GO GLUTEN-FREE
Diets for Athletes and Active People
by Margaret M. Harris, Ph.D., M.S., H.C. and Nanna Meyer, Ph.D., R.D., C.S.S.D., FACSM
LEARNING OBJECTIVES
• To understand the difference between celiac disease, gluten
intolerance, and wheat sensitivity
CELIAC DISEASE
• To gain knowledge on diagnosis and management for varying
levels of gluten intolerance
• To gain knowledge on special issues when following a glutenfree diet, especially for active individuals
Key words:
Celiac Disease, Gluten Intolerance, Wheat, Ingredients, Carbohydrate
THE GLUTEN-FREE FAD
B
y the end of 2011, an estimated $1.3
billion of gluten-free (GF) products had
been purchased and produced. That’s an
increase of 110% during the last 10 years, making
the GF market one of the fastest growing markets
(8). Walking through a store, the amount of
sections promoting GF products is apparent.
More restaurants and bakeries also are offering
GF sections on their menus. The question
always arises, however, whether the GF ideology
is a fad, a result of true increasing food allergies,
or a meritorious claim to healthier living. This is
an important and pertinent question for the
athlete. Many athletes are turning to GF diets
under the idea that the diet provides health
benefits and improved athletic performance.
WHAT IS GLUTEN?
Gluten is a protein that is found in wheat and other
grains, such as barley, kamut, and spelt. Gluten
has an elastic and gluelike capacity that makes
grain products chewy. Commonly consumed
gluten-containing products include pasta, bread,
pastries, croutons, and cereals. Gluten is a hidden
ingredient in many food products on the market:
soy sauce, pie fillings, foods that contain ‘‘hydrolyzed protein,’’ some canned foods, deli meats,
22
beer, foods with sugar alcohols, sauces, and fast
food. Gluten also may be found in preservatives,
breading, and thickening agents.
For some people, eating GF is a choice. But for a
growing number of people, eating GF is necessary. People for whom a GF diet is beneficial and
even life-saving are those with celiac disease
(CD), gluten intolerance (GI), and wheat allergy
(WA). Although these types of sensitivities to
gluten are different in their origins, they are
treated the same way: a GF diet.
CD is not a food allergy. It is an autoimmune
disorder in which the small intestine is hypersensitive to gluten. The digestive tract contains tiny
hairlike projections called villi, where food is
absorbed. These villi are destroyed in people with
unmanaged CD. When the villi are not functioning
properly, nutrient deficiencies will result because
carbohydrates, fats, proteins, vitamins, and minerals, and even water in some instances, cannot be
absorbed. In the athlete, the malabsorption also
leads to decreased exercise performance (5,8).
Some symptoms of CD include diarrhea or
constipation (or a combination of both), intestinal
cramping, gas, pale fatty runny stools (steatorrhea), anemia, weight gain, or unexplained weight
loss with an increased appetite. Weight gain has
been a puzzling yet new observation. Once labeled a malabsorption syndrome, the hallmark of
CD has been wasting. Today, many people with
CD are normal weight or overweight.
CD affects not only the gut but also many other
parts of the body and organs. The primary symptoms are listed in Table 1. Some people do not
exhibit any symptoms until CD has become severe. Individuals often have CD for more than
a decade before a diagnosis is made. True CD
is a life-threatening condition and has been associated with many other disorders, such as leaky
gut syndrome, hypothyroidism, type I diabetes,
and other autoimmune diseases.
ACSM’s HEALTH & FITNESS JOURNALA | www.acsm-healthfitness.org
Copyright © 2013 American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
VOL. 17/ NO. 1
Once considered a rare disease, the prevalence of CD has
increased dramatically during the last 100 years. Today, it is
thought to affect 1% of the population (2). This disease is underdiagnosed, and this estimate is thought to be grossly underestimated. Because this disease is genetically based, first-degree
relatives will have an increased risk of also being diagnosed with
CD, as high as 1 in 22 (2). Diagnosis is based on a blood test.
However, false-negatives are an issue. A combination of blood
tests (i.e., testing for antibodies and tissue damage), genetic
markers, and history is ideal. A tissue biopsy of the small intestine is the ultimate standard for CD diagnosis. Because the
only treatment available for CD is a strict GF diet, a person may
want to try a GF diet even if his or her test is negative. People
who test negative at first may test positive years later. When
undergoing testing, individuals who have been following a GF
diet will yield negative results on blood tests and biopsies
because the body will have had a chance to heal. For accurate
testing for CD, the patient needs to eat gluten for several weeks
before the test.
GLUTEN INTOLERANCE
GI is very similar to CD. People with GI suffer similarly to people
with CD but do not test positive for CD. Unlike CD, where the
person can have no gluten in his or her diet from any source,
people with GI exhibit a range of gluten sensitivity. Some may be
able to eat small amounts of gluten until they reach a threshold,
whereas others cannot tolerate any gluten. About 5% to 10% of the
population may have some degree of GI, but higher estimates have
also been reported (3). The reason for this dramatic rise (in both
GI and CD) is unknown. Marion Nestle, author of Food Politics,
claims that the higher prevalence is caused by more awareness of
the disorder (hence, better diagnosis) (7).
Unfortunately, blood tests cannot be routinely used to diagnose
GI. Individuals with GI may exhibit more than 100 documented
symptoms associated with GI, and people do not react similarly.
Some commonly seen symptoms that improve with a GF diet
are included in Table 1. Gluten ataxia, one of the symptoms, is a
relatively new concept that involves neurological dysfunction
VOL. 17/ NO. 1
that exhibits itself as reduced coordination and muscle control
(3). If an athlete has gluten ataxia, serious implications for sports
performance may result.
GI often can be subtle and will worsen with continued gluten
consumption over time. Continued consumption of gluten with
true gluten sensitivity will contribute to further deterioration
of the body and lead to a multitude of degenerative symptoms
(i.e., osteoporosis). Because gluten sensitivity is an autoimmune
response, continued consumption of gluten can manifest other
autoimmune disorders.
