In this post we will answer 3 key questions commonly asked about older adults and protein intake.
- What is the recommended amount of protein for older adults?
- What and when is the best way to consume protein for older adults?
- Do older adults need supplements?
As we discussed in this comprehensive post, the ageing process is unfortunately associated with a progressive decline in muscle mass and strength, loss of independence, increased risk of chronic and cardiovascular disease, reduced quality of life, lower immunity, reduced metabolism and increased risk of all-cause mortality.
Substantial evidence supports the use of regular strength/ resistance training programmes in older adults to counteract this loss of muscle mass and strength. Strength programmes (consisting of just 2-3 sessions per week, of 12-20 sets per muscle group), providing they are sufficiently challenging the muscles to adapt, have been shown to not only maintain muscle mass and strength, but even improve it. These positive results are seen in all ages, even into the 10th decade of life! (1).
Adequate nutrition is also key. Protein is essential for the functioning and growth of muscles. Adequate protein intake combined with resistance training stimulates muscle protein synthesis, leading to muscle growth. For adults, the current UK Reference Nutrient Intake (RNI) for protein is 0.75g of protein per kilogram of body weight, per day (2).
That is roughly 45g for an average woman, and 55g for an average man. This does vary depending on physical activity levels. The American College of Sports Medicine (ACSM) recommends higher levels for active adults who are lifting weights regularly or engage in regular high-intensity running or cycling: 1.2-1.7g/kg/body weight/day (3).
What is the recommended amount of protein for older adults?
The RNI currently recommends the same levels of protein intake for older adults. However increasing research is now suggesting older adults should have even higher protein recommendations. Some bodies have already taken these suggestions on board.
The ACSM have higher recommendations for older adults: 1g/kg/body weight/day (3). The European Society for Clinical Nutrition and Metabolism (ESPEN) recommends 1.0-1.2g/kg/body weight/day (4).
The evidence supporting this increase comes from a range of studies: some looking at immediate muscle protein synthesis response to protein ingestion, some looking at the longer term effects of a range of protein intakes, either through controlled or observational studies (5).
It is thought the higher protein requirements of older adults is multifactorial. It seems reasonable that increased protein may help to stimulate muscle protein synthesis to counteract the age-related physiological changes leading to loss of muscle mass and strength.
What’s even more revealing is the emerging evidence showing that older adults are less responsive to the ingestion of protein. More protein is actually required to stimulate the same levels of muscle protein synthesis. This is known as anabolic resistance to protein.
One study revealed a 16% reduced muscle protein synthesis response in older adults compared to younger men (6). Another revealed that 67% more dietary protein was required in older adults compared to younger to reach protein synthesis plateaus (7).
Protein synthesis plateaus are when maximum protein synthesis is achieved: when the ingestion of further protein has no additional additive effect to the protein synthesis. In adults, most studies report this at 20g of protein, with no significant differences seen between 20g and 40g of protein intake- a plateau/threshold has been reached (8). Indicating that younger adults require approximately 20g protein/ meal.
Whereas a number of studies have indicated that the protein dose for maximally stimulated muscle protein synthesis in older adults is double that dose: 40g protein/ meal (7, 8). Importantly, older adults are still able to achieve the same maximum muscle protein synthesis as seen in younger adults, but higher protein intake is required.
Studies investigating muscle protein synthesis to higher protein diets over periods of days and weeks suggest that requirements may be even higher than recommended by the ACSM and ESPEN.
One group of researchers utilised a higher dose in a randomised trial in older adults (1.5g/kg/body weight/day); the higher protein group demonstrated significantly greater muscle protein synthesis compared with current recommended dose group (9).
Another group compared the recommended dose with double that (1.6g/kg/body weight/day) over a 10 week period in older men. The double dose group showed increases in appendicular lean mass and leg power, whereas decreases were seen in the group intaking the current recommended dose (10).
Taking all of this into account, we feel strongly that the recommended dose of protein for older adults should be increased. Doses of >1.0-1.5g/kg/body weight/day appear to be required in older adults.
What and when is the best way to consume protein for older adults?
More research is revealing the importance of the distribution of protein intake over the day. Most studies are showing that a more even protein distribution across the day, with frequent consumptions of protein, leads to better outcomes, including greater improvements in muscle mass and strength (5).
Most older adults in western societies are currently consuming an uneven protein distribution across the day – typically with low levels at breakfast, medium levels at lunch and higher levels at dinner. As discussed previously, it is currently thought approximately 40g protein intake is required in older adults to achieve a maximum muscle protein synthesis response.
Breakfast and lunch are therefore unlikely to be providing sufficient protein to stimulate this, meaning this response is only being stimulated once per day at dinner time. A more sensible approach appears to be spreading this intake out over the day, aiming for 40g/meal, adding up to 1.2/g/kg/body weight/day- achieving both the ACSM and ESPEN recommendations.
However more research is required into the effects of distribution patterns. Owing to some studies, such as the randomised trial discussed above compared 1.5 to 0.8g/kg/body weight/day in older adults: this study also compared different distribution patterns and found no significant differences in the positive benefits achieved in the higher protein groups (9).
Do older adults need supplements?
This is another area drawing a lot of attention in research and the media. Protein supplementation can provide an easy way of increasing protein intake. Most adults eating a western diet including meat and dairy are thought to already exceed the recommended protein doses. There are some suggestions that this intake decreases with age, due to a variety of factors including decreased appetite.
As the evidence builds up indicating older adults require higher levels of protein, it is perhaps sensible to consider whether this can be achieved through diet, or whether a regular supplement could be helpful. This should be an individual choice, made based on current dietary intakes and circumstances.
Another supplement gaining attraction is Leucine: an essential branched-chain amino acid with very important targets in anabolic signaling- it increases protein synthesis and decreases protein breakdown (11). It appears to be the most ‘essential’ of the essential amino acids in muscle protein synthesis.
Leucine is present in most proteins, most abundant in proteins from animal sources; it is also found in legumes, cereals and fruits, but at lower quantities. International guidelines currently recommend a leucine intake of 3g at each main meal in older adults (12). Leucine is rarely labelled in food composition information, therefore it can be difficult to know the amount you are consuming.
A great review was recently published on leucine, with useful supplementary tables including the amounts in a large variety of common foods and different examples meals over a 7 day period which all include the recommended 3g leucine.
Take a look at the review to find out more- (12). Studies investigating leucine supplementation alone are currently inconclusive: some reporting positive results, some reporting no significant differences with the addition of leucine to an already higher protein diet (5).
A supplement mixture with much more positive results in older adults is leucine-and-vitamin-D-enriched whey protein (3g leucine, 800 IU vitamin D, 21g whey protein). Positive increases in muscle protein synthesis have been shown with this supplement in acute settings in both health and sarcopenic older men (13).
Longer term controlled trials also support the addition of this supplement into the diets of healthy and sarcopenic older men and women: with positive results on muscle function, muscle mass measurements and quality of life measures (14, 15). This combination therefore seems to be a well-rounded and evidence based supplement to consider adding in to the diet of older adults!
Based on this evidence our recommendations are:
- The recommended protein intake for older adults should be increased: >1.0-1.5g/kg/body weight/day
- Protein intake is likely most effective when consumed evenly across the main meals of the day
- Leucine is essential, however in most balanced diets likely already include enough to meet the recommended intake and the evidence for leucine supplementation alone is currently inconclusive
- There is some good evidence for addition of a leucine-and-vitamin-D-enriched whey protein (3g leucine, 800 IU vitamin D, 21g whey protein) into the diets of healthy and sarcopenic older adults