Monday, December 21, 2009

High dietary animal protein links to lower population growth and greater longevity

Roger Williams, the biochemist who first identified, isolated, and synthesized pantothenic acid, wrote a book titled Nutrition Against Disease (Pitman, 1971), in which he has a chapter titled "How Can We Delay Old Age?" In this chapter he discusses human population growth, because the goal of extending life span conflicts a bit with the growth of population. He points out that if life spans get extended and population growth also continues, in 200 years "Tokyo, New York, and London would each have populations several times that of the entire present world population."

In this context he remarks that in The Geography of Hunger, the author Josue d Castro states that he thinks that "hunger, particularly protein deficiency, is an important factor in creating the problem of overpopulation." To support his hypothesis, de Castro cites several observations that support, such as the fact that cattle become sterile if overfattened. de Castro also produced the following table indicating that human populations display an inverse relationship between birth rates and amount of dietary animal protein.

Williams comments on this data (collected before the introduction of hormonal contraception):

"There seems, however, to be an interesting principle involve which should be further explored. Nature does take measures to prevent the extinction of a species, and when extinction is threatened––by starvation for example––it may be that an exaggerated sex urge is one of he devices used to perpetuate the race. It may be that this contributes to the high birth rate among people who are ill fed. A parallel is found in the area of plant physiology where t has been observed that plants often grow vegetatively as long as well fertilized, and tend to go to seed (reproduce) only when conditions become adverse.

The contrary possibility that a decrease in human birth rates could automatically be brought about by the provision of certain nutritional factors is at least worthy of study.”

Of interest, international data from 2004 also indicate that healthy life expectancy may also correlate inversely with animal protein intake. The following table based on WHO data shows that nations with lower animal protein intake and higher birth rates (e.g. Mexico, China, Thailand, India) generally have lower life expectancy than nations with higher animal protein intake and lower birth rates (e.g. Japan, Sweden, Switzerland, Italy).

These data suggest that vegetarian diets both increase population growth and decrease life expectancy. It does look like these two phenomena (increased birth rate and decreased life expectancy) arise from a common biological condition, and quite possibly de Castro and Williams have named it: animal protein (and perforce, methionine) deficiency.

Addendum 11/18/11:

I made a couple of important errors in my reasoning in this post:

1.  The reduced fertility found in modern nations with higher protein intake could equally be interpreted as an indication that high intake of animal protein might increase the prevalence of infertility in humans. Thus, the data may indicate that low animal protein intake improves fertility.

In fact, we have data indicating that high animal protein intake poisons the uterus with ammonia, reducing the viability of embryos.

“These data show that consumption of a high protein [25%] diet results in the excess accumulation of ammonium in the fluid of the female reproductive tract of mice. These high levels of ammonium subsequently impair the formation of the fetal progenitor cells and increase cell death at the blastocyst stage. These data from in vivo-developed mouse blastocysts are similar to those for blastocysts developed in culture in the presence of 300 uM ammonium. Therefore, it is not advisable to maintain mice on a high protein diet. These data have significant implications for animal breeding, and for patients attempting IVF treatment.”
Gardner, D. K., Stilley, K. S., Lane, M., 2004. High protein diet inhibits inner cell mass formation and increases apoptosis in mouse blastocysts developed in vivo by increasing the levels of ammonium in the reproductive tract (abstract). Reprod. Fertil. Dev. 16(2):190.

…amino acid inclusion, especially that of glutamine, significantly increases the level of
ammonia within embryo culture media systems. It was shown that the benefits of amino
acid addition could be annulled by the effect of ammonia build-up, partly from degradation of glutamine over the course of embryo culture, and partly as a result of deamination of amino acids during metabolism. Early embryos appear to be sensitive to levels of ammonia as low as 100 mM and levels above 300 mM yield significant detrimental effects.”
Thompson, J. G., Lane, M., Robertson, S., 2006. Adaptive responses of early embryos to their microenvironment and consequences for post-implantation development. In: Wintour, E. M., Owens, J. A. (Eds.), Early Life Origins of Health and Disease. Adv. Exp. Med. Biol. 573. Springer, New York, NY, pp. 58–69.

2.  At the time the data was collected, the populations with low animal protein intake, high fertility, and low life expectancy also had relatively high infant mortality rates, which drives down the average the life expectancy.  Thus, this data does NOT show that high animal protein intake increases longevity.   Further, although most consider high infant mortality a terrible thing, in fact it is a pretty normal biological phenomenon; most organisms produce far more fertile seeds than surviving offspring.  Modern medical care reduces infant mortality, possibly by preserving lives of weaker, more disease-prone individuals.

3.  The most long-lived nation on the second table is Japan, but Japanese do not have a 'liberal' animal food intake by U.S. standards, although it is higher than in Mexico, China, Thailand, etc..  However, here again Japan has a low infant mortality rate compared to developing nations, making it look as though adults live longer in Japan than in those developing nations, when in reality the main difference is fewer deaths in infants in Japan versus developing nations.