The best way for people to determine if they are GI is to be
evaluated and diagnosed by a gastrointestinal specialist and work
with a registered dietitian on following an elimination diet. On
this diet, a person completely eliminates all gluten and gluten-rich
foods for several weeks and then slowly adds these foods back
into the diet. Record keeping is essential to determine symptoms
before and after the diet. Because this diet is quite difficult to
follow, consultation with a registered dietitian is critical. The
diagnosis of GI is still evolving and may also include testing for
steatorrhea.
WHEAT ALLERGY
WA differs from GI and CD. People who have a WA have a
systemic response to wheat similarly to how people with nut
allergies may react. Symptoms of WAs are similar to symptoms of
other allergies, namely, hives, swelling, and possibly stomach pain.
CONCERNS FOR THE ATHLETE, FITNESS
PROFESSIONAL, AND ACTIVE INDIVIDUAL
Individuals who train strenuously and competitively need to plan
their nutrition carefully for optimized athletic performance and
decreased gastrointestinal symptoms. Quickly absorbing carbohydrates before, during, and after training are backed by years
of scientific research to improve such performance (4). Many
athletes are turning to the GF diet to reduce gastrointestinal
symptoms. Anecdotal claims suggest that the GF diet also will
TABLE 1: Some Common Symptoms of Celiac
Disease and Gluten Intolerance
Abdominal bloating, gas, pain,
cramping, or distension
Unexplained weight
loss/obesity
Chronic diarrhea (can be
accompanied by constipation)
Pale, foul-smelling stool
(steatorrhea)
Anemia or other nutritional
deficiencies
Irritability, anxiety,
depression, fatigue
Bone or joint pain
Hypoglycemia
Muscle cramps, mouth sores,
hair loss
Missed menstrual periods
Gluten ataxia
Tingling or numbness in
extremities
Bone density loss
(osteoporosis/osteopenia)
Extremely itchy rash
ACSM’s HEALTH & FITNESS JOURNALA
Copyright © 2013 American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
23
Go Gluten-Free
amounts of gluten. However, pasta and breads made from GF
courses (i.e., rice, corn, quinoa) are available.
Many GF products are not enriched with vitamins and
minerals as are conventional products. People on GF diets may
be at risk for micronutrient deficiencies, although GF flours are
naturally nutrient dense. Athletes may find it difficult to adhere
to a strict GF diet, filled with wholesome GF grains, fruits, and
vegetables, especially when traveling. In addition, these foods
are high in fiber that may pose additional gastrointestinal issues
during training. Athletes and active individuals need more
assistance when planning a GF diet at home or on the road to
prevent nutrient deficiencies. Supplementation may need to be a
consideration.
reduce inflammation and improve performance. Unfortunately,
these claims are testimonial based with limited research to support them. Athletes who improve performance with a GF diet
may have undiagnosed CD or GI. They may improve their nutrient intake by switching to a GF diet, or they may lose weight,
and thus feel and perform better. Therefore, a GF diet would
naturally improve performance. More research is needed to
prove or disprove this theory for people without CD or GI.
Although a low body mass index is considered to be a hallmark
of CD, obesity in CD patients is higher than was suspected. For
example, one study found that almost one half of CD patients are
overweight at the time of diagnosis (9). Some preliminary research suggests that overweight people with CD lose weight
when placed on a GF diet (1). Overcompensation for intestinal
malabsorption is one explanation for this phenomenon. When the
intestinal tract is damaged, nutrients cannot be absorbed, resulting
in micronutrient deficiencies, which may drive food cravings (6).
The issues that arise from consuming a GF diet, however, also
need to be addressed. GF diets are significantly more expensive
than non-GF diets. Developing a healthy GF pantry can be quite
challenging. Many GF products are energy dense but not necessarily nutrient dense. For example, in a regular box of crackers,
the primary ingredient used is white flour. In GF crackers, the
flours may include potato starch, rice flour, or other GF flours.
These flours are processed and are more energy than nutrient
dense. These products might be a good option during training,
when rapidly absorbing carbohydrates are necessary. During the
off season, these foods can become a source of excess energy. The
type(s) of GF flour will determine the amount of fiber in the
product. Athletes should check labels and focus on lower fiber
options before, during, and after exercise training.
GF diets do not mean carbohydrate-free diets, a concept
commonly confused. Whether an athlete is on a GF diet by choice
or necessity, the proper amount of carbohydrates is needed to fuel
training and competition. Many GF products available on the
market consist of rapidly absorbed carbohydrates. Pastas and
breads, typically recommended for intense training, contain high
24
DINING OUT GLUTEN-FREE
Athletes and active individuals may travel a great deal for
competition or work. These individuals should be familiar with
foods allowed on a GF diet. Table 2 summarizes foods to avoid,
foods to carefully consider, and foods to consume when
following a GF diet. Fortunately, many restaurants provide GF
options. Extreme care should be noted because these menu items
may not always be GF. Athletes and active individuals should be
aware of hidden sources of gluten (i.e., soy sauce). Finally, in a
restaurant, cross contamination is always a concern. The following points should be considered when dining:
•
If the menu contains many breaded or fried foods, cross
contamination may result. The cooks may not realize that
cooking GF foods on equipment with gluten-rich foods will
contaminate the food. For example, GF foods cooked in the
same oven or grill station where gluten-rich foods were cooked
could become contaminated. For example, is the chicken prepared on the same grill where the hamburger bun is toasted?
•
Customers should call the restaurant and ask about the
knowledge of the chef and kitchen staff with GF. Customers
should be provided with a detailed answer about how the
kitchen is prepared for GF recipes rather than general
statements. If a consumer calls the restaurant and is not
reassured with specifics about how GF menus are prepared,
he or she should choose an alternative dining establishment.
