Traditional Preparation Methods Improve Grains' Nutritive Value

Soaking or Germinating Grains

The most basic method of preparing grains is prolonged soaking in water, followed by cooking. This combination reduces the level of water-soluble and heat-sensitive toxins and anti-nutrients such as tannins, saponins, digestive enzyme inhibitors and lectins, as well as flatulence factors. It also partially degrades phytic acid, which is a potent inhibitor of mineral absorption, an inhibitor of the digestive enzyme trypsin and an enemy of dental health (1). This improves the digestibility and nutritional value of grains as well as legumes.

I prefer to soak all grains and legumes for at least 12 hours in a warm location, preferably 24. This includes foods that most people don't soak, such as lentils. Soaking does not reduce phytic acid at all in grains that have been heat-treated, such as oats and kasha (technically not a grain), because they no longer contain the phytic acid-degrading enzyme phytase. Cooking without soaking first also does not have much effect on phytic acid.

The next level of grain preparation is germination. After soaking, rinse the grains twice per day for an additional day or two. This activates the grains' sprouting program and further increases their digestibility and vitamin content. When combined with cooking, it reduces phytic acid, although modestly. Therefore, most of the minerals in sprouted whole grains will continue to be inaccessible. Many raw sprouted grains and legumes are edible, but I wouldn't use them as a staple food because they retain most of their phytic acid as well as some heat-sensitive anti-nutrients (2).

Grinding and Fermenting Grains

Many cultures around the world have independently discovered fermentation as a way to greatly improve the digestibility and nutritive value of grains (3). Typically, grains are soaked, ground, and allowed to sour ferment for times ranging from 12 hours to several days. In some cases, a portion of the bran is removed before or after grinding.

In addition to the reduction in toxins and anti-nutrients afforded by soaking and cooking, grinding and fermentation goes much further. Grinding greatly increases the surface area of the grains and breaks up their cellular structure, releasing enzymes which are important for the transformation to come. Under the right conditions, which are easy to achieve, lactic acid bacteria rapidly acidify the batter. These bacteria are naturally present on grains, but adding a starter makes the process more efficient and reliable.

Due to some quirk of nature, grain phytase is maximally active at a pH of between 4.5 and 5.5, which is mildly acidic. This is why the Weston Price foundation recommends soaking grains in an acidic medium before cooking. The combination of grinding and sour fermentation causes grains to efficiently degrade their own phytic acid (as long as they haven't been heat treated first), making minerals much more available for absorption (4, 5, 6, 7). This transforms whole grains from a poor source of minerals into a good source.

The degree of phytic acid degradation depends on the starting amount of phytase in the grain. Corn, rice, oats and millet don't contain much phytase activity, so they require either a longer fermentation time, or the addition of high-phytase grains to the batter (8). Whole raw buckwheat, wheat, and particularly rye contain a large amount of phytase (9), although I feel wheat is problematic for other reasons.

As fermentation proceeds, bacteria secrete enzymes that begin digesting the protein, starch and other substances in the batter. Fermentation reduces lectin levels substantially, which are reduced further by cooking (10). Lectins are toxins that can interfere with digestion and may be involved in autoimmune disease, an idea championed by Dr. Loren Cordain. Grain lectins are generally heat-sensitive, but one notable exception is the nasty lectin wheat germ agglutinin (WGA). As its name suggests, WGA is found in wheat germ, and thus is mostly absent in white flour. WGA may have been another reason why DART participants who increased their wheat fiber intake had significantly more heart attacks than those who didn't. I don't know if fermentation degrades WGA.

One of the problems with grains is their poor protein quality. Besides containing a fairly low concentration of protein to begin with, they also don't contain a good balance of essential amino acids. This prevents their efficient use by the body, unless a separate source of certain amino acids is eaten along with them. The main limiting amino acid in grains is lysine. Legumes are rich in lysine, which is why cultures around the world pair them with grains. Bacterial fermentation produces lysine, often increasing its concentration by many fold and making grains nearly a "complete protein", i.e. one that contains the ideal balance of essential amino acids as do animal proteins (11, scroll down to see graph). Not very many plant foods can make that claim. Fermentation also increases the concentration of the amino acid methionine and certain vitamins.

Another problem with grain protein is it's poorly digested relative to animal protein. This means that a portion of it escapes digestion, leading to a lower nutritive value and a higher risk of allergy due to undigested protein hanging around in the digestive tract. Fermentation followed by cooking increases the digestibility of grain protein, bringing it nearly to the same level as meat (12, 13, 14, 15). This may relate to the destruction of protease inhibitors (trypsin inhibitors, phytic acid) and the partial pre-digestion of grain proteins by bacteria.

Once you delve into the research on traditional grain preparation methods, you begin to see why grain-eating cultures throughout the world have favored certain techniques. Proper grain processing transforms them from toxic to nutritious, from health-degrading to health-giving. Modern industrial grain processing has largely eschewed these time-honored techniques, replacing them with low-extraction milling, extrusion and quick-rise yeast strains.

