Phytates and lectins.
And I'm not the only one thinking it. ;-)
( I apologize for the failed formatting for the tables... it evidently isn't compatible with SP word processing) www.westonaprice.org/food-features/living-
Living With Phytic Acid
Phytic acid in grains, nuts, seeds and beans represents a serious problem in our diets… we eat a lot of high-phytate foods like commercial whole wheat bread and all-bran breakfast cereals.
Phytic acid is the principal storage form of phosphorus in many plant tissues, especially the bran portion of grains and other seeds. It contains the mineral phosphorus tightly bound in a snowflake-like molecule. In humans and animals with one stomach, the phosphorus is not readily bioavailable. In addition to blocking phosphorus availability, the “arms” of the phytic acid molecule readily bind with other minerals, such as calcium, magnesium, iron and zinc, making them unavailable as well. In this form, the compound is referred to as phytate.
Phytic acid not only grabs on to or chelates important minerals, but also inhibits enzymes that we need to digest our food, including pepsin, needed for the breakdown of proteins in the stomach, and amylase, needed for the breakdown of starch into sugar. Trypsin, needed for protein digestion in the small intestine, is also inhibited by phytates.
I have witnessed the powerful anti-nutritional effects of a diet high in phytate-rich grains on my family members, with many health problems as a result, including tooth decay, nutrient deficiencies, lack of appetite, and digestive problems.
Phytic acid is present in beans, seeds, nuts, grains—especially in the bran or outer hull; phytates are also found in tubers, and trace amounts occur in certain fruits and vegetables like berries and green beans. Up to 80 percent of the phosphorus—a vital mineral for bones and health—present in grains is locked into an unusable form as phytate. When a diet including more than small amounts of phytate is consumed, the body will bind calcium to phytic acid and form insoluble phytate complexes. The net result is you lose calcium, and don’t absorb phosphorus. Further, research suggests that we will absorb approximately 20 percent more zinc and 60 percent magnesium from our food when phytate is absent.
Seeds and bran are the highest sources of phytates, containing as much as two to five times more phytate than even some varieties of soybeans, which we know are highly indigestible unless fermented for long periods.
The chart below shows the variability of phytate levels in various common foods as a percentage of dry weight. Phytate levels in terms of milligrams per hundred grams are shown in the next chart.
High-phytate diets result in mineral deficiencies.
The zinc- and iron-blocking effects of phytic acid can be just as serious as the calcium-blocking effects.
Nuts have a marked inhibitory action on the absorption of iron due to their phytic acid content.
Over the long term, when the diet lacks minerals or contains high levels of phytates or both, the metabolism goes down, and the body goes into mineral-starvation mode. The body then sets itself up to use as little of these minerals as possible.
THE EXPERIMENTS OF EDWARD MELLANBY
As early as 1949, the researcher Edward Mellanby demonstrated the demineralizing effects of phytic acid. Mellanby discovered that consumption of high-phytate cereal grain interferes with bone growth and interrupts vitamin D metabolism. His studies showed that excessive phytate consumption uses up vitamin D.
Interestingly, his experiments showed that unbleached flour and white rice were less anti-calcifying than whole grains that contain more minerals but also were higher in phytic acid. Other experiments have shown that while whole grains contain more minerals, in the end equal or lower amounts of minerals are absorbed compared to polished rice and white flour. This outcome is primarily a result of the blocking mechanism of phytic acid, but may be secondarily the result of other anti-nutrients in grains.
Phytase is the enzyme that neutralizes phytic acid and liberates the phosphorus. This enzyme co-exists in plant foods that contain phytic acid.
Ruminant animals such as cows, sheep and goats have no trouble with phytic acid because phytase is produced by rumen microorganisms; monogastric animals also produce phytase, although far less. Mice produce thirty times more phytase than humans, so they can be quite happy eating a raw whole grain. Data from experiments on phytic acid using mice and other rodents cannot be applied to humans.
In general, humans do not produce enough phytase to safely consume large quantities of high-phytate foods on a regular basis. However, probiotic lactobacilli, and other species of the endogenous digestive microflora can produce phytase. Thus, humans who have good intestinal flora will have an easier time with foods containing phytic acid.
Phytase is destroyed by steam heat at about 176 degrees Fahrenheit in ten minutes or less. In a wet solution, phytase is destroyed at 131-149 degrees Fahrenheit.31 Thus heat processing, as in extrusion, will completely destroy phytase—think of extruded all-bran cereal, very high in phytic acid and all of its phytase destroyed by processing. Extruded cereals made of bran and whole grains are a recipe for digestive problems and mineral deficiencies.
