I attended Robb Wolf's day-long Paleo Solution seminar on Saturday, which I highly recommend. Robb is super nice guy, and really knows his stuff!
There was a question that I meant to ask him, but didn't get a chance. If grains contain anti-nutrients because they "don't want to be eaten," why wouldn't that be true of all plants? Presumably brocolli does not want to be eaten either, so why doesn't it protect itself in the same way? I think Peter at the High Fat Nutrition blog is actually starting to argue this--that all fruits and plants are problematic in some way (except for root vegetables and tubers, since being underground is their "protection.")
The evolutionary logic is that everything wants to survive and procreate. Animals can fight and flee, but plants require passive defenses of some kind.
When the passive defenses are chemical, unless the animal evolved specific countermeasures they are going to suffer a variety of consequences from eating those plants.
Other passive defenses include armor (the hard shell of nuts), and being underground (tubers), which reduce the need for chemical defenses. Fruit is a unique case because the plant wants you to eat it, which is where the procreation part comes in.
I can't name any that aren't , I've been digging for the optimal vegetables for a while, I keep coming back to a good variety of wild meat, it's what I crave...and the animals I'm eating have systems for breaking down those plants, humans use external processes(cooking -fermentation) to make plants safe...
I make sure to cook/ferment my limited plant intake appropriately
As just one little part of the puzzel.... a current research suggests that many phytochmicals that benefit us actually work as they act as low level toxins, this then elicits an adaptive response from the body that is long term net-protective.
Obviously they have other mechanisms of action as well but this is an interesting one.
There are many different evolutionary strategies taken by different plants and animals.
For example, pine nuts depend on squirrel consumption in order to propagate. The tree makes absolutely the most attractive nuts to the squirrel imaginable: delicious and covered in a hard shell that can last the winter. The squirrels gather and bury the nuts. Stashes that get abandoned due to death or a forced move of the squirrel then bloom into new trees.
Michael Pollan has pointed out that in regards to gardening, it is not exactly clear if we are using the plants to our liking, or if the plants are using us to help propagate them.
Plants don't "want" anything. Fruits and plants are not "problematic". One of the few actually poisonous plants we regularly eat is the potato which is an underground tuber.
Almost all the plants we eat reguarly now are the result of artificial selection through agriculture. Toxins tend to taste bad as so most plants have been selected to contain less and less of them. We now probably eat a great deal less plant anti-nutrients than our ancestors did. These anti-nutrients have been eaten by our ancestors throughout evolutionary history. Maybe avoiding them entirely would be like avoiding all bacteria? We do have very effective livers than can detoxify a wide range of compounds.
Evolution is complex and not usually obvious. Producing toxins cost energy. A plant producing lots of defensive compounds will be out-grown by a plant not producing any. Many plants only take defensive action when damaged.
Chemical communication is not confined to the animal kingdom since plants do some pretty strange things too. Watson describes how the acacia tree responds to browsing, or being beaten with a stick, by increasing the levels of tannin in its leaves within minutes. Remarkably, the tannin levels then rise in neighbouring trees, and, due to its bitter taste, repel the browsers before they can do any further damage. This example of plant communication is not restricted to acacia trees, and has been demonstrated in other plants as well as between plants and animals. Tearing the leaves of seedling poplar trees results in a widespread increase in phenols, which are known to inhibit the growth of butterfly larvae. Tobacco plants warn each other of tobacco mosaic virus attack by releasing methyl salicylate, which is then converted to the protective salicylic acid in uninfected plants.
Mammals are also rarely the biggest threat to plants. Insects, viruses and fungi are often bigger threats to survival and plant toxins often target insects rather than people. It is much easier to taste bad than be poisonous.
And I don't want to eat broccoli. So live and let live I say!
My theory is that the things that plants want us to eat are the least likely to have anti-nutrients and more likely to have bonuses like vitamins i.e. fruit (let's just pretend that the fructose is at adequate wild levels, ahem). All other things have detrimental attributes if you look hard enough.
Broccoli for instance is chock full of glucosinolates. They were once thought of as the predominant cause of goiter—a thyroid disease that produces a large swelling of the neck. The goitrogens in broccoli increase the need for iodine when consumed in small amounts and can damage the thyroid gland when consumed in large amounts.
WAPF is king of all 'veggies are trying to kill you knowledge:' http://www.westonaprice.org/abcs-of-nutrition/177-bearers-of-the-cross.html
Just as an aside, brocolli does contain defenses, like most crucifers, hence having much more of a bite while raw. The fact that humans can cook just means we can bypass this. Of course, brocolli is somewhat palatable raw, but more as interesting crudites than a major food source. That some crucifers contain more defense than others is revealing. Those foods that are relatively low quality foods (strictly in the sense of high fibre:calories) like brocolli will require less defense than carbier plants. Plants are a product of their evolution as much as we are and producing defence mechanisms is an investment that much be traded off against other investments (such as more growth, higher energy stores), in the same way that humans wouldn't benefit from evolving to be 9ft tall and as strong as an ape.
Fruit certainly do want to be eaten, hence the addictive fructose and other such appealing traits. Lamentably even fruits don't want you to fully digest them, they want their seeds to quickly escape intact, hence the effect of large amounts of fruit on the digestive system. Of course it's not of much interest to the fruit whether you can live healthily on fruit, so long as you can continue eating fruit.
When cows and other ruminants eat grass, it strengthens the root system of the grass. As long as the entire plant is not killed, being eaten may be adaptive. Some plants may contain more chemical defenses in more critical areas of the plant, which may allow them to benefit from being eaten without being killed completely.
I think that something that needs to be considered is the evolutionary history of the plant and the animal that eats it. Evolutionary theory would expect some kind of arms-race between the two. Plants develop toxins for their protection, animals develop strategies to tolerate the toxin.
Now I don't know if there are any plants that have a co-evolution with human consumption that is long enough for this kind of arms-race. And I mean, we humans physiologically being able to tolerate toxins.
Probably (some) phytochemicals have health benefits for humans, because they are toxins or stressors that have hormetic effects. I would hypothesise that hormetic effects (which are specific adaptations of an organism to a certain stressor, e.g. exercise, cold, ...) can only occur if we have specific mechanisms to deal with them. This would imply a long enough time for natural selection to give us these mechanisms?
Please correct me if the above reasoning is flawed.
The other important thing humans do to neutralise toxins and antinutrients, is food preparing. As Richard Wrangham hypothesises, cooking probably exists for longer than previously thought, and could have had a major effect on human evolution. See his book, Catching Fire (or here or here) for some ideas.
no they don't and if you do happen to consume more than the allowed amount of plants (according to her highness mother nature) zombies will be sent forth with pitch forks to devour you to see how you like it !!!!!
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