ARE ULTRA-PROCESSED FOODS RISKY FOR PEOPLE WITH DIABETES?

As the current dietary demon, scary headlines about the risks of eating and drinking so-called ultra-processed foods (UPF) seem to greet us on at least a weekly basis, if not daily. Should people with diabetes be concerned?

Ultra-processed foods and risk of diabetes

Regular readers of GI News will already be aware that a number of studies have investigated the associations between the consumption of ultra-processed foods and risk of type 2 diabetes in observational studies (See this month’s What’s New? and the July 2022 edition of Diabetes Care).

While there are indeed associations between ultra-processed food consumption and risk of developing type 2 diabetes, they are consistently related to specific foods and drinks like processed meats and soft drinks (soda’s) that fall into the NOVA ultra-processed food category. We have known about these associations long before the NOVA system was conceived, and arguably it is not helping to clarify the situation, given the fact that certain ultra-processed foods (e.g., breakfast cereals; wholegrain breads; fruit-based products; and yoghurt and dairy-based desserts) are associated with decreased risk of type 2 diabetes.

Therefore, people at risk of diabetes need much more specific dietary advice than simply avoiding/limiting ultra-processed foods. For example, existing dietary guidelines already advise saving processed meats and soft drinks for special occasions.

Ultra-processed foods and people with existing diabetes

Surprisingly few studies have investigated the effects of ultra-processed food on people with existing diabetes.

As discussed in this month’s Food for Thought, there is no clear relationship between a foods glycemic index (GI) or glycemic load (GL) and food processing. This is important, because as regular readers of GI News know, systematic reviews and meta-analyses of randomised controlled trials consistently find that consuming low GI/GL foods and drinks instead of high GI/GL alternatives significantly improves glycated haemoglobin (HbA1c) by 0.31%-points in people with diabetes, and also improves fasting glucose (-0.36 mmol/L), LDL-Cholesterol (-0.17 mmol/L), non-HDL-Cholesterol (-0.20 mmol/L), triglycerides (-0.09 mmol/L), body weight (-0.66 kg), and body mass index (-0.38 kg/m2).

Unfortunately, there are as of yet no randomised controlled trials investigating the effect of diets containing large amounts of ultra-processed foods, compared to small amounts, in people with diabetes. However, a new study investigating the association between UPF consumption and HbA1c has been recently published and has received lots of media attention. It’s important to note that it was a cross-sectional analysis of baseline data from a randomised controlled trial. Not to be confused with a randomised controlled trial – it is in fact a kind of observational study, and a kind that is rated as one of the lowest quality, scientifically. It included 273 (small number for an observational study) black American mostly female (72.5%) adults (average age 61 years) with type 2 diabetes living in Texas, USA. Average HbA1c was 8.04% and average length of type 2 diabetes since diagnosis was 11 years.

Research assistants coded 1,494 reported food and beverages according to the NOVA system using data collected previously using the 24-hour recall method. For each participant, daily UPF consumption in grams per day and the proportion that UPFs contributed to the total grams of food and beverage intake (% grams of total grams) were calculated.

Small but statistically significant associations were found between higher UPF consumption and higher HbA1c levels, with each 1% higher UPF intake corresponding to a 0.02%-point higher HbA1c among the participants. However, in conclusion, the authors noted that longitudinal (a better kind of observational study) and experimental studies (i.e., randomised controlled trials) are warranted to examine the effect of reducing UPF consumption in people with diabetes.

Unfortunately, however, when the study was published, headlines around the world screamed:

• “Ultra-processed foods pose unique dangers for people with type 2 diabetes”
• “Ultra-Processed Foods: A Dangerous Craving for Type 2 Diabetics”
• “Ultra-Processed Foods Risky for Type 2 Diabetes”

Based on the current evidence-base, there is at this point in time no compelling evidence that people with existing diabetes should be particularly concerned about ultra-processed foods in general, with respect to blood glucose levels. Current scientific evidence indicates that the amount and quality of carbohydrate in the diet are much more important for blood glucose levels than processing.

Read more: