Amino Acid and Mortality Connection
The role of dietary protein and its amino acid composition in long-term health outcomes is not fully understood. Specifically, little research has been conducted on how the intake of various amino acids impacts all-cause and cause-specific mortality. This study aims to evaluate the relationship between dietary amino acid composition and mortality rates over a long period, using data from the Golestan Cohort Study, a large, longitudinal study conducted in Golestan Province, Iran.
Data from 47,337 participants were analyzed, including 27,293 women, with an average age of 51.9 years. The participants’ dietary intake of amino acids was tracked from 2004 to 2008, and mortality data was collected through September 2022. The study used Cox proportional hazards regression models to examine the hazard ratios (HR) and 95% confidence intervals (CI) for mortality in relation to quintiles of amino acid intake, with the third quintile serving as the reference group.
Over a median follow-up period of 15 years, 9,231 deaths were recorded. The study found that individuals in the lowest quintile of essential amino acid intake had a significantly higher risk of all-cause mortality (HR: 1.16, 95% CI: 1.07–1.26) compared to the reference group. Similar trends were observed for intake of branched-chain, aromatic, sulfur-containing, and non-essential amino acids, with the highest mortality risks seen in the lowest quintiles for each group.
Non-linear associations were found, with higher mortality risks for participants in the first quintile of amino acid consumption, and a significant age interaction (P < 0.05) suggesting that the effects of amino acid intake on mortality varied between middle-aged adults (< 65 years) and older adults (≥ 65 years). For the older age group, a low intake of amino acids was particularly associated with increased mortality risk.
The findings of this study suggest that dietary patterns low in amino acids are associated with increased mortality risks, particularly in older adults. This non-linear relationship underscores the importance of considering amino acid composition in dietary recommendations, with higher amino acid intake potentially offering health benefits and reducing mortality risks, especially for older individuals.
Commentary by YourDailyFit Columnist Alice Winters
The Golestan Cohort Study provides valuable insights into the role of dietary amino acids in long-term health outcomes, shedding light on the complex relationship between amino acid intake and mortality. The study’s non-linear findings emphasize the importance of understanding the nuances in amino acid consumption across different demographic groups, such as age.
One of the most striking aspects of the study is the age-dependent effect of amino acid intake on mortality risk. For middle-aged adults (<65 years), higher amino acid consumption appeared to correlate with worse health outcomes, which is counterintuitive to conventional wisdom about the importance of adequate protein intake for maintaining health. However, this may reflect the fact that amino acids alone cannot account for health outcomes and that other lifestyle or dietary factors may be at play in middle-aged individuals. It is also possible that for this age group, a balanced, well-rounded diet might be more beneficial than simply increasing amino acid intake, especially if the amino acids come from lower-quality protein sources.
In contrast, the study’s finding that low amino acid intake was particularly detrimental for older adults is more aligned with established research on the importance of protein in aging. As we age, the body’s ability to synthesize and utilize protein diminishes, making adequate amino acid intake crucial for preserving muscle mass, bone health, immune function, and overall longevity. Low amino acid intake in the elderly can lead to sarcopenia (muscle loss), frailty, and other age-related diseases, which could explain the higher mortality risks observed in the lowest quintiles of amino acid intake among older participants.
The study also underscores a critical, often overlooked point: it’s not just the total amount of protein or amino acids in the diet, but the *composition* of those amino acids that matters. Branched-chain amino acids (BCAAs), aromatic amino acids, and sulfur-containing amino acids all play distinct roles in metabolic processes and may influence health outcomes in different ways. For instance, BCAAs are essential for muscle protein synthesis and may help with muscle preservation, while sulfur-containing amino acids like methionine play a role in detoxification and antioxidant defense. Thus, the amino acid profile of the diet could be an important factor in the overall health benefits derived from protein.
Furthermore, the study’s methodological approach, using Cox proportional hazards regression, is robust in its attempt to control for various confounding factors, although it remains susceptible to bias due to the observational nature of the study. While the findings are compelling, they cannot establish causality, and more randomized controlled trials would be necessary to definitively link amino acid intake to mortality outcomes.
Finally, it’s important to note that the study participants were from a specific region in Iran, which may limit the generalizability of the findings to other populations with different dietary patterns or genetic backgrounds. It would be useful to see similar studies in diverse populations to validate these findings.
In conclusion, this study offers significant food for thought regarding the role of amino acid intake in mortality risk. It highlights the importance of a balanced, age-appropriate diet and raises important questions about how amino acids—individually and in combination—can influence long-term health. For older adults in particular, ensuring an adequate intake of high-quality amino acids may be key to improving survival outcomes and enhancing quality of life in later years.