Choosing a restaurant that obtains foods from sustainable
sources such as local/organic farms can help a customer feel
safer when ordering GF foods. Conventional meat and farmed
fish may have been fed grain (and gluten)-filled food, which
may be problematic for some individuals.
The Gluten-Free Restaurant Awareness Program is a network
that provides a resource of restaurants that serve GF menus
following consistent guidelines (http://glutenfreerestaurants.org/).
These tips, for a person with a true allergy, GI, or CD, may
prevent extreme discomfort or a trip to the hospital.
•
ACSM’s HEALTH & FITNESS JOURNALA | www.acsm-healthfitness.org
Copyright © 2013 American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
VOL. 17/ NO. 1
TABLE 2: Foods and Ingredients of Concern to a GF Diet
Avoid
Be Careful*
You Can Safely Consume
Gluten-rich ingredients
Foods with possible hidden gluten (avoid unless
labeled ‘‘gluten-free’’)
No gluten
Semolina wheat (pasta, bread, pastries)
Oatsy
Buckwheat
z
Spelt
Fried foods (i.e., french fries)
Rice (brown or white)
Kamut
Beer, malt beverages, hard lemonade, and coolers
Quinoa
Barley
Breads
Potato starch
Rye
Pastries
Tapioca
Bulgur
Processed lunch meat
Xanthan gum
Farina
Cereals
Fruits
Matzo meal
Grains
Vegetables
Durum wheat
Cookies
Dairy (milk, cheese, etc.)
Triticale
Cakes
Amaranth
Croutons
Arrowroot
Gravies
Corn
Imitation meats/seafood
Cornmeal
Self-basting poultry
GF flours (rice, potato, soy, corn, bean, teff,
amaranth, millet, flax, arrowroot)
Salad dressings
Polenta
Sauces (i.e., soy sauce)
Hominy grits
Canned soups
Corn tortillas
Medications`
Wine
Supplements`
Distilled spirits
Preservatives
Cider
Food additivesP
Meat/seafood (unbreaded)
k
Products you handle
Beans, seeds, nuts (unprocessed)
SeasoningsP
Coconut (milk, flour, flakes)
*The safest way to ensure something is gluten-free is to choose simple whole foods and avoid boxed and processed foods. For example, tomato paste in
tomato sauce may contain gluten agents but are not disclosed in ingredients.
y
Oats may be cross contaminated. Choose GF oats. If you have celiac disease, proceed with caution; some people still react to GF oats.
z
Spelt contains gluten, although less than other flours. People with gluten intolerance can experiment with spelt. People with wheat allergy and celiac disease
should not eat spelt.
`
May contain binding agents that contain gluten.
P
Ingredients include malt flavoring, food starch, hydrolyzed protein, hydrogenated vegetable protein, textured vegetable protein, monosodium glutamate, and so on.
k
Playdough, cosmetics, toothpaste, and so on.
THE GF PANTRY
Table 2 lists the foods that are GF (as well as those that are
gluten-rich or have hidden gluten). Even when products should
technically be GF, contamination with gluten may still be
present (9). Individuals should choose simple wholesome foods
or products with the ‘‘gluten-free’’ label. Checking ingredients,
even of known products, may ensure that the product is truly
GF. Because companies frequently change their formulations,
something that was GF one year may not be GF the next.
Oats are one product that may or may not be safe for
individuals following a GF diet. Oats should not contain any
gluten but are typically manufactured in plants where cross
contamination occurs. If oatmeal is commonly purchased,
individuals should look for a label that specifically states that
VOL. 17/ NO. 1
the product was processed without cross contamination. The
label should say ‘‘gluten-free’’ as opposed to ‘‘wheat-free.’’ Although this should be a safer alternative to people with GI, people
with diagnosed CD still need to be careful. Because oats contain
a protein that is similar in structure to gluten, some people with
CD can still react to oats, even if they are certified GF.
Spelt is an ancient grain that also contains gluten. However,
spelt contains less gluten than other gluten-rich products and is
nutritionally superior (more protein, fiber, and other nutrients)
than wheat. Although a person with CD and WAs should not
consume spelt, some people with lesser degrees of GI can safely
experiment with this highly nutritious grain.
Finally, to avoid cross contamination at home, a designated
GF toaster is advised. When baking, GF foods should be baked
ACSM’s HEALTH & FITNESS JOURNALA
Copyright © 2013 American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
25
Go Gluten-Free
before gluten-filled foods and then the oven should be cleaned.
Everyday household chores also need to be carefully reviewed.
For example, many dishwashing gloves are coated with wheatbased flour. The glue in stamps and envelopes also may contain
gluten, as do many cosmetics, art supplies, sunscreens, lotions,
soaps, detergents, medicines, and supplements. For a complete
safe list, go to www.celiac.com.
Health and fitness professionals may encounter clients who
inquire about GF diets, their health effects, and whether eating
GF may be a good choice for them. Many individuals experience GI symptoms but are not diagnosed with GI or CD. If
symptomatic, the best referral a health and fitness professional
may give to the client is to a medical professional to confirm a
possible issue. However, the client may remain undiagnosed
because of limitations of the tests. If the client is symptomatic
but not diagnosed or is nonsymptomatic but is interested in
trying a GF diet, it is important to inform them about the fact
that GF diets also may be low in carbohydrate and can affect
performance and recovery. In addition, GF diets may be low in
micronutrients, resulting in deficiency. The best guidance for a
serious exerciser with or without GI symptoms and interested in
trying a GF diet would be provided by a nutrition professional
(http://www.eartight.org/programs/rdfinder/). This is especially
true if the client wants to learn more about GF grains, starchy
vegetables (they are always GF), and other creative ways of integrating GF foods into a wholesome and athletically sound diet.
