Thoughts on the Health Benefits of Whole Grains
Last Updated: May 28/2014.
This is an ongoing investigation. There are many ways to look at grains in the diet. Here are the ways I want to explore in this writing:
1) What are the ways that plants have evolved? This will give us an overview on what molecules they use for themselves, and in what context they appear.
2) How has interaction with humans (agriculture) changed the grains that we eat? Many plants that we consider weeds today were once cultivated; many cultivars would not perform without human intervention
3) How have we evolved, in the context of eating and digesting plants?
4) What specifically does our digestion system do to break down and use the various elements of plants? How do we live symbiotically with yeasts and bacteria that help us digest food?
5) What are the dangers and benefits of every grain?
6) What are the best grains for our sustenance and health?
7) What is the best way to prepare them?
This blog started with my attempts to bake breads with more whole grains in them. Specifically, I intended to work my way through Peter Rienhart's book, 'Whole Grain Breads'. I have said many times in this blog that I feel Reinhart's bread is too sweet, and that I am already sold on whole grains and he doesn't need to add so much sugar and fat for me to like them. However, it would appear that not all people are like me.
Benefits of Whole Grains
Recently I picked up the book 'Whole Grains and Health' (2007) and read of studies that the authors say prove the beneficial effects of whole grains in the diet --
- whole grains reduce the risk of coronary artery disease
- whole grains reduce the incidence of diabetes
- whole grains prevent obesity which leads to other health risk factors (by increasing satiety).
- whole grains have a higher fibre content which appears to be a prophylactic against colon cancer.
The book has an air about it that it is not a true report on what science has found, but rather it seems to be a vehicle for grain producers and their marketing systems. Nutritional panels and dietary guidelines set up by governments in response to these earlier 'scientific' findings have suggested that humans should have somewhere on the order of three servings per day of whole grains to maintain health. But despite this, most humans in the developed world (less than 10% in the U.S. meeting the criteria, over 97% in the U.K. who do not) are nowhere near this amount. And the researchers are not sure why.
But another book that I've recently looked at, 'Food and Western Disease -- health and nutrition from an evolutionary perspective' (2010), suggests that humans are not yet evolved to handle an agricultural diet based on grains and milk, that humans are better equipped to digest a paleolithic diet of fruits, vegetables, nuts, and meat: unlike some other animals, humans are not actually seed and grain eaters. Many of our worst chronic illnesses, these authors maintain, are due to certain properties of the diet we are consuming. It does not help much that we consume whole grains, they say: the best science suggests that we ought not to consume any grain.
So what is the average person supposed to do? Are we to consume more whole grains, or none at all?
An Old Nutritional Study
The last thing I randomly read before nodding off one night not too long ago, was a curious study reported in the journal of nutrition in 1943. A couple of researchers working with dogs learned that some of the canines had difficulty with digestion and motility of food if they were deficient in certain B-complex vitamins, especially pantothenic acid, or B5. In other words, dogs that were deficient in vitamin B5 took longer to digest their meals, and were slower to evacuate following ingestion. From observing this, the researchers made the hypothesis that a similar vitamin deficiency might be behind the human "palling for appetite" for whole grains. They organized a study where extra B5 from a special yeast was baked with the whole wheat bread, and where volunteers were given calcium pantothenate (B5 precursor) prior to whole wheat meals. In comparisons to non-fortified whole wheat flour, and with bread flour, they discovered that a small amount (1 mg) of B5 did help in the digestion of the carbohydrate, but it did not appear to help in the digestion of the protein.
I do not have the expertise to fit this particular older study into the whole gamut of nutritional research that has been done over the years, but I am slightly astonished at this particular study because today we tend to think that whole grains provide a good source of natural B5 on their own, so it seems slightly absurd to supplement it further. Furthermore, it doesn't seem surprising to me to learn that adding calcium pantothenate to the meal would not help digestion of protein because the protein binds the calcium and prevents it from working or being absorbed. I was also astonished to learn that the researchers apparently assumed that whole wheat has slow digestion rates and slow motility, at least in some vitamin-deficient people. Usually today we associate higher bran diets with quicker motility.
