’s benefits to health, adding yoghurt to your diet is wise if you tolerate dairy. People with lactose intolerances can usually eat yoghurt because of lactose-digesting bacteria in yoghurt. Unsure which yoghurts to add to your diet? Then this post: Five Best Probiotic Yoghurts to Add to Your Diet may help.
