Higher Taurine Intake in the Diet Correlates with Some Measures of Strength in Middle Age
Taurine is a amino acid mainly found in fish and meat in the diet. It is not an essential amino acid, and can be synthesized in humans. Circulating taurine levels in the bloodstream decline with age by about 50% by middle age for reasons that have yet to be determined. Studies in aged mice and non-human primates have shown modestly improved function and slowed aging following taurine supplementation. Past human studies of taurine supplementation have produced entirely unimpressive outcomes, but given that they predated present aging clocks it may be that the researchers were evaluating the wrong metrics. Taurine may act on the pace of aging through a range of different mechanisms, and it remains unclear as to which of these are more or less important.
In the context of recent studies on taurine supplementation, today's open access paper seemed interesting. The authors report on correlations between taurine intake in the normal diet with a few measures of fitness and muscle strength in middle-aged individuals. Human studies of taurine supplementation require a dose in the range of 1.5-6.0 grams per day to remove the 50% loss in circulating taurine. This supplement dose is the human equivalent extrapolated from the effective doses in mice and non-human primates. Here, dietary intake of taurine in the study participants was estimated to be ~200 milligrams per day, which is actually higher than previously reported averages, particularly for vegetarians. Given that, one might argue that taurine levels in the diet are a proxy for the influence of some other better-studied aspect of dietary choices on long-term health, such as overall protein intake.
Taurine has diverse valuable biological functions, including antioxidant activity and regulation of osmotic pressure. Maintaining physical fitness from middle age is important for healthy life expectancy. Although taurine administration improves muscle endurance and strength, its role in maintenance remains unclear. We aimed to clarify the longitudinal taurine intake association with fitness changes.
Participants comprised men and women aged ≥40 years who participated in the third (2002-2004; Baseline) and seventh (2010-2012; Follow-up) waves of the National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) and completed a 3-day dietary weights recording survey at baseline. A table of taurine content was prepared for 751 foods (including five food groups: Seaweed; Fish and shellfish; Meat; Eggs; and Milk and dairy products) from the Standard Tables of Food Composition in Japan (1,878 foods) 2010. Four physical fitness items (knee extension muscle strength, sit-and-reach, one-leg standing with eyes closed, and maximum walking speed) were measured at baseline and follow-up. We analyzed the association of taurine intake with physical fitness change, employing a general linear model (GLM) and trend tests for baseline taurine intake and follow-up fitness change. Adjustments included baseline variables: sex, age, height, weight, educational level, self-rated health, smoking status, depressive symptoms, and clinical history.
The estimated average daily taurine intake was 207.5 ± 145.6 mg/day at the baseline. When examining the association with the four physical fitness parameters, higher taurine intake positively increased the change in knee extension muscle strength and reduced the decline in knee extension muscle strength in the subgroup analysis of participants aged ≥65 years. No relationship was found between taurine intake and the remaining three fitness factors.