Scientists have known that the types of bacteria present in the gut influence overall health for a long time. One of the first indications of this association came from a French microbiologist, Henri Tissier. He noticed that breastfed babies had large quantities of bifidobacteria in their guts, whereas formula-fed babies lacked these bacteria and struggled with repeated episodes of diarrhoea.
Since then, numerous studies have been done supporting the link between gut bacteria and disease risk, with some showing links between diet, gut health, and type 2 diabetes. Evidence shows that unhealthy diets cause gut bacteria imbalances that promote insulin resistance and low-grade inflammation, leading to blood sugar imbalances and diabetes.
Consequently, researchers have investigated whether probiotics can restore gut bacteria balance and lower blood sugar in individuals with prediabetes and type 2 diabetes. While the results have been conflicting, there is convincing evidence that probiotics reduce inflammation and improve blood sugar control in prediabetes and type 2 diabetes.
Keep reading to learn how probiotics help prediabetes and type 2 diabetes and the types of probiotics to consider adding to your diet.
What are probiotics
The World Health Organisation (WHO) defines probiotics as “live organisms, which when administered in adequate amounts, confer a health benefit on the host.”
Many different bacteria exist in the gut, but those that provide health benefits are probiotics. The two main bacteria species providing health benefits are Lactobacillus and Bifidobacterium. These bacteria are believed to promote health by boosting immunity, reducing cholesterol, preventing cancer, and lowering blood pressure (Shi et al., 2016). However, not all probiotics provide the same benefits so consuming a variety is crucial.
How Probiotics Affect Prediabetes and Type 2 Diabetes
Although we know that probiotics can maintain gut bacteria balance, the exact pathway through which they prevent diabetes or improve glucose control is not clear. Scientists suggest that probiotic bacteria may interact with each other to increase insulin secretion and sensitivity and glucose control (Ding et al., 2021).
Recent research shows that probiotics increase the production of hormones promoting satiety such as glucagon-like peptide 1 (GLP-1) and peptide YY (PYY), to prevent overeating and diabetes. Consuming probiotics with prebiotics (carbohydrates that feed probiotics), herbs and other dietary supplements may also boost the production of beneficial compounds that maintain gut lining integrity, reduce low-grade inflammation and boost insulin sensitivity (Ding et al., 2021).
Animal models of diabetes show that specific probiotic bacteria improve glucose control. Benefits have been seen with probiotics containing Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus gasseri, Lactobacillus reuteri and Lactobacillus rhamnosus (Bock et al., 2021).
For example, Lactobacillus casei improved glucose tolerance, lowered lipid levels, boosted immunity, and reduced oxidative stress while Lactobacillus johnsoniiimproved gut barrier integrity. Bifidobacterium lactis was also shown to lower lipid and insulin levels (Bock et al., 2021).
A meta-analysis of 38 studies with a total of 2086 participants investigated the effects of probiotics, prebiotics and synbiotics (a combination of probiotics and prebiotics) on blood sugar control in individuals with diabetes. Probiotics reduced fasting blood glucose, insulin, total cholesterol, and triglycerides, while increasing high-density lipoprotein ‘good’ cholesterol levels. However, probiotics did not reduce glycated haemoglobin (HbA1c) and low-density lipoprotein ‘bad’ cholesterol levels in these studies (Bock et al., 2021).
Another meta-analysis of 17 randomised controlled trials with 836 participants [423 taking probiotics and 413 controls] investigated the effects of probiotics on inflammation and glucose control in adults with type 2 diabetes. Compared to the control group, participants taking probiotics had significantly lower levels of inflammatory proteins. The probiotic group also had significantly lower fasting blood glucose, HbA1c and insulin resistance (Ding et al., 2021).
Similarly, another meta-analysis of 17 clinical trials involving 1, 105 participants (551 taking probiotics and 554 controls) with type 2 diabetes showed that probiotics significantly reduced fasting glucose, fasting insulin, and insulin resistance (Ruan et al., 2015).
Probiotics have not only proven helpful in type 2 diabetes, but they are also effective in prediabetes. In a double-blind, randomised controlled trial, 120 adults with prediabetes were allocated to receive either a probiotic and symbiotic supplement or a placebo for 24 weeks. At the end of the study, participants receiving the probiotic and symbiotic supplements had significantly lower fasting plasma glucose, HbA1c and improved insulin resistance (Kassaian et al., 2018).
What are the best sources of probiotics?
Probiotics are presented in certain dairy products and fermented foods. Popular probiotic-containing foods include kefir, kimchi, pickles, sauerkraut, fermented millet (ogi), fermented locust beans (iru), fermented cassava and miso. If probiotic foods are inaccessible, supplements are a good alternative.
Please note that you must take probiotics daily to reap their benefits because they only remain in your gut for a few days at a time. Eating asparagus, Jerusalem artichokes, onions and garlic, prebiotic foods will provide beneficial carbohydrates to feed probiotics and help them grow and multiply in the gut.
In summary, probiotics are a valuable addition to your diet whether you are healthy or have prediabetes or type 2 diabetes.
Probiotics can boost your immunity, maintain the integrity of your gut lining, lower your blood glucose, insulin, HbA1c, cholesterol and triglycerides and boost your good cholesterol levels. Remember, you must take probiotics daily, whether from food or supplements, to reap their benefits. Always consult a doctor before taking supplements.
- Kechagia, M., Basoulis, D., Konstantopoulou, S., Dimitridadi, D., Gyftopoulou, K., Skarmoutsou, N., & Fakiri, E.M. (2013) Health benefits of probiotics: a review. ISRN Nutrition, doi: 10.5402/2013/481651.
- Shi, L.H., Balakrishnan, K., Thiagarajah, K., Ismail, N.I.M., & Yin, O.S. (2016) Beneficial properties of probiotics. Tropical Life Sciences Research, 27(2): 73-90.
- Bock, P.M., Telo, G.H., Ramalho, R., Sbaraini, M., Leivas, G., Martins, A.F., Schaan, B.D. (2021) The effect of probiotics, prebiotics or synbiotics on metabolic outcomes in individuals with diabetes: a systematic review and meta-analysis. Diabetologia, 64: 26-41.
- Ruan, Y., Sun, J., He, J., Chen. F., Chen, R & Chen, H. (2015) Effect of probiotics on glycaemic control: A systematic review and meta-analysis of randomised, controlled trials. PLOS One, 10(7): e0132121.
- Kassaian, N., Feizi, A., Aminorroaya, A., Jafari, P., Ebrahimi, M.T., & Amini, M. (2018) The effects of probiotics and symbiotic supplementation on glucose and insulin metabolism in adults with prediabetes: a double-blind, randomised clinical trial. Acta Diabetologica, 55: 1019-1028.
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