But there is something refreshing about this study, that brings to mind what we used to think of as true science: an observation in one arena leads to a hypothesis (perhaps in another arena) which gets tested. Despite the fact that the research was funded by a baking company who probably had a vested interest in the outcome results, the findings are noted, and can be tested or referenced by others in further studies, and the results can help in the later elaboration of a better working hypothesis.
Winning in the Marketplace vs winning for health
I was fascinated that a particular yeast could have such a huge effect on digestion. Unfortunately, the study does not name the yeast used. It is likely no longer available as a commodity. Today, we probably have less choice in the type of yeast we can purchase: the cheapest and most versatile and effective yeast has 'won' in the marketplace, which may not have won for us any health benefits.
The same goes for the type of wheat we have now, since the 1940s. Norman Borlaug developed the shorter wheat varieties that were smut resistant, and ushered in the so-called green revolution. Although he didn't use transgenic methods (which are being tried today), he did use mutagenic techniques to get a strain of wheat that was easy for farmers to grow. But is that wheat the best for our health? The rise in celiac disease and gluten sensitivity might suggest that not all humans can tolerate the new wheat.
It would seem that although I love dense loaves full of whole grains, not everyone loves them like me, and perhaps one reason is that not everyone can digest them.
The Perfect Food
There is no perfect food. When I was a young boy, I remember reading in one place that "honey is the most nearly perfect food," and elsewhere that "milk is the most perfect food." It is enough to have two such conflicting reports to lend suspicion to their claims, even for a youngster. Probably I was reading some propaganda put out by the various marketing boards who were tasked with selling product to consumers.
So although I love whole grain breads, and I believe they are more healthy than their processed alternatives, I am still a bit suspicious of all the health claims. The wheat marketing boards are very powerful, and they have one objective: to get you to consume more wheat.
The fact is, you can't eat just one thing forever and expect to have eternal excellent health, no matter how nearly perfect it is. Even if you eat too much of a good thing, you are going to end up with problems. And in the real world, nothing is a total benefit: there are going to be some drawbacks or imbalances even if you eat a lot of whole grains in your diet.
So, in addition to the supposed or assumed benefits of whole grains listed above (which have had many scientific studies that seem to corroborate them), one runs across some dangers in some studies. I will merely list some of them here, in no particular order.
Possible Dangers of Whole Grains
* Phytates - Plants store their phosphorus in bran and grain hulls, and these phytochemicals can make up to 5-10% of the dry weight of a plant. It chelates or binds to calcium, magnesium, iron, zinc, copper and niacin, making these nutrients less able to be metabolized (in fact, I have seen a study that says more measurable minerals come out than what we can measure go in, meaning that the bran is scooping up more minerals in the bowels that might be there from other foodstuffs and excreting them before they can be metabolized). That is why some call phytate an 'anti-nutrient'. Cooking reduces the effect, as will sprouting, soaking and fermenting (or leavening).
* Lignans - many of these elements that plants use to protect themselves are considered beneficial to humans (e.g. for their antioxidative properties), but some of them may mimic hormones, and the long-term effects of these in the diet are impossible to predict
* Glucose spikes (High Glycemic Index) and Insulinemia- carbohydrates of any kinds cause spikes in blood glucose following a meal, and the body responds by cranking up insulin production (insulinemia is a high level of insulin in the blood), to get the glucose into the cells where it is needed. It is postulated by some that this up-down cycle leads eventually to insulin-resistance (type 2 diabetes). Although whole grains supposedly have a slightly lower glycemic index than processed grains, any grain carb is going to have this effect, and there are better carbs with lower glycemic indexes than grains.
* Serum lipid profile: the amount of fat in the blood, seems to be elevated by grain-fed diets. Doctors are not only interested in Cholesterol, but they also like to measure your triglycerides and other fats in the bloodstream. Low Glycemic Index carbs, unlike grains, even whole grains, will bring down the serum lipid profile.
