July 26, 2023


The cases for and against dietary protein for healthy aging

An endeavor to settle the debate of high- vs. low-protein diets for increasing lifespan and healthspan

Peter Attia

Read Time 7 minutes

To date, there is very little strong evidence on nutrition and aging, with perhaps the exception of protein consumption. Yet despite the many studies investigating the relationship between protein intake and aging, debate nevertheless continues to rage over whether dietary protein has a net positive or negative effect when it comes to human longevity. As many reading this will be aware, I am in favor of increasing protein intake well above the recommended dietary allowance, but advocates of low-protein diets cite concerning effects on the mammalian target of rapamycin (mTOR) and IGF-1. So what should we make of these data? And why do I still maintain that protein intake is an important part of nutrition for healthy aging?

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  1. Peter, thank you and the team for all you do.
    I’m turning 50 this year and, over the last 12 months, dramatically increased my protein intake to near your daily recommendations. I’ve also, during this same period, began supplementing with creatine almost daily. Combined with a more intense workout schedule than I ever had before, I’ve seen some great gains. But I don’t want to be on a high “animal protein” diet forever. I think many of us would appreciate a recommendation/general guidelines on what to look for in vegan protein sources (e.g., eating piles of beans and rice) and supplements — a discussion of optimal ingredient composition (necessary amino acids and quantities, soy vs. pea and hemp, etc.) as well as more concrete thoughts on amount (if, as discussed in the Don Layman podcast, only a “percentage” of the vegan protein is being utilized for muscle protein synthesis). Finally, do vegan sources of protein affect mTOR in the same way that animal sources do? Having clarification on these questions would be an enormous help in diversifying diets and avoiding animal saturated fats.

  2. As an RN still working full time at 70, I agree with previous postings that I would love some targeted advice for older subscribers. As busy as I stay with career, family and community, actionable items that I can prioritize would be great. Peter, I’ve read and re- read your book, and my PCP has ordered a copy. Sleep, exercise and protein (and fighting 15 lbs I’d like to lose)are my goals

  3. Peter,
    Good article, thanks. I am 88 and in pretty good health. Wishing to hit mid-90-100 what you write is of intense interest. For those of us in the group’s upper age percentile, a synopsis of the main points, based on age, where the data is available, would be very useful for all age cohorts. Sometimes it is very difficult to pick what applies to an individual out of the entire text.

  4. Excellent article and timely for me. I have been trying to reconcile taking rapamycin and the Baylor College of Medicine “Glynac” study. I know from online comments that some are trying to do both. If the premise of chronic versus acute is correct, then what is the amount and timing of dosing.? Taking the amino acids in the Glynac study is clearly chronic and I suppose the standard 6 mg once a week of rapamycin is probably what we hope is an acute suppression of mtor. The Glynac study was done on humans (although a small number) while the only human trial of rapamycin (Mannick) was for another end point. Question- what is the dosage in quantity and timing? Can we hear more about this?

    • Hi Pat,

      Neither glycine nor (N-acetyl-) cysteine are important stimulators of mTORC1, so you don’t have anything to be concerned about there.

  5. I always appreciate your thoughts and analysis. You (causally) mention mTOR and IGF-1 in relation to cancer. I suggest this is worthy of a deeper dive into the effects of protein and other supplements (like creatine) for readers with cancer or recovering from cancer since these may (possibly?) lead to proliferation of certain conditions.
    Similarly, your analysis of the effects soy protein and/or other supplements (choline, L-Arginine, etc…) on hormonal cancers would be interesting. I know you are very focused on hormone levels in patients, and certainly aware of the research about T, DHT, and E2 in metabolic function….. but a discussion of protein, supplementation, and hormone optimization in the context of various diseases and cancers would be useful. After all, many of us, especially as we age are dealing with a variety of maladies.

  6. Internist, still working FT at 69, cutting back for sleep and exercise. Would also appreciate your protein sourcing recs. Agreed w/ concerns above, trying to both be kinder to the planet and avoid other health consequences of eating tons of meat and still get enough to fuel muscle building. Some of my current non-meat protein option greatest hits are: whey protein isolate to boost one meal per day (add to smoothie or 1/2 c. steel cut oats); soy crisps I found on line to make keto Kind bars; stir fry or curry w/ tofu/edamame – sometimes with some smaller amount chicken or shrimp added. I also note that 6 oz. can of some brands of tuna contain >40 gr. protein – so doesn’t take much. Smoked salmon. Perhaps it is as important what one is NOT eating, when planning proportions of dietary macronutrients — food combining to get protein with lots of legumes and grain can raise insulin levels.

  7. PA is an amazing person and his highly intelligent whom I have a lot of respect for, however his push on the consumption of excess protein in the diet seems to be more academic masturbation than something that is based on real world facts. I would like to hear his thoughts on the blue zones where people are living a healthy and active life well over 100 years of age and none of these people are getting half the protein he is telling us we need to have to live that long.

  8. I would be interested in your current thinking about periodic multi-day fasting. My understanding of your thinking is you are concerned about the loss of muscle mass. But, if I’m reading you correctly, multi-day fasts have a salutary effect on mitochondrial health (due to mTOR inhibition?) and it would seem you could then return to a high protein diet and resistance workouts to quickly rebuild any lost muscle mass. Thoughts?

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