High red meat consumption increases risks of CVD and diabetes

Higher consumption of both unprocessed and processed red meat is associated with higher risks of cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM), according to a meta-analysis involving >4.4 million people by researchers from the University of Hong Kong (HKU).

The WHO has classified processed meat as carcinogenic to humans (Group 1) and red meat as probably carcinogenic to humans (Group 2A). [www.who.int/news-room/questions-and-answers/item/cancer-carcinogenicity-of-the-consumption-of-red-meat-and-processed-meat] “Red meat is increasingly attracting attention not only for individual health, but also for planetary health,” wrote the researchers. “[However,] observational studies have shown inconsistent associations of red meat consumption with CVD and T2DM.”

To comprehensively assess the association, the researchers screened observational studies and randomized controlled trials published by 30 June 2022 from PubMed, Web of Science, Embase, and Cochrane Library. Forty-three studies (n=4,462,810; female, 61.7 percent) on CVD and 27 studies (n=1,760,774; female, 64.4 percent) on T2DM were included in the systematic review and meta-analysis (SR/MA). By including more recent studies published in or after 2020, the SR/MA has by far the largest sample size to date. [Eur Heart J 2023;44:2626-2635]

Results showed that each 50g/day increase in consumption of processed red meat was significantly associated with higher risks of CVD (hazard ratio [HR], 1.26; 95 percent confidence interval [CI], 1.18–1.35; I²=64.1 percent) and T2DM (HR, 1.44; 95 percent CI, 1.27─1.63; I²=90.5 percent).

Although the risks were lower, unprocessed red meat consumption (per 100 g/day increment) was also positively associated with CVD (HR, 1.11; 95 percent CI, 1.05–1.16; I²=33.4 percent) and T2DM (HR, 1.27; 95 percent CI, 1.16–1.39; I²=88.7 percent).

“Whether the associations vary by sex and setting [ie, Western vs Eastern] remains unclear,” said the researchers. Western settings included dietary patterns in the US, Europe, and Australia, which were characterized by higher intake of processed meat, red meat, butter, high-fat dairy products, and refined grains, while Eastern settings included dietary patterns in Asia and West Africa, which were characterized by higher intake of whole grains, vegetables, and seafood.

Subgroup analyses showed no difference in the associations by sex. However, compared with Eastern settings, red meat consumption was associated with higher risks of T2DM (p=0.000 for processed red meat) and stroke (p=0.010 for unprocessed red meat) in Western settings. “The associations were possibly due to smaller servings of red meat in Eastern cuisines,” explained the researchers. Additionally, the higher percentage of body fat in Western vs Eastern individuals also played a role, given that body composition is closely related to stroke and T2DM.

“With Western dietary culture increasingly influencing Eastern dietary culture, people in Hong Kong are consuming increasing amounts of processed and unprocessed red meat,” commented Dr Jane Zhao of the School of Public Health, HKU. “If this trend continues, Hong Kong may face a similar situation of increased CVD and T2DM risks seen in the US, Europe and Australia.”