* C-reactive protein (CRP) is manufactured in the liver as a response to inflammation. People who eat a lot of low glycemic index carbs (that leaves out most grain eaters, even whole grain eaters), will have less CRP in their bloodstream. In other words, it looks like the body is treating something in the grains and other foods that have a high glycemic index as inflammatory and therefore dangerous to the body. But there may be other causes of inflammation. High fat intake, especially trans fats, have also been linked to increased CRP.
* Satiety: There have been a lot of studies that look at satiety (a very subjective element in food): if a whole grain satiates for longer than a refined grain, then some researchers suggest that even if there is increased glucose and insulin, there won't be any long term effects because individuals won't eat again until they are hungry. The cells will use up their stores of glucose before fat can be manufactured. Satiety research studies seem incomplete to me, somehow. They always leave me hungry for more information.
* Acrylomides - when starches are heated, they form this substance which is a known carcinogen. The darker the crust, the darker the toast, the more acrylomide. So roasting whole grains may not be a great idea.
* Lysine - the one essential amino acid not found in significant amounts in grain, lysine is needed for all protein synthesis and many metabolic processes. Lysine and vitamin C supplementation might be necessary for those attempting to increase the amount of whole grains they ingest.
* Tyramine - a molecule that acts like a catecholamine, meaning it will behave like a neurotransmitter releaser; it is in the root of wheat, but generally not found in the wheat berry or flour. However, when fermented with natural yeasts (any sourdough), it does appear in foods that have the amino acid Tyrosine, and it can begin to disrupt the endocrine system. By displacing norepinephrine, for example, it might cause increased heart rate or blood pressure. It has the potential to similarly displace dopamine and epinephrine. Although it apparently doesn't cross the blood-brain barrier, some reports say it is implicated in migraines. Tyramine is metabolized by enzymes (Monoamine oxidase, or MAO) that are found on mitochondria, in other words, in virtually every cell in the body. It might be a problem if there is an overabundance of Tyramine in the diet, however.
*Methionine, another essential amino acid is found in high levels in whole grains; evidence is mounting that restricting its consumption may be beneficial, however. It is converted to homocysteine in the body, and high levels of this is associated with heart and artery disease.
* Urea - if one gets >15% of one's total energy from wheat protein, apparently urea levels climb, resulting in renal hyperfiltration. This might have long-term effects, possibly even renal failure.
* Mineral Loss - Wheat fiber is said to bind Iron, Calcium, Magnesium, Zinc, Sulphur, and Phosphorus, making them ineligible to be metabolized.
* Vitamin Loss - ingestion of wheat may lead to a rapid excreting of certain vitamins, among them Niacin (Vitamin B3), Pantothenic Acid (B5), Riboflavin (B2), Thiamin (B1), and Vitamin B6. These are all water soluble vitamins, which may be flushed from the colon by the gelling effect of the bran. It may, however, increase the reabsorption of Vitamin B12.
* N1-methylnicotinamide is found increased in the blood plasma when there is too much nicotinamide (an amide of niacin/B3, also called vitamin PP, found in wheat germ and yeast), and this is postulated to play a role in the increased insulin resistance seen in type 2 diabetes.
* Cariogenic Nature of whole grains - possibly because they bind calcium leading to its poor uptake, or because of the reduced lysine in whole grain diets, whole grains may contribute to tooth decay.
* Rachitogenic - a diet of only whole grains may lead to rickets, a condition where the bones bend and distort, caused by a deficiency in Vitamin D or parathyroid imbalances.
* Gluten has been associated with celiac disease, and various degrees of intolerance, but it has also been associated with schizophrenia, and autism, and Alzheimers. It would appear that some parts of wheat cross the blood-brain barrier following digestion.
