Nutrition key to keeping sarcopoenia at bay in older adults

Malnutrition is a significant risk factor for sarcopoenia in elderly, community-dwelling adults, according to a new Singapore study. Nutrition biomarkers in the blood, such as plasma essential amino acids (EAAs) and vitamins, show similar predictive utility.

“[T]he present study characterized the nutritional profile of sarcopoenia using specific nutritional and metabolic biomarkers of essential amino acids, vitamins and nicotine metabolism,” researchers said.

Of the 189 elderly participants (mean age, 73.2±5.3 years; 63.0 percent female), 46 percent were sarcopoenic. These participants tended to be frail, smokers and bear more depressive symptoms. [J Gerontol A Biol Sci Med Sci 2020;75:309-317]

Of the individual sarcopoenia components, low lower limb strength was the most common (75.1 percent), followed by low muscle mass (56.1 percent) and low gait speed (13.8 percent). A comparable proportion of males and females had sarcopoenia (p=0.946).

Logistic regression analysis revealed a significant link between nutrition status and sarcopoenia risk. Mean scores in the Mini Nutritional Assessment, for example, were significantly lower in those with the condition (12.24±0.14 vs 13.01±0.13; odds ratio [OR] 0.453, 95 percent confidence interval [CI], 0.315–0.651; p<0.001). The risk of malnutrition was likewise higher in older sarcopoenic patients (OR, 9.877, 95 percent CI, 3.210–30.390; p<0.001).

Other nutritional factors significantly associated with sarcopoenia were body mass index, leptin, adiponectin and high-density lipoproteins.

Many EAAs also emerged as significant sarcopoenic factors. For instance, lysine (p=0.04), methionine (p=0.001), phenylalanine (p=0.01), threonine (p=0.002), isoleucine (p=0.015), leucine (p=0.009), valine (p=0.001) and the total levels of branched-chain amino acids (p=0.002) were significantly lower in elderly adults with the condition.

“Taken together, our results suggest a close association between protein metabolism and sarcopoenia,” the researchers said. “The anabolic action of [amino acids] on muscle protein synthesis is mainly due to the EAA content of a meal. Furthermore, the dose required to elicit such a response may be higher in elderly as compared to healthy younger individuals.”

This highlights the importance of dietary factors, particularly protein quality, in older adults. “We suggest that the elderly [people] meet at least the current recommended intake of dietary protein by consuming varied protein sources (such as meat, fish, poultry, eggs, legumes and soy), which provide diversity and complementarity of EAAs, in order to sustain lean tissue mass,” they added.

Notably, markers of nicotine metabolism―such as cotinine (148.81±21.75 vs 37.73±19.84 nmol/L; OR, 1.002, 95 percent CI, 1.001–1.004; p=0.008) and trans-3’-hydroxycotine (61.59±11.64 vs 15.18±10.62 nmol/L; OR, 1.005, 95 percent CI, 1.000–1.008; p=0.031)―were significantly elevated in participants with sarcopoenia.

This may be due to the ability of nicotine metabolites to leak into the bloodstream and travel to the skeletal muscles, which, in turn, can accelerate wasting, the researchers explained. [Physiol Res 2015;64:419-426]

“Taken together, our results suggest that nutrition and smoking as lifestyle-related factors contribute to the risk of sarcopoenia,” they said. “The findings from this study provide a firm basis and potential specific targets and directions for the nutritional approach to the prevention and treatment of sarcopoenia in ageing populations.”