Are high protein diets a cause of heart disease?

High protein diets have become a popular weight-loss strategy for many, but animal studies and larger epidemiological studies in humans have indicated that they are a risk factor in cardiovascular disease.

The link between a high protein diet and heart disease

A recent mice study by researchers at Washington University School of Medicine is now able to explain why a high protein diet may contribute to heart disease, due to its impact on arterial plaques. In this article, I will review the findings in this study, and suggest how making small adaptations to your diet may help to protect against heart issues.

Arterial plaques contain a mix of cholesterol, calcium deposits, fat, and dead cells. An immune cell, called a macrophage, has an important role in cleaning up dead cells and toxic waste from the plaque so that it stays stable and doesn’t build up in size. A plaque is embedded in the arterial wall, so as it grows, it can cause blockages in the artery, preventing blood flow and increasing blood pressure. A plaque can also become unstable if the immune cells - macrophages - don’t clean up properly, which can lead to the artery bursting, causing a heart attack.

How is a high protein diet linked to an increased risk of a cardiac event?

The study by Zhung and co. found that in a high protein and high-fat diet, the arterial plaques not only grew, but they also became unstable. The study compared this to mice on a low-protein and high-fat diet, and although these mice gained weight, their plaques were not affected.

This is a noteworthy observation, as the mice on the high protein diet didn’t gain weight but did show an increased risk of cardiovascular disease. As such, those on a high protein diet should be cautious, as even though it can lead to weight-loss, it may harm your heart health. A couple of scoops of protein powder in your daily smoothie can amount to 40 grams of protein, which is almost the recommended daily allowance, so tracking protein consumption is key for those with an increased risk of heart disease.

The research also explains why protein has an impact on the stability and size of plaques, due to its effects on a protein found in macrophages called mTOR. When proteins are consumed in excess and broken down into their constituent elements called amino acids, mTOR is activated. In this process, the macrophage ceases its cleaning duties and begins to grow. This encourages toxicity to build around the plaque; through a chain of events the macrophages die, and these dead cells become part of the core of the plaque, increasing its instability.

Interestingly, the study found that certain amino acids are more potent at activating mTOR, including leucine and arginine. Leucine is found in red meat, so protein consumed from fish and plants might be a better source of protein for those at risk of heart issues.

This is a fascinating new concept, which may help to develop therapies to prevent plaques from building up in arteries and becoming unstable. Further research should look to understand which amino acids are implicated in mTOR so that dietary approaches can be adopted to ensure that the risk of cardiac events from plaques is minimised.

Do you have heart issues or have an increased risk of cardiovascular disease based on family history? If you do, or you are worried about your health, weight and/or protein consumption, consult your doctor and a qualified nutrition professional.

By working with a specialist nutritionist you can understand what your body needs, as each of us are different and require different nutrients. A nutritionist can offer tailored dietary and lifestyle advice to support overall health, and circulatory health.