With projections that up to one-third of young people alive today will develop diabetes in their lifetime, it is timely to pay attention to two very interesting new studies on diabetes that have been published recently. This is a short update detailing continuing discoveries from our scientific community regarding the way the food we eat affects the onset of diabetes.
ANTIOXIDANTS AND DIABETES;
The first bit of science to look at is a prospective study published in late 2017 in the journal Diabetologia (the journal of the European Association for the Study of Diabetes) in which the scientists observed that the more antioxidants you eat, the lower is your risk of type-2 diabetes.
Previous research had shown that a diet rich in fruits and vegetables is associated with a lower risk of certain cancers and cardiovascular conditions. Other studies were pointing to a link between certain isolated antioxidants such as Vitamin C and E, lycopenes and flavonoids and reduction in type-2 diabetes risk (2,3). However, humans in the real world eat foods, not single nutrients removed from a whole food package.
In this latest study 64,223 middle-aged French women free of diabetes underwent diet analysis to quantify the overall antioxidant capacity in each of their diets. Their health was then monitored from 1993 when the study started until 2008 when the study ended. It was discovered that diabetes risk diminished with increasing antioxidant consumption up to a plateau of 15 mmol/day. This higher level of antioxidants was easily achieved through eating high amounts of fruits and vegetables in general and especially prunes, blueberries, strawberries, tea, dark chocolate, walnuts, hazelnuts and moderate amounts of red wine (so that the health benefits from polyphenol content could prevail over the damaging effects of alcohol itself (5)). Women with the highest antioxidant scores had a reduction in diabetes risk of 27% compared to those with the lowest scores. This link persists even after accounting for other diabetes risk factors such as smoking, hypertension, high cholesterol level, lower level of education, family history of diabetes and, the strongest risk factor of all, being overweight.
The specific reason for this beneficial effect of antioxidants is unclear at this time. Earlier studies have noted that oxidative stress plays a major role in the development of type-2 diabetes and that high levels of free radicals result in the fall of antioxidant defence mechanisms which lead to damage of cell components and enzymes and the development of insulin resistance (4). Antioxidants can certainly counter these free radical effects but, as research continues, it is likely that more specific actions directly on the sensitivity of cells to insulin will be elucidated.
LOW-FAT PLANT-BASED DIETS PREVENT DIABETES;
Even more thought-provoking is the second study regarding diabetes and food intake. Its results were published very recently, on February 9, 2018, showing that a plant-based diet improves both numbers of beta-cells and their function (6). Beta-cells are the cells in the pancreas that produce and release insulin. As the researchers point out, a key factor in the development of type-2 diabetes is the insulin resistance that occurs in muscle and liver cells along with the impairment of pancreatic beta-cell function (7). Traditional diabetes treatment is not aimed at improving beta-cell function even though such therapy would target the action of the very cells that are running into trouble during development of diabetes. And it’s not like we do not have a therapy that will be successful. Beta-cell function and beta-cell numbers are known to be positively influenced by both diet (8,9,10) and physical activity (8).
This latest research included 75 participants with BMIs of between 28 and 40 and no history of diabetes who were randomized to follow either a low-fat plant-based diet (38 participants) or to make no diet changes at all (37 participants) for the study period of 16 weeks. The low-fat plant-based diet consisted of vegetables, grains, legumes and fruits with no animal products or added fat. The resulting diet provided 75% of its energy from carbohydrates, 15% from protein and 10% from fat. Participants were excluded from the study if they smoked, drank alcohol, abused drugs, were pregnant or lactating or were currently eating a plant-based diet. No changes were made in either group in amount of physical activity and no changes in medications were made.
Beta-cell function and insulin secretion rate, insulin sensitivity, blood glucose levels and BMI were monitored over the course of the study. Results show that individuals who are overweight but have no history of diabetes can improve beta-cell function and cell sensitivity to glucose (reducing insulin resistance), reduce their blood insulin level and decrease both their fasting blood glucose levels and their blood glucose levels after meals. This is achieved simply by improving the macronutrient quality of the diet with no limit on the amount of calories being consumed. The low-fat plant-based diet group also lowered their body weight and body fat, especially in the abdominal area, compared to the control group. Lower body fat increases the ability of beta cells to regulate blood sugar and therefore helps prevent diabetes. Significant reductions in total cholesterol, LDL-cholesterol and HDL-cholesterol were also observed in the intervention group.
On the other hand, the control group showed no reduction in body fat and no significant changes in plasma lipid concentrations or markers of blood sugar level control. After-meal blood sugar levels were high resulting in increased insulin secretion and no improvement in beta-cell glucose sensitivity. In fact their insulin resistance increased. Worsening of these measurements are the very factors that result in beta-cell dysfunction and development of diabetes.
The exciting outcome of this trial is that choosing a low-fat plant-based diet can prevent the development of diabetes by both decreasing insulin resistance and increasing beta-cell function, two of the main causal factors of the disease. The researchers note that the subjects in this study were “generally health-conscious individuals” who were willing to make significant dietary changes and “may not be representative of the general population”. Regardless, the point is made that choosing to eat only plant-based food is a direct route to preventing metabolic changes that inevitably result in the development of diabetes. Doesn’t it make more sense to get to the root of the disease in this way rather than introducing medications that act by increasing glucose elimination from the body or through trying to squeeze more insulin out of an already struggling pancreas? The American Diabetes Association has endorsed the low-fat plant-based diet. Its 2018 Standards of Medical Care in Diabetes encourages a plant-based eating pattern as an effective option for type-2 diabetes prevention and management.
1 Mancini, F.R., Affret, A., Dow, C., Balkau, B., Bonnet,F. et al. Dietary antioxidant capacity and risk of type 2 diabetes in the large prospective E3N-EPIC cohort. Diabetologia 2018; 61:308–316.
2 Dakhale, G.N., Chaudhari, H.V., Shrivastava, M. Supplementation of vitamin C reduces blood glucose and improves glycosylated hemoglobin in type 2 diabetes mellitus: a randomized, double-blind study. Saudi Pharm J 2016; 24:547–553.
3. Manning, P.J., Sutherland, W.H., Walker, R.J. et al. Effect of high-dose vitamin E on insulin resistance and associated parameters in overweight subjects. Diabetes Care 2004; 27:2166–2171.
4 Maritim, A.C., Sanders, R.A., Watkins, J.B. Diabetes, oxidative stress, and antioxidants: a review. J Biochem Mol Toxicol 2003; 17: 24–38.
5 Hodge, A.M., English, D.R., O’Dea, K., Giles, G.G. Alcohol intake, consumption pattern and beverage type, and the risk of type 2-diabetes. Diabet Med 2006; 23:690–697.
6 Kahleova, H., Tura, A., Hill, M., Holubkov, R., Barnard, N.D. A Plant-Based Dietary Intervention Improves Beta-Cell Function and Insulin Resistance in Overweight Adults: A 16-Week Randomized Clinical Trial. Nutrients 2018; 10: 189.
7 Ferrannini, E., Gastaldelli, A., Miyazaki, Y., Matsuda, M., Pettiti, M., Natali, A., Mari, A., DeFronzo, R.A. Predominant role of reduced beta-cell sensitivity to glucose over insulin resistance in impaired glucose tolerance. Diabetologia 2003; 46: 1211 to 1219.
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