Three ways to keep muscles and bones stronger, for longer
We all want to stay fit and healthy, well into old age. But that’s not going to happen by chance: to maintain physical strength, you need to up your game. That means eating more protein.
Protein builds muscle and bone. The reason why you need more, the older you get, is that your ability to digest and absorb amino acids — the “building blocks” of protein structures, reduces over time. You need more, just to stay at the same level.
There are two musculoskeletal conditions that can arise from insufficient protein: sarcopenia and osteoporosis. Sarcopenia is age-related muscle loss and function. Osteoporosis is loss of bone density.
They are both “closely related”. Weak muscles can lead to a fall, a fall can lead to a fracture.
Sarcopenia can begin as early as age 40, and over time result in 50% or more loss of muscle strength. The greatest loss of muscle mass occurs in elderly people who eat a low protein diet.
Bone, like muscle, is also protein dependent. Protein makes up about 50% of bone volume, and a third of bone mass. Low intake causes “marked” deterioration in bone mass and strength and is seen in hip fracture patients.
“Consequently, dietary proteins are as essential as calcium and vitamin D for bone health and osteoporosis prevention.”
To keep your musculoskeletal system in peak condition, there are three elements of your protein intake to consider: quantity, quality, and digestibility.
Quantity: how much is the right amount?
The current recommended daily amount (RDA) of protein for adults is 0.8g per kilogram of body weight a day. That advice has remained unchanged for years, and is in dire need of an update, in light of the data currently at our disposal. Many experts now recommend that protein intake should be at least 1.2 to 2.0g per kilogram, per day.
“.. literature suggests that consuming protein in amounts greater than the RDA can improve muscle mass, strength and function in older adults.”
Here’s a guide to sourcing sufficient protein.
Adapted from British Nutrition Foundation
However, getting the right protein in the right amount is a little more complex than working out your requirements based on body weight.
Protein is not something that the body stores; amino acids are used almost immediately once they enter the blood. Therefore, you should ensure that protein is eaten at each meal: an even intake throughout the day has been shown to result in greater muscle synthesis than a skewed distribution.
Quality, not just quantity
Your second consideration is the quality of your food choices. Almost any food will give you some protein; it is not enough just to tot up the amount in each item.
The protein of your choice must contain all the “indispensable” amino acids, also known as essential amino acids.
There are nine indispensable amino acids (IAAs): leucine, lysine, isoleucine, methionine, phenylalanine, tryptophan, histidine, threonine, and valine. A food that contains good levels of all nine amino acids is called a complete, or quality protein. It has no “limiting” amino acid.
No limits
A limiting amino acid is one that is present in a food in very low quantities. Cereal proteins, such as rice and wheat, are limited in the amino acid lysine. Legumes, on the other hand, have sufficient lysine, but limited methionine.
The IAAs aren’t just required to make muscle and bone — they are also needed for the synthesis of neurotransmitters, hormones, antibodies, enzymes, and collagen. And when it comes to muscle mass and bone density, the branched-chain amino acid leucine is of paramount importance.
Light on leucine
“Leucine may be more important in older adults than in young individuals.”
Studies show that older adults need more leucine than young adults to achieve the same increase in muscle protein synthesis. It is estimated that the amount required is 7g-12g daily.
However, and that’s a big however, quantity and quality are nothing without the third key element of protein intake: the digestibility of the protein in question.
Digestibility: what the body uses
Digestibility is everything. If you can’t digest the protein in your food, and extract the amino acids it contains, it’s not much good to you.
The Digestible Indispensable Amino Acid Score (DIAAS) is now recommended by the Food and Agriculture Organization of the United Nations (FAO) as the most accurate measurement of protein digestibility. DIASS measures the amount of amino acid digestion that occurs by the time food reaches the end of the small intestine. After that, any amino acids left in the gut will just continue through the colon on their outward journey.
For that reason, you should focus on those quality proteins that have the highest DIAAS scores. According to the FAO, anything with a score of 1.0 or above is classified as an excellent source of protein. A high score is between 0.75 and 0.99. If a food or food product scores less than 0.75, it’s not considered a good source of protein.
Here’s a quick guide to some DIAAS scores.
To obtain a top score, there can be no limiting amino acids. Therefore, the best proteins are all animal-source: they have no limiting amino acid, and the greatest digestibility. They are the best proteins for muscle maintenance in the elderly.
“A greater proportion of daily protein intake derived from animal- vs. plant-based sources is associated with better muscle maintenance in older and more clinically compromised individuals.”
Consuming adequate, high-quality, highly digestible protein at each meal may delay or even prevent the onset of sarcopenia and osteoporosis. People plan ahead for all sorts of eventualities: building bone and muscle strength at any age is a wise investment for future health.
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Kumud Gandhi is a Nutritional Food Scientist bestselling Author, Broadcaster, and Keynote Speaker on the subject of nutritional health for productivity & performance in the workplace. In 2010 Kumud founded ‘The Cooking Academy’ a cookery school that focusses on cooking for nutritional health and wellbeing. Kumud regularly presents to international audiences on a variety of topics such as ‘Eating for Immunity and a Lifetime of Wellness’. She is an expert in the field of Wellness in the Workplace and works with organizations to create transformational change in employee health & well-being through nutrition and health coaching.
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