water intake

A number of studies have suggested that an increased water intake could lower markers of type 2 diabetes (T2D). A new study published in the British Journal of Nutrition showed that an increased water intake was associated with lower plasma glucose levels in men, but not in women.


It is commonly recommended to drink eight 8-ounce servings of water per day. Although there is little science behind this arbitrary rule, drinking water is essential to stay hydrated and to maintain a healthy metabolism. Additionally, an increased water intake may be associated with a reduced risk of type 2 diabetes (T2D) as water reduces arginine vasopressin (AVP) secretion, a hormone that regulates blood pressure, and increases blood plasma volume thereby decreasing the plasma concentration of glucose.

Only a small number of studies have investigated the relationship between water intake and hyperglycemia (high blood glucose levels), and the results have been conflicting. Nevertheless, water intake is a simple and inexpensive target for health promotion if it indeed lowers markers of T2D. A new study published in the British Journal of Nutrition aimed to investigate the role of water intake on glycated hemoglobin (HbA1c), a marker of plasma glucose concentration.

The researchers studied analyzed unweighted food diaries of a large population from the United Kingdom. Plain water was defined as water with no added flavours, sweeteners, nutrients, or stimulants, whereas other beverages were included in a separate category. HbA1c was measured through blood samples.

A surprising result from this study was that only 76% of men and 88% of women reported consuming plain water. Additionally, higher water intake was associated with lower HbA1c in men, but not in women. This surprising sex difference may be due to changes in hormone levels of women during different stages of the menstrual cycle which may contribute to increased fluid retention.  Finally, the researchers found that substituting water for sweetened beverages was not associated with reduced HbA1c, suggesting that the addition of plain water to the diet is a more important factor than eliminating sweetened beverages altogether.

A major limitation of this study is that other covariates of health were not included, such as physical activity and blood pressure. Physical activity could both increase thirst and decrease cardiometabolic disease risk. Thus, this study cannot conclude that decreased plasma glucose is a direct effect of increased water intake. Future studies should be conducted including other health-related factors such as exercise, as well as to understand the mechanisms behind the sex differences shown in this study.


Written By: Neeti Vashi, BSc

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