Lately I have noticed a ton of bad press for gluten in the fitness community but what is it and why do people say you should avoid it?
Gluten is a protein found in wheat and similar grains such as rye and barley. Gluten gives grain products their elasticity and their chewy texture. As such they are found in higher proportions in whole grain products.
Gluten is found in many grains including:
Celiac Disease and Gluten Sensitivity
Celiac disease is a serious autoimmune disease where the consumption of gluten containing products causes a reaction which can lead to abdominal discomfort, diarrhoea, and pain as well as malabsorption of nutrients, poor growth rate and an increased risk of early death. The only treatment for celiac disease is a gluten free diet. It is estimated that less than 1% of people worldwide have this condition although increased screening for celiac disease has seen a rise in those being diagnosed.
We will focus in this article on the rising rate and self-diagnosis of gluten sensitivity which can be defined as an intolerance to gluten which can lead to symptoms such as bloating, pain, lethargy and joint pain. The symptoms of gluten sensitivity overlap with those seen in celiac disease, but if clinical tests fail to meet the standard for diagnosing celiac disease then gluten sensitivity remains a possible diagnosis. Gluten sensitivity is estimated to affect around 6% of the population in the USA
What causes gluten related side effects?
A healthy intestinal tract will absorb food and allow for optimal uptake of nutrients such as proteins to the body. In patients with celiac disease or gluten intolerance, their gastrointestinal problems are related to the fact that gluten, being indigestible to them, can lead to an inflammatory reaction which causes the intestinal villi to be damaged which, over time, can lead to the undigested proteins crossing directly thought the wall and entering the bloodstream where it will induce a rapid immune system response to try to combat this.
How do I know if I am gluten intolerant?
Taking a blood draw and stool analysis test and testing for the presence of specific antibodies is the only reliable measure but if you experience symptoms such as the below after ingestion of gluten products but not otherwise, then you may be at risk of being gluten sensitive.
Bloating and gas
Slow growth rates especially in children not diagnosed yet Attention Deficit Disorder Autism
If you present with these then certainly it is a good idea to try removing gluten from the diet for a few weeks but what about if no symptoms such as these present themselves? This is where we get on to tricky ground.
The Anti-Gluten Bandwagon
Major figures in the fitness world have recently railed against the use of gluten arguing it can cause issues for virtually everyone and recommending everyone avoids their intake regardless of whether they present with the symptoms outlined previously. Gluten has been accused of everything from raising cortisol and insulin, and predisposing the body to fat gain to causing accelerated ageing and causing decreased thyroid function. This comes from people in the mainstream such as Charles Poliquin and Timothy Ferris who many of you will know. It is these claims which we will examine now. Charles Poliquin lists the following reasons for why you would want to avoid gluten:
1. Gluten inflames the brain.
2. The glutamate content in gluten kills brain cells.
3. Gluten has been linked to autism.
4. Gluten is associated with osteoarthritis.
5. Gluten can induce depression.
6. Gluten will ramp down your thyroid.
7. Gluten aggravates menopausal symptoms.
8. Gluten is associated with accelerated aging.
9. Gluten exacerbates the symptoms of autoimmune diseases.
10. Gluten weakens tooth enamel and leads to cavities.
11. Gluten negatively affects body composition.
Gluten damages the brain/Linked to Autism
Among celiac sufferers it is noted that they are more likely to have declining brain function over time. Some hypothesise that gluten by itself will cause these issues for everyone. An interesting case study (1) among autistic children attempted to measure if autistic children could benefit from a Gluten and Casein free diet (GFCF). This is recommended quite frequently by many. The results that came back showed no benefits for sleep, attention or bowel function. The researchers only selected children who did not have any gastrointestinal issues so the results may well have differed for those with GI issues. While there is an association between poor GI/gluten intolerance and autism this is irrelevant for people who have not got autism. It certainly does not mean that those who ingest gluten can become autistic!
Studies in the field demonstrate that neurological impairment from ingestion of glutens can occur without the commonly noted GI symptoms associated with gluten sensitivity (2) and that the prevalence of gluten related antibodies such as IgG, IgA or both is much higher in those with neurological dysfunction (3).
The argument that gluten weakens brain function is based on research such as this where specific antibody testing is used to detect gluten sensitivity even where there may be no GI symptoms present. While the case for avoiding glutens in this case is warranted there is no evidence on glutens causing diminished brain function in those without gluten sensitivity.
