Frequent exposure to elevated blood sugar levels causes a variety of hormonal and metabolic changes that can adversely affect health and lead to disease. Poor control of postprandial glycemia (the level of glucose in the blood following a meal) has been linked to heightened mortality rates and cardiovascular disease, adding to the urgency of finding effective treatments, particularly for diabetes patients. Improved glucose control can reduce complications associated with the disease and help to maintain β-cell function.
Naturally, diet is at the core of efforts to remedy the problem, and postprandial glycemic control and its metabolic health outcomes have been extensively studied. Manipulating carbohydrate types consumed or increasing fibre content, for example, have been shown to help, as has exercise. The search is still on, however, for a diet-centered treatment that could help patients to control their postprandial glycemia and reduce reliance on drug interventions.
The promise of protein
At Newcastle University’s Institute of Cellular Medicine, we’re studying the role that whey protein may be able to play in this field. Although whey protein has already been the subject of numerous studies over the years, there are still plenty of aspects to explore, particularly in relation to glycemia in diabetes patients. In fact, you could say that we’ve barely begun to understand whether whey protein, possibly linked with an exercise regime, has the potential to become an intervention of choice for blood sugar control for this group in the longer term.
The existing literature, and our own studies into the metabolic health outcomes of whey protein, has created a good basis for further exploration. Current findings from lab-based studies show that whey protein taken before or with a meal can positively affect postprandial glycemia.
Significant knowledge gaps exist, however. For example, most whey protein-based studies have drawn their conclusions based on studies in healthy participants rather than patient populations. Often, effects have been measured during a very limited timeframe– focusing primarily on the effects of whey protein intake before or with just one or two meals. Additionally, experimental dosages of whey protein per meal have been as high as 55 grams, reflecting a level that introduces far more protein and calories than may be appropriate to consume on a daily basis.
The tip of the iceberg
Here at the Institute, our attention is currently focused on whey protein’s effect on glycemic control for diabetes patients – both from diet and exercise standpoints. We’re curious, for example, about how whey protein might be used alone or perhaps together with moderate exercise to help control postprandial glycemia.
There are several mechanisms by which whey protein affects glycemic control. It appears that it can, for example, slow gastric emptying and stimulate GLP-1 and GIP gut hormones to influence the appearance of sugar in the blood after a meal. Additionally, its amino acids are able to act directly on β-cells in the pancreas to increase insulin secretion. A third mechanism is through potential appetite suppressing effects, which may help to reduce the patient’s weight – an effect which is well known to enhance glycemic control.
Other researchers have studied these mechanisms in detail, examining whether consuming whey protein before or together with a main meal reduces glycemia compared with a no-whey-protein control both in healthy and diabetic participants. However, many studies have used test foods such as instant mashed potato or large amounts of white bread as meals – revealing that further research is needed based on ‘normal’ meals for diabetes patients. But that’s just the tip of the iceberg. What particularly interests my team is the opportunity to examine the effect of using whey protein supplements over a much longer period of time.
We have already examined the impact of reducing whey protein dosages to just 15-20 grams, demonstrating efficacy both with concentrated and hydrolyzed forms. Longer-term interventions have yet to be conducted, however, using these ‘realistic’ portions of protein.
Studying longer-term effects is likely to prove very interesting, but of course rather complex! Of particular interest is whether people will become habituated, showing a reduced response to a whey protein regime over time. Based on current knowledge, we would expect to maintain the initial response and, due to the appetite suppression effects of consuming protein before a meal, participants may reduce their overall energy intake and therefore lose weight, which may lead to improvements in glycemic response via that route, too. Monitoring changes in body composition will help to understand these aspects.
Incorporating exercise is also likely to help reduce post-prandial glycemia and assist weight management. Future studies should investigate exercise and nutrition interventions in combination to help develop healthy lifestyle recommendations for glycemic control.
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