According to the CDC, more than 29 million Americans have type 2 diabetes. Another 86 million American adults (more than 1/3 of the population) have pre-diabetes, and within 5 years, up to 30% of these will develop it.[i] The numbers are equally grim in other industrialized countries. For example, according to the non-profit Diabetes UK, by 2025, more than 4.5 million people will have type 2 diabetes in the UK.[ii] That is, over 8% of the adult population of these countries will have this one disease.
The only good news is that there is a way to improve these statistics: diet. And recent research has shown that fiber is the key.
A recently published article in Science[iii] by researchers at Rutgers University, in conjunction with colleagues from Shanghai Jiao Tong University, demonstrated that by adding a variety of fiber to the diet, a distinct group of gut bacteria are fed and produce highly anti-inflammatory short chain fatty acids which reduce inflammation and help control appetite. A shortage of these SCFAs is associated with type 2 diabetes and other inflammatory diseases as well.
The researchers randomized patients with type 2 diabetes in into two groups. Both received the same dietary recommendations in terms of calories and major nutrients, but the treatment group was also given a large amount of dietary fibers (in the form of whole grains and other foods). Both groups were given the same medication to control blood glucose levels. After 12 weeks, the patients on the high fiber diet had a greater reduction of blood glucose and had lost more weight.
The really interesting thing:
“…of the 141 strains of short-chain fatty acid-producing gut bacteria identified by next-generation sequencing, only 15 are promoted by consuming more fibers and thus are likely to be the key drivers of better health. Bolstered by the high-fiber diet, they became the dominant strains in the gut after they boosted levels of the short-chain fatty acids butyrate and acetate. These acids created a mildly acidic gut environment that reduced populations of detrimental bacteria and led to increased insulin production and better blood glucose control.”
That is, fiber improves health by boosting levels of the bacteria that secrete anti-inflammatory SCFAs, which in turn modulates the pH level in the gut reducing levels of detrimental bacteria.
What came to mind, reading about this latest research, is the work of Jeff Leach and colleagues, who looked at the diet and biomes of the Hadza, one of the last true hunter-gatherer tribes left. On average, Americans, for example, eat about 15 grams of fiber a day. The Hadza – who have bacterial microbiome diversity that we can only dream about – eat about 100 grams.[iv]
So the take away message for today: eat more fiber.
[iii] iping Zhao, Feng Zhang, Xiaoying Ding, Guojun Wu, Yan Y. Lam, Xuejiao Wang, Huaqing Fu, Xinhe Xue, Chunhua Lu, Jilin Ma, Lihua Yu, Chengmei Xu, Zhongying Ren, Ying Xu, Songmei Xu, Hongli Shen, Xiuli Zhu, Yu Shi, Qingyun Shen, Weiping Dong, Rui Liu, Yunxia Ling, Yue Zeng, Xingpeng Wang, Qianpeng Zhang, Jing Wang, Linghua Wang, Yanqiu Wu, Benhua Zeng, Hong Wei, Menghui Zhang, Yongde Peng, Chenhong Zhang. Gut bacteria selectively promoted by dietary fibers alleviate type 2 diabetes. Science, 2018; 359 (6380): 1151 DOI: 10.1126/science.aao5774