References
1. Cheng J, Brar P, Lee A, Green P. Body mass index in celiac disease: Beneficial
effect of a gluten-free diet. J Clin Gastroenterol. 2010;44(4):267Y71.
2. Fasano A, Berti I, Gerarduzzi T, et al. Prevalence of celiac disease in
at-risk and not-at-risk groups in the United States: A large multicenter
study. Arch Intern Med. 2003;163:286Y92.
Recommended Readings and Resources
Case S. Gluten-Free Diet: A Comprehensive Resource Guide. 4th ed.
Canada: Case Nutrition Consulting; 2010.
Celiac Disease Foundation [Internet]. Available from: http://celiac.org/.
Food and Drug Administration [Internet]. 2011 [cited 2011 Aug 2].
A glimpse at ‘‘gluten-free’’ food labeling. Available from:
http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm265212.htm.
Gluten Intolerance Group [Internet]. Available from: http://www.gluten.net/.
Libonati J, Libonati C. Understanding celiac disease. Today’s Dietitian.
2009;11(6):50 [Internet] [cited 2009]. Available from: http://
www.todaysdietitian.com/newarchives/060109p50.shtml.
National Institutes of Health [Internet]. Available from: http://www.celiac.nih.gov/.
University of Chicago Disease Center [Internet]. Available from:
http://www.celiacdisease.net/.
University of Maryland Center for Celiac Disease [Internet]. Available from:
http://medschool.umaryland.edu/celiac/.
Disclosure: The authors declare no conflicts of interest and do
not have any financial disclosures.
Margaret M. Harris, Ph.D., M.S., H.C., is
an assistant professor in the Sport Nutrition
Program at the Health Sciences Department at
the University of Colorado Colorado Springs.
She has worked in community outreach for the
last 10 years in the areas of obesity, general
health and wellness, and food deserts.
Nanna Meyer, Ph.D., R.D., C.S.S.D., is an
assistant professor and graduate director of
the Sport Nutrition Program in the Health
Sciences Department at the University of
Colorado Colorado Springs. She is a consultant to the U.S. Olympic Committee and
sport dietitian of U.S. Speed Skating.
3. Hadjivassiliou M, Sanders DS, Grunewald RA, Woodroofe N,
Boscolo S, Aeschlimann D. Gluten sensitivity: From gut to brain. Lancet
Neurol. 2010;9:318Y30.
4. IOC Consensus Statement on Sport Nutrition. 2010 [cited on 2010
Oct 27]. Available from: http://www.olympic.org/Documents/Reports/
EN/CONSENSUS-FINAL-v8-en.pdf; http://www.olympic.org/
Documents/Reports/EN/en_report_1251.pdf.
5. Martin S. Against the grain: An overview of celiac disease. J Am Acad
Nurse Pract. 2008;20:243Y50.
6. Murray JA, Watson T, Clearman B, Mitros F. Effect of a gluten-free diet on
gastrointestinal symptoms in celiac disease. Am J Clin Nutr. 2004;79:663Y73.
7. Nestle M. Gluten intolerance becoming more becoming more
commonplace. San Francisco Chronicle [Internet] 2009. Available from:
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/05/29/
FDTT17NK4F.DTL.
8. NTDaily.com [Internet]. North Texas: NT Daily.com [cited 2011 Oct 25].
Available from: http://www.ntdaily.com/?p=59107.
9. Thompson T, Lee AR, Grace T. Gluten contamination of grains, seeds
and flours: A pilot study. J Am Diet Assoc. 2010;110:937Y40.
CONDENSED VERSION AND BOTTOM LINE
The prevalence of celiac disease (CD) has increased significantly. Concomitantly, the gluten-free (GF) diet has become a popular approach to eating. A strict GF diet for
athletes who have CD, wheat allergy, or gluten intolerance
will improve health and may enhance performance. Athletes with suspect gastrointestinal symptoms, fatigue, or
skin rash should seek evaluation and consult with a sport
dietitian. Athletes with gluten restrictions (by choice or
need) can train safely, confidently, and productively. However, research has not examined how GF diets may impact
the athletic performance of athletes or active individuals
who choose GF eating plans.
10. Venkatasubramani N, Telega G, Werlin SL. Obesity in pediatric celiac
disease. J Pediatr Gastroenterol Nutr. 2010;51(3):295Y7.
26
ACSM’s HEALTH & FITNESS JOURNALA | www.acsm-healthfitness.org
Copyright © 2013 American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
VOL. 17/ NO. 1
RESEARCH
Commentary
Gluten-Free Diet: Imprudent Dietary Advice for the
General Population?
Glenn A. Gaesser, PhD; Siddhartha S. Angadi, PhD
ARTICLE INFORMATION
Article history:
Accepted 29 May 2012
Keywords:
Wheat
Gluten
Gut microbiota
Fructan-type resistant starch
Copyright © 2012 by the Academy of Nutrition and Dietetics.
2212-2672/$36.00
doi: 10.1016/j.jand.2012.06.009
G
LUTEN-FREE DIETING HAS GAINED CONSIDERABLE
popularity in the general population.1-3 Between
2004 and 2011 the market for gluten-free products
grew at a compound annual growth rate of 28%,
with annual sales expected to reach approximately $2.6 billion in 2012.2 As of April 20, 2012, Amazon.com listed 4,765
entries for the topic “gluten-free.” A Google search at the same
time for “gluten-free diet” produced more than 4.2 million
results. The number-one reason consumers cite for buying
gluten-free products is that they are perceived to be healthier
than their gluten-containing counterparts.3 Endorsements
from celebrities have undoubtedly contributed to the increased awareness of possible health benefits of gluten avoidance, including weight loss.4,5
Despite the health claims for gluten-free eating, there is no
published experimental evidence to support such claims for
the general population. In fact, there are data to suggest that
gluten itself may provide some health benefits, and that gluten avoidance may not be justified for otherwise healthy individuals. Our primary purpose is to briefly describe this evidence and raise awareness of the potential pitfalls of adopting
a gluten-free diet in persons without diagnosed gluten-related disorders.
