We all know that nutrition is one of the pillars of health. To live a long and healthy life it’s important to get the details right, and one ongoing topic of dietary research is protein. Like carbohydrates and fats, both the amount and quality matter.
Nutritional research is tricky, often relying on observational studies that offer hints but not definitive answers. A recurring debate is whether plant proteins are healthier than animal proteins. Researchers from McMaster University in Ontario recently set out to explore that question.
Their study, published in Applied Physiology, Nutrition, and Metabolism, looked at data from nearly 16,000 adults. Surprisingly, it doesn’t seem to matter whether protein comes from plants or animals when it comes to overall mortality, though animal protein showed a slight protective effect against cancer deaths.
Confusion Around Eating Protein
The recommended dietary allowance (RDA) for protein in Canada and the U.S. is 0.8 grams per kilogram of body weight per day. Another way to approach protein amounts is the acceptable macronutrient distribution range (AMDR), which is broader, at 10 to 35 percent of daily calories. Most people already fall comfortably within this range, often several times higher than the RDA.
Debate remains over how much protein is optimal, especially for older adults. Some studies suggest more protein supports muscle health and longevity, while others raise concerns. One study linked high protein intake with a 75 percent increase in overall mortality and a four-fold higher cancer risk in adults aged 50–65.
Interestingly, that risk disappeared when the protein came from plants, lending support to guidelines like Canada’s Food Guide, which favors plant protein. But instead of focusing on protein amounts, the McMaster researchers looked at usual amounts of protein, only differing in the source of protein.
“There’s a lot of confusion around protein – how much to eat, what kind and what it means for long-term health. This study adds clarity, which is important for anyone trying to make informed, evidence-based decisions about what they eat,” said study co-author Stuart Phillips, professor at McMaster, in a press release.
Read More: How Much Protein Do You Actually Need in Your Diet?
Plant vs. Animal Protein
To provide clarity, the team analyzed data from the Third National Health and Nutrition Examination Survey (NHANES III), which gathered dietary information from U.S. adults between 1988 and 1994. Close to 16,000 people, ages 19 and up, were included.
The researchers used advanced statistical methods, including the National Cancer Institute (NCI) method and multivariate Markov Chain Monte Carlo modeling, to account for daily fluctuations in protein intake.
“It was imperative that our analysis used the most rigorous, gold standard methods to assess usual intake and mortality risk. These methods allowed us to account for fluctuations in daily protein intake and provide a more accurate picture of long-term eating habits,” said Phillips.
Results showed no link between total, animal, or plant protein and risk of death from any cause, including cardiovascular disease and cancer. Even when both protein sources were analyzed together, the findings held steady. There was a hint that animal protein may slightly reduce cancer-related mortality but no significant relationship emerged for plant protein.
Protein That Promotes Health and Longevity
The takeaway? The data don’t support the idea that one protein source is inherently more harmful or beneficial for longevity than another. If anything, animal protein may be mildly protective against cancer deaths, but the difference is small.
As with all observational studies, the findings can’t prove cause and effect. Still, when combined with decades of clinical trial evidence, the results offer reassurance for people who enjoy a mixed diet.
“When both observational data like this and clinical research are considered, it’s clear both animal and plant protein foods promote health and longevity” concluded first author Yanni Papanikolaou in the statement.
This article is not offering medical advice and should be used for informational purposes only.
Read More: Adding More Plant-Based Proteins to Your Diet Could Increase Your Life Expectancy
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