Gluten and body composition
It is impossible for anyone to gain fat unless they are in a caloric surplus. That is a basic fact, so the idea grains can cause fat gain via some other process is false. It also assumes that in a normal, mixed diet comprising different foods that it is the grains which cause the fat gain and not the meats, nuts, oils etc you may be consuming. Again, this is not correct. A review of grain consumption by Giacco (4) et.al showed that higher grain intake was associated with a lower BMI over lower intakes. The same study also showed the GI of the grain (whole grain versus refined) made no difference to this. Going further, a recent study (5) comparing low carb and high carb diets showed no difference in outcome for body composition. Finally, if we observe those who consume the highest proportion of grains such as vegetarians and look at people in places like Asia who historically have eaten a high proportion of grains we see that they tend to weigh less than those who eat less grains.
Gluten is associated with osteoarthritis.
Poliquin's assertion that gluten is associated with osteoarthritis has some support. Research conducted by Elkan et.al (6) found positive health changes in a group of arthritis patients who went on a gluten free vegan diet. The researchers remarked:
"A gluten-free vegan diet....induces changes that are potentially atheroprotective and anti-inflammatory, including decreased LDL and oxLDL levels and raised anti-PC IgM and IgA levels."
This study does not say anything about what aspect of the gluten free vegan diet may have contributed to these positive changes, nor does it provide any information on how these positive health improvements affected the subjects' arthritis. Other research (7,8) shows a correlation between gluten consumption and arthritis in celiac patients. If you suffer from arthritis it may be worthwhile to give up gluten even if you do not have any other symptoms associated with gluten intolerance, however, a correlation between arthritis sufferers benefiting from avoiding gluten is not the same as saying all arthritis is caused by gluten or that if you do remove gluten you will experience an improvement in symptoms.
Gluten can induce depression
It would not be surprising to find out that sufferers from gluten sensitivity would be more likely to be depressed as would anyone suffering from a disease but this is a LONG way from saying gluten can cause depression, especially in those without sensitivity to gluten. Research in this area shows both support for the theory that gluten is associated to increased depression (9) and that it makes no difference (10).
Saying gluten can cause depression is scientifically inaccurate and not really worthy of further comment. Assuming you have no issues with gluten tolerance the idea it can cause depression is laughable at best and a gross misunderstanding of the research.
Gluten, thyroid function, and autoimmune disease
There is a substantive body of research supporting a correlation between autoimmune diseases where having one increases the likelihood of having another (11,12,13) and this includes a link between autoimmune thyroid disease and celiac disease. Does gluten consumption cause thyroid down regulation though? The evidence is this regard is entirely absent. For those who believe they have no gluten intolerance there is no reason to stop grain consumption. For those suffering from autoimmune diseases, removing gluten from the diet can definitely be beneficial potentially.
Gluten and Aging
A review of the research shows no research linking gluten and accelerated aging unless we count the increased breakdown of physical function seen in celiacs. If you think you are going to look ten years younger by giving up gluten and have no sensitivity to it at all good luck with that.
Gluten, PMS and Dental Decay
There is not much to say here except unless you are gluten intolerant there is nothing to suggest either of these will be an issue. If you do suspect gluten may be behind these symptoms it is worthwhile eliminating gluten for a month and seeing how you go.
Other claims investigated
Glutens contain phytates that limit nutrient absorption
Phytates reduce the absorption of other nutrients and there is evidence (14) showing that big grain consumers such as vegetarians are more likely to suffer from deficiencies in minerals such as zinc, which, as bodybuilders we should be particularly concerned about given its importance for testosterone production. With that being said phytates are by no means found only in gluten containing products and they also found in a range of vegetables. As many gluten bashers wax lyrical about the benefits of green vegetables this is somewhat at odds against the advice to avoid gluten due to phytates.
Suffice it to say, that unless you plan to live off bread there is no reason by under a mixed diet you will experience any nutrient deficiencies.
Gluten causes inflammation
The argument that gluten causes inflammation which in turn causes disease is one I have heard frequently but is it supported by evidence? Studies (15,16) comparing whole grains and refined grains showed an inverse relationship between whole grains (higher in gluten) and inflammation but a positive relationship to refined grains. Katcher et.al's study also showed an improvement in cardiovascular risk factors and a reduction in bodyfat - So much for gluten causing fat gain.
Lectins in gluten products can cause cellular damage
Lectins are sugar binding proteins which can interfere with nutrient absorption (17). The pectin content of grains is a concern as not only can they interfere with nutrient absorption it potentially cause leptin resistance (18). Leptin is a master hormone in the body with a multitude of effects on downstream hormones including testosterone, growth hormone, insulin, cortisol and many more. Anything which can blunt its effects would obviously present significant adverse health and body composition effects.
While this sounds worrying it should be noted that the data on lectin largely relates to animal studies with an absence of human studies. Until such time as human studies are conducted it’s too soon to banish grains, and other lectin containing plant foods until we see adverse reactions in humans.