The work of Alessio Fasano with celiac patients has shown that gluten is never wholly cleaved into its amino acids, and so cannot be metabolized as other proteins are; furthermore, some chunks of Gliadin (part of gluten) can land in certain gut cell receptors and cause the release of zonulin, a natural peptide produced by the body to regulate the tight junction between cells. Normally, this causes water to flow into the intestine so that the gluten is washed away, but some gluten will enter the resultant (usually temporary) leaky gut: most people''s immune system can handle this molecule, and excrete it, but celiac patient's immune system goes on to attack the gut's cells. Furthermore, if the immune system cannot handle all of the gluten in a timely manner, it proves toxic to virtually every tissue in the body that it encounters. What is more, the extra zonulin in the body can alter the tight junction of cells elsewhere (for example, the lungs, the nasal passageways, the blood brain barrier...). On the other hand, zonulin is also a precursor for haptoglobin 2, whose purpose is to bind Hb to form stable HP-Hb complexes to prevent Hb-induced oxidative tissue damage. However, it appears that the amount of zonulin in the blood is a pretty good indicator of a lot of chronic autoimmune diseases (like diabetes, and multiple schlerosis), although Fasano himself will point out that unlike celiac disease, no cause and effect environmental or genetic triggers have been found for these diseases, and despite his findings, he himself has not given up gluten, because he loves pizza.
* Fructose and Fructans have been implicated in both fructose malabsorption and fructose intolerance. There may even be problems with fructose metabolism in the liver for everyone. A lot of this research comes on the heels of the over-consumption of liquid corn fructose, which seems to be an additive in a lot of processed foods, and with rising obesity rates, many people wondered if there could be connection. Corn is especially high in fructose, but wheat contains fructans (linear and banching polymers of fructose), and people with fructose malabsorption find benefit from a gluten-free diet (although it is not the gluten that is the culprit, in their case). Symptoms of fructose malabsorption are what you would expect: the fructose remains in the bowel, and the bacteria feast on it and cause abdominal soreness, bloating, gas, fatigue, and eventually even anxiety and depression. Of greater concern for all of us is the way fructose is metabolized in the liver. Obesity specialist Dr. Robert Lustig has presented some interesting information on this (e.g. the video: sugar: the bitter truth). Fructose has been implicated in non-alcoholic fatty liver disease, diabetes, obesity, increased triglycerides, uric acid and more free radicals.
* Vomitoxin, or deoxynivalenol (DON), is the most commonly found trichothecene mycotoxin found in grains that are susceptible to Fusarium head blight (scab), and the fungus responsible is generally ubiquitous in many grains. It remains on cleaning, milling and baking, and is considered an expensive contaminant of grains for human and animal consumption that must be controlled. It is not known to be carcinogenic, teratogenic or mutagenic, but it will bind to the ribosome in cells in the body to inhibit protein synthesis. If ingested in large enough quantities, it can cause anorexia while simultaneously increasing the brain's uptake of the amino acid tryptophan and the synthesis of serotonin.
* Trichothecenes are a chemical class of sequiterpenoid mycotoxins, generally arising as metabolites from fungi in grain, each of which have a core of fused cyclohexene/tetrahydropyran rings (Foroud). The most well-known is DON, but several others have been identified, and they have been placed in six classes based on their chemistry: types A (a class which contains the extremely dangerous T-2 toxin, HT-2 toxin, and others), B (a class which contains the ubiquitous 4-deoxynivalenol (DON), nivalenol (NIV), 3-O-acetyl DON (3-ADON), and 15-O-acetyl DON (15-ADON), type C (represented by crotocin) type D, type E, and type F (represented by verrucarin). Of the 80 trichothecenes discovered so far, only a few are found in grains, in particular: T-2 toxin, diacetoxyscirpenol, deoxynivalenol, nivalenol, and satratoxins. In Canada, the US, South Africa, and England, deoxynivalenol is present in corn, wheat, barley and other cereals; nivalenol has also been found. A German study found also several other types in the bread there. Types D, E and F are rarely found in food, but they can become airborne and cause problems in buildings.
* Triglycerides rise in blood plasma when carbohydrates make up the bulk (>60%) of the entire caloric intake, and this has been linked with atherosclerosis, pancreatic inflammation, diabetes, and cardiac disease. Wheat seems to be the worst offender. Perhaps the reason is the limiting amino acid lysine, which (with Methionine) is turned into Carnitine, which is needed to turn fats into energy for the cells. Carnitine is found in the bran of cereals; but if you are eating a lot of wheat bread that has no bran, you may require a carnitine supplement (in Canada, I am told that carnitine is illegal to sell; you have to be content with making your own, with adequate lysine, methionine, vitamins B6 and C). If your triglycerides are high, consider more Omega-3 fatty acids (flax seed oil, and seaweed, for vegetarians), some carnitine supplementation if it is available to you, and lots of exercise.