THE PHYTATE THRESHOLD
For best health, phytates should be lowered as much as possible, ideally to 25 milligrams or less per 100 grams or to about .03 percent of the phytate-containing food eaten. At this level, micronutrient losses are minimized. (For phytate content of common foods as a percentage of dry weight, see below.)
White rice and white bread are low-phytate foods because their bran and germ have been removed; of course, they are also devitalized and empty of vitamins and minerals.
PHYTIC ACID AND YOU
The purpose of this article is not to make you afraid of foods containing phytic acid, only to urge caution in including grains, nuts, and legumes into your diet. It is not necessary to completely eliminate phytic acid from the diet, only to keep it to acceptable levels.
An excess of 800 mg phytic acid per day is probably not a good idea. The average phytate intake in the U.S. and the U.K. ranges between 631 and 746 mg per day.
In practical terms, this means properly preparing phytate-rich foods to reduce at least a portion of the phytate content, and restricting their consumption to two or three servings per day. Daily consumption of one or two slices of genuine sourdough bread, a handful of nuts, and one serving of properly prepared oatmeal, pancakes, brown rice, or beans should not pose any problems in the context of a nutrient-dense diet. Problems arise when whole grains and beans become the major dietary sources of calories— when every meal contains more than one whole grain product or when over-reliance is placed on nuts or legumes.
Unfermented soy products, extruded whole grain cereals, rice cakes, baked granola, raw muesli and other high-phytate foods should be strictly avoided.
In general, nuts contain levels of phytic acid equal to or higher than those of grains. Therefore those consuming peanut butter, nut butters, or nut flours will take in phytate levels similar to those in unsoaked grains.
It is best to avoid nut butters unless they have been made with soaked nuts—these are now available commercially. Likewise, it is best not to use nut flours—and also coconut flour—for cooking unless they have been soured by the soaking process.
FOOD SOURCES OF PHYTIC ACID
As a percentage of dry weight
FOOD MINIMUM MAXIMUM
Sesame seed flour 5.36 5.36
Brazil nuts 1.97 6.34
Almonds 1.35 3.22
Tofu 1.46 2.90
Linseed 2.15 2.78
Oat meal 0.89 2.40
Beans, pinto 2.38 2.38
Soy protein conc. 1.24 2.17
Soybeans 1.00 2.22
Corn 0.75 2.22
Peanuts 1.05 1.76
Wheat flour 0.25 1.37
Wheat 0.39 1.35
Soy beverage 1.24 1.24
Oats 0.42 1.16
Wheat germ 0.08 1.14
Whole wheat bread 0.43 1.05
Brown rice 0.84 0.99
Polished rice 0.14 0.60
Chickpeas 0.56 0.56
Lentils 0.44 0.50
PHYTIC ACID LEVELS
In milligrams per 100 grams of dry weight
Brazil nuts 1719
Cocoa powder 1684-1796
Brown rice 12509
Oat flakes 1174
Almond 1138 - 1400
Peanut, roasted 952
Peanut, ungerminated 821
Peanut germinated 610
Hazelnuts 648 – 1000
Wild rice flour 634 – 752.5
Yam meal 637
Refried beans 622
Corn tortillas 448
Entire coconut meat 270
White flour 258
White flour tortillas 123
Polished rice 11.5 - 66
PHYTATES: A BENEFICIAL ROLE?
As evidence of the detrimental effects of phytates accumulates, reports on alleged beneficial effects have also emerged. In fact, a whole book, Food Phytates, published in 2001 by CRC press, attempts to build a case for “phytates’ potential ability to lower blood glucose, reduce cholesterol and triacylglycerols, and reduce the risks of cancer and heart disease.”
One argument for the beneficial effects of phytates is based on the premise that they act as anti-oxidants in the body. But recent studies indicate that an overabundance of anti-oxidants is not necessarily a good thing as these compounds will inhibit the vital process of oxidation, not only in our cells but also in the process of digestion.
Another theory holds that phytates bind to extra iron or toxic minerals and remove them from the body, thus acting as chelators and promoting detoxification. As with all anti-nutrients, phytates may play a therapeutic role in certain cases.
Phytates represent just one of many anti-nutrients in grains, nuts, tubers, seeds, and beans. These include oxalates, tannins, trypsin inhibitors, enzyme inhibitors, lectins (hemagglutinins), protease inhibitors, gluten, alpha-amylase inhibitors, and alkylresorcinols.
Anti-nutrients exist in these plant foods because they are part of the process of life. The natural world requires them in order to perform many important tasks, including protection against insects, maintaining freshness of seeds for germination, and protection against mold and fungus.