INDICATIONS FOR A GLUTEN-FREE DIET
Gluten is a protein composite consisting of gliadins and glutenins, and is found in foods processed from wheat and related grains such as barley and rye. There is a spectrum of
gluten-related disorders, including celiac disease, gluten sensitivity, and wheat allergy.1,2 Wheat allergy is an adverse immunologic reaction specific to wheat proteins.1,2 Prevalence
of documented wheat allergy is quite low, estimated at only
about 0.1% of individuals in Westernized countries.1 Because
wheat allergy can be treated with wheat avoidance, a wheatfree diet may be more permissive than a strict gluten-free
diet.1 Gluten sensitivity (also referred to as nonceliac gluten
1330
JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS
intolerance), is characterized by a heightened immunologic
reaction to gluten in genetically susceptible people.6 Clinical
diagnosis is generally based on responses to a gluten-free
diet.1 Common symptoms of gluten sensitivity, such as fatigue and headaches, and gastrointestinal distress, including
gas, bloating, and diarrhea, frequently improve with the
adoption of a gluten-free diet. The inherent subjectivity in
diagnosis and resolution of these symptoms likely contributes
to the popularity of gluten-free diets.
Celiac disease is a complex autoimmune enteropathy that
affects the small bowel after ingestion of gluten-containing
grains, including wheat, rye, and barley, in genetically susceptible people.7 Estimated prevalence of celiac disease is approximately 1%.8,9 The disease can manifest itself in a range of
clinical presentations, including malabsorption syndrome
and a spectrum of symptoms affecting multiple target organs.10 A strict gluten-free diet is an established remedy for
individuals with celiac disease because it has been shown to
lower incidence of related diseases, such as gastrointestinal
cancers.7-9,11 Lifelong adherence to a strict gluten-free diet,
devoid of proteins from wheat, rye, barley, and related cereals, remains the gold standard of treatment in celiac disease.7-9
There are some data to suggest that following a gluten-free
diet may ameliorate gastrointestinal and/or systemic symptoms in individuals with systemic lupus erythematosus, dermatitis herpetiformis, irritable bowel syndrome, rheumatoid
arthritis, type 1 diabetes, thyroiditis, and psoriasis.12,13 Gluten-free diets have also been used by patients with autism
spectrum disorders (ASD).2,14 However, there are no definitive data to support the use of gluten-free diets in ASD,15 and
the American Academy of Pediatrics does not support the use
of gluten-free diets as a primary treatment for individuals
with ASD.16
Apart from the demonstrated effectiveness of a gluten-free
diet for treating the spectrum of gluten-related disorders and
the conditions mentioned above, evidence-based research
supporting the merits of a gluten-free diet as a healthier option for the general population is lacking.
GLUTEN-FREE DIET AND WEIGHT LOSS: WHERE
IS THE EVIDENCE?
Despite the growing popularity of gluten-free diets and celebrity endorsements of the merits of a gluten-free diet for
weight loss,4,5 there are no published reports showing that a
gluten-free diet produces weight loss in persons without celiac disease or gluten sensitivity. There are a number of studies of patients with celiac disease that reported weight change
as an outcome measure following a gluten-free diet.17-19
© 2012 by the Academy of Nutrition and Dietetics.
RESEARCH
Strict adherence to a gluten-free diet in celiac disease generally improves body mass index (BMI) status.17 However, normalization of BMI while following a gluten-free diet is not
always observed. In a study of 369 adults with celiac disease
who followed a gluten-free diet for an average of 2.8 years, 22
of 81 (27%) initially overweight or obese patients gained
weight.17 In a study of 371 adults with celiac disease who
followed a gluten-free diet for 2 years, 55 of 67 (82%) initially
overweight patients gained weight.18 Among 149 children
with celiac disease who followed a gluten-free diet for at least
12 months, the percentage of overweight children almost
doubled (11% to 21%).19
These reports indicate that for a significant percentage of
overweight or obese patients with celiac disease, body weight
may actually increase on a gluten-free diet. This may be due in
part to enhanced absorption of nutrients associated with
healing of intestinal lining while following a gluten-free diet.
Whether weight gain would be observed in persons without
celiac disease or gluten sensitivity remains to be established.
In this regard it is important to note that gluten-free does not
necessarily mean low-energy, and some gluten-free products
actually have a greater energy value than corresponding gluten-containing foods.3 Furthermore, a gluten-free diet may be
deficient in whole grains and fiber,3 both of which have been
shown to be inversely associated with BMI.20
WHEAT AND GASTROINTESTINAL HEALTH
Naturally occurring fructan-type resistant starches in wheat,
such as oligofructose and inulin, are beneficial for creating a
healthy composition of gut bacteria,21-28 and these diet–
microbe interactions in the colon may protect the gut from
some cancers, inflammatory conditions, and cardiovascular
disease.27,28 Wheat is the most widely consumed grain in the
United States, and contributes approximately 70% to 78% of
the oligofructose and inulin in typical North American diets.29,30 Wheat-derived nondigestible carbohydrates have
been reported to decrease postprandial glycemia and insulinemia, reduce fasting triglycerides, and reduce body
weight.21 Oligofructose has been shown to improve immune
status, lipid metabolism, and vitamin and mineral absorption.25 By removing the major source (wheat) of fructan-type
resistant starches in American diets, strict adherence to a gluten-free diet could have adverse consequences.
In fact, recent evidence suggests that a gluten-free diet may
lead to reductions in beneficial gut bacteria.31 Ten healthy
subjects followed a gluten-free diet for 1 month by replacing
gluten-containing foods with equivalent products certified as
gluten-free.31 The gluten-free diet significantly reduced a
number of beneficial bacteria in fecal samples of the subjects,
including Bifidobacterium, Lactobacillus, Clostridium lituseburense, and Faecalibacterium prausnitzii, and increased levels of
pathogenic Enterobacteriaceae and Escherichia coli.
