Protein? How Much for Long Life?
Most people feel better if they consume more protein. But protein leaves a nitrogen “ash” which many older kidneys do not like. How do you know if you are digesting and using protein to rebuild your body over and over again?
To answer this, a team of Japanese researchers fed isocaloric diets with varying amounts of protein to young and middle-aged male mice. They found that the mice were metabolically healthier when fed moderate-protein diets.
Much of our body is made up of, or repaired, by protein. Hormones dock into receptors, that are made up of proteins. But what is the best ratio of dietary macronutrients (proteins, carbohydrates, fats) with cardio-metabolic health and aging in mice, especially protein?
Protein & Health
This study published in GeroScience on April 28, 2023, investigated the amount of dietary protein needed to improve metabolic health in mice approaching old age.
They recruited young (6 months old) and middle-aged (16 months old) male C57BL/6NCr mice who were fed isocaloric diets with varying protein content (5 to 45 %) for two months. After two months, the effect of varying protein diets was assessed based on measurements of skeletal muscle weight, liver and plasma lipid profiles, and self-organizing map (SOM) cluster analysis of plasma amino acid profiles.
Findings:
A low-protein diet led to the development of mild fatty liver, with increased levels of hepatic lipids in middle-aged mice as compared to young mice.
In contrast, a moderate-protein diet led to reduced blood glucose concentrations and lipid levels in both liver and plasma.
These findings indicate that a moderate-protein diet (25% and 35%) kept both young and middle-aged mice metabolically healthier.
Protein requirements change through the course of life, being higher in younger reproductive mice, reducing through middle age, and rising again in older mice as protein efficiency declines.
The same pattern is likely to be observed in humans.
How do we look at “Protein” in blood work?
Your total protein on a basic metabolic panel, as an adult, should ideally be in the 7’s.
Your total protein is made up of globulin and albumin. You need these to be “Goldilocks Just Right” or else you might not be digesting protein. Or you may be leaking protein into your urine through leaky renal basement membranes.
This has to be figured out.
Many times the total protein and its components may be insufficient, but this is ignored by most doctors as a warning sign that things are not able to heal.
What do you need to absorb protein?
Stomach acid, not excessive bile, pancreatic enzymes, not excessive food sensitivities, healthy kidneys to avoid leakage and much more. It is a tapestry of events. But it starts with moderate protein intake. Which most simplistically means a bit of protein at most meals.
Consuming enough protein is particularly important for older people, more than we had previously thought. Oops, I guess that means me, too, ha!
Older adults who didn't get enough protein demonstrated significantly more functional limitations across all age groups, according to a study of 11,680 people between ages 51 and up that was published online in February 2019 in the Journal of Nutrition, Health & Aging.
The importance of getting enough protein is clear. But how much protein is enough?
Protein - How Much?
The current recommended dietary allowance, or RDA, for adults is 0.8 grams per kilogram of an individual's body mass (or 0.36 grams per pound of body weight). This is the minimum daily intake to prevent a deficiency. But not ideal.
Over the past decade, researchers found that increasing protein intake is safe and can help minimize muscle loss when cutting calories while dieting.
In 2015, a comprehensive review in Applied Physiology, Nutrition, and Metabolism suggests that eating a moderate amount – 25 to 35 grams – of high-quality protein during each meal "stimulates protein synthesis and promotes muscle health."
This study also found evidence that increasing the proportion of dietary protein intake could help with weight and fat loss for some people with obesity on a certain eating regimen, and can help prevent weight regain.
So, what’s your total protein on your metabolic panel?
Dr. B.
References:
Moderate protein intake percentage in mice for maintaining metabolic health during approach to old age. GeroScience, 2023.
From the items I’ve been reading the recommended protein intake for seniors over 60 is 1.2gm per kg to reduce sarcopenia.
Thanks for this article. Gabriel Lyon, Andrew Huberman & Peter Attia have been presenting similar information that, when applied to my metabolically challenged clients, facilitates fat loss and lean mass preservation. For myself, I’m an omnivore that shoots for 35 -40 grams of protein per meal. At 61, I feel stronger when I eat this way.