A panel of experts reviewed current research to assess any health benefits from reducing red meat intake and make dietary recommendations.
Meat is a good source of protein, vitamins, and minerals, but previous research has suggested that diets rich in red meat (beef, lamb, or pork) or processed meat (smoked or cured meats such as bacon or sausages) can increase the risk of heart disease, type 2 diabetes, and some cancers. Current dietary guidelines from public health bodies around the world, including the World Health Organization, recommend limiting consumption of red and processed meat, to reduce the risks of developing these chronic illnesses. A panel of 14 international experts set out to rigorously review the available evidence to assess any health benefits from reducing red and processed meat intake. They also aimed to develop dietary guidelines to allow individuals to make personal choices about their diet, based on the certainty level of available scientific evidence, the extent of any health benefits and their dietary preferences. The panel recently reported their findings in the Annals of Internal Medicine.
Current guidelines recommend reducing red and processed meat intake
The researchers used the Nutritional Recommendations (NutriRECS) guideline development process, which includes rigorous methods for evaluating the certainty of study evidence. They reviewed over 150 studies, which included more than six million participants. The panel did not consider the environmental or animal welfare impacts of eating red meat.
The researchers performed four parallel systematic reviews on randomized controlled trials and observational studies looking at the health impact of red meat and processed meat consumption on heart disease, type 2 diabetes, and cancer.
In one systematic review of 12 trials including 54,000 people, the researchers did not find a statistically significant association between red meat consumption and the risk of heart disease, diabetes, or cancer. In three systematic reviews of studies following millions of people, they noted a very small reduction in risk among those who had three fewer servings of red or processed meat per week, but the association was uncertain.
In a review of studies looking at people’s attitudes to eating meat, they noted that people eat meat because they see it as healthy and tasty and are reluctant to change their dietary habits.
Extensive review studies suggest limited health benefits of reducing red meat
The majority of the panel concluded that adults can continue their current levels of consumption of red meat and processed meat. Their reasons for not recommending reducing red meat consumption is that they considered the certainty of the evidence for adverse health impacts is low, the reduction in health risk small, and that people are unlikely to change their diet for a small health benefit. However, three of the panel concluded that there is weak evidence to support recommending reducing red and processed meat consumption.
The panel did not consider the environmental impact of red meat consumption
“Based on our research, it’s uncertain whether there are true health concerns related to moderate consumption of red or processed meats,” said Dr. Bradley Johnston, Dalhousie University, Canada, one of the lead authors of the study. However, he pointed out that the panel focused on health outcomes and did not assess animal welfare or environmental aspects. He acknowledged that these are important issues, and people may want to reduce their meat consumption for these reasons.
Recommendations spark controversy and highlight nutrition research difficulties
The panel’s recommendations are contradictory to current medical advice and have drawn criticism from organizations such as the American Heart Association and the Harvard TH Chan School of Public Health, who interpret the evidence differently. They say that the review should not change current recommendations on healthy and balanced eating patterns for the prevention of chronic disease. They maintain that diets high in healthy plant-based foods are important both for human health and environmental sustainability.
The controversy around the review highlights some of the challenges with nutrition studies. It is problematic to perform randomized controlled trials in this area, in which two groups follow controlled diets for long periods and health outcomes are compared. Observational studies, which look at health outcomes in large populations with differing diets, may be affected by lifestyle or other factors, and it can be difficult to adjust study findings to take account of these effects. This means that nutritional study results may be open to differing interpretations.
Dr. Johnston commented that the controversy around their review study is due to a difference in approach, as the panel aimed to develop recommendations for individuals rather than for public health or society. “We hope our work will help people make more informed decisions from an individual perspective,” said Dr. Johnston “If there is a very small risk reduction – and the evidence base is uncertain, people then need to make their own decisions rather than having governments tell us we should reduce our red and processed meat consumption without being transparent and rigorous with their methods.” The debate will no doubt continue for some time.
Written by Julie McShane, MA MB BS