Many people will not be willing to go through the trouble of grinding and fermentation to prepare grains. I can sympathize, although if you have the right tools, once you establish a routine it really isn't that much work. It just requires a bit of organization. In fact, it can even be downright convenient. I often keep a bowl of fermented dosa or buckwheat batter in the fridge, ready to make a tasty "pancake" at a moment's notice. In the next post, I'll describe a few recipes from different parts of the world.

Further reading:

How to Eat Grains
A Few Thoughts on Minerals, Milling, Grains and Tubers
Dietary Fiber and Mineral Availability
A New Way to Soak Brown Rice

How to Eat Grains

Our story begins in East Africa in 1935, with two Bantu tribes called the Kikuyu and the Wakamba. Their traditional diets were mostly vegetarian and consisted of sweet potatoes, corn, beans, plantains, millet, sorghum, wild mushrooms and small amounts of dairy, small animals and insects. Their food was agricultural, high in carbohydrate and low in fat.

Dr. Weston Price found them in good health, with well-formed faces and dental arches, and a dental cavity rate of roughly 6% of teeth. Although not as robust or as resistant to tooth decay as their more carnivorous neighbors, the "diseases of civilization" such as cardiovascular disease and obesity were nevertheless rare among them. South African Bantu eating a similar diet have a low prevalence of atherosclerosis, and a measurable but low incidence of death from coronary heart disease, even in old age.

How do we reconcile this with the archaeological data showing a general decline in human health upon the adoption of agriculture? Humans did not evolve to tolerate the toxins, anti-nutrients and large amounts of fiber in grains and legumes. Our digestive system is designed to handle a high-quality omnivorous diet. By high-quality, I mean one that has a high ratio of calories to indigestible material (fiber). Our species is very good at skimming off the highest quality food in nearly any ecological niche. Animals that are accustomed to high-fiber diets, such as cows and gorillas, have much larger, more robust and more fermentative digestive systems.

One factor that reconciles the Bantu data with the archaeological data is that much of the Kikuyu and Wakamba diet came from non-grain sources. Sweet potatoes and plantains are similar to the starchy wild plants our ancestors have been eating for nearly two million years, since the invention of fire (the time frame is debated but I think everyone agrees it's been a long time). Root vegetables and starchy fruit have a higher nutrient bioavailibility than grains and legumes due to their lower content of anti-nutrients and fiber.

The second factor that's often overlooked is food preparation techniques. These tribes did not eat their grains and legumes haphazardly! This is a factor that was overlooked by Dr. Price himself, but has been emphasized by Sally Fallon. Healthy grain-based African cultures typically soaked, ground and fermented their grains before cooking, creating a sour porridge that's nutritionally superior to unfermented grains. The bran was removed from corn and millet during processing, if possible. Legumes were always soaked prior to cooking.

These traditional food processing techniques have a very important effect on grains and legumes that brings them closer in line with the "paleolithic" foods our bodies are designed to digest. They reduce or eliminate toxins such as lectins and tannins, greatly reduce anti-nutrients such as phytic acid and protease inhibitors, and improve vitamin content and amino acid profile. Fermentation is particularly effective in this regard. One has to wonder how long it took the first agriculturalists to discover fermentation, and whether poor food preparation techniques or the exclusion of animal foods could account for their poor health.

I recently discovered a paper that illustrates these principles: "Influence of Germination and Fermentation on Bioaccessibility of Zinc and Iron from Food Grains". It's published by Indian researchers who wanted to study the nutritional qualities of traditional fermented foods. One of the foods they studied was idli, a South Indian steamed "muffin" made from rice and beans. Idlis happen to be one of my favorite foods.

The amount of minerals your digestive system can extract from a food depends in part on the food's phytic acid content. Phytic acid is a molecule that traps certain minerals (iron, zinc, magnesium, calcium), preventing their absorption. Raw grains and legumes contain a lot of it, meaning you can only absorb a fraction of the minerals present in them.

In this study, soaking had a modest effect on the phytic acid content of the grains and legumes examined (although it's generally more effective). Fermentation, on the other hand, completely broke down the phytic acid in the idli batter, resulting in 71% more bioavailable zinc and 277% more bioavailable iron. It's safe to assume that fermentation also increased the bioavailability of magnesium, calcium and other phytic acid-bound minerals.

Fermenting the idli batter also completely eliminated its tannin content. Tannins are a class of molecules found in many plants that are toxins and anti-nutrients. They reduce feed efficiency and growth rate in a variety of species.

Lectins are another toxin that's frequently mentioned in the paleolithic diet community. They are blamed for everything from digestive problems to autoimmune disease, probably with good reason. One of the things people like to overlook in this community is that traditional processing techniques such as soaking, sprouting, fermentation and cooking, greatly reduce or eliminate lectins from grains and legumes. One notable exception is gluten, which survives all but the longest fermentation and is not broken down by cooking.

