- and older people should ideally consume more than the official recommendations
Undernourishment and lack of protein is common among older people. Evidence even suggests that the recommended daily intake of protein is too low, at least as far as seniors is concerned. The problem is most likely a slowdown of the muscle-building enzyme processes. The quality of protein also has something to say just like the amount of physical activity is a factor.
We humans need protein not just to build muscle but for our energy turnover and in order to produce hormones, antibodies, and neurotransmitters for our nervous system. Protein consists of various amino acids that serve like building blocks and are combined in accordance with the many functions of protein. Lysine is an essential amino acid that is found in large concentrations in muscle tissue. It is therefore vital that we get plenty of lysine from our diet and also get plenty of those vitamins and minerals that are needed to ensure normal lysine metabolism.
Many older people fail to even get the recommended daily amount of protein (also known as the dietary reference intake level), which is around 0.8 grams per kilo of body weight. In fact, this amount is considered far too little and that is believed to affect their health. Not only does is lead to increased loss of muscle mass, it also impairs their immune system and causes faster ageing.
Lack of protein enhances age-related loss of muscle mass
There should ideally be a balance between the breakdown and buildup of muscle tissue. However, as part of our ageing process the breakdown tends to become faster than the buildup. After the age of 50 we normally lose around 0.5 - 1 percent of our muscle mass per year. This loss increases substantially once we reach the age of 65-70 years.
The loss of muscle mass also leads to unsuitable weight loss. For instance, the Health, Aging and Body Composition Study showed that older people with the largest protein intake lost 40% less weight than the quintile that consumed the least protein over a three-year period.
Factors that are important for the buildup of muscle cells
The buildup of cells in the muscle mass are controlled by many factors, namely the nutrients from food and physical activity. The essential amino acids play a determining role in the protein synthesis, and lysine is considered one of the most important regulators. As part of the natural ageing processes, muscles gradually lose their ability to respond to lysine, whereas larger dosages appear to stimulate the protein synthesis. Therefore, it is advisable for older people to get plenty of amino acids, especially lysine, from foods such as eggs, meat, fish, dairy products, and beans. However, it is important to stress that vegetable protein sources tend to be less effective than animal protein sources at building muscle, because animal protein has a more complete combination of amino acids. Studies reveal that soy protein is less effective than protein from cheese whey and meat. This is simply because these two sources contain more lysine and other nutrients that are important for building muscle mass.
Needless to say, physical activity and resistance training are also important for the building of muscle mass, throughout life. In contrast, lack of physical activity, alcohol abuse, smoking, hormonal changes such as menopause, slow metabolism, inflammation, and chronic disease may have a negative impact on the body's protein metabolism and muscle building. The earlier mentioned ageing processes enhance the negative influence.
Protein, muscle mass, and hip fractures
Epidemiological studies show that low protein intake is linked to age-related loss of muscle mass. Low intake of calories, protein, and lysine is also associated with reduced muscle mass in older people who have sustained hip fractures.
How much protein do older people need?
Although many factors affect the age-related loss of muscle mass, science has become increasingly aware of the increasing need for protein. As mentioned, the official recommendation for daily protein intake is around 0.8 grams for each kilo of body weight. However, for several years researchers have recommended that older people get at least 1 - 1.2 grams of protein per kilo of body weight each day in order to maintain healthy muscles. In the case of acute or chronic disease the daily recommendation is around 1.2 - 1.5 grams of protein for each kilo of body weight, and older people suffering from severe disease or who display signs of severe undernourishment, two grams of protein per kilo of body weight may be needed. This is more than twice the amount that is officially recommended for elderly people in general.
Protein should preferably come from a balanced diet with animal and vegetable sources that ensure full coverage of all the needed amino acids and sufficient amounts of lysine, which is primarily found in eggs, meat, fish, and dairy products. It is normally recommended to stick with white meat and fish, and it may be good idea to introduce a meatless day once a week.
The balanced diet should also provide nutrients such as B vitamins and vitamin C, iron, zinc, and selenium, which is necessary for the lysine metabolism and the buildup of muscle mass. The same goes for coenzyme Q10 that is essential for the energy metabolism in all cells. Most of the coenzyme Q10 that we need gets produced by the body, but the endogenous production decreases as we grow older, calling for supplementation. Special protein beverages are available for older people and patients who are unable to cover their need for calories and nutrition by means of a normal healthy diet.
Approximate protein content (in grams) per 100 grams of food :
|Meat and fish||20|
|Tofu and quinoa||15|
|Cooked brown/white beans||6-7|
|Bread and pasta||5-6|
Protein intake, blood sugar, and physical activity
Middle-aged and older people are in particular need of a balanced diet with adequate amounts of protein combined with physical activity and a certain degree of resistance training, as this has a positive synergistic effect on the building of muscle mass. It is advisable to get protein with all main meals to ensure stable blood sugar levels, as this is also important for the muscles.
In relation to physical training, the synthesis of muscle protein peaks around one hour after the training session has been terminated, and the building of muscle tissue may continue for another 24 hours. It is therefore best to ingest adequate amounts of protein after training in order to provide the muscles with the necessary amino acids and also to give the muscles optimal conditions for being rebuilt after the muscle breakdown caused by training.
Make sure to get plenty of lysine and other nutrients for your muscles throughout life.
Francesco Landi et al. Protein Intake and Muscle Health in Old Age: From Biological Plausibility to Clinical Evidence. Nutrients 2016
Linnane et al. Cellular redox activity of coenzyme Q10: effect of coQ10 supplementation on human skeletal muscle. Free Rad Res 2002
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