Key Findings from a 2024 Study on US Prospective Cohorts and a Meta-Analysis
A recent study titled “Ultra-processed foods and cardiovascular disease: analysis of three large US prospective cohorts and a systematic review and meta-analysis of prospective cohort studies” by Kenny Mendoza and colleagues (2024) has shed new light on the relationship between ultra-processed foods (UPFs) and cardiovascular disease (CVD). By analysing data from three large US prospective cohorts and conducting a systematic review and meta-analysis, the research highlights the significant role UPFs play in increasing the risk of cardiovascular disease (CVD).
The findings emphasize that not all UPFs carry the same level of risk, urging a more nuanced understanding of how specific types of processed foods contribute to heart-related health issues.
Ultra-processed Foods and Health Risks: What We Know So Far
Heart disease, Type 2 diabetes, cancer, dementia, and irritable bowel syndrome — these are just a few conditions that have been linked to diets high in ultraprocessed foods (UPFs). But what exactly are UPFs, and why are they so prevalent in our diets?
UPFs make up about 73% of the U.S. food supply and include a wide variety of products. From traditionally “unhealthy” options like soft drinks, sweets, burgers and hot dogs to seemingly “healthy” choices such as whole grain breads, breakfast cereals, flavoured yoghurts, and plant-based milks, the ultraprocessed category is vast and diverse.
New Findings from this Major Study
Last week Dr. Mendoza and colleagues published one of the largest and longest-running studies on ultraprocessed foods and heart health. Published in a Lancet journal, the study followed more than 200,000 U.S. adults, who completed detailed diet questionnaires starting in the 1980s and were followed for about 30 years. Most participants were white health professionals, and the study analysed how their consumption of UPFs related to cardiovascular disease risk.
After accounting for lifestyle factors like smoking, exercise, family health history, and sleep, the researchers found that those who consumed the most UPFs were 11% more likely to develop cardiovascular disease and 16% more likely to develop coronary heart disease compared to those who ate the least. Although there was a slight increase in stroke risk, it was not statistically significant.
The researchers also conducted a separate analysis by combining data from 19 other studies, involving about 1.25 million adults. Here, the results showed a 17% increased risk of cardiovascular disease, 23% increased risk of coronary heart disease, and 9% higher risk of stroke for those consuming the most UPFs compared to the lowest consumers.
Strengths and Limitations of the Study
The study is “one of the most robust” of its kind due to its large sample size and regular dietary assessments. However, the study did have limitations. The diet questionnaires didn’t specifically measure food processing levels, so researchers had to estimate which foods were likely ultraprocessed after the fact.
Furthermore, some foods, like breakfast cereals, may have changed in nutrient composition over the years, making it harder to apply these findings to today’s diets.
Another limitation is that the study’s participants were mostly white and highly educated, meaning the results may not be fully generalizable to other populations.
What Foods Pose the Highest Risk to Health?
The study didn’t just look at overall UPF consumption — it also sought to identify which foods were the worst offenders. Of the 10 categories of UPFs examined, two stood out as high risk: sugar-sweetened drinksand processed meats (such as hot dogs, bacon, chicken sausages etc). When these two categories were removed from the data, most of the risk associated with UPFs disappeared.
Conversely, certain UPFs were associated with reduced risks of cardiovascular disease. These included breakfast cereals, flavoured yoghurts, frozen yoghurts, ice cream, and savoury snacks like packaged popcorn and crackers. This aligns with earlier research, which has suggested that whole grain cereals, breads, and yoghurts are either neutral or even beneficial to heart health.
The key difference between harmful and less harmful UPFs may lie in their nutritional profiles. For example, processed meats are high in sodium and saturated fats, while sugary soft drinks are high in sugars. In contrast, whole grain cereals and breads, even when ultraprocessed, can provide fibre vitamins, and minerals that are beneficial to heart health.
Takeaways: What Should We Be Eating?
So, what does this all mean for our diets? Experts agree on several key points:
- Emphasize minimally processed foods: It’s hard to go wrong with whole fruits, vegetables, legumes, nuts, and whole grains. Eating more of these foods and fewer ultraprocessed options is consistently linked to better health.
- Avoid processed meats and sugary soft drinks: These two categories have repeatedly been associated with poor health outcomes, particularly heart disease. Reducing them from your diet is a wise move.
- Not all UPFs are created equal: While some UPFs, like processed meats and sugary soft drinks, are clearly increasing the risk others may offer nutritional benefits. Cereals, whole grain breads, and certain dairy products can provide essential nutrients, even if they fall under the “ultraprocessed” label.
Foods, like fortified cereals, whole grain breads, and certain dairy products (e.g., low-fat yogurt or fortified milk), can still provide essential nutrients despite being processed. These foods may be enriched with vitamins, minerals, or fibre, contributing to a balanced diet. For instance:
- Fortified cerealscan be a good source of iron, folic acid, and other micronutrients that are essential, especially for individuals with dietary restrictions or increased needs.
- Whole grain breadsdeliver dietary fibre, which supports digestive health and helps manage blood sugar levels.
- Dairy products, even when processed, often offer calcium, vitamin D, and protein, which are critical for bone health and muscle function.
Conclusion
In summary, while it’s important to be cautious with certain UPFs, it’s equally important to recognize that some can offer nutritional benefits. The key lies in distinguishing between those that are predominantly harmful and those that contribute to a healthy, balanced diet. This research calls for a more nuanced approach to dietary guidance, emphasizing the need to differentiate between various UPFs to better address their specific contributions to heart health issues.
For more information:
https://www.thelancet.com/journals/lanam/article/PIIS2667-193X(24)00186-8/fulltext