* Baker's Asthma is a fairly common allergic reaction to those who are exposed to flour in the air they breathe. The proteins involved in the allergy have been identified, and all come from the prolamin superfamily. In addition to the air-borne allergic reaction, and through the ingestion of it, some allergy sufferers are affected by touching wheat flour (which can cause atopic dermatitis), and rarely exercise-induced anaphylaxis can occur, if someone with a severe allergy exercises following consumption of wheat.
Ambiguous or Untested Parts of Grains which May Need More Study
* Melanoidins are final products of the Maillard reaction, when sugars and amino acids are heated and browned. While we hear much of the negatives regarding some of these flavourful products, there are some benefits too: they may have chemoprotective, antioxidant and antimicrobial properties, as well as the ability to chelate different minerals. In the human gut they can also act as dietary fibre and promote the growth of bifidobacteria. See Morales, F. et. al. (2012, Apr) "Physiological relevance of dietary melanoidins" Amino acids 42:4 pp 1097-109
* Advanced glycation end products (AGEs) are produced in the body in the natural aging process, but they can be ingested from food which is heated. Many of the final products of the Maillard reaction will produce AGEs, which are widely considered proinflammatory. However, they may also contain some beneficial antioxidants.
* Hydroxymethylfurfural (HMF) is part of the Maillard reaction, or browning indicators, in bread, caused by the dehydration of sugars. It is found in both crumb and crust, in levels that range widely (0.9-1.76mg/kg of bread), and it will increase in bread that is stale. The concern from eating it is that once metabolized, it can potentially leave residues of 5-sulfooxymethylfurfural (SMF), which is reactive, binds to DNA and becomes mutagenic.
* 2,5-diketopiperazines or DKPs (also known as cis-cyclic dipeptides) are small cyclopeptides (2 amino acids have a peptide bond) that are easily absorbed through the digestive tract. These peptides are most commonly found as natural products (it is in wheat, so it is in bread, but it found especially in sourdough bread) and have been shown to have antimicrobial, antitumoral, antifungal, antiviral, cytotoxic, and neuroprotective effects. Obviously much more study needs to be done, but some of them also seem to bind to some micro-opiod receptors. If by cytotoxic the researchers mean antineoplastic, that's good, but if they also destroy cells that we need, that's bad. There are more in an acid environment (hence the sourdough connection), and there is more in the crust than in the crumb, because heat will increase the synthesis of the bonds. Pharmaceutical industry is interested in DKPs for drug delivery mechanisms. So what do the natural products do when they bond to our lipid lined cells?
*Arabinoxylan - generally considered a beneficial antioxidant and immunoaugmentative, this indigestible polysaccharide found in the bran or hull wall of whole grains, may have a laxative effect, or cause fermenting and gelling in the lower bowel. Natural source arabinoxylan from grain shouldn't be a problem unless your colon is already compromised.
*Alkylresorcinols are lipids found in wheat and rye bran, and they may prevent cancer genesis. It was once thought that they were an anti-nutrient, but it seems they may increase levels of vitamin E. They are of interest to whole grain marketers because they are plasma markers of who is really eating whole grains. Yes, there are marketers and government agents in our midst, spying on what we eat and trying to get us to consume more whole wheat. Like drug testing, you can't hide from them. It is no joke.
* Betaine (so named because it was first found in beets) is a commonly appearing part of grains. It acts as a methyl donor (like some vitamins), and may reduce homocysteine, an amino acid that has been associated with heart disease, as well as protecting the liver and kidneys.
