Recently I have seen a number of articles looking at how the diet needs of the seniors (over 60 y.o.) are very different from younger people. One characteristics of many seniors is a decrease of microbiome diversity — the same situation that happens with some medical conditions.
Changes with Age
“Beyond descriptive connections between microbial composition and host health status, very few studies to date have dissected the causal role of the gut microbiota during ageing. ” 
“Besides microbiota diversity, reduced microbiota-related metabolic capacity, such as lower short-chain fatty acids (SCFAs) levels, in old age may also be associated with aging-related maladies such as irregular bowel transit, reduced appetite, frailty, weight loss, cognitive decline, hypertension, vitamin D deficiency, diabetes, arthritis, sarcopenia, etc. [47–50].”
- “As signature bacteria of the long life we identified specifically Eubacterium limosum and relatives that were more than ten-fold increased in the centenarians.” 
- “In centenarians, we observed a reduction in the quantity of enterobacteriaceae, bifidobacteria, and bacteroides and an increase in clostridia sensu stricto. The presence of Bifidobacterium longum in the gut seems to be a particular feature in centenarians. It is interesting to note that only 1 strain of B. longum was isolated from each centenarian subject.” 
Diet Changes Suggested in the literature
- A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly. 
- “We conclude that increasing the proportion of leucine in a mixture of essential amino acid can reverse an attenuated response of muscle protein synthesis in elderly”
- Insufficient Protein Intakes is Highly Prevalent among Physically Active Elderly.
- A Distinct Pattern of Circulating Amino Acids Characterizes Older Persons with Physical Frailty and Sarcopenia: Results from the BIOSPHERE Study.
- “Older adults with Physical frailty and sarcopenia(PF&S) were characterized by higher levels of asparagine, aspartic acid, citrulline, ethanolamine, glutamic acid, sarcosine, and taurine. The profile of non (PF&S) participants was defined by higher concentrations of α-aminobutyric acid and methionine. “
- Effects of Adherence to a Higher Protein Diet on Weight Loss, Markers of Health, and Functional Capacity in Older Women Participating in a Resistance-Based Exercise Program.
- A meal with mixed soy/whey proteins is as efficient as a whey meal in counteracting the age-related muscle anabolic resistance only if the protein content and leucine levels are increased.
- “Most published results, based on data from either epidemiological or short-term studies, indicate a potential beneficial effect of increasing protein intake in elderly adults. These data demonstrate that elderly adults, compared with younger adults, are less responsive to low doses of amino acid intake . However, this lack of responsiveness in healthy older adults can usually be overcome with higher levels of essential amino acid (EAA) consumption . This is also reflected in studies comparing varying levels of protein consumption , suggesting that the lack of muscle responsiveness to lower doses of protein intake in elderly adults can be overcome with a higher level of protein intake. The requirement for a larger dose of protein to generate responses in elderly adults similar to the responses in younger adults provides the support for a beneficial effect of increased protein in older populations .” 
Back to my primary topic of this blog
Old muscle in young body: an aphorism describing the Chronic Fatigue Syndrome .
- “The data support the hypothesis that patients with CFS are subjected to some of the problems typical for muscle aging, which is probably related to disorders of muscle protein synthesis and biogenesis of mitochondria.
There is a lot of literature recently published stating the same things:
- Higher protein content than a younger person “The optimum amount for elderly adults (0.24 g/kg/meal) is approximately 70% greater than that for young adults (0.8 g/kg/day) , indicating an age-associated anabolic resistance to dietary protein.”
- Leucine content is very important. See this page for the suggested foods and this page also.
- 2.5 g is 1 serving of Greek Yogurt = 5 eggs, but half the calories
- Study with an addition of ( 3.2 g L-leucine, 0.9 g L-valine, 0.9 g L-isoleucine) 
Some 15 years ago, I recall many people with CFS/ME had significant improvement with non-denatured whey — an excellent source of protein.
Translation to American
0.24 g/kg/meal – means for a 200 lb person we are talking ~ 3 oz/day of good quality protein that is high in Leucine.