Diet of Plant Protein Associated With Reduced Mortality Interview with:
Mingyang Song Sc.D, research fellow
Clinical and Translational Epidemiology Unit and Division of Gastroenterology MGH and Department of Nutrition
Harvard T.H. Chan School of Public Health What is the background for this study? What are the main findings?

Response: Previous studies have been focused on the amount of protein intake, while little is known regarding the health effect of different food sources for protein intake. In this study, we found that high animal protein intake was associated with higher mortality, whereas high plant-based protein was associated with lower mortality. Replacement of animal protein with plant protein was associated with lower mortality. Overall, the findings support the importance of food sources for protein intake for long-term health outcomes. What should readers take away from your report?

Response: The most important take-home message is that it is not just the amount of protein intake that matters to health. What foods people choose to consume to obtain protein is equally important from a broad dietary perspective. Plant is a better source than animal products. If people do have to choose among animal products, try to avoid processed red meat and choose fish or chicken instead. What recommendations do you have for future research as a result of this study?

Response: Future studies should examine the mechanisms for the opposite associations of animal versus plant protein intake with mortality, possibly by using some intermediate, clinically targetable biomarkers. Is there anything else you would like to add?

Response: In this study, we noted that the protein-mortality associations were mainly restricted to participants who were considered to have an unhealthy lifestyle, whereas the associations were pretty null in the healthy-lifestyle group.

An “unhealthy” lifestyle was defined by having any of the following habits:
1) current or past smoking,
2) heavy alcohol drinking (>=1 drink/day in women, >=2 drinks/day in men),
3) underweight or obesity (BMI=25.0 kg/m2),
4) physical activity of <150-min/week at moderate level.

Although we expected the associations to be weaker in the healthy lifestyle group, we did not expect them to be completely null compared to the unhealthy lifestyle group. However, when we looked deeper into the data, we noted that, at similar amount of animal protein intake, the unhealthy lifestyle group consumed more process and unprocessed red meat, egg, and high-fat dairy, whereas the healthy lifestyle group consumed more fish and poultry. At similar amount of plant protein intake, the unhealthy-lifestyle group consumed less fiber, fruit, vegetables, and whole grains than the healthy-lifestyle group. Thus, we suspect that the different food sources of protein intake in the two groups may contribute to the stronger results in the unhealthy-lifestyle group than in the healthy-lifestyle group. Thank you for your contribution to the community.


Song M, Fung TT, Hu FB, et al. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Intern Med. Published online August 01, 2016. doi:10.1001/jamainternmed.2016.4182.

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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Last Updated on August 2, 2016 by Marie Benz MD FAAD