* Serine is an amino acid considered non-essential because it can be synthesized in the body from other ingested elements. It still is important in many metabolic and enzymatic pathways. Serine plasma levels have been shown to be elevated following a high grain diet. Despite its necessary role, its side-chain can be glycosylated and in that form may be implicated in diabetes. It is also found to be an agonist in the N-methyl-D-aspartate (NMDA) receptor, which mediates fast synaptic transmissions in the central nervous system -- in other words, it has a roll in memory and learning. But some suggest that too much activation may lead to neuron damage as occurs in stroke, Alzheimer's and Huntington's.
* Wheat dextrin is a water-soluble dietary fiber, almost as potent as psyllium husk (the ingredient in Metamucil) that regulates the GI tract. It binds water to it, forming a thick gel, and will flush out your colon. It will also have a moderating effect on the absorption of glucose.
* Selenium is one of the trace minerals that has been found in whole wheat, and concerns were once raised that abnormally high selenium levels were found in some wheat that was grown with selenium-rich soils, or when grown with pesticides that contained selenium. Many feel that the trace mineral is important as an anti-cancer preventative and to clear mercury from the body, but high doses may be toxic and cause skin, hair and teeth problems, as well as being teratogenic. On the other hand, deficiencies in the trace mineral have been linked to both cardiac trouble and cancer. There is an optimal amount to take, but how much is not entirely clear. Since different soils contain differing levels of selenium, it will be very difficult to tell how much each person is ingesting, and whether supplementation is needed or not.
* Reductones are compounds with an enediol structure next to a carbonyl-group, which may be entirely or almost entirely formed during the Maillard reaction (i.e. in the crusts of bread). They are fairly acidic, and act as antioxidants.
* Octacosanol is an alcohol found in wheat germ oil, and contains vitamin E, postulated to increase exercise endurance and improve muscle strength. However, many store-bought whole wheat flours will have rancid oils, and the benefits may not be applicable.
* Phytosterols are steroid alcohols found in the oils of many plants in small amounts. Some believe that it may help reduce the risk of heart disease, and others believe that it may cause atherosclerosis, infarcts, and aortic valve stenosis. Cholesterol is very similar in molecular structure to some phytosterols; this has lead some to presume it has a levelling effect, while others claim that it adds to the harm cholesterol might do.
* Phytoestrogens are hormone-like substances that may interfere with the reproductive system of the predators of plants (humans), a complex defence-mechanism that may cause sterility. They are endocrine disruptors; but some are suggested to have an antioxidative effect.
* Lectins are proteins produced by plants that specifically select other proteins and carbohydrates. Since they bind to certain sugars (they contain sugar residues), they are glycated (or glycosylated). They are ubiquitous in both the plant and animal kingdoms for selection of molecules. They bind to certain receptors in the animals that ingest them. Cooking sometimes destroys them, but not always. They may interfere with intestinal metabolism, causing mucous, diarrhea or bloating, and even binding with part of the the body's own villi. Some may be beneficial, for example binding to pathogens and so complementing the human immune system. Resistant to enzyme breakdown, they can penetrate the intestine and become deposited in the internal organs. They have a potential to cause many negative effects, including atherosclerosis, insulin resistance, cancer and autoimmunity, especially if consumed in high quantities, and from single sources.
* Glycosides are converted to cyanide, and then thiocyanate, which is a potentially goitrogenic substance that may increase the need for iodine and may cause goitre even if dietary iodine intake is high.
* Protease inhibitors are substances in beans and seeds, which inhibit protein- degrading enzymes in the digestive tract such as trypsin, chymotrypsin and amylase. This very ancient defence mechanism of plants allows their seeds to pass through the entire gastrointestinal system (mouth–oesophagus–stomach–gut) undamaged, thereby surviving excretion and later to grow in the ground. The concentration of protease inhibitors in beans and cereals is so high that the digestion of dietary proteins (including other than those in the seed) can be substantially reduced
* Glutamic Acid is found in abundance in wheat gluten (25%) and other whole grains, and MSG can be made from it. Some people seem to be sensitive to MSG and some have linked it to asthma.
