In previous entries, I made mention of a paleolithic-style diet being optimal for human consumption. By "optimal" I meant you can rely on your appetite to direct you to stay lean (if you are already lean), or be a tad more careful about what you eat and lose the extra fat (in a later post I will explain exactly how to lose the fat!), and, it seems pretty scientifically clear from epidemiological and observational studies (and from a few small studies on people with actual disease) that if you spend your whole life eating this way, also get plenty of sleep, a moderate amount of exercise, and appropriate social interaction, your chances of getting Western diseases such as ischemic heart disease, type II diabetes, many autoimmune diseases, stroke, acne, depression, hypertension, obesity, osteoporosis, and tooth decay are very small. Ooo ooo cool! Sign me up!
There's just one *little* caveat which I will elucidate more fully today - the strict paleo folks avoid grains (including corn, wheat, rye, buckwheat, oats, quinoa, spelt, rice - except maybe wild rice). Or beans and legumes - including chickpeas, peanuts, and especially soy. Or sometimes cow's or goat's milk (though I will go into more detail about milk in a separate post). Also, some will avoid potatoes, tomatoes, eggplants, and other nightshades. Hmm. Kind of a drag, really. (Though once you've gone over to the dark side of paleo, those large pants and type II diabetes seem like way more of a drag than giving up your daily dinner roll).
How could beans and grains be bad for you? Well, let me count the ways:
Lectins: Lectins sit on the outside of plants, attached to sugar molecules. Their roll in nature is thought to be to protect the plant from plant-eating animals. While lots of plants have lectins, the highest concentrations are in seeds, soybeans, beans, potatoes, and peanuts. Normal cooking doesn't destroy the lectins, though pressure cooking will (except for wheat agglutinin - that nasty bugger is impossible to kill), and your stomach and digestive tract don't seem to break them down completely either. (Well, who cares?) Turns out these lectins can penetrate your gut and fly around willy nilly within your body, and there is a mounting body of scientific evidence that lectins play a role in atherosclerosis, insulin resistance, cancer, and autoimmune disease (1). Wheat agglutinin has been shown to bind leptin receptors, which could explain leptin resistance (the first step on the road to obesity). Unfortunately, the theoretical biochemical mechanisms of these things in each separate disease state are becoming clear, and it ain't pretty. Oh. (Now there's no way to get away from lectins - tons of plants have them! But if you vary your plant consumption you'll be exposed to less of the same ones all the time. And seeds and beans, the plant's precious resource for future plant generations, have the most concentrated versions.) To add to the problem, post-modern genetically modified wheat and soy have enhanced lectin activity. Lectins are pesticides, after all, and these superwheats and supersoybeans are more resistant to pests and/or Roundup pesticide. This means the wheat we eat today is very different than the wheat we grew up with 30 years ago, and GMO soybean is questioned as a cause in the rise of peanut allergies in children.
Protease inhibitors: Live in beans and seeds and cereals. They keep the gut from breaking down protein entirely. That means if you eat protein + cereal, your absorption of the protein can be diminished.
Phytoestrogens and isoflavones: These are plant-made hormones that can disrupt the endocrine system. They also might be powerful antioxidants, but that isn't entirely clear. Soy is chock-full of them.
Glycoalkaloids: on the skins of potatoes - can be poisonous in large quantities - probably fine in small quantities.
Plant sterols: thought to decrease the absorption of cholesterol, these guys have been added to margarine recently. Seeing as how margarine is not exactly a health food, adding plant sterols to it seems to me like sprinkling lipitor on your pizza. A certain cardiologist blogger makes a convincing argument to steer clear of sterols.
Phytic Acids: Found on all grains, and while you can get rid of these with warm soaking and fermenting, the phytic acids in oats won't reduce that way, as oats have no natural phytases. These bind dietary minerals, such as calcium, magnesium, zinc, iron, you name it. So if you consume the unreduced phytic acids with every meal, a lot of the minerals in your food will go down the toilet. Literally.
The kicker is, humans have been consuming grains for 10,000 years. Over time we developed a million ways to reduce the toxic effects of these grains via various traditional harvesting and cooking techniques. Without these techniques (hand milling, soaking, sprouting, long fermentation times rather than quick-rise yeast) and getting a lot of our calories from wheat (whose giladins and glutens are among the toughest to get rid of), cereals and beans become sources of nutrient depleting, empty calories, and vectors of biochemical mayhem within the body. Take a grain and smash it flat to mix all the phytic acids and lectins together, then puff it and oxidize the seed oils, add sugar and sell it as chocolate puff cereal - we aren't exactly evolved to eat that.
It's not that a little bit will be all that bad (unless, perhaps, you have autoimmune disease, which I will go into later). It's that massive exposure in every meal day in day out... well...
(Information from this post was taken almost entirely from Staffan Lindeberg's Food and Western Disease. In addition, some of the thoughts about genetically modified wheat and soy come from The Unhealthy Truth.)