Gerry Gajadharsingh writes:

“I think the takeaway message is in the title, adequate protein intake in midlife tied to healthy aging, is the important message. And by the way, adequate protein intake is critical, for most other bodily functions as well not just healthy aging.

One conclusion from the research below was that Physicians should therefore advise midlife patients to meet or perhaps modestly exceed the recommended dietary allowance for protein of 0.8 g/kg per day and to make plant protein a substantial component of daily dietary protein intake. The NHS currently suggests 0.75g/kg of body weight.

However, it’s not as simple as just looking at the total daily protein intake and it’s not the weight of the food we’re talking about but the protein content of the food. For example, a 125 g steak contains about 30 g of protein and 125 g of chicken contains around 50 g of protein, 125g of lentils contains around 14g of protein.

And then it’s not just about the protein. Proteins are broken down into amino acids. There are around 20 of them and 9 are labelled essential amino acids which means the body can’t make them and needs to get them from outside sources. Different foods have different amino acid profiles.

And then there is the issue of rate-limiting amino acids, The term “rate limiting amino acid” is used to describe the essential amino acid present in the lowest quantity in a food protein relative to a reference food protein like egg whites which has all 9 essential amino acids at 100% availability. When an essential amino acid is not provided in adequate amounts in the diet, protein synthesis is limited to the rate at which that essential ammonia acid is available. Plant proteins have a reduced content of essential amino acids in comparison to animal proteins and a significant reduction of rate limiting amino acids such as methianone, lysine and tryptophan meaning lower protein synthesis.

These amino acids from the digestion of proteins and synthesis in the body have critical functions within the body, including building muscle and other tissue, manufacturing all enzymes and every cellular reaction that occurs within the body is mediated via an enzyme, manufacture of certain peptide hormones such as thyroxine, manufacture of neurotransmitters, a critical part of the immune system such as immunoglobulins, the list goes on.

I would estimate that the majority of patients that I see, apart from those whom I’ve given dietary advice or undertaken the Metabolic Balance individualised nutritional program or indeed read my iBook, have inadequate protein intake. Probably more correctly inadequate intake of the essential amino acids.

One of the key recommendations from Metabolic Balance is to eat protein at each meal and vary your protein, i.e. not eating the same protein more than once a day. This generally insures adequate intake of these essential amino acids and minimising the rate limiting amino acids. Plant proteins should of course, be a part of this protein mix, but as you can see from the example above lots of plant proteins don’t contain high levels of protein or essential amino acids, or they contain more rate-limiting amino acids, therefore affecting protein synthesis. It is, for this simple reason why I tend to advise a variety of different dietary proteins.”

https://www.thehealthequation.co.uk/metabolic-balance-nutritional-programmes/

https://www.thehealthequation.co.uk/ibook/

 

Medscape

Diana Swift

Intake of protein, especially from plants, in middle age is associated with higher odds of healthy aging and positive mental and physical health status in older women, a recent analysis of the Nurses’ Health Study (NHS) data suggests.

The study is said to be the first to examine the long-term impact of midlife protein consumption on later health status.

Writing in the American Journal of clinical nutrition, a team led by Andres V. Ardisson Korat, DSc, a nutritional epidemiologist at the USDA Human Nutrition Research Center on Aging at Tufts University in Boston, Massachusetts, found the following midlife protein-related odds ratios (ORs) for later healthy aging measured at ages 70-93.

For each 3% energy increment from various protein sources:

  • 1.05 (95% CI, 1.01-1.10) for total protein
  • 1.07 (1.02-1.11) for animal protein
  • 1.14 (1.06-1.23) for dairy protein
  • 1.38 (1.24-1.54) for plant protein

In substitution analyses, significant positive associations were observed for the isocaloric replacement of animal or dairy protein, carbohydrate, or fat with plant protein — with increased ORs for healthy aging of 1.22-1.58 for each 3% of energy replacement.

On the measure of physical function, for example, replacing calories from all macronutrient variables with equivalent calories from plant protein was associated with 20%-60% higher odds of having no physical function limitations. Plant protein was also associated with higher odds for good mental status.

“Other studies have looked at protein intake in older adults, but we felt midlife was a more relevant etiological window,” Dr Ardisson Korat said in an interview. “Our findings generally align, however, with those of protein intake in older populations, which have shown that protein can reduce the risk of frailty.”

He added that the benefits of protein, especially from plant sources, would likely apply to men as well and increasing plant protein intake is not difficult. “If you want a snack during the day, eat a handful of nuts instead of potato chips,” he advised. And eating several meals a week featuring beans, peas, lentils, tofu, whole grains, or seeds is an easy way to boost dietary plant protein, which comes with health-promoting soluble and insoluble fiber as well as antioxidant and anti-inflammatory polyphenols and other phytochemicals.

Conversely, plant but not animal protein consumption in older adulthood was linked to a lower risk of frailty in a previous NHS study.

Higher plant protein intake was associated with a better probability of achieving healthy aging defined by changes in functional impairments, self-reported health/vitality, mental health, and use of health services in the Spanish Seniors-Estudio Sobre Nutricion y Reisgo Cardiovascular.

In contrast, animal protein intake in middle adulthood has been linked to an increased risk of premature death from chronic diseases driven by cardiovascular disease mortality.