Soaking, sprouting, fermenting, grinding and cooking are the techniques by which traditional cultures have been making the most of grain and legume-based diets for thousands of years. We ignore these time-honored traditions at our own peril.

Real Food VII: Lentils

Lentils are a healthy food that comes with a few caveats. They have more protein and less carbohydrate than any other legume besides soybeans and peanuts, and they contain a remarkable array of vitamins and minerals, particularly B vitamins. One cup delivers 90% of your RDA of folate, so between lentils and liver there's no need for those sketchy prenatal vitamins.

Lentils must be properly prepared to be digestible and nutritious! I can't emphasize this enough. We did not evolve eating legumes, so we have to take certain steps to be able to digest them adequately. As with all beans and grains, proper soaking is essential to neutralize their naturally occurring toxins and anti-nutrients. Anti-nutrients are substances that interfere with the absorption of nutrients. Soaking activates enzymes in the seeds themselves that degrade these substances. It also cuts down substantially on cooking time and reduces flatulence.

Phytic acid is an anti-nutrient that's abundant in beans, grains and nuts. It can dramatically reduce the absorption of important minerals such as iron, calcium, magnesium and zinc, leading to deficiencies over time. It may be one of the main reasons human stature decreased after the adoption of agriculture, and it probably continues to contribute to short stature and health problems around the world.

Lentils and other seeds also contain trypsin inhibitors. Trypsin is one of the digestive system's main protein-digesting enzymes, and seeds probably inhibit it as a defense against predators. Another class of toxins are the lectins. Certain lectins are able to bind to and damage the digestive tract, and even pass into the circulation and possibly wreak havoc. This is a short list of a few of the toxins found in beans and grains. Fortunately, all of these toxins can be reduced or eliminated by proper soaking. I like to soak all legumes for a full 24 hours, adding warm water halfway through. This increases the activity of the toxin-degrading enzymes.

Here's a method for preparing lentils that I've found to be effective. You will actually save time by doing it this way rather than cooking them without soaking, because they cook so much more quickly:

1. 24 hours before cooking, place dry lentils in a large bowl and cover with 2" of water or more.
2. After 12 hours or so, drain and cover the lentils with very warm water (not hot tap water).
3. Drain and rinse before cooking.
4. To cook, simply cover the soaked lentils with fresh water and boil until tender. I like to add a 2-inch piece of the seaweed kombu to increase mineral content and digestibility.

many thanks to *clarity* for the CC photo

Leptin

I've been puzzled by an interesting question lately. Why is it that certain cultures are able to eat large amounts of carbohydrate and remain healthy, while others suffer from overweight and disease? How do the pre-industrial Kuna and Kitavans maintain their insulin sensitivity while their bodies are being bombarded by an amount of carbohydrate that makes the average American look like a bowling ball?

I read a very interesting post on the Modern Forager yesterday that sent me on a nerd safari through the scientific literature. The paper that inspired the Modern Forager post is a review by Dr. Staffan Lindeberg. In it, he attempts to draw a link between compounds called lectins, found in grains (among other things), and resistance to the hormone leptin. Let's take a step back and go over some background.

One of the most-studied animal models of obesity is called the "Zucker" rat. This rat has a missense mutation in its leptin receptor gene, causing it to be nonfunctional. Leptin is a hormone that signals satiety, or fullness. It's secreted by fat tissue. The more fat tissue an animal has, the more leptin it secretes. Normally, this creates negative feedback that causes it to eat less when fat begins to accumulate, keeping its weight within a narrow range.

Zucker rats secrete leptin just fine, but they lack leptin receptors in their brain. Their blood leptin is high but their brain isn't listening. Thus, the signal to stop eating never gets through and they eat themselves to morbid obesity. Cardiovascular disease and diabetes follow shortly thereafter, unless you remove their visceral fat surgically.

The reason Zucker rats are so interesting is they faithfully reproduce so many features of the disease of civilization in humans. They become obese, hypometabolic, develop insulin resistance, impaired glucose tolerance, dyslipidemia, diabetes, and cardiovascular disease. Basically, severe metabolic syndrome. So here's a rat that shows that leptin resistance can cause something that looks a whole heck of a lot like the disease of civilization in humans.

For this model to be relevant to us, we'd expect that humans with metabolic syndrome should be leptin-resistant. Well what do you know, administering leptin to obese people doesn't cause satiety like it does in thin people. Furthermore, elevated leptin predicts the onset of obesity and metabolic syndrome. It also predicts insulin resistance. Yes, you read that right, leptin resistance may come before insulin resistance.

Interestingly enough, the carbohydrate-loving Kitavans don't get elevated leptin like europeans do, and they don't become overweight, develop insulin dysfunction or the metabolic syndrome either. This all suggests that leptin may be the keystone in the whole disease process, but what accounts for the differences in leptin levels between populations?