The PREVIEW Study Newsletter #10 – June 2018

In this issue:

• Protein intake and pre-diabetes & eLeaning

Editorial

Lifestyle habits such as sedentariness and physical inactivity are associated with increased risk of developing Type 2 Diabetes (T2D). These habits are among the hardest to change and many of us struggle lifelong, despite the best of intentions.

As a part of the PREVIEW Project, an interactive eLearning module was developed with an aim to contribute to T2D prevention at the community level. We are proud to announce that the eLearning module is now freely available. This module does not aim to provide information specific to management of T2D, but rather offers insights into why prevention matters and what individuals can do to lower their risk of developing T2D.

You will also find information about why targeting bad habits is particularly beneficial and how new habits can be achieved. Apart from information and practical advice, participants are invited to take part in quizzes to help consolidate learning. In one example, we learn how ready we are to change our lifestyle habits. This helps us understand ourselves and where we stand on the learning curve. The eLearning module can be accessed from the link below and shared freely with interested organisations and individuals.

In the remainder of the newsletter Professor Brand-Miller provides insights on the health and safety aspects of animal and plant proteins

Maija Huttunen-Lenz
Stuttgart, Germany

Protein intake: healthy or not for pre-diabetes?

Increased protein intake has been recommended in the treatment of obesity, mainly because of its high satiating effect compared to calories derived from carbohydrate and fat. However, unwanted effects of protein on kidney function and large bowel risk markers for cancer have been suggested. The scientific literature reports mixed findings (some positive, some negative). One aim of the PREVIEW project is to bring some clarity to the role of protein in the diets of people with pre-diabetes. Grith Møller, one of our Ph.D. students from the University of Copenhagen, made this the focus of her thesis.

What do the PREVIEW population studies tell us?

In our first analyses of over 76,000 healthy individuals included in the combined PREVIEW population data, we developed a novel protein scoring system based on both quantity and type of protein, i.e., plant or animal in origin. Using this, we found that a higher intake of total protein, particularly from plant sources appeared to be associated with a lower level of HbA1c, a marker of postprandial blood glucose levels. This is a good outcome, implying a lower risk of developing type 2 diabetes.

Secondly, we found that higher total protein intake, especially of protein derived from plants, was associated with higher eGFR, a marker of better kidney filtration. These findings were still statistically significant after adjustments for potential confounders in some populations (eg Dutch), but not others (eg Finnish). However, studies like this are purely ‘observational’ in nature and can’t prove that it was the protein itself that was responsible for the good health markers.

What does the PREVIEW intervention study tell us?

In this investigation, we studied a subgroup of 310 individuals with pre-diabetes who were enrolled in the PREVIEW intervention study. Here we estimated protein intake from 4 day dietary records completed by the PREVIEW participants at various time points. As expected, we confirmed that the higher the recorded protein intake, the higher the excretion of urea, a breakdown product of protein. After 12 months, there was no increase or decrease in eGFR. Similarly, there was no change in creatinine clearance, another marker of kidney function. In addition, there was no sign of increased protein (albumin) in the urine, a third marker of kidney function.

Thus again, in the PREVIEW project, there is no indication that higher protein intake is having harmful effects on the kidneys in people with risk factors for developing type 2 diabetes. This result still needs confirmation at the 24 and 36 month time points to ensure there are no longer term adverse effects of higher protein intake.

What about cancer markers?

Another concern about high protein diets is their potential effect on large bowel health and particularly, whether they increase the risk of colorectal cancer. The scientific literature shows mixed findings.

In our PREVIEW intervention study, a subgroup of 94 individuals were asked to collect their stools (faeces) for 3 days at baseline and at 12 months of the intervention. Stool samples were analysed for short chain fatty acids (SCFA), total phenols, ammonia and acidity (measured by their pH). A drop in pH and an increase in short chain fatty acids such as acetic, propionic and butyric is a sign of increased fermentative activity by ‘friendly’ microbes. For example, higher intake of dietary fibre intake is known to reduce pH and increase SCFA in the large bowel. But an increase in phenol and ammonia concentration in the faeces is considered a sign of increased putrefactive (un-friendly) microbial activity.

Reassuringly, in these PREVIEW participants, we found no consistent associations between higher total protein intake, whether from animal or plant sources, and any of the colorectal cancer markers. Furthermore, there were no signs that red meat produced detrimental changes compared with other sources of protein. After adjustment for confounders including age and dietary fibre, there was a positive association between changes in ammonia and changes in the protein score. This suggests that higher total protein intake, even from plant sources, will increase the amount of nitrogen in the faeces.

Taken together, these findings suggest that a modest increase in protein intake, especially from plant sources, does no harm. But there is still a need to follow up our participants at the 36 month time point and to rule out adverse long term outcomes (20 years!), especially of very high protein intake, from red meat, processed meat, and other animal sources, such as dairy and eggs.

References

Grith Møller, Health effects on an increased protein intake on kidney function and colorectal cancer risk factors, including the role of animal and plant protein sources – the PREVIEW project. Ph.D. thesis 2018. Dep NEXS, UCPH, DK.