As Percentage of Dry Weight
Sesame seeds, dehulled 5.36
100% Wheat bran cereal 3.29
Soy beans 1.00 - 2.22
Pinto beans 0.60 - 2.38
Navy beans 0.74 - 1.78
Parboiled brown rice 1.60
Peanuts 1.05 - 1.76
Coconut meal 1.17
Whole corn 1.05
Wheat flour 0.96
Brown rice 0.84 - 0.94
Chickpeas 0.28 - 1.26
Lentils 0.27 - 1.05
Milled (white) rice 0.2
NUTRIENTS IN GRAINS AND OTHER FOODS
In milligrams per 100 grams.
Calcium Phosphorus Iron Calories
Whole grain wheat flour 34 346 3.9 339
Unenriched white flour 15 108 1.2 364
White rice 9 108 0.4 366
Milled rice 10-30 80-150 0.2-2.8 349-373
Brown rice 10-50 170-430 0.2-5.2 363-385
Milk 169 117 0.1 97
Free range buffalo steak 4 246 3.8 146
Cheese, mozarella 505 354 0.4 300
UPDATE ON PHYTIC ACID
Phytates become a problem when grains make up a large portion of the diet, and calcium, vitamin C and fat-soluble vitamins, specifically fat-soluble vitamin D, are low. Vitamin C reduces the iron and perhaps other mineral losses from phytic acid. Vitamin D can mitigate the harmful effects of phytates. Calcium (think raw milk, raw cheese, yogurt, and kefir) balances out the negative effects of phytates.
PHYTIC ACID IN POTAOES, YAMS, AND SWEET POTATOES
White potatoes have 0.111-0.269 percent of dry weight of phytic acid, a level approximately equivalent to the amount in white rice. Cooking does not significantly remove phytates in potatoes, but consumption of potatoes with plenty of butter or other animal fat in the context of a nutrient dense diet should be enough to mitigate the effects of phytate. Yams contain an amount of phytate equal to or less than that in white potatoes, and sweet potatoes contain no phytate at all.
PREPARATION OF BEANS
If beans are a staple of your diet, extra care is needed in their preparation, including soaking for twenty-four hours (changing the soaking water at least once) and very long cooking. In general, soaking beans and then cooking removes about 50 percent of phytic acid. One report with peas and lentils shows that close to 80 percent of phytic acid can be removed by soaking and boiling. Boiling beans that haven’t been soaked may remove much less phytic acid.
PREPARATION OF NUTS
We still do not have adequate information on nut preparation to say with any certainty how much phytic acid is reduced by various preparation techniques. Soaking in salt water and then dehydrating to make “crispy nuts” makes the nuts more digestible and less likely to cause intestinal discomfort, but we don’t know whether this process significantly reduces phytic acid, although it is likely to reduce at least a portion of the phytic acid.
Roasting probably removes a significant portion of phytic acid. Roasting removes 32-68 percent of phytic acid in chick peas and roasting grains removes about 40 percent of phytic acid. Germinated peanuts have 25 percent less phytic acid than ungerminated peanuts. The real problem with nuts comes when they are consumed in large amounts, such as almond flour as a replacement for grains in the GAPS diet. For example, an almond flour muffin contains almost seven hundred milligrams of phytic acid, so consumption should be limited to one per day. Eating peanut butter every day would also be problematic. www.paleoplan.com/2011/03-30/why-no-grains
What Are Lectins?
Lectins are proteins found in animals (including you) and plants – they’re everywhere, especially in grains, legumes (especially soy), nuts, and seeds
Wheat contains a lectin called wheat germ agglutinin, or WGA. Lectins are sticky little buggers and the WGA goes into your small intestine and gloms onto the brush border. It then tricks your body into taking it across the border of your intestine intact, where it is seen as a foreign invader by your immune system. Antibodies are created in response to the lectins, and unfortunately, lectins often look a lot like other parts of your body. They may look like cells in your brain, pancreas, etc., so the same antibodies that were created to attack the lectin will actually go launch attacks on your own body. This is where autoimmune issues arise, like diabetes type 1, celiac disease, lupus, and multiple sclerosis.
To make things worse, on their way into your body, lectins damage the walls of your intestines, helping to create “leaky gut”, so that other large particles can cross the intestinal barrier, enter your bloodstream and begin other immune cascades. This is basically how food sensitivities start. Something goes in (like the WGA) and makes some holes in your gut that lets big particles of food into your blood stream. Then your immune system gets VERY overwhelmed and confused and starts attacking things at random – gluten, blueberries, asparagus, olive oil, etc
Should you not eat nuts and seeds?
I think the reason that nuts and seeds are allowed on the diet but not grains and legumes is that grains and legumes contain a whole host of other “anti-nutrients” beyond just lectins.
Edited by: EXOTEC at: 9/10/2013 (22:14)
...the problem with people these days is
they've forgotten we're really just animals ...
We did not create the web of life; we are but a strand in it.
We don't have souls. We ARE souls. We have bodies.
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