The Protein Paradox!

Is dietary protein intake good or bad for aging and longevity? 

Decades of research in the sports and performance arena have supported the importance of protein intake for a lean, strong body, with the suggestion that this becomes even more important as we age,  reducing the incidence of sarcopenia (progressive age related muscle loss) that can lead to frailty. 

Indeed a higher protein intake has been linked with better physical function, a decreased rate of muscle loss, a decreased rate of hip fractures and bone mass density loss in older adults and even stronger immune function and better recovery from illness.

The science of short term muscle support versus healthy aging and longevity, however, appears to be at odds, with some studies suggesting that a high protein diet activates pathways (such as mTOR and IGF-1) that accelerate aging, induce systemic inflammatory effects and increase risk of heart disease, diabetes and cancers amongst many other pathologies. 

Interestingly there appears to be a different effect with regards to protein intake relative to age which could explain this conflict in the data. 

Indeed  data from The Nurses Health Study featured in Journal 'Cell Metabolism' suggests that in mid-life (50-65 Yrs of age) a high protein diet is associated with a 75% increase in overall mortality and a 4-fold increase in cancer and diabetes in an 18 year follow up period. What is remarkable, however, is that these negative associations seem to be abolished or attenuated when the source of protein is plant based! 

Conversely in the group of respondents over 65 yrs of age, a high protein intake was associated with reduced cancer and overall mortality. 

So, age appears to matter as does the source of protein.

To back up these findings a more recent study published in The American Journal of Clinical Nutrition using dietary data from the nurses study (NHANES) confirmed that protein intake during midlife was associated with higher odds of healthy aging with each 3% increment in energy from protein increasing the odds of absence of physical function limitations and good mental status, however, the impact of plant based proteins was much more significant than animal or dairy proteins. 

Take Outs:

1. Protein is an essential nutrient for growth and repair, which makes it important to aim for the recommended daily intake of 0.8g protein per kilogram of body mass in general (e.g. if you are 60kg aim for 60 x 0.8 =  48 grams).

2. If you are 65 yrs of age or older, it seems that increasing this to 1-1.2g per kg of body mass per day (e.g. 60-72g for the same 60kg individual) can help to reduce the likelihood of frailty and keeping you functional for longer.

3. The evidence is clear that plant   proteins are superior to animal proteins with dairy proteins somewhere in-between so emphasise these and limit red and processed meat for optimal health. Perhaps try to gradually replace animal and dairy based proteins with plant based sources such as legumes (lentils, beans, chickpeas), soy products (tofu, tempeh, edamame), nuts and seeds (almonds, walnuts, chia seeds, pumpkin seeds), or grains (quinoa, brown rice, wholewheat bread).

4. Avoiding protein intakes above 1.2g per kg body mass seems wise due to evidence of potential harm, particularly when the protein is derived from red or processed meats.

Written: Sept 2025

Your gut microbiota may hold the key to longevity! 

Studies have shown that those who are healthier in older age tend to have gut bacteria strains that are more like the typical microbiome of younger individuals. 

With gut microbiota typically shifting as we age with the decline in beneficial bacteria and increase in potentially pathogenic microbes, we can employ strategies to keep our microbiome healthier such as:

1. Ensure you're eating enough fibre to promote the growth of beneficial bacteria and enhance microbial diversity.
2. Consider supplementing with a probiotic to improve gut health, enhance immune function and reduce inflammation.
3. Exercise regularly. This has been shown to restore favourable ratios of bacteria, improve short chain fatty acid production and boost intestinal mucosal immunity. 

Written: June 2025

What difference could making positive dietary changes make to your lifespan? 

Many studies support a link between positive food choices and health but we are now starting to see data to suggest that habitual food habits impact life expectancy. 

In a recent study analysing UK Biobank data of just under 470,000 participants, where a model was applied to estimate life expectancy gains from sustained dietary changes, it was suggested that dietary shifts towards ‘longevity associated dietary patterns’ could add up to 10 years to life. 

The largest gains were driven by whole grains, nuts and fruit consumption and lack of processed foods and sugary beverages. 

Written: May 2025