* Histidine can be synthesized by human adults (not infants), and after a whole grain diet is instituted, an increase in plasma histidine is noted. For some people with a deficiency in the enzyme histidase, this may cause hyperactivity, speech impediment, developmental delay, learning difficulties, and even mental retardation.
* Butyrate (or Butyric Acid, or Butanoic Acid) is a weak short-chain fatty acid that some colonic bacteria create from fermenting fiber residues (like resistant starch, bran and pectin) and other colonocytes consume. It is said to inhibit colonic tumour cells and promote healthy epithelial cells in the colon, but precisely how is not understood.
* Alpha-aminobutyric acid (AABA) is found to be decreased following regular whole grain ingestion. This carboxylic acid, with an amino group attached in one of three isomers (alpha, beta, gamma) that are manufactured by plants to protect themselves from pathogens (the more famous and more widely studied isomer is GABA, found in the central nervous system as a neurotransmitter). The clinical significance of the AABA depletion is unknown, but there have been studies that suggest the ratio of AABA to the amino acid Leucine in plasma may be a diagnostic marker for some metabolic disorders, among them liver injury, Reye's syndrome, homocystinuria, and hyperglycaemia.
* Phenolic Acids are considered beneficial anti-oxidants. These acids are present in wheat bran in a bound form, but they can be hydrolyzed for metabolism. Ferulic, sinapic, vanillin, coumaric and syringic acids are the most common phenolic acids in wheat, but hydroxybenzoic, chlorogenic, gentisic, and caffeic acids have also been found, depending on the soil the wheat was grown in. Milling strongly effects their presence or absence, and their availability for metabolism depends largely on whether they have been freed for use via hydrolysis; many remain insoluble bound.
* Polyphenols of several classes appear in grains, and little yet is known about them or how they work together. They can be categorized into hydrolyzable tannins, phenylpropanoids (lignins, flavonoids), and condensed tannins; there are thousands of flavonoids alone, and these are subclassed as flavonols, flavones, flavanones, isoflavones, catechins, anthocyanidins and chalcones. Despite their promise, certain polyphenols are known carcinogens, some interfere with thyroid hormones (isoflavones are one example of a polyphenol that has an estrogen-like effect, which may be either beneficial or detrimental) and some polyphenols inhibit iron absorption. On the other hand, some studies call them micronutrients and say some are preventative of cancer and cardiovascular diseases. (Polyphenol oxidase, or PPO) is the cause of undesirable brown discolouration of processed wheat products (e.g. noodles). It is concentrated in the bran, and is one of the reason why mills like to remove as much bran as possible. Even in white flours, some PPO remains. Many food industries have used detergents to remove them.
* Ferulates are found in lignin as part of a plant's wall (in many different forms) and it is one of the antioxidant phenols bound in bran that is thought to have benefits in the fight against cancer.
* Linoleic Acid (LA) is one of the Omega-6 fats needed by the body, but which recent nutritional studies suggest we are consuming far too much of. It competes with the Omega-3 fats that we also need, but that which we get not enough of. LA is in most foods we eat; we only need somewhere on the level of 2200-6600 mg/day for optimal health, and just 2 slices of whole wheat bread will give you 500 mg. Flax seed has some short-chain Omega-3 fats, and adding this to the bread might help balance the fats you ingest via bread. There is some discussion whether flax seeds pass through the human gut untouched, so no benefit is derived. Flax meal is better, but it has to be fresh; soaking the seeds might also help in their digestion. Flax seed does not provide the long-chain Omega-3's (EPA and DHA), like those found in fish oil or some algae and seaweed. There is some discussion over whether the body can manufacture the necessary long-chain Omega-3's from the short-chain fats. It may be able to, if it has enough magnesium, zinc, Vitamin B-6, and vitamin C. Vegetarians can take some algae supplements for DHA, which the body can convert to EPA. Some lactobacillus microorganisms (like those that help make sourdough bread) live in the gut and can manufacture Omega-3 fats for us (another reason why sourdough is overall a good choice in breads).
