That study that purported to show that diets high in meat, eggs, and dairy could be as harmful to health as smoking supposedly suggested that people under 60 who eat lots of meat, eggs, and dairy are four times as likely to die from cancer or diabetes.
But if you look at the actual study, you'll see that's simply not true. Those eating a lot of animal protein didn't have four times more risk of dying from diabetes; they had 73 times the risk. What about those that chose moderation? Those in the moderate protein group, who got 10 to 19% of calories from protein, they just had about 23 times the risk of death from diabetes, compared to those consuming the recommended amount of protein, which comes out to be about 6 to 10% of calories from protein, around 50 or so grams a day.
So the so-called low protein intake is actually the recommended protein intake, associated with a major reduction in cancer, and overall mortality in middle age, under age 60, but note, it says not in older populations. When it comes to diabetes deaths, lower overall protein intake is associated with a longer life at all ages, but for cancer, it seems to flip around age 60. These results suggest that low protein intake during middle age followed by moderate to high protein consumption in old adults may optimize health span and lifespan.
Some have suggested that the standard daily allowance for protein is 0.8 grams of daily protein for every healthy kilogram of body weight. That may be fine for most, but maybe older people require more. This is the study upon which the RDA was based, and though there was a suggestion that the elderly may have a somewhat higher requirement, there was just not enough evidence to make different recommendations. The definitive study was published in 2008 and it found no difference in the protein requirements between young and old. The same RDA should be adequate for the elderly.
But adequate intake is not necessarily optimal intake. The protein requirement studies don't address the possibility that protein intake well above the RDA could prove beneficial, or so suggests a member of the Whey Protein Panel and a consultant for the National Cattlemen's Beef Association.
If you follow sedentary individuals over the age of 60, they lose about 1% of their muscle mass every year. If you force people to lie in bed all day for days at a time, anyone would lose muscle mass, but older adults may lose muscle mass on bed rest six times faster than young people.
So it's use it or lose it for everyone, but the elderly appear to lose it faster, so they better use it. The good news is in contrast to the 12-year U.S. study, a similar study in Japan found that the age-related decreases in muscle mass were trivial. Why the difference? It turns out the participants were informed about the results of their muscle strength, and so often tried to improve it by training before their next exam for the study, especially the men who got so competitive their muscle mass actually went up with age, which shows that the loss of muscle mass with age is not inevitable; you just have to put in some effort.
And adding protein does not seem to help. Adding more egg whites to the diet did not influence the muscle responses to resistance training, and that's based on studies funded by the American Egg Board itself. Even the National Dairy Council couldn't spin it. Evidently strength training induced improvements in body composition, muscle strength and size, and physical functioning are not enhanced when older people increase their protein intake by either increasing the ingestion of higher-protein foods or taking protein supplements. Is there anything we can do diet-wise to protect our aging muscles?
Vegetables. Consuming recommended levels of vegetables was associated with cutting the odds basically in half of low muscle mass.
Why?
The alkalizing effects of vegetables may neutralize the mild metabolic acidosis that occurs with age, and, you know, it may be that little extra acid in our body that facilitates the breakdown of muscle.
Muscle wasting appears to be an adaptive response to acidosis. We appear to get a chronic low-grade acidosis with advancing age because our kidneys start to decline, and because we may be eating an acid-promoting diet, which means a diet high in fish, pork, chicken, and cheese, and low in fruits and vegetables.
And as you can see, beans and other legumes are the only major source of protein that's alkaline instead of acid forming. And indeed a more plant-based diet, a more alkaline diet was found to be positively associated with muscle mass in women aged 18 through 76 years old.
So if we are going to increase our protein consumption after age 60, it would be preferable to eat plant-based proteins to protect us from frailty. No matter how old we are, a diet that emphasizes plant-based nutrition is likely to maximize health benefits in all age groups.