Optimising protein for strength and healthspan

Over the past decade there has been a growing trend for high-protein products driven mainly by increased awareness of health benefits as well as extensive marketing and social media promotion. Protein is indeed crucial to the growth, repair and maintenance of the body’s tissues, including muscle, as well as playing a central role in reactions in the body, immunity and  coordination of bodily functions. 

The building of muscle is crucial to  leading a healthy life and ageing well. Apart from muscles’ obvious role in maintaining physical function, particularly as we age, muscle plays an important role in metabolic health. Skeletal muscle takes up 70–80% of post-meal glucose, the more muscle we have the lower blood sugar is overall after a meal as well as reduced insulin spikes.

Protein, just like fats and carbohydrates, is an essential macronutrient - meaning it is a nutrient required in relatively large amounts for the body to function. Protein is essential to the structure, function and regulation of practically all organs and tissues in the body.

Having a basic understanding of proteins is fundamental to making informed decisions on our diet and wider health. The quality and quantity of protein we consume must be intentional. Proteins containing all essential amino acids (those we must get from our food or drink) are known as complete proteins whilst those missing at least one of the essential amino acids are termed incomplete proteins. Complete proteins are typically animal products and include things like meat, fish, eggs and dairy although there are also a few plant products which are complete sources, such as quinoa and soy. The great majority of plant-based sources of protein are however incomplete sources of protein and include things like seeds, nuts, beans and grains.  Individuals following a vegan diet must therefore consume a varied combination of incomplete proteins in order to ensure they are consuming a complete protein profile. 

Plant and animal protein sources and calorie content.

The proportion of protein in different foods also varies widely. Naturally occurring food is composed of a mix of macronutrients with certain foods having a much higher proportion of protein than others.  Generally, animal products will have a high proportion protein and also contain a varied amount of fat but very little carbohydrate. Plant sources of protein generally have a lower proportion of protein and will either have a significant proportion of carbohydrates (eg beans and legumes) or a high proportion of fat (eg nuts and seeds). From this perspective it is important to be mindful that in order to consume a certain amount of protein you may be consuming vastly different amounts of calories, depending on your protein source.

Another important aspect to consider is what is known as protein bioavailability which refers to the amount of protein from food which is absorbed, digested and actually available for use by our body. There are numerous factors which affect protein bioavailability and these include composition, structure, digestibility and processing of the food. Generally, however, animal sources of protein have a higher bioavailability than plant sources of protein particularly due to the presence of fibre in plants. 

This higher bioavailability, or usability, and complete amino acid profile (complete versus incomplete proteins) of animal protein versus plant protein is why animal protein is generally considered higher quality. This implies that to get the same amino acid density through plant sources one would need to consume larger volumes of food as well a combination of different plant proteins.

So how much protein do we actually require per day? Currently the recommended optimal levels vary between 1.6 to 2.2 g of protein per kg of body weight per day for the general population. Different individuals will have varying requirements depending on age, level of activity, body composition as well as other factors. Individuals requiring relatively higher levels of protein include older adults, active individuals (particularly those partaking in resistance training), individuals trying to increase muscle mass and people recovering from injury or surgery.

One key factor which must be considered when determining optimal, personal requirements of protein is our age. As discussed previously, preserving muscle mass as we age is of utmost importance in terms of both our metabolic health as well as maintaining functionality and independence. As we age our muscle becomes less responsive/ sensitive to the presence of amino acids, and subsequently the building of muscle (or muscle protein synthesis). This phenomenon is termed ‘anabolic resistance’. This implies that older adults require higher protein intake than younger people in order to achieve equivalent muscle protein synthesis.

This anabolic resistance is significantly influenced by activity levels. Inactive individuals, even when young, may display anabolic resistance. Strength/ resistance training, particularly in older adults, is perhaps the most crucial factor in overcoming anabolic resistance. Consistent resistance training makes muscle more sensitive to the muscle building effects of protein. 

Therefore, consistently getting optimal amounts of protein on a daily basis requires taking all these factors into consideration. Once you know your personal protein requirements consider how you may achieve this on a daily basis. Choose high quality protein sources which fit your dietary plan; aim to eat at least 20g of protein per meal; consume protein-rich snacks; supplement with protein shakes such as whey if you are unlikely to meet your targets. Also, be mindful of the current trend of protein marketing etc etc . For example, in the United Kingdom a food may be labelled as being “a source of protein” when as little as 12% of its calories are coming from protein whilst the threshold for a food to be labelled “high protein” is just 20% of total calories coming from protein. 

If you would like to test your personal risk factors for developing chronic diseases of ageing, find out more about the Longevity Annual health check and download the longevity doctor guide to healthy living.