I find it absolutely fascinating that scientists often bother to estimate the effects of diet by feeding controlled quantities of food, especially plant food, to rats to see what happens.

For example, there is a common substance in cooked food that, if fed in even modest quantity to rats, causes the rats to get cancer and die in no time. This raises concerns for humans because, well, the rats died. So the substance must be “bad for you.”

But this approach to nutritional science, and the reasoning that goes with it, is deeply flawed.


Now, you may wish to jump in and say, “No, wait, nutritional scientists are much smarter than that … they know that humans and rats are different.” Fair enough. But the framework for understanding this difference in evolutionary terms is largely undeveloped at the science end of it, and is probably never going to be developed in the administrative side of it … where agencies like the FDA are making decisions. As for the mildly to poorly informed public side of it, forget about it, that ain’t going to happen. (Until, of course, we update our system of science education.)

The reason the rats die by ingesting even modest quantities of stuff that humans seem to be able to eat in abundance is because humans have been eating cooked food, in my opinion, for nearly two million years. We have co-evolved with cooked food. Rats not so much.

In the broader perspective, co-evolution between plants and animals shapes both the plant and the animal in ways that are often powerfully manifest in that dietary interaction. One organism eats another organism, and stuff happens. Strategies are selected in the eater to enhance eating, and strategies are selected in the eatee … in this case the plant … to either avoid being eaten or to take advantage of what might be an unavoidable situation, being a part of another organism’s diet.

In the meantime, the food industry, food science, and regular people who eat stuff wander often blindly if not aimlessly amongst a sea of conflicting information. One day coffee is good for you. A week later it is bad for you. Later that year a certain amount of coffee is good for you, but only if you drink half decaffeinated brew. Then it is discovered that the decaffeination process will make you die. Then it is discovered that it won’t.

And there is a reason for this confusion. We love coffee because of the complex aroma and taste (these are related phenomena) and because of the narcotic substance it contains (caffeine). But the caffeine and many of the odors and flavors are the product of a plant strategy to avoid being eaten. These secondary compounds are, essentially, poisons designed as insecticide, fungicide, nematode-i-cide, or whatever-i-cide.

Ditto for almost all of our spices. Go get a grasshopper and make it smell a freshly crushed basil leave. You won’t believe the expression on that grasshopper’s face.

Humans brewing coffee beans in hot water or eating leaves are not really part of the evolutionary equation. Most of the evolution other than domestication by us has to do with the grasshopper and the leafy plant, or the fungus and the coffee seed (that bean is a seed, obviously … the baby plant, subject to great chemical attention by the mother coffee plant). The relationship between humans … Homo cuisineensis … and these plants is quirky, to say the least.

Quirky in a tastes great, may get you stoned, might make you sick kind of way.

Children are averse to leafy green things, and especially the really concentrated green plants that adults eat and pretend to like such as Brussels sprouts and asparagus. Pregnant women are nauseated more often by a certain subset of foods. When you look at these foods, you find that they often contain compounds that could affect fetal development or other biological systems. Spinach is not necessarily good for you if you are a growing child.

There is, of course, a fair amount of research on this topic of co-evolutionary perspectives on human diet, and over time I hope to write more on it. For now, consider this set of questions and issues the next time you read about some new research related to stuff you ingest. In fact, you can start now with these items fresh off the presses:

Eating your greens could prove life-saving if a heart attack strikes from PhysOrg.com
A diet rich in leafy vegetables may minimize the tissue damage caused by heart attacks, according to researchers at the Albert Einstein College of Medicine of Yeshiva University. Their findings, published in the November 12 Proceedings of the National Academy of Sciences, suggest that the chemical nitrite, found in many vegetables, could be the secret ingredient in the heart-healthy Mediterranean diet.

[...]

Genetic technology reveals how poisonous mushrooms cook up toxins from PhysOrg.com
Heather Hallen spent eight years looking for poison in all the wrong places. Alpha-amanitin is the poison of the death cap mushroom, Amanita phalloides. The Michigan State University plant biology research associate was looking for a big gene that makes a big enzyme that produces alpha-amanitin, since that’s how other fungi produce similar compounds. But after years of defeat, she and her team called in the big guns – new technology that sequences DNA about as fast as a death cap mushroom can kill.

[...]

Long-term beta carotene supplementation may help prevent cognitive decline from PhysOrg.com
Men who take beta carotene supplements for 15 years or longer may have less cognitive decline, according to a report in the November 12 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

[...]

Herbal Sex Pills Pose Hidden Dangers from PhysOrg.com
(AP) — Many of the pills marketed as safe herbal alternatives to Viagra and other prescription sex medications pose a hidden danger: For men on common heart and blood-pressure drugs, popping one could lead to a stroke, or even death.

[...]

Comments

  1. #1 chezjake
    November 12, 2007

    Fascinating and well written post. I’ll look forward to future related posts.

  2. #2 Jeb, FCD
    November 12, 2007

    I seem to remember reading quite a long time ago that children are naturally averse to green veggies. The specfic example was broccoli. It tends to really aggravate a child’s gag reflex.

    BTW, I don’t pretend to like Brussels sprouts now, though as a teen I DETESTED them. Same for asparagus. Is it because, like my vision, as I age my tastes become unrefined or is there a deeper physiological “thing” going on?

    I would like a reference for

    Spinach is not necessarily good for you if you are a growing child.

    Kthxbai.

  3. #3 Nathaniel
    November 13, 2007

    I was just talking with a coworker today about how I believe that one of the many reasons that humanity has spread across the globe is that we can consume so many things without being killed my them. There are a great many things that are toxic to most animals that are not to us. The only animal that has anything on us is the goat… I never could stomach tin cans.

    It is true though, most spices and a great many other plants, are toxic to most animals. Hot peppers didn’t evolve to be spicy so that we could make salsa. I never even gave a pregnant mother’s cravings and morning sickness to the body getting rid of toxins. I suppose that makes sense. Our development within the womb would likely remain mostly unchanged over the past 2 million years because the vast majority of the mutations in the genes that govern that development would result in an inviable fetus. This would mean that although a spice might not be toxic to an adult, it could still pose a threat to a developing fetus.

    I actually love veggies like spinach, broccoli, celery, peas, etc… and I have always loved spices like garlic and hot peppers. I think most kids don’t like them because they think they look nasty, not because they don’t really want to eat them. Either that or they’ve heard that normal kids don’t like veggies so they assume that they do not like them.

    Even if something is toxic to you, it doesn’t make it bad. Too much iron is toxic, not enough is also bad. Even things like arsenic can be beneficial in VERY small doses. This is because every toxin produces an effect in the body and a certain amount of stress can be good for you. Still… you won’t catch me downing poisons to make myself stronger. I think I’ll stick to good old fashioned spices for now.

  4. #4 Warren
    November 13, 2007

    A specialized subset of the veggies you mention would be chili peppers, I suspect. Wasn’t capsaicin originally a defense strategy against birds?

  5. #5 greg laden
    November 13, 2007

    Warren: Capsaicin is probably a defense strategy aimed at non-birds. Birds are totally immune to it. Even birds who normally would not encouter it are not bothered by it.

    Likely, the primordial pepper is bird-dispersed.