Grains: The Good, the Bad, & the Ugly

Like any other food, grains can have both beneficial and adverse health effects.  Ongoing studies have demonstrated that certain susceptible populations do much better on a gluten free or grain free diet, while most people are well equipped to tolerate small to moderate amounts of grains as part of a balanced diet.

Humans transition from hunter gatherers to farmers :

            Grains are a relatively new addition to the human diet, which until about 10,000-20,000 years ago consisted of wild meats, fresh fruits and vegetables.   As the planet’s population started to rise around the Pleistocene Era, humans abruptly transitioned from a hunter-gatherer lifestyle to becoming farmers.  Grains have since become a staple food, and the dominant source of both calories and protein (up to 80%) in many developing countries.  It is estimated that “three cereals: wheat, maize and rice together comprise at least 75% of the world’s grain production” (Cordain, 1999, p. 21).

Benefits of Grain Consumption :

When combined with adequate amounts of meat and plant based foods, grains can be a cheap way to boost caloric intake.   In this sense, they have helped tremendously in helping to keep an increasingly overpopulated world fed.  Other benefits of whole grains include their ability to flush the body of excess lipids, which make them a valuable option for anyone trying to prevent cardiovascular disease, high cholesterol, and obesity.  Grains also contain B vitamins (except for B12), trace minerals, and anti-carcinogenic compounds which help protect against certain hormonally-mediated cancers.

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Negative impacts of a grain-heavy diet :

On the other hand, the displacement of nutrient-rich foods with a grain-heavy diet can have a negative impact on health.  The chelating effect of whole grains can flush both undesirable elements AND essential nutrients from the body.  Additionally, a diet too-high in grains is usually deficient in essential nutrients like B12 and iron, and can inhibit the bioavailability of many important nutrients, as demonstrated in the table below (click on table to view in full size).  (Gibson, Perlas, Hotz, 2006, p.161, 162).

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The bioavailability of zinc, copper, iron, calcium and magnesium in cereal grains is also typically low.  For example, zinc from animal sources is 4 times more bioavailable.  It has been suggested that the substitution of heme foods with fiber & phytate rich grains is a large contributing factor to the global iron-deficiency epidemic. Cereal grains’ inherent nutritional imbalances can give rise to conditions like dwarfism (zinc deficiency), bone mineral pathologies (calcium deficiency), iron-deficiency anemia, vitamin B12 & D deficiencies, and Pellagra (niacin and tryptophan deficiency).  In a study by Cohen, examining 51 different populations from around the world; physical stature, life span, and overall quality of life declined with the transition from a hunter-gatherer to an agricultural lifestyle.   A strong piece of supporting evidence that humans were not meant to consume a diet so high in grains is the fact that a plant-based diet alone cannot provide all of the essential nutrients required by humans. Whole grains contain no Vitamin A, no Beta-carotene (with the exception of yellow corn), no Vitamin C, and no Vitamin B12.  Cordain proposes that “The human nutritional requirement for vitamin B12 clearly demonstrates that vegetarian diets based entirely upon cereal grains, legumes and other plant foods were not the sole dietary components which shaped the human genome.” (Cordain, 1999; p. 27).

Susceptible populations :

        Many conditions have been shown to improve with the elimination of grain consumption.  Thus far, only two autoimmune diseases have conclusively been linked directly with wheat consumption; celiac disease, in which the microvilli of the small intestine are destroyed by wheat proteins, and a skin condition called dermatitis herpetiformis.  However, ALL grains contain carbohydrate-binding proteins called lectins, which have the potential to “interact with a variety of other cells in the body” and “represent powerful oral immunogens capable of eliciting specific and high antibody responses” (Cordain, 1999, p. 45).  Simply put, because of their resistance to digestive breakdown, lectins can wind up circulating systemically, causing self-destruction of various body tissues.  Cordain believes that the secondary metabolites developed by cereal grains to ward off predatory herbivores “can be either toxic, anti nutritional, benign, or somewhere in between, dependent upon the physiology of the consumer animal” (Cordain, 1999, p. 42).   Like any other food, grains may be tolerated better by some people as compared to others.  There is still much research to be done in elucidating the relationship of grains to allergies and autoimmune reactions.  However, many people with wide-ranging autoimmune conditions find that eliminating some or all grains from their diets helps to ameliorate their symptoms.

A common link found between autoimmunity and conditions like autism and schizophrenia are genes that code for the human leukocyte antigens (HLA).  Many autistic children experience improvement on a gluten-free diet, and interestingly, research shows that populations who consume little to no gluten-containing grains (rye, wheat, barley) have a lower prevalence of schizophrenia.  Studies have long shown that certain gluten peptides can behave like opioids, and that their effects can be reversed by using an opioid-antagonist drug called naloxone (Cordain, 1999, p. 58).  Some side effects of opioids (ie. heroin, codeine, methadone, morphine) include constipation, sedation/drowsiness, and respiratory depression.  They are usually prescribed to increase pain tolerance.

A variety of neurological conditions respond favorably to a gluten –free, grain-free or low-grain diet.  One of the earliest examples comes from a 1921 report by the Mayo Clinic demonstrating the Ketogenic Diet’s (KD) efficacy in treating a broad range of epileptic conditions. The diet consists of a high fat, adequate protein, and low carbohydrate diet.  KD is now an accepted treatment for epilepsy; strict compliance significantly reduces seizure frequency in up to one-third of patients (Aguirre Castaneda, Mack, Lteif, 2012, p. e512); better results than any one drug or combination of drugs. The KD has also demonstrated neuroprotective activity, and has shown promising results in ameliorating a wide array of neurodegenerative conditions including Alzheimer’s and Parkinson’s disease.  While its mechanism of action is still unknown, the KD’s ability to reduce inflammation has shown great promise in the treatment of a variety of conditions such as diabetes, obesity, and even brain and prostate cancers (Masino & Rho, 2012, p. 15, 16).

The takeaway message here is that the affordability of grains makes them an important supplement/ addition to boost the caloric content of many individuals’ diets worldwide.  Most people seem capable of tolerating a moderate amount of grains, as part of a well-balanced diet.   Although, with food allergy-related conditions on the rise, that issue is currently up for debate. The research does make one thing very clear: some highly susceptible populations are better off consuming a minimal amount of grains or eliminating them from their diets altogether.

REFERENCES

Aguirre Castaneda, R.L., Mack, K.J., Lteif, A. (2012). Successful Treatment of Type 1 Diabetes and Seizures with Combined Ketogenic Diet and Insulin.  Pediatrics, 129; e512. DOI: 10.1542/peds.2011-0741Cordain, L. (1999). Cereal Grains: Humanity’s Double-Edged Sword.  World Rev Nutr Diet. Basel, Karger, 84, p. 21, 22, 23, 27, 33, 42, 45, 58.

Gibson, R.S., Perlas, L., & Hotz, C. (2006).  Improving the bioavailability of nutrients in plant foods at the household level.  Proceedings of the Nutrition Society, 65, 160-161.

Masino, S.A., Rho, J.M. (2012). Jasper’s Mechanisms of the Epilepsies. Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK50785/ .

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