The high potassium foods diet is a healthy diet. It is the type diet that the longest living populations eat. But there are other types of diets that also seem to promote life extension. One frequently mentioned but rarely followed for long is a diet of severe calorie restriction.
Severe Calorie Restriction Prolongs Life
The severe calorie restricted diet (20 to 40% fewer calories than an unrestricted diet) is often mentioned for its ability to prolong lifespan and reduce disease. It has been studied since the 1930s when McCay (1) found it prolonged life span in rats. Since then it has been studied in yeast, fruit flies, earthworms, rats, dogs, and nonhuman primates, as well as humans.
The studies in the lower animals are to discover the metabolic pathways that are affected by calorie restriction. This approach may lead to medications that can give the same result, or show ways of eating to get the same result without the restriction.
Showing how a diet works in other primates is one step short of showing that it would work in humans. In the 1980s several colonies of animals were put on calorie restricted diets and have been kept on that diet until the present.
Severe Calorie Restriction Prolongs Life? Kind Of, Maybe
Two centers working with primates are beginning to show an interesting difference. The animals in the different colonies are the same species and are very similar. The diet of the animals is very similar. Both had the same proportion of protein, fats and carbohydrates. They both put the experimental animals on 30% fewer calories than the controls. But there was a difference in the results.
One group of restricted animals showed less diabetes, cancer, cardiovascular disease and brain atrophy than the controls (2). The other group of restricted animals showed less diabetes and cancer, but no difference in cardiovascular disease or death related to aging (3). What was the difference?
The difference was in the control groups. In the control group for the animals with the best results from restricting calories, the control group got 30% of their calories from sucrose. In the other control group only 4% of calories came from sucrose.
The increased sucrose in the first control group made the control group do a lot worse than the calorie restricted group. Just restricting the sucrose improved the second control group so much that the calorie restricted group hardly did any better.
So it may not be calories that make a big difference. What food those calories come from may be far more important.
Other Macronutrient Calorie Studies
There have been other studies showing that restricting calories from fats or carbohydrates does not increase longevity, but restricting calories from amino acids does. These studies may well have a similar problem to the calorie restricted diet studies.
What matters is each individual component of the diet. Sugar is not the same as broccoli, although the calories from both are mostly carbohydrate. Olive oil is not the same as beef fat, although the calories from both are mostly from fat.
Severe calorie restriction may not be so important. It may be that most of the life extension in a calorie restricted or a macronutrient restricted diet is from restricting a few individual components of the diet.
Studies on restricting individual components of the diet are still early, but some of them are beginning to show results. The next few posts will discuss some of the results.
To Find Potassium Tables
The potassium content is rarely mentioned in any dietary studies except those specifically dealing with potassium and sodium. This is despite the strong evidence of its ability to improve life shortening disease. To find posts that have tables with the potassium content of a specific food, look here under the food group. If you want to find the potassium content of a vegetable, fruit, fruit juice, dried fruit, dairy product, beef, poultry or fish you can go directly by clicking the link.
1. The effect of retarded growth upon the length of life span and upon the ultimate body size. McCay CM, Crowell MF, Maynard LA. Nutrition 1935;5:155.
2. Caloric restriction delays disease onset and mortality in rhesus monkeys. Colman RJ, Anderson RM, Johnson SC, Kastman EK, Kosmatka KJ, Beasley TM, Allison DB, Cruzen C, Simmons HA, Kemnitz JW, Weindruch R. Science 2009 Jul 10;325(5937):201-4. doi: 10.1126/science.1173635.
3. Impact of caloric restriction on health and survival in rhesus monkeys from the NIA study. Mattison JA, Roth GS, Beasley TM, Tilmont EM, Handy AM, Herbert RL, Longo DL, Allison DB, Young JE, Bryant M, Barnard D, Ward WF, Qi W, Ingram DK, de Cabo R. Nature 2012 Sep 13;489(7415):318-21. doi: 10.1038/nature11432.