The present findings are consistent with those observed for protein intakes in older adulthood, Dr Ardisson Korat said.

“This study underscores the health advantages for midlife adults consuming adequate dietary protein — particularly plant protein — as one component of pursuing a healthy lifestyle,” said Douglas R. Dirschl, MD, chair of orthopedic surgery at Baylor College of Medicine in Houston, Texas. Most Americans consume adequate amounts of protein, but according to Dr Dirschl, who treats many older patients for osteoporotic fractures and other musculoskeletal conditions, many US diets are subpar in this nutrient.

While protein is essential for bone and muscle formation and maintenance, “a surprising number of Americans are protein deficient, even those who seem hale and are overweight,” he said.

Dietary Recommendations for Midlife Patients

Physicians should therefore advise midlife patients to meet or perhaps modestly exceed the recommended dietary allowance for protein of 0.8 g/kg per day and to make plant protein a substantial component of daily dietary protein intake, Dr Dirschl said.

Luke D. Kim, MD, MEd, a geriatrician at the Cleveland Clinic in Cleveland, Ohio, noted that patients with lower socioeconomic status or with difficulty in day-to-day functioning are likely to have suboptimal protein intake. Such patients may need encouragement to eat more protein. “But we should keep in mind that showing a higher associated odds ratio of better health with increased protein take does not mean causality,” he said.

According to Rachel L. Amdur, MD, an internist at Northwestern Medicine in Chicago, Illinois, the long-term follow-up data from the NHS are uniquely helpful. “Middle-aged persons may think they no longer need much dietary protein and need to be reminded. Sometimes eating carbohydrates is just easier,” she said in an interview. Physicians need to assess and counsel patients on nutrition at all stages of life. “As I tell my patients, it’s best to think of your future self now.”

In agreement is Louis J. Morledge, MD, an internist at Northwell Health in New York City. “I firmly counsel my patients about adequate and often increased protein intake in middle life. But this is always within a larger framework of overall nutritional health.” He added that middle-aged persons often find themselves “stuck in food ruts,” and one of his clinical focuses is to advise patients about the importance of healthier food choices so they can better adjust to mental, emotional, physical, and skeletal changes as they age.

Study Details

The NHS analysis drew on prospective data from 48,762 nurses under the age of 60 years in 1984. Total protein, animal protein, dairy protein, and plant protein were derived from validated food-frequency questionnaires.

Adjusting for lifestyle, demographics, and health status, the investigators identified 3721 (7.6% of cohort) eligible participants. The mean age of participants at baseline was 48.6 years; 38.6% had body mass indexes (BMI, in kg/m2) greater than 25, 22.9% were current smokers, and 88.2% were married.

Healthy aging was defined as freedom from 11 major chronic diseases, good mental health, and no impairments in cognitive or physical function, as assessed in the 2014 or 2016 NHS participant questionnaires. Diseases/treatments included cancer, type 2 diabetes, myocardial infarction, coronary artery bypass graft or coronary angioplasty, congestive heart failure, stroke, kidney failure, chronic obstructive, pulmonary disease, Parkinson’s disease, multiple sclerosis and amyotrophic, lateral sclerosis.

Mean total protein consumption as a percentage of energy was 18.3% (standard deviation, 3%), slightly higher than the average 16.0% in the US diet. Of this, 13.3% was derived from animals, 3.6% from dairy products, and 4.9% from plants.

Total protein intake was positively associated with higher education levels, being physically active, higher BMI, and a baseline history of hypertension and hypercholesterolemia. Conversely, total protein intake was inversely associated with intakes of total carbohydrates, nuts, alcohol, and sugar-sweetened beverages.

The associations between protein intake and healthy aging are complex and not fully understood, the authors stated.

Effects of Protein Intake

In studies of older adult populations, lower protein intake  has been associated with lean mass loss. Animal protein supplementation studies in older adults have shown lean mass gains potentially related to amino acid composition.

In terms of mechanisms, evidence suggests that protein-related activation of the rapamycin complex 1 pathway may play a role, the authors suggested. The activity of this signaling pathway decreases with age.

Rapamycin, a compound used to prevent organ transplant rejection, has been associated with delayed aging. In the body, dietary protein and exercise activate this pathway, thereby stimulating muscle protein synthesis and possibly improving physical function.

As for the differential associations of plant and animal protein on the chronic disease domain of the healthy aging phenotype, Dr Ardisson Korat and coauthors said plant protein has been associated with favorable levels of important risk factors for cardiometabolic diseases, such as reduced LDL cholesterol, lower blood pressure, and insulin sensitivity, as well as decreased levels of proinflammatory markers.

Conversely, total and animal protein intakes have been positively associated with concentrations of insulin-like growth factor 1, which is implicated in the growth of malignant cells in breast and prostate tissue.

This study is the first step in evaluating the long-term health effect of protein intake in midlife, the relevant development window for most chronic conditions, the NHS study authors said. More research is needed, however, to corroborate the study findings in other populations and identify underlying mechanisms.

This study was supported by the USDA Agricultural Research Service and the National Institutes of Health. The authors reported no conflicts of interest. The commentators disclosed no relevant competing interests.