- Flax may have its own separate problems. For example, studies have shown that chickens fed flax to increase the Omega-3 content of their yolk will have slower growth, and smaller livers, due to the usual problems of mucilage and phytic acid and trypsin inhibitors that other grains have to varying degree. In addition, flax contains linatine, a flax-specific toxin, that inhibits Vitamin B6 (Pyridoxine) and proteolytic enzymes, making some minerals unavailable. Pigs fed flax also achieve less weight. While lower weight might be a laudable goal for humans (as opposed to animals who are bred for slaughter), it ought not to come at the expense of Vitamin and mineral deficiency.
- Urethane (Ethyl Carbamate) occurs naturally in food produced by fermentation, including bread. It may be increased in products fermented with yeast that was nourished with urea, but it is likely present in most bread at levels of 10 ppb.
- Ochratoxin A is a mycotoxin contaminant found growing on many food products, including barley and wheat grains. Another mycotoxin found on wheat is sterigmatocysin.
- Inorganic metals and organic contaminants (such as polycyclic aromatic hydrocarbons (PAHs) or benzo(a) pyrene are taken up by plants grown on soil that is contaminated due to its nearness to industrial centres or highways. It will concentrate in the oil of the plant. A scary book to read is Duff Wilson's 'Fateful Harvest: The True Story of a Small Town, a Global Industry, and a Toxic Secret', which suggests that many industrial wastes, including heavy metals, are entering the soil due to unscrupulous and unregulated fertilizer practices.
- Benzaldehyde is tumour-causing in mice. It is found in many foods, including bread (5-10 ppm).
- Furfural is a carcinogen, found in bread made with wheat (1-14 ppm). It is a monocyclic aromatic hydrocarbon that contains oxygen, an aldehyde that is part of bran. Sometimes you'll see it referred to as Furan. It can also be found in fruit and vegetable juices and nutrition drinks, in small amounts.
- Fiber is usually considered an anti-carcinogen, but there have been studies which suggest this is inconclusive, and even the odd study that suggests it is carcinogenic. In any case, 'fiber' is an aggregate of various materials that contain carbohydrates, some of them indigestible by humans (although some flora that inhabit the human gut may digest parts of them and release beneficial substances to humans). Elements of fiber include cellulose, hemicellulose, pectin, and lignin, and they are often categorized by whether or not they are soluble in water. More study of this area needs to be done.
- Aflotoxins are ubiquitous mycotoxins, considered to be carcinogenic and mutagenic, very bad for the liver. They come from species of Aspergillus, and Aspergillus fungus can get on grain at harvest or during storage. But the spores are everywhere and there doesn't seem to be much anyone can do about it, except try to avoid what becomes obviously mouldy. Levels of contamination have been set by regulatory agencies, but bad outbreaks still occasionally occur. It should be noted that some species of Aspergillus are beneficial, for example the ones that ferment soy to make Miso.
- Citrinin is a mycotoxin found in many cereals (maize, wheat, barley, rice) that has been found genotoxic and carcinogenic in animals
Fumonisins are contaminants of corn and other grains affected by Fusarium
- On the other hand, wheat germ contains two Quinones (2-MBQ and 2,6-DMBQ) in the form of glucoside. When yeast ferments wheat germ, glucosidase releases the quinones, and these have been shown to be anti-carcinogenic -- in particular, it prevents and inhibits colon cancer (in both animal and human studies).
* Exorphins: don't forget the exorphins! They may be in tiny amounts, but what does it do to our nervous system? These morphine-like compounds are narcotizing, addictive, numbing, and potentially hallucinating (although surely there are in such small amounts in bread, their actual effect must be miniscule).
Obviously, I have just scratched the surface of these topics. Just as obviously, the subject is extremely complex, and science itself has just begun to scratch the surface of what goes on in our digestion of whole grains. I guess I have a suspicious nature, and the science does not always convince me. We tend to see what we are looking for and conveniently fail to see what we are not expecting, especially if it doesn't always fit in with our assumptions.
Somewhere along the line, we have to decide what we are going to eat. I think that it should be a variety of foods. I think that whole foods are going to be best -- but I don't know this, and I would not say that it will be true for everybody.
What we each need, I think, is a way to measure what works for us.