https://orcid.org/0000-0002-4516-3853
Dear Editor,
Simojoki et al. [Citation1] reported estimates of protein and amino acid inadequacy in a national sample before and after simulation scenarios of partial replacement of total red meat with plant protein sources. We were very surprised by the very high figures for the proportion of people who apparently did not meet requirements. The lowest estimates were for adults aged 18-64 y, but 5-7% inadequacy in protein intake in a reference population is still very high, increasing up to 10% in the replacement scenarios. In contrast, we and others, have found virtually no insufficient protein intake in comparable western countries, e.g. 0.3% in French adults of the same age [Citation2]. Higher figures can be found in the literature but are explained by methodological shortcomings [Citation3].
Although the authors relied on only two 24h recalls, they used a very good method to estimate usual intakes and then adequacy, but they did not account for the common problem of under-reporting. The authors acknowledged this limitation but gave no indication of the importance of this bias. We calculated the ranges of variation in energy intake from the precision estimates of the means and sample sizes, and derived that the lower range of usual energy intake was ∼600kcal, and that ∼10% of the men aged 18-64 y had intakes <1200kcal. Using individual data with impossibly low usual energy intakes greatly overestimates the proportion of people with insufficient protein and amino acid intakes. Of note, since the bias was the same for protein and amino acids, the authors’ finding that amino acid inadequacy was always much lower than protein inadequacy is correct, and confirms that protein is a matter of quantity not quality when taken at the authentic level of the diet [Citation2]. However, we were surprised that lysine did not top the list in the cereal scenario [Citation2] and we think that this may be due to the very high lysine content reported for the cereal aggregate used.
Not excluding under-reporters may also be sufficient to explain the increase in inadequacy estimates in the scenarios where meat was replaced by lower-protein plant sources, but this increase was further overestimated by the use of non-isoenergetic substitution scenarios. For men aged 18-64 y, the scenarios led to up to a further 5% reduction in energy intake, which should mean ∼5% decrease in protein intake and seems to explain almost half of the increase in inadequacy estimates.
Although the authors remain cautious in their conclusion, we believe it is important to analyze the sensitivity to potential methodological pitfalls and to have accurate estimates of the risk of deficiency. This is crucial to avoid conflating nutrients with energy and pointing the finger at the wrong nutritional issue in the dietary transition in high-income countries. When replacing meat with plant sources in healthy diets, the nutrients of concern in energy-replete populations are neither protein [Citation4] nor amino acids [Citation3,Citation5]. As expressed by the authors, replacing red meat with healthy plant sources offers benefits for long-term human and planetary health.
Author contributions
FM, CG, HF and JFH discussed and approved the conception of the work. FM wrote the first draft. CG, HF and JFH reviewed the work for intellectual content. All authors approve the final version of the work to be published and agree to be accountable for all aspects of the work.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability statement
The spreadsheet will be made available upon reasonable request.
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References
- Simojoki M, Männistö S, Tapanainen H, et al. The impacts of partial replacement of red and processed meat with legumes or cereals on protein and amino acid intakes: a modelling study in the finnish adult population. Ann Med. 2023;55(2):2281661. doi:10.1080/07853890.2023.2281661.
- de Gavelle E, Huneau JF, Bianchi CM, et al. Protein adequacy is primarily a matter of protein quantity, not quality: modeling an increase in plant: animal protein ratio in french adults. Nutrients. 2017;9(12):1333. doi:10.3390/nu9121333.
- Mariotti F, Gardner CD. Dietary protein and amino acids in vegetarian diets-A review. Nutrients. 2019;11(11):2661. doi:10.3390/nu11112661.
- Dussiot A, Fouillet H, Perraud E, et al. Nutritional issues and dietary levers during gradual meat reduction - a sequential diet optimization study to achieve progressively healthier diets. Clin Nutr. 2022;41(12):2597–2606. doi:10.1016/j.clnu.2022.09.017.
- Fouillet H, Dussiot A, Perraud E, et al. Plant to animal protein ratio in the diet: nutrient adequacy, long-term health and environmental pressure. Front Nutr. 2023;10:1178121. doi:10.3389/fnut.2023.1178121.