Long term studies
A study conducted by Jenkins et.al (19) found adding fibre to the diet did not negatively affect risk factors for heart disease but the increased fibre intake did increase levels of LDL (the so called bad cholesterol). Jenkins remarked that wheat fibre was relatively less effective compared to oat bran and other more soluble fibres.
Set against this two large Scandinavian studies (20,21) showed a positive association between higher whole grain intakes and risk factors associated with cardiovascular disease. The second one showed a persistent benefit of high whole grain consumption despite adjusting for other lifestyle factors such as exercise and smoking. Further support for the positive effects of grain consumption against health outcomes (22,23,24) suggest strongly that grain consumption is positively correlated with healthy life outcomes.
The evidence relating to gluten and effects on health is far from one sided and many of the allegations made against gluten are based on associations found in the small minority of people with celiac disease and those with associated illness being used to disparage consumption of gluten containing products for everyone. Some distinguished people misunderstand that association of gluten consumption with symptoms in those with pathologies absolutely does NOT mean causation between gluten consumption and poor health in the general population.
While there does seem to be a case to limit gluten consumption and rotate carbohydrate sources given the potential adverse consequences of lectin this requires more research to be conducted to verify the occurrence in humans. The increase in non-celiac gluten sensitivity problems is a real problem. Whether it is due to improved screening or an actual increase in the numbers who have gluten intolerance issues is unclear but if you suspect you may be in this camp, eliminating gluten foods from the diet for a month and then reintroducing them and monitoring for any ill effects is recommended.
Overall, the long term evidence supports grain consumption for protecting against everything from heart disease and cancer which makes their inclusion as part of a healthy, mixed diet a sensible strategy for those who are focused not just on body composition but also health.
2. Hadjivassiliou M, Boscolo S, Davies?Jones GA, Gr³newald RA, Not T, Sanders D, et al. The humoral response in the pathogenesis of gluten ataxia.
3. Hadjivassiliou M, Gibson A, Davies-Jones GAB, Lobo A, Stephenson TJ, Milford-Ward A.Is cryptic gluten sensitivity an important cause of neurological illness?
4 Giacco et.al (2011): Whole grain intake in relation to body weight: From epidemiological evidence to clinical trials.
5. Wycherley TP et. al (2010): Long-term effects of weight loss with a very low carbohydrate and low fat diet on vascular function in overweight and obese patients.
6. Elkan et.al (2008): Gluten-free vegan diet induces decreased LDL and oxidized LDL levels and raised atheroprotective natural antibodies against phosphorylcholine in patients with rheumatoid arthritis: a randomized study
7. Bourne, J.T., Kumar, P., Huskisson, E.C., et al. (1985). Arthritis and coeliac disease.
8. Lubrano, E., Ciacci, C., Ames, P.R., et al. (1996). The arthritis of coeliac disease: prevalence and pattern in 200 adult patients.
9. Fera, T et.al (2003): Affective disorders and quality of life in adult coeliac disease patients on a gluten-free diet.
10. Addolorato G (2001): Anxiety but not depression decreases in coeliac patients after one-year gluten-free diet: a longitudinal study.
11. Collin P et.al (1994): Autoimmune thyroid disorders and coeliac disease
12. Hakanen M et.al (2001): Clinical and subclinical autoimmune thyroid disease in adult celiac disease.
13. Akcay MN et.al (2003): The presence of the antigliadin antibodies in autoimmune thyroid diseases.
14. Hunt JR (2002): Moving toward a plant-based diet: are iron and zinc at risk?
15. Qi L, et al (2006): Whole-grain, bran, and cereal fiber intakes and markers of systemic inflammation in diabetic women.
16. Jensen MK, et al (2006): Whole grains, bran, and germ in relation to homocysteine and markers of glycemic control, lipids, and inflammation
17. Cordain et.al (1999): Modulation of immune function by dietary lectins in rheumatoid arthritis
18. Jonsson et.al (2009): Agrarian diet and diseases of affluence – Do evolutionary novel dietary lectins cause leptin resistance?
19. Jenkins DJ, et al (2002): Effect of wheat bran on glycemic control and risk factors for cardiovascular disease in type 2 diabetes.
20. Majken K Jensen, Pauline Koh-Banerjee, Frank B Hu, Mary Franz, Laura Sampson, Morten Gr°nbµk and Eric B Rimm (2004): Intakes of whole grains, bran, and germ and the risk of coronary heart disease in men
21. Jacobs et.al (2004): Reduced mortality among whole grain bread eaters in men and women in the Norwegian County Study.
22. D R Jacobs et.al (1999): Is whole grain intake associated with reduced total and cause-specific death rates in older women?
23. Liu et.al (1999): Whole-grain consumption and risk of coronary heart disease
24. Shatzkin et.al (2007): Dietary fiber and whole-grain consumption in relation to colorectal cancer in the NIH-AARP Diet and Health Study