Bryce said...

These conclusions certainly seem to jive with everything else I've learned about longevity, especially as it pertains to caloric restriction, nutritional quality, and reproduction.

Interesting that when calories are hard to come by, longevity seems to go up while reproduction seems to come down, but when low quality calories are plentiful, the opposite is true.

Fascinating find, Don!

Dennis Mangan said...

Control for income and you might see all these correlations disappear, because the industrialized countries have lower birth rates.

Don said...


"Control for income and you might see all these correlations disappear, because the industrialized countries have lower birth rates."

Lower birth rates and longer life expectancies are found in nations with both higher incomes and higher protein intakes. My post already noted lower birth rates in industrialized (higher income, higher protein) countries.

Even in wealthy nations, lower birth rates are found in the higher income, again higher protein intake social strata. For example, in the U.S., birth rates are higher in the lower economic classes, where also the diet consists of more carbohydrate and less protein, and, as Taubes notes, we also see more obesity.

Obese mothers, skinny malnourished children, large families among poor, carbohydrate-consuming people, and in wealthy, protein-and-fat consuming people, lean mothers, robust children, and smaller families.

Some attribute these differences to "education" but I believe diet plays a key role.

Hunter-gatherers (The Original Affluent Society*) don't have "higher education" but they fit the model, despite "low income." A typical lean, non-contracepting H-G woman has only 5 live births per reproductive lifetime, but a typical non-contracepting but fat agricultural (carb-based) woman has 12. See Frisch RE, Fatness and Fertility, Sci Am. 1988 Mar;258(3):88-95.


Daniel said...

Or maybe, first world countries eat more animal fat and have better health care.

Thailand and Mexico are low on the list you mention but have two of the lowest AGE ADJUSTED rates of cancer in the world.

By the way, they eat of a lot of fat in Thailand from coconuts, so this isn't an anti-fat point.

Dennis Mangan said...

Diet certainly plays a role in obesity, and lower SES eat more carbs. But as people get wealthier they eat more animal products and choose to have fewer children, a switch that's happening in China now for instance. So it would be hard to disentangle cause and effect here.

SES correlates with IQ, the real driver of class differences, IMO. But in the old days, medieval England for example, higher IQ and SES people had more surviving children, in which good nutrition almost certainly played a large part.

Nations with higher birth rates and lower life expectancy are also those that are poorer, hence with worse health care, worse sanitation, poor nutrition, not to mention more tropical disease.

Don said...


You say: "But as people get wealthier they eat more animal products and choose to have fewer children.."

I question the level of "choice" involved. We humans like to think that human actions all arise from conscious decision. This arises always in population discussions. People ignore the effect of food supply on human action and reproduction, but readily acknowledge the effect of food supply on actions and reproduction of other species. Its part of our erroneous conception of humans as "outside" of nature.

"hence with worse health care, worse sanitation, poor nutrition, not to mention more tropical disease."

All of these could stem from poor nutrition. Poor nutrition >> poor brain function >> poor sanitation and health care.

Poor nutrition >> weak immunity >> more tropical disease.

Poor nutrition >> ill health and low cognitive power >> poor food production >> poor nutrition.

Aaron said...

Don, could you comment on this?

For a long time now, I've seen studies linking protein restriction and reduced MitoROS.

You are now coming along saying that increasing protein might increase longevity. That is probably the case if you are in a malnourished state, but once you have adequate protein, excess protein is probably detrimental.

Don said...


The page you linked to has two articles. One points the finger at protein as the primary cause of oxidative damage to mitochondria. The second points out that 40% protein restriction (needed to reduce the ROS damage to mitochondria) results in accelerated sarcopenia (thus longevity without function). So they ( did a study with ER (energy restriction) but not protien restriction. They found:

"The ER diet was able to improve myosin and actin FSR [fractional synthesis rate] and grip force. Therefore, the synergistic effects of CR with maintained protein intake may help to limit the progression of sarcopenia by optimizing the turnover rates and functions of major proteins in skeletal muscle."

This study gets at what I was saying in my previous post. You can only restrict protein so much without causing loss of functional tissue. Sure, with protein restriction you can live long but be bed-ridden for lack of muscle tissue. Who wants that?

Not me. Especially when experiments with mammals have shown you can extend lifespan 15-20% with no energy restriction nor protein restriction nor loss of body mass or function, simply by regular intermittent fasting. Will post on this soon.


Keep in mind that if white North Americans were broken out into a separate category their life expectancy would rival that of Japan's.

Don said...


Especially if you factor out of U.S. mortality deaths from auto accidents and homicides (higher than any where else in the world, I believe).

Auto accidents drive down our life expectancy due to many occuring in young males.


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