Immunostimulatory properties of fecal samples were also
reduced after 1 month following a gluten-free diet. For example, the gluten-free diet reduced production of the potent
neutrophil chemoattractant tumor necrosis-␣. Three-day
food diaries (2 weekdays and 1 weekend day) at the beginning
and end of the 1-month diet period indicated that total energy
and macronutrient intake were not changed, with the exception of a lower polysaccharide intake while following the gluten-free diet. A reduction in polysaccharide intake on a gluSeptember 2012 Volume 112 Number 9
ten-free diet is not unexpected.32 Thus, a gluten-free diet
produced potentially adverse changes in gut health as a result
of reduced intake of naturally occurring fructans in wheat
products that have a prebiotic action.
By contrast, increasing whole-grain wheat intake has been
reported to increase beneficial gut bacteria.33 In a doubleblind, randomized, crossover study consisting of two 3-week
dietary periods with a 2-week washout in between, 31
healthy women and men added to their diet either 48 g/day
100% whole-grain wheat breakfast cereal or 48 g/day wheatbran cereal. Fecal samples were collected before and after the
3-week dietary period. After 3 weeks following the diet supplemented with 48 g/day 100% whole-grain wheat breakfast
cereal, numbers of fecal Bifidobacterium were increased by
approximately 10%. Addition of wheat bran to subjects’ habitual diets had no effect. Both 100% whole-grain wheat and
wheat-bran conditions increased the numbers of lactobacilli
in fecal samples, but the 7.4% increase after the 100% wholegrain wheat condition was significantly greater than the 5.0%
increase observed after the wheat– bran condition. The results indicate a prebiotic effect of whole-grain wheat breakfast cereal. It has been proposed that one of the mechanisms
by which whole-grain foods confer health benefits is via their
beneficial effect on gut bacteria.21-28 These findings may help
explain the well-established inverse relationship between
whole-grain food intake and risk of cardiovascular diseases.25,26
GLUTEN AND HEALTH
Gluten itself may actually be beneficial to the diets of individuals with dyslipidemia without celiac disease or gluten sensitivity. In 24 adults with hyperlipdemia, increased consumption of wheat gluten for 2 weeks on a weight-maintenance
diet reduced serum triglycerides by 13%.34 In this randomized
crossover study, subjects consumed diets that differed with
respect to gluten, wheat fiber, and bran content. The higher
gluten content of the diet was achieved by having subjects
consume bread that contained 53.1% protein. This increased
gluten intake by 60 g/day, which accounted for 10% of total
energy. High levels of wheat fiber and bran did not reduce triglyceride levels when gluten levels were the same in each diet.
Only under the high-gluten condition, regardless of wheat fiber
content, were triglyceride levels reduced. Therefore, it appeared
that the reduction in serum triglyceride levels was attributable
to the gluten itself rather than the wheat fiber.
In a randomized crossover study of men and women with
hyperlipidemia,35 subjects consumed either a control diet or a
diet in which 11% of the carbohydrate in the control diet was
replaced with vegetable protein (as wheat gluten) for 1 month.
This resulted in a 78 g/day increase in gluten intake. Total energy,
dietary fiber, and fat intake were the same during each diet period. Increasing daily gluten intake for 1 month reduced serum
triglycerides by 19.2%, uric acid by 12.7%, and creatinine by 2.5%.
In addition, low-density lipoprotein oxidation was reduced by
10.6% in the high-gluten diet. The authors concluded that high
intake of vegetable protein in the form of added wheat gluten
could have beneficial effects on triglyceride levels and oxidized
low-density lipoprotein similar to those of monounsaturated fat
and soy protein.
In addition to the potential benefits of gluten for improving
blood lipid levels,34,35 gluten may play a role in blood pressure
JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS
1331
RESEARCH
control. For example, wheat gliadin hydrolysates have been
reported to inhibit angiotensin I-converting enzyme (ACE).36
Thewissen and colleagues36 extracted gliadin from commercial wheat gluten and demonstrated that several of the resulting peptide fractions from the gliadin hydrolysates exhibited
ACE-inhibitory activity. Because ACE converts angiotensin I
into angiotensin II (vasoconstrictor) and degrades bradykinin
(vasodilator), inhibition of ACE could facilitate reduction in
blood pressure. Whole-grain consumption has been shown to
reduce blood pressure,37 with wheat itself having a demonstrated effect.38 Although the dietary fiber component of
whole grains is thought to play a role,39 it is also possible that
gluten, via one of its constituent proteins gliadin, may contribute to the blood-pressure–lowering effect of whole
grains.36
Gluten may also boost the immune system in humans. This
may be due in part to the very high glutamine content of
gluten (⬃40% of total amino acids). Glutamine supplementation, for example, has been reported to reduce incidence of
infectious complications in patients following surgery.40 In a
small study of nine healthy volunteers, five subjects received
3 g/day wheat gluten hydrolysate for 6 days (41). After 6 days,
natural killer cell activity was increased significantly (by approximately 6% to 57%; P⬍0.05) in all five subjects who received the wheat gluten hydrolysate. No change was observed
in the four control subjects.41 There were no reported side
effects. An increase in natural killer cell activity could be expected to enhance immune monitoring against tumor development and viral infections.42 Epidemiologic evidence supports a protective role for whole-grain consumption to reduce
cancer risk,43 with specific effects attributable to wheat.44,45
CONCLUSIONS
Gluten-free diets are clearly indicated for patients with celiac
disease or for persons with gluten sensitivity, and may be
beneficial for individuals with other chronic autoimmune disease conditions such as psoriasis, rheumatoid arthritis, and
type 1 diabetes.12,13 With the substantial growth in the gluten-free products market,2 a greater number of food choices
are now available to individuals for whom gluten avoidance is
essential. There are many gluten-free grains available to help
consumers obtain the benefits of whole grains and overcome
some of the nutritional deficiencies (eg, inadequate intakes of
thiamin, riboflavin, niacin, folate, and iron) reported to be associated with gluten-free diets.9,46 A gluten-free diet can be a
well-balanced diet if care is taken in choosing whole-grain
products, including more legumes, and selecting foods with
lower energy density. This does not imply that a gluten-free
diet, per se, is a healthier diet.
