Protein Requirements May Be Higher Than Current Recommendations For Athletes and Older Adults

The recommended daily allowance of protein is 0.18 grams per Kg of ideal body weight (0.4 grams per pound). If you’re currently overweight, your ideal weight is what you’d like to get down to. Physically active individuals need more, so multiply this by about 2 for serious strength trainers (who need protein to repair and build muscle), and by about 1.5 for endurance athletes (who also need to repair muscle, and actually burn a little protein during longer sessions) [1]. I’m not sure what the recommendation is for non-athletes who just participate in some strength training or cardio to stay in shape, probably a factor of safety of 1.5 is fine. I thought these recommendations were the “state of the art” at the time I wrote my book a little over a year ago.

But there is now some evidence that athletes and older adults may need more. I first came across this newer science on Jeff Rothchild’s excellent website on nutrition for athletes. There is a newer technique for estimating protein needs that may be more accurate than previous estimates based on nitrogen balance. And research using it shows certain populations need more protein, including athletes undergoing significant strength training or endurance training, and adults over 65.

First some background: protein requirements are often estimated based on nitrogen balance: basically how much nitrogen are you excreting compared to what you took in through your diet. Follow the link to see how this relates to protein requirements. The newer technique is the “Indicator Amino Acid Oxidation Technique” (IAAO). The idea is that if your are deficient in any essential amino acid, your body will start burning all other amino acids. Measuring this phenomenon vs protein intake gives and accurate indication of protein requirements. For a background on the science, see [2].

Jeff published the article “I’m An Endurance Athlete, How Much Protein Do I Actually Need?” which goes over research results showing IAAO predicts endurance athletes need more protein than previously thought [3].

I was intrigued by this and searched in google scholar for “Indicator Amino Acid Oxidation Technique” and found a gold mine of sources. First there’s a PhD dissertation by Arash Bandegan which goes into the topic in lots of detail, and also show endurance trained athletes, as well as strength trained athletes, have higher protein requirements than currently recommended. I also found a similar result in a paper about bodybuilders [4].

As an old guy, most intriguing to me were two papers on protein requirements for adults over 65, showing that both men [5] and women [6] need higher protein than the current RDA.

There is a nutrition working group from Austria, Germany, and Switzerland that gives recommendations for protein intake. These have been revised upwards [7] based on the recent scientific findings. In particular, the revised RDA for men and women over 65 is 1 gram of protein intake for kilogram of bodyweight (0.45 grams per pound of bodyweight), 25% higher than the previous recommendation of 0.8.

Others had previously recommended that adults over 65 might need more protein based on different reasoning: A reason that is commonly given to not go overboard with protein consumption (especially from animal sources) is that it can cause an excess of insulin growth factor 1 (igf-1) which has adverse health consequences. But after 65 people tend to be deficient in igf-1, so it should be beneficial to increasing protein intake over the current recommended allowance after 65 [8]. See also the discussion of protein for older adults in the Tufts health newsletter.

Putting all this together, I think the recommendations in [7] are the most up to date.

In my next post I’ll cover a couple of other protein related topics:

  1. What is the safe upper limit of protein intake? This is an important issue for people eating various high protein diets.
  2. Can vegans get enough protein? (The short answer is yes, but I think you need to know about good higher protein plant foods).

References

  1. Bilsborough S, Mann, N, “A Review of Issues of Dietary Protein Intake in Humans”, International Journal of Sport Nutrition and Exercise Metabolism, 2016
  2. https://academic.oup.com/jn/article/138/2/243/4664973
  3. https://www.ncbi.nlm.nih.gov/pubmed/30779631
  4. https://academic.oup.com/jn/article/138/2/243/4664973
  5. https://www.ncbi.nlm.nih.gov/pubmed/26962173
  6. https://www.ncbi.nlm.nih.gov/pubmed/25320185
  7. https://www.ncbi.nlm.nih.gov/pubmed/30904906
  8. Bilsborough S, Mann, N, “A Review of Issues of Dietary Protein Intake in Humans”, International Journal of Sport Nutrition and Exercise Metabolism, 2016
  9. Longo, V, The Longevity Diet, Avery, 2018

12 thoughts on “Protein Requirements May Be Higher Than Current Recommendations For Athletes and Older Adults

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