Tuesday, 15 December 2009

Cooking, ageing and fertility

Our ancestors were using fire over 1 million years ago. Even if Homo sapiens began to use fire for regular cooking only 100,000 years ago, it is still a long time. Certainly much longer than 5-10,000 since agriculture became the way of life.

There are plenty of convincing arguments that cooking is Paleolithic enough, and that there is no need to go raw meat, which is why the paleo and primal approaches do no focus too much on cooked vs. raw food. The raw foodists, of course, have made up their minds already and see cooking as source of all evil.

While I will continue eating heat processed meat, for culinary and cultural reasons, I am not al all convinced that this is the optimal strategy. Here are the reasons.

1. While cooked meat is digestible, apparently raw meat is even more digestible. There is less residue left for bacteria in the gut. "Rotting in the gut" is one of the arguments brought up by vegetarians.
2. Organ meats, bone marrow and brain, which were the best Paleo parts healthwise do not require cooking for easier consumption. It is the tougher muscle meat which is more palatable when cooked.
3. Cooked meat has less nutrients.
4. Cooked meat likely contains less carnosine (certainly older meat contains less carnosine)
5. Cooked meat is more acidic. More acidic food requires more fresh vegetables to balance the acids. This can be harder to achieve if you consider the carbs and bulk of the food.
6. Cooked, or more specifically grilled, fried or roasted, contains mutagenic and carcinogenic substances.
7. Meat heat processed together with carbohydrates contains Advanced Glycation Endproducts (AGEs), which are mutagenic and accelerate ageing. This is probably something the Paleo hunters were not used to. Meat was roasted but not with sugar glazing or batter. Soups were probably invented later, when cauldrons became available.

In my opinion AGEs are the most dangerous and most overlooked Neolithic inventions in cooking which only appears to be Paleo. And AGEs are produced easily, even without proper carbohydrate ingredients. Caramelised onion, steak marinated with honey added, soup with meat and carrots, this is all about Maillard reaction and further steps leading to AGEs.

Now, from the evolutionary point of view, AGEs appear not to be a problem as the consequences do to apply to reproduction or parenting. But if you are 40 and considering having children, there are reasons for concern:
"(...) a recent study has found a significantly higher sperm nuclear DNA fragmentation in diabetic men. As advanced glycation end products (AGEs) are important instigators of oxidative stress and cell dysfunction in numerous diabetic complications, we hypothesized that these compounds could also be present in the male reproductive tract."

"We found a class of compounds known as advanced glycation end products (AGEs) in the male reproductive tract. These are formed as the result of glycation (the addition of sugar)," said Dr. Mallidis, "and accumulate during normal ageing. They are dependent on life style - diet, smoking etc - and in many diabetic complications are centrally implicated in DNA damage. We believe that they play a similar role in the male reproductive system." The scientists intend to follow up their work by trying to determine how AGEs cause and contribute to DNA damage. They believe that they may have uncovered a new role for AGEs, and that their influence goes far beyond diabetes and its complications. "We must now try to develop strategies to protect sperm, and to diminish the accumulation of AGEs," said Dr. Mallidis. Such strategies could involve changes in diet, disrupting a step in the formation of AGEs, or increasing the body's protection against AGEs, possibly through the use of dietary supplements.

And AGEs are relevant not only to diabetes.

But if you want to slow down the clock, it might be worth considering steak tartare, carpaccio, sashimi, stroganina, ceviche or other raw meat/fish dishes instead of well done steak or a long cooked stew. Also, butter made from unpasturised milk might be a better option, though hardly Paleolithic. For some reason butter has the highest content of AGE of all products, which may be due to pasteurisation in high temperatures. Also commercial yoghurt contains AGEs from added powdered milk, which is also "cooked". Here is more on AGE content:
(more scientific sources are easy to Google)

Of course, if you forage for nuts, make sure they are raw, not roasted, as roasting it nothing less than Maillard, Amadori and other reactions wich ultimately end up as AGEs. The same applies to coffee, which is roasted for the very purpose of enhancing flafour and increasing AGE content.

Having said that, high carbohydrate (particularily fruit fructose and milk galactose) vegetarian diet probably generates more AGEs in vivo that can be ingested as food by carnivore cooks. In addition, vegetarians also eat cooked/fried processed foods, such as soy products, quorn, breads, chips, baked potato.

Here is a good overview of the AGE:
"While it may be impossible to totally avoid glycotoxin consumption, it is possible to reduce their content by changing the way food is prepared, and thus steaming, boiling, poaching, stewing, stir-frying, or using a slow cooker is strongly advised. These methods not only cook foods with a lower amount of heat, they also retain foods moisture during the cooking processandresearchers haveproved that waterandmoisture inhibit the reactions forming AGEs."

And more on AGE in healthy people (non-diabetic):

Probably the best way to handle AGEs is to eat massive amounts of raw vegetables along with minimally heat processed meat.

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