Dairy products, such as cheese and milk, and unprocessed meat may actually benefit heart health.
Many studies suggest that a diet that avoids red meat and dairy but is rich in fruit, vegetables, nuts, and whole grains is the best for heart health.
However, new research suggests that we should amend these guidelines.
The Prospective Urban Rural Epidemiological (PURE) study — which was led by Prof. Salim Yusuf, the director of the Population Health Research Institute (PHRI) at McMaster University in Hamilton, Canada — suggests that the results of these traditional studies may be biased and outdated.
Specifically, explain the researchers, such studies are based on the dietary habits of high-income countries and rely on data from decades ago. For these reasons, the new study aimed to make a more comprehensive analysis of people's dietary patterns across the world.
Its findings were presented at the 2018 annual conference of the European Society of Cardiology, held in Munich, Germany.
The researchers have also published their results in the journal The Lancet.
Diet quality and cardiovascular health
For the PURE study, Prof. Yusuf and colleagues examined the link between diet and heart health in almost 140,000 healthy people, aged 35–70, who were clinically followed for over 9 years.
The quality of the participants' diets was assessed using a food score. To develop the score, the researchers included foods that previous studies suggested might lower the risk of premature death, such as: fruit, vegetables, nuts, legumes, fish, dairy products, and meat.
PHRI's Andrew Mente, the study's co-principal investigator, summarizes the findings. "People who consumed a diet emphasizing fruit, vegetables, nuts, legumes, fish, dairy products, and meat had the lowest risks of cardiovascular disease and early death," he says.
"Regarding meat, we found that unprocessed meat is associated with benefit."
Specifically, compared with people who scored the lowest on the quality of their diet, those with the highest quality score were 11 percent less likely to experience a major cardiovascular event, 17 percent less likely to have a stroke, and 25 percent less likely to die of any cause.
Additionally, the findings suggest that the intake of refined carbs should be limited, but that dairy and unprocessed red meat may be healthful.
'Dairy products and meat are beneficial'
The researchers replicated their findings in four further studies. Overall, the results were confirmed in a total sample of more than 218,000 people from over 50 countries spread across the globe.
"Our results appeared to apply to people from different parts of the world and so the findings are globally applicable," explains Mahshid Dehghan, who is also a co-principal investigator affiliated with PHRI.
Prof. Yusuf explains that, while these findings may go against traditional beliefs, they are a better reflection of our modern, international dietary habits.
"Thinking on what constitutes a high-quality diet for a global population needs to be reconsidered. For example, our results show that dairy products and meat are beneficial for heart health and longevity. This differs from current dietary advice."
Prof. Salim Yusuf