"Muscle" requires selective food, and there are rules for eating - dietary nutrition prevention and treatment strategies for sarcopenia

With the aging of the population becoming increasingly serious, the health of the elderly has become a hot social issue. Sarcopenia (SP) is a common aging disease. With the increase of age, the incidence of this disease is getting higher and higher, and it inevitably affects the health of the elderly, increasing the incidence of fractures, falls, infections, death and other risks.

In 2010, the European Working Group on Sarcopenia in Older People (EWGSOP) proposed that sarcopenia is a syndrome of widespread and progressive decrease in skeletal muscle mass and strength, and the resulting decline in physical fitness, decreased quality of life, death and other adverse consequences.

As we age, the various systems of the human body gradually age and cause systemic dysfunction, such as cardiovascular, respiratory, and digestive diseases, which promote the development of osteoporosis and sarcopenia. Human bone mass reaches its peak at the age of 30, and then begins to decrease gradually. After the age of 50, 1% to 2% of muscle is lost each year, and after the age of 60, muscle loss accelerates to 3% per year. At the same time, there is a 1.5% decrease in muscle strength each year.

Age-induced aging is associated with a decline in muscle mass and strength, which, when turned into sarcopenia, can lead to adverse health outcomes. With age, there is increased inflammation, satellite cell senescence, decreased myocyte regeneration and protein synthesis, and an age-related decrease in sex hormones. Both sexes experience sarcopenia due to a decrease in testosterone in men and estrogen in women. Men show greater loss of muscle mass, while women often show sarcopenia because women have much lower muscle mass levels than men when they are young.

Ethanol can act on osteoclasts and osteoblasts, reducing bone formation and increasing bone resorption, causing bone loss and eventually osteoporosis. Excessive ethanol intake has adverse effects on musculoskeletal health. Excessive drinking can also have adverse effects on gonadal function, protein metabolism, calcium metabolism, and physical activity.

The dietary recommendations for sarcopenia are to eat a combination of meat and vegetables, and eat more high-quality protein, calcium, and vitamin-containing foods, as follows:

0 1Sufficient energy and protein

Adequate daily energy intake can prevent dietary protein from being consumed as fuel. When dietary intake is less than 80% of the recommended amount, oral nutritional supplements (ONS) are recommended. ONS can effectively prevent muscle attenuation in frail elderly people and improve muscle mass, strength and exercise capacity in patients with sarcopenia. The intake of ONS preparations is 400~600kcal/d and should be taken between meals or after exercise.

Protein metabolism is the core of the nutritional problem of sarcopenia, and insufficient protein intake is also the primary factor for malnutrition in patients with sarcopenia. Protein accounts for about 20% of muscle mass. When the elderly do not take in enough protein and the rate of myosin breakdown exceeds the synthesis, myosin loss will occur, leading to sarcopenia. Therefore, protein supplementation is the most important measure to prevent and slow the development of sarcopenia. For the elderly in good physical condition, the appropriate daily protein intake is 1.0-1.2g/kg, of which high-quality protein such as animal protein and whey protein should account for half.

In addition, the daily protein intake should be reasonably distributed to the three meals instead of concentrated in one meal, only in this way can the skeletal muscle synthesis effect be more significant. However, for the elderly with liver or kidney diseases, appropriate protein intake goals should be set according to their disease conditions under the guidance of doctors or clinical nutritionists.

Amino acids are the basic units of protein nutrition and metabolism. Supplementing some essential amino acids and branched-chain amino acids can help improve the physical functions of patients with sarcopenia. Leucine, valine and isoleucine are collectively called branched-chain amino acids (BCAA). Branched-chain amino acids accelerate anabolism and muscle growth by promoting the release of insulin and growth hormone.

0 2n-3 fatty acids

Fatty acids are important substances in human life activities, and different types of fatty acids have their specific functions and uses. Polyunsaturated fatty acids are inseparable from human health, and are divided into two major series, n-6 and n-3, according to their structure. n-3 polyunsaturated fatty acids can participate in muscle protein synthesis and degradation by reducing inflammatory responses and the body's oxidative activity, and delay the occurrence of sarcopenia. Flaxseed oil, perilla oil, soybean oil, and deep-sea fish such as salmon and cod are the main sources, and the above foods can be consumed in moderation.

0 3Supplement vitamin D

Vitamin D is currently the vitamin with the most theoretical research and clinical practice support that can effectively prevent and treat sarcopenia. It can finely control skeletal muscle cells through genomic and non-genomic mechanisms. Related studies have shown that a decrease in its level will lead to a decrease in muscle mass, thereby increasing the risk of sarcopenia. The "Chinese Expert Consensus on Sarcopenia Prevention and Intervention in the Elderly (2023)" recommends that routine vitamin D supplementation is not recommended for elderly patients with sarcopenia. It is more meaningful to guide vitamin D supplementation based on the patient's serum 25(OH)D concentration. Supplementation can be given when serum 25(OH)D is <50nmol/L.

The content of vitamin D in foods such as fish oil and egg yolk is relatively high. In addition, it is recommended to engage in appropriate outdoor activities and receive sunlight to promote the synthesis of vitamin D in the body.

【 References 】

[1] Sun Jianqin. “Muscle” must not be lost: A complete guide to the prevention and treatment of sarcopenia[M]. Shanghai: Shanghai Science Popularization Press, 2022.6.

[2] Chinese expert consensus group on dietary nutrition management of dysphagia. Expert consensus group on dietary nutrition management of dysphagia (2019) [J]. Chinese Journal of Physics and Rehabilitation, 2019, 41(12): 881-888.

[3] Cui Hua, Wang Zhaohui, Wu Jianqing, et al. Chinese expert consensus on prevention and control of sarcopenia in the elderly (2023) [J]. Chinese Journal of Geriatrics, 2023, 42(02): 144-153.

[4] Guo Yu, Zhao Qiancheng, Li Ying, et al. Research progress on sarcopenia in the elderly and its nutritional intervention [J]. Food Industry Science and Technology: 1-13 [2023-11-10].

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Author: Wu Yunfeng, Gao Caiping, Zhang Yujuan

Unit: Neurorehabilitation Center, Yangzhi Rehabilitation Hospital, Tongji University, Shanghai

Chief Judge: Zhai Hua (Shanghai Yangzhi Rehabilitation Hospital Affiliated to Tongji University, Vice Chairman of the Science Popularization Working Committee of the Chinese Rehabilitation Medicine Association)

Editor: Jia Jing (Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine)