For decades, dietary advice has focused mainly on lowering fats and sugars to protect heart health. However, a growing body of research shows that not getting enough protein can also affect the cardiovascular system. Scientists now believe that inadequate protein may interfere with how the body manages blood pressure, insulin, and cholesterol — all of which play crucial roles in heart function.
Emerging nutrition research is reframing how we think about protein — not just for muscles, but for the heart.
Several research teams across North America and Europe have been investigating the relationship between protein intake and cardiovascular disease over the past decade. These studies include both randomised controlled trials (RCTs) and large observational analyses.
A study examined 15 RCTs, comparing low-fat diets that differed in protein content. The study found that long-term high-protein diets (providing 25 percent or more of total calories) did not significantly change cholesterol levels, triglycerides, or blood pressure compared with lower-protein diets (20 percent or less).[1]
In contrast, a large umbrella review reported that higher total protein intake, especially from plant sources, was linked with a lower risk of cardiovascular disease and overall mortality. This pattern remained consistent across several cohort studies involving hundreds of thousands of participants.[2]
Evidence now suggests that both the quantity and the source of protein matter. A 2023 meta-analysis published in Vascular Health and Risk Management showed that people who consumed more plant-based proteins—such as lentils, beans, and nuts—had a significantly lower risk of developing heart disease compared to those who relied primarily on animal proteins.[3]
Similarly, an analysis found that higher protein consumption supports better cardiometabolic health, improving markers such as blood glucose regulation and body composition.[4]
Inadequate protein intake, particularly when replaced by refined carbohydrates, may lead to loss of lean muscle mass and insulin resistance — both of which can raise cardiac risk.
A related study reinforced these findings, reporting that diets higher in plant protein were associated with lower rates of cardiovascular morbidity and mortality in long-term population cohorts.
The type of protein is as important as the amount consumed. Plant-based proteins not only provide amino acids but also come with fibre, antioxidants, and minimal saturated fat — nutrients that support vascular health. Replacing some animal protein with plant protein can reduce cholesterol levels and improve blood pressure control. On the other hand, very low protein intake may remove these benefits and negatively affect heart function.
Protein plays a direct and indirect role in maintaining cardiovascular health:
It helps preserve lean muscle mass, crucial for metabolism and glucose control.
It aids in insulin regulation, which influences vascular health.
Specific amino acids support blood vessel elasticity and blood pressure regulation.
Thus, balancing adequate protein intake — ideally from diverse and plant-forward sources — can complement traditional advice about reducing fats and sugars.
Although evidence shows a strong association between adequate protein intake and lower cardiovascular risk, scientists caution that causation has not been fully proven. Most long-term RCTs measure biochemical markers, not clinical heart disease events. Future studies will need to explore optimal protein quantity, the best plant-to-animal protein ratio, and how these effects vary across age groups and health conditions.
Heart-healthy eating is not just about cutting fats and sugars — it’s also about including enough quality protein. Research across multiple journals consistently shows that sufficient protein intake, particularly from plant sources, supports better cardiovascular outcomes. As the evidence grows, ensuring the right balance of protein should become a central part of public health nutrition for heart disease prevention.
1. Schwingshackl, L., Hoffmann, G. Long-term effects of low-fat diets either low or high in protein on cardiovascular and metabolic risk factors: a systematic review and meta-analysis. Nutr J 12, 48 (2013). https://doi.org/10.1186/1475-2891-12-48
2. Ding M, Liu L. Effect of Low Protein Diet on Patients with Cardiovascular Disease: A Systematic Review and Meta-Analysis. Iran J Public Health. 2024 Aug;53(8):1695-1708. doi: 10.18502/ijph.v53i8.16275. PMID: 39415851; PMCID: PMC11475163.
3. Diab, A., Dastmalchi, L. N., Gulati, M., & Michos, E. D. (2023). A Heart-Healthy Diet for Cardiovascular Disease Prevention: Where Are We Now? Vascular Health and Risk Management, 19, 237–253. https://doi.org/10.2147/VHRM.S379874
4. Hu, Frank B. (2005) Protein, body weight, and cardiovascular health. The American Journal of Clinical Nutrition, Volume 82, Issue 1, 242S - 247S
5. Yakima D. Vogtschmidt, Anne Raben, Ilona Faber, Claudia de Wilde, Julie A. Lovegrove, D. Ian Givens, Andreas F.H. Pfeiffer, Sabita S. Soedamah-Muthu. July 2021. Is protein the forgotten ingredient: Effects of higher compared to lower protein diets on cardiometabolic risk factors. A systematic review and meta-analysis of randomised controlled trials, Atherosclerosis. Volume 328, (124-135).
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