It is now a known fact, how we live and eat affects our health. We know that it is important to prefer antioxidant and anti-inflammatory foods, whole and rich in fiber, to practice moderate physical activity and to keep blood pressure, blood sugar and cholesterol under control. However, there is also another parameter to pay attention to and which is directly linked to diet and lifestyle, insulin, the hormone that allows glucose to enter the cell. In fact, if insulin is present in excess, it can also be harmful, increasing the risk of obesity, cardiovascular problems and even cancer. This emerges from two recent scientific studies published both by groups of scientists from the prestigious Harvard T. H. Chan School of Public Health (Romanos Nanclares et al, Am J Clin Nutr, 2022 - Wan et al, Diabetes Care, 2022).
Insulin, what it is and how it works
Insulin is a hormone produced by the pancreas and has the task of stimulating the entry and use of glucose by the body's cells. Since we are used to giving importance mainly to blood sugar, which is the amount of glucose in the blood, insulin often takes a back seat. Yet it is precisely insulin alterations that open the doors to conditions such as pre-diabetes and diabetes, even when blood sugar is still normal. In fact, high blood glucose levels require higher amounts of circulating insulin to lower sugars. A continuous production of insulin in large quantities can, in the long term, cause a condition called insulin resistance, whereby the cells do not respond adequately to insulin, whose action therefore loses its effectiveness. To compensate for this, the pancreas secretes even more insulin. Therefore, a sedentary lifestyle, an unbalanced diet too rich in refined foods and sugars and insulin resistance are all conditions that cause an increase in insulin in the blood. We may not perceive this increase as it is necessary for our body to bring blood sugar back to normal levels. But our health can perceive it instead with harmful consequences.
Too much insulin, the risks
Both studies we are talking about today focused on the effects that a diet with a high insulin index, that is, capable of stimulating high insulin production, can have on health. In both cases, the scientists drew on data collected from previous clinical studies, such as the Nurses' Health Study and the Health Professionals Follow-up Study, in order to have a very large sample of the population to be analyzed, almost 170,000 volunteers in the first case and 106344 in the second case followed for a large number of years, just over 30. The insulin index of the diet was assessed on the basis of data on eating habits provided by the study participants. Well, what has emerged is that a diet with a high insulin index increases the risk of cancer in the long run. In particular, the first study observed a higher incidence of breast cancer, especially in the most aggressive and resistant form. Not only that, a diet of this type has been shown to increase the risk of cardiovascular disease with an often fatal course, as the second study points out. Finally, a diet with a high insulin index is associated, over time, with an increased risk of becoming overweight, obese and suffering from diabetes.
Therefore, even if our blood sugar is normal, it is important to follow a healthy and balanced diet, which does not stimulate an excessive release of insulin. Obviously, in healthy people, you can sometimes break the rule, the problem is in fact linked to a constant excess of insulin maintained over time. The Western-style diet is the typical diet capable of increasing insulin production. Instead, a diet based on a high intake of whole fruits, vegetables, especially green leafy vegetables, and low in red and processed meat, in sugary drinks, in refined grains and in poultry has been shown to stimulate low insulin release. Furthermore, as highlighted by various researches, it is important to avoid a sedentary lifestyle, ensuring moderate physical activity to keep not only blood sugar but also insulin under control (Farhadnejad et al, Nutrition Journal, 2021).