What 300 grams of ultra-processed foods per day does for your diabetes risk

What 300 grams of ultra-processed foods per day does for your diabetes risk

A new meta-analysis shows that even a small increase in ultra-processed food intake can increase type 2 diabetes risk, especially if consumption exceeds 300 grams per day.

In a recently published study in theDiabetes and Metabolism JournalResearchers examined the associations between ultra-processed food intake (UPF) and the risk of type 2 diabetes (T2D).

UPFs are industrial formulations made from whole food scraps, often modified and enhanced with food additives. UPFs are typically energy dense, high in sugar, sodium and fat and only fiber. Therefore, UPF intake could lead to poor diet quality and excessive energy intake, contributing to higher risks of obesity and other diseases. High UPF consumption may also impair insulin signaling and increase the risk of T2D. Food additives in UPFs such as artificial sweeteners and emulsifiers may also contribute to disrupting gut microbiota and promoting insulin resistance.

About the study

Processed meat showed the strongest diabetes link between UPF subgroups – 34% higher risk per serving, outperforming sugary drinks and other categories.

In the present study, researchers meta-analyzed the relationship between UPF use and T2D risk. First, they identified studies from PubMed, Web of Science and Embase databases using relevant search terms. This meta-analysis was limited to prospective studies that reported relative risk (RR) estimates and 95% confidence intervals for the associations between T2D risk and UPF uptake. Studies that do not follow the NOVA classification (of food groups) were excluded.

The following data were extracted from eligible studies: sample size, age, follow-up duration, nutritional assessment methods, exposure range, covariates, relative risks (RRs), and timing of UPF assessment, among others. The Newcastle-Ottawa Scale and the Oxford Center for Evidence-based medicine criteria were used to assess bias and evidence speed. Dersimonian-Laird random effects models were used for the meta-analysis comparing highest versus lowest UPF intake and individual UPF subgroups.

In addition, nonlinear and linear dose-response meta-analyses were performed for different UPF units (serving/day, absolute grams (G)/day, and percentage of g/day) using the two-stage random effects with restricted cubic brans and the two-stage generalized real estate injured squares estimation method using least squares forcing, respectively. Publication bias was assessed using Egger's test and funnel plots.

Sensitivity analyzes were performed by excluding each study from the meta-analysis one by one to assess the robustness of the results. Heterogeneity was examined using I-squared statistics and Cochran's Q test. Furthermore, subgroup analyzes on methodological characteristics and potential effect modifiers were conducted to identify sources of heterogeneity.

Results

Whole grains in ultra-processed cereals likely drove their unexpected protective effect, highlighting that not all industrial foods pose identical risks.

In total, the study included 10 publications in 12 prospective cohort studies. Most studies were conducted in Europe (five) and North America (four). Seven publications were of high quality, while three were of moderate quality. The meta-analysis of highest and lowest UPF intake categories included 38,308 cases of diabetes from over 714,000 participants.

The summary RR was 1.48 for T2D risk with moderate to high heterogeneity. Despite the heterogeneity in RR magnitude across studies, a consistent positive association was observed. No publication bias was identified. Among studies reporting associations for individual UPF subgroups, sugar- and artificially-sweetened beverages and processed meat were positively associated with T2D risk.

Conversely, packaged sweet snacks and desserts, as well as packaged savory snacks and ultra-processed grains and breads, were found to be inversely associated, although the inverse association for sweet snacks and desserts was not statistically significant (RR = 0.92, 95% CI: 0.85–1.00). These inverse associations may be partially explained by factors such as the flavanol content in chocolate-based products or the inclusion of whole grain bread in the cereal subgroup.

In subgroup analyzes by region, higher summary RRs were observed for European and North American studies compared to studies from other regions. This regional variation may be associated with higher processed meat intake in Western populations, which was the UPF subgroup most strongly associated with T2D. The summary RRs for the highest versus lowest UPF intake categories were comparable across studies using different UPF units.

The Asian and South American populations showed milder UPF-diabetes links than Westerners, likely due to different dietary patterns and smaller portion sizes.

Eight studies reported associations examining the percentage of G/day as a unit of UPF intake using the proportion of G/day. Each 10% g/day in UPF intake was significantly associated with a 14% higher risk of T2D, without evidence of nonlinearity. Four studies used absolute G/day as the unit of UPF intake. Each 100 g/day increase in UPF intake was associated with a 5% increased risk of T2D.

A nonlinear relationship was observed only for absolute G/day intake, with a steeper increase in risk at intake levels of 300 g/day. Likewise, four studies used servings per day as the unit of UPF intake. One use per day in the UPF intake significantly increased the risk of T2D by 4%, and this association was linear.

Furthermore, results remained robust in sensitivity analyzes that excluded one study at a time.

Conclusions

In summary, the meta-analysis found a positive association between UPF intake and T2D risk. Higher UPF consumption was associated with a 48% increased risk of T2D. The association remained statistically significant after adjusting for body mass index (BMI), although the effect was partially attenuated, suggesting that BMI may mediate part of the relationship.

The associations persisted after adjusting for diet quality and total energy intake, suggesting an independent effect. A nonlinear relationship was observed specifically for absolute G/day intake, with a steeper increase in T2D risk at intake levels exceeding 300 g/day of UPF. Given the growing increase in UPF intake, further efforts are needed to reduce UPF consumption by increasing access to minimally processed or unprocessed foods.

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