The global population is aging, especially in developed countries such as Germany, Japan and the United States. In developing countries such as China and India, this problem is becoming increasingly serious. It is estimated that by 2050, the global population over 60 years old will exceed 2 billion, of which 500 million are in China. This will create a huge worry, because as age increases, muscle mass and function will decline significantly, and people's physical condition will also change accordingly. This loss of muscle is called sarcopenia, as is osteoporosis (increased risk of fractures due to bone loss). The attenuation of muscle mass occurs early (between 20 and 30 years old) and continues throughout a person's life. This process is relatively gentle in the first few decades (about 3% per decade) and increases in old age (more than 7% per decade).
Up to 50% of older adults develop sarcopenia, and lifestyle choices can have a substantial impact on reducing the risk of sarcopenia.
Recent studies have shown that protein, especially milk protein, can reduce muscle attenuation
Consuming the recommended daily amount of protein may not maintain muscle mass
ق Increasing protein intake can increase muscle protein synthesis
Studies have shown that compared with casein (Tang et al., 2009; Pernis et al., 2011), soy protein (Tang et al., 2009), and free amino acids (Kezianos et al., 2008), whey protein Can promote muscle protein synthesis to a greater extent
Scientific background:
The relationship between muscle protein synthesis and muscle protein breakdown promotes muscle balance. A net negative balance indicates muscle atrophy, and ultimately a small, sustained loss of muscle mass will lead to sarcopenia syndrome. In older adults, this may be due to a reduced stimulatory effect on anabolic signals responsible for muscle protein synthesis (Fry et al., 2011).
Muscle protein synthesis is achieved through the mTORC1 (mammalian target of rapamycin complex 1) pathway, which is the intersection of energy, exercise and nutrient signaling (DrummondDe, 2009). During the postprandial phase after protein intake, plasma leucine rises, stimulating intracellular changes that lead to the production of new proteins. The greatest stimulation of muscle protein synthesis occurs after adequate intake of leucine (approximately 2.5 g per meal) (Diucota and Lehman, 2010). The concentration of leucine in the blood depends on the leucine content in the food and the digestion rate of the food (Danjin et al., 2001).
Recent recommendations emphasize protein intake patterns that maximize the use of dietary protein, maximize muscle protein synthesis, reduce the rate of muscle attrition, and improve health. For a mixed protein meal, this is equivalent to 30 grams of protein per meal (Paden-Jones & Rasmussen, 2009). However, if the food is rich in branched-chain amino acids and leucine (such as whey protein), the amount of protein required will be reduced
In-depth understanding:
Dietary intakes in Europe exceed the current Population Reference Intakes (PRI) (European Food Safety Authority, 2011), however, current intake patterns favor protein intake at lunch or dinner. There is no available evidence on intake patterns in older adults; however, existing research (with students) suggests cultural differences (Figure 2). Protein intake at breakfast is low in all people, with the French tending to consume the most protein at lunch, while the Dutch or Americans consume more protein at dinner (De Castro et al., 1997). This provides the opportunity to fortify dairy proteins in meals, especially breakfast, to maximize daily protein synthesis and reduce the risk of muscle attenuation.
Supplementary information:
1) Protein intake exceeding current recommendations can help maintain muscle protein synthesis (Morais et al., 2006). However, protein intake patterns can have a substantial impact on minimizing muscle protein attrition. (Paden-Jones and Rasmussen, 2009). There have been calls for changes in protein recommendations to reflect recent findings in protein intake patterns. (Lehman, 2009).
2) Milk protein, especially whey protein, is a high-quality protein. Compared with other dietary proteins, it is rich in high concentrations of leucine and can stimulate muscle protein synthesis to the greatest extent, maximizing muscle mass. Reserved to a limited extent. (Philips et al., 2009)
3) MealsThe daily intake of protein exceeds current recommendations (European Food Safety Authority, 2011). However, adult intake patterns, as well as intake in older adults, may be lower than required to maintain optimal muscle mass. (Paden-Jones and Rasmussen, 2009).
4) Protein intake pattern will tend to consume more protein at lunch or dinner depending on eating habits (Decasciu et al., 1997). This has brought business opportunities for protein-fortified products (especially breakfast foods) to maintain muscle protein synthesis.
(Text/New Zealand Fonterra Group R&D Scientist Aaron Fanning)