A Diet Strong in Plant-Based Protein Promotes Healthy Aging

We all look forward to our senior years when we can leave our hectic working life behind and enjoy the fruits of those labours.  Unfortunately for many people, this dream doesn’t come to pass and numerous retirement years are spent battling chronic illness.  However, there now exists extensive evidence that we have the opportunity to influence how we age.  One powerful step we can take involves the foods that we choose to eat.

 

A New Study  (1)

Consuming enough protein during midlife is associated with good health in older adulthood but it’s not just any old protein that works the best.  The source of the protein is also important.   A new study published in 2024 by the Harvard T.H. Chan School of Public Health analyzed data from over 48,000 women who had taken part in the Nurses’ Health Study.  Study results illustrated that women who ate higher amounts of plant-based protein had reduced risks of heart disease, cancer, diabetes and cognitive decline and enjoyed good health as they aged.

Participants in this study were women between the ages of 38 and 59 who were in good physical and mental health at the start of the trial. For the purpose of this analysis, healthy aging was defined as being free from eleven major chronic diseases, having good mental health, and not having impairments in either cognitive or physical function.  The eleven chronic diseases participants were aiming to be free of were cancer, type-2 diabetes, myocardial infarction, coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty, congestive heart failure, stroke, kidney failure, chronic obstructive pulmonary disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis.)

Intake of protein, including total protein, animal protein, dairy protein (a subset of animal protein), and plant protein, was assessed from validated food frequency questionnaires collected from study participants every four years, from 1984 to 2016.  Plant-based protein sources included fruits, vegetables, bread, beans, legumes, cereals, nuts, beans, peanut butter, and pasta. Animal-sourced protein sources included meats such as beef, pork, lamb and chicken, dairy products, fish/seafood, eggs and cheese.

Here are the results:

• Higher protein intake from any source was positively associated with healthy aging.
• Greater intake of plant protein was associated with 41% higher likelihood of remaining free from physical limitations in senior years while greater intake of animal protein was associated with 5% higher likelihood of remaining free from physical limitations.
• Substituting plant protein in place of animal or dairy protein was associated with higher likelihood of healthy aging, good physical function, good mental status and absence of chronic disease in old age.
• Only plant protein was significantly associated with higher likelihood of preserving good mental status.
• A 3% increase in total protein in the diet increased the likelihood of healthy aging in women by 5%.
• A 3% increase in animal protein in the diet increased the likelihood of healthy aging in women by 7%.
• A 3% increase in dairy protein in the diet increased the likelihood of healthy aging in women by 14%.
• A 3% increase in plant protein in the diet increased the likelihood of healthy aging women by 38%.

The research team for this analysis noted that some of these benefits likely stem not just from the plant protein but from the fiber, phytonutrients like polyphenols and other beneficial micronutrients that are also components of plants but have almost no presence in animal-sourced foods.   They also acknowledged that other studies with more diverse cohorts are needed.  The Nurses’ Health Study encompasses mainly white females who work in health care.  Nevertheless, this new paper adds strength to the existing evidence illuminating the benefits of plant protein over animal protein for healthy aging.

 

Previous Studies on Protein Sources and Early Mortality

In 2016 researchers examined how the source of protein affects mortality.  Over 131,000 male and female participants were followed for three decades.  Results showed the following; (2)

• Replacing 3% of energy from dietary animal protein with an equivalent amount of plant protein was associated with a 10% lower risk of premature death from all causes and a 12% lower risk of premature death from cardiovascular disease
• Eating higher amounts of plant protein was linked to a lower risk of premature death from all causes and premature death from cardiovascular disease
• Eating higher amounts of animal protein was associated with a higher risk of premature death, particularly death from cardiovascular disease

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A study published on July 13 2020 encompassing more that 416,000 people found that greater plant protein intake was associated with reduced overall mortality in both sexes.  Results are as follows: (3)

• Replacing red meat with plant protein resulted in a 13% lower risk of overall mortality in men and a 15% lower risk in women.
• Replacing eggs with plant protein reduced the risk of overall death by 24% in men and 21% in women
• Replacing just 3% of calorie intake from animal protein with an equivalent amount of plant protein resulted in…
  • A 10% decreased risk of early death from any cause for both men and women
  • An 11% lower risk of early death from cardiovascular disease in men and a 12% lower risk in women

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In 2024, another study from the Harvard T.H. Chan School of Public Health using data from nearly 203,000 men and women demonstrated the following: (4)

• Eating a higher plant-to-animal protein ratio was associated with a 19% lower risk of cardiovascular disease including coronary artery disease.
• Eating a higher plant-to-animal protein ratio combined with higher protein levels overall was linked to a 28% lower risk of cardiovascular disease and a 36% lower risk of coronary artery disease.

Replacing red and processed meat with plant protein sources, particularly legumes and nuts, was likely the reason for this lowering of risk. Such replacements also improve blood lipid levels, blood pressure and inflammation.  Study authors point out that the average American eats a 1:3 plant-to-animal protein ratio.  This study suggests that a ratio of at least 1:2 is substantially more effective at preventing cardiovascular disease.  For coronary artery disease, an optimal plant-to-animal protein ratio would be 1:1.3 or higher. (E)

 

In Summary

The message being delivered by all these scientific investigations is clear.  For protection from cardiovascular disease and for enjoying a long healthy life, both women and men benefit from obtaining most of their dietary protein from plants like fruits, vegetables, legumes, nuts and seeds.

 

SOURCES:

1  Ardisson Korat, A.V., Shea, M.K., Jacques, P.F., Sebastiani, P., Wang, M., Eliassen, A.H., Willett. W.C., Sun. Q. Dietary protein intake in midlife in relation to healthy aging – results from the prospective Nurses’ Health Study cohort. Am J Clin Nutr. 2024 Feb;119(2):271-282. Doi: 10.1016/j.ajcnut.2023.11.010. Epub 2024 Jan 17. PMID: 38309825; PMCID: PMC10884611.

2  Song, M., Fung, T.T., Hu, F.B., et al. Association of animal and plant protein intake with all-cause and cause-specific mortality. JAMA Intern Med. 2016;176 (10):1453-1463. Doi:10.1001/jamainternmed.2016.4182

3  Huang, J., Liao, L.M., Weinstein, S.J., Sinha, R., Graubard, B.I., Albanes, D. Association Between Plant and Animal Protein Intake and Overall and Cause-Specific Mortality. JAMA Intern Med. 2020;180(9):1173–1184. Doi:10.1001/jamainternmed.2020.2790

4  Glenn, A.J., Wang, F., Tessier, A.J., Manson, J.E., Rimm, E.B., Mukamal, K.J., Sun, Q., Willett, W.C., Rexrode, K.M., Jenkins, D.J., Hu, F.B.. Dietary plant-to-animal protein ratio and risk of cardiovascular disease in 3 prospective cohorts. Am J Clin Nutr. 2024 Dec;120(6):1373-1386. Doi: 10.1016/j.ajcnut.2024.09.006. PMID: 39631999.