Despite numerous health claims and the exploding popularity of gluten-free products, there are no published data to
support a weight loss claim for a gluten-free diet.3 Results of
several studies of patients with celiac disease suggest that a
gluten-free diet may actually worsen BMI status in some
overweight and obese individuals. Gluten-free baked goods
can be high in fat and total energy.9 Moreover, whole-grain
intake is inversely associated with BMI, and wheat is the most
widely consumed grain in America. Thus, going gluten-free
for purposes of weight loss may have unintended consequences. Randomized-control trials are necessary to establish
the effect of a gluten-free diet on weight loss in overweight or
1332
JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS
obese individuals for whom a gluten-free diet is not medically
indicated.
Gluten-rich grains, especially wheat, may have health benefits attributable to naturally occurring fructan-type resistant
starches as well as gluten itself. By creating a healthy composition of colon bacteria, whole-grain wheat products may protect the gut from some cancers, inflammatory conditions, and
cardiovascular disease. Gluten, and one of its component proteins gliadin, may contribute to blood pressure control and
immune function. Because wheat is the main source of gluten
in the American diet,29,30 these studies may help explain the
consistent findings of health benefits of whole-grain consumption.25,26,43,44
There is no evidence to suggest that following a gluten-free
diet has any significant benefits in the general population.
Indeed, there is some evidence to suggest that a gluten-free
diet may adversely affect gut health in those without celiac
disease or gluten sensitivity.31 Additional research is needed
to clarify the health effects of gluten, and potential consequences of avoiding gluten-containing grains.
References
1.
Piezak M. Celiac disease, wheat allergy, and gluten sensitivity: When
gluten free is not a fad. JPEN J Parental Enterol Nutr. 2012;36(suppl
1):68S-75S.
2.
Sapone A, Bai JC, Ciacci C, et al. Spectrum of gluten-related disorders:
Consensus on new nomenclature and classification. BMC Med. 2012;
10:13.
3.
Marcason W. Is there evidence to support the claim that a gluten-free
diet should be used for weight loss? J Am Diet Assoc. 2011;111(11):
1786.
4.
Hasselbeck E. The G-Free Diet: a Gluten-Free Survival Guide. New York,
NY: Center Street Books; 2009.
5.
Miley Cyrus: Gluten-free diet is responsible for weight loss. Huffington Post website. http://www.huffingtonpost.com/2012/04/10/
miley-cyrus-gluten-free-diet-weight-loss_n_1414641.html. Accessed
April 20, 2012.
6.
Hadjivassiliou M, Grunewald RA, Davies-Jones GAB. Gluten sensitivity as a neurological illness. J Neurol Neurosurg Psychiatry. 2002;72(5):
560-563.
7.
Briani C, Samaroo D, Alardini A. Celiac disease: From gluten to autoimmunity. Autoimmunity Rev. 2008;7(8):644-650.
8.
Catassi C, Fassano A. Celiac disease. Curr Opin Gastroenterol. 2008;
24(6):687-691.
9.
Niewinski MM. Advances in celiac disease and gluten-free diet. J Am
Diet Assoc. 2008;108(4):661-672.
10.
Cascella NG, Kryszak D, Bhatti B, et al. Prevalence of celiac disease and
gluten sensitivity in the United States Clinical Antipsychotic Trials of
Intervention Effectiveness study population. Schizophrenia Bull.
2011;37(1):94-100.
11.
Haines ML, Anderson RP, Gibson PR. Systematic review: The evidence
base for long-term management of celiac disease. Aliment Pharmacol
Ther. 2008;28(9):1042-1066.
12.
Green PH. Mortality in celiac disease, intestinal inflammation, and
gluten sensitivity. JAMA. 2009;302(11):1225-1226.
13.
El-Chammas K, Danner E. Gluten-free diet in nonceliac disease. Nutr
Clin Pract. 2011;26(3):294-299.
14.
de Magistris L, Familiari V, Pascotto A, et al. Alterations of the intestinal barrier in patients with autism spectrum disorders and in their
first-degree relatives. J Pediatr Gastroenterol Nutr. 2010;51(4):418424.
15.
Mulloy A, Lang R, O’Reilly M, Sigafoos J, Lancioni G, Rispoli M. Gluten-free
and casein-free diets in the treatment of autism spectrum disorders; a
systematic review. Res Autism Spectrum Disord. 2010;4(3):328-339.
16.
Buie T, Campbell DB, Fuchs GJ 3rd, et al. Evaluation, diagnosis, and
treatment of gastrointestinal disorders in individuals with ASDs: A
consensus report. Pediatrics. 2010;125 (suppl 1):S1-S18.
September 2012 Volume 112 Number 9
RESEARCH
blind, placebo-controlled,
2008;99(1):110-120.
crossover
study.
Brit
J
Nutr.
17.
Cheng J, Brar PS, Lee AR, Green PHR. Body mass index in celiac disease.
Beneficial effect of a gluten-free diet. J Clin Gastroenterol. 2010;44(4):
267-271.
34.
18.
Dickey W, Kearney N. Overweight in celiac disease: Prevalence, clinical characteristics, and effect of a gluten-free diet. Am J Gastroenterol.
2006;101(10):2356-2359.
Jenkins DJA, Kendall CWC, Vuksan V, et al. Effect of wheat bran on
serum lipids: Influence of particle size and wheat protein. J Am Coll
Nutr. 1999;18(2):159-165.
35.
19.
Valletta E, Fornaro M, Cipolli M, Conte S, Bissolo F, Danchielli C. Celiac
disease and obesity: Need for nutritional follow-up after diagnosis.
Eur J Clin Nutr. 2010;64(11):1371-1372.
Jenkins DJA, Kendall CWC, Vidgen E, et al. High-protein diets in hyperlipidemia: Effect of wheat gluten on serum lipids, uric acid, and
renal function. Am J Clin Nutr. 2001;74(1):57-63.
36.
20.
Gaesser GA. Carbohydrate quantity and quality in relation to body
mass index. J Am Diet Assoc. 2007;107(10):1768-1780.
Thewissen BG, Pauly A, Celus I, Brijs K, Delcour JA. Inhibition of angiotensin I-converting enzyme by wheat gliadin hydrolysates. Food
Chem. 2011;127(4):1653-1658.
21.
Neyrinck AM, Delzene NM. Potential interest of gut microbial
changes induced by nondigestible carbohydrates of wheat in the
management of obesity and related disorders. Curr Opin Clin Nutr
Metab Care. 2010;13(6):722-728.
37.
Behall KM, Scholfield DJ, Hallfrisch J. Whole-grain diets reduce blood
pressure in mildly hypercholesterolemic men and women. J Am Diet
Assoc. 2006;106(9):1445-1449.
38.
22.
Gibson GR. Prebiotics as gut microflora management tools. J Clin Gastroenterol. 2008;42(suppl 2):S75-S79.
Tighe P, Duthie G, Vaughan N, et al. Effect of increased consumption of
whole-grain foods on blood pressure and other cardiovascular risk
markers in healthy middle-aged persons: A randomized controlled
trial. Am J Clin Nutr. 2010;92(4):733-740.
23.
Delzenne NM, Cani PD. Gut microbiota and the pathogenesis of insulin resistance. Curr Diab Rep. 2011;11(3):154-159.
39.
24.
Jonnalagadda SS, Harnack L, Liu RH, et al. Putting the whole grain
puzzle together: Health benefits associated with whole grains—Summary of American Society for Nutrition 2010 Satellite Symposium. J
Nutr. 2011;141(5):1011S-1022S.
Streppel MT, Arends LR, van’t Veer P, Grobbee DE, Geleijnse JM. Dietary fiber and blood pressure: A meta-analysis of randomized placebo-controlled trials. Arch Intern Med. 2005;165(2):150-156.
40.
Novak F, Heyland DK, Avenall A, Drover JW, Su X. Glutamine supplementation in serious illness: A systematic review of the evidence. Crit
Care Med. 2002;30(9):2022-2029.
25.
Harris KA, Kris-Etherton PM. Effects of whole grains on coronary
heart disease risk. Curr Atheroscler Rep. 2010;12(6):368-376.
41.
26.
Slavin J. Why whole grains are protective: Biological mechanisms.
Proc Nutr Soc. 2003;62(1):129-134.
Horiguchi N, Horiguchi H, Suzuki Y. Effect of wheat gluten hydrolysate on the immune system in healthy human subjects. Biosci Biotechnol Biochem. 2005;69(12):2445-2449.
42.
27.
Fava F, Gitau R, Lovegrove J, Tuohy KM. The gut microflora and lipid
metabolism: Implications for human health. Curr Med Chem. 2006;
13(25):3005-3021.
Herberman RB, Oltaldo JR. Natural killer cells: Their roles in defenses
against disease. Science. 1981;214(4516):24-30.
43.
Jacobs DR, Marquart L, Slavin J, Kushi LH. Whole-grain intake and
cancer: An expanded review and meta-analysis. Nutr Cancer. 1998;
30(2):85-96.
44.
Fardet A. New hypotheses for the health-protective mechanisms of
whole-grain cereals: What is beyond fibre? Nutr Res Rev. 2010;23(1):
65-134.
45.
Reddy BS, Hirose Y, Cohen LA, Simi B, Cooma I, Rao CV. Preventive
potential of wheat bran fractions against experimental colon carcinogenesis: Implications for human colon cancer prevention. Cancer Res.
2000;60(17):4792-4797.
46.
Case S. Gluten-Free Diet: A Comprehensive Resource Guide. Regina, Saskatchewan, Canada: Case Nutrition Consulting; 2006.
28.
Rastall RA, Gibson GR, Gill HS, et al. Modulation of the microbial ecology of the human colon by probiotics, prebiotics and synbiotics to
enhance human health: An overview of enabling science and potential applications. FEMS Microbiol Ecol. 2005;52(2):145-152.
29.
van Loo J, Coussement P, de Leenheer L, Hoebregs H, Smits G. On the
presence of inulin and oligofructose as natural ingredients in the
Western diet. Crit Rev Food Sci Nutr. 1995;35(6):525-552.
30.
Moshfegh AJ, Friday JE, Goldman JP, Ahuja JKC. Presence of inulin and
oligofructose in the diets of Americans. J Nutr. 1999;129(7 suppl):
1407S-1411S.
31.
De Palma G, Nadal I, Collado MC, Sanz Y. Effects of a gluten-free diet
on gut microbiota and immune function in healthy adult human subjects. Br J Nutr. 2009;102(8):1154-1160.
32.
Kinsey L, Burden ST, Bannerman E. A dietary survey to determine if
patients with coeliac disease are meeting current healthy guidelines
and how their diet compares to that of the British general population.
Eur J Clin Nutr. 2008;62(11):1333-1342.
33.
Costabile A, Klinder A, Fava F, et al. Whole-grain wheat breakfast
cereal has a prebiotic effect on the human gut microbiota: A double-
AUTHOR INFORMATION
G. A. Gaesser is a professor, Exercise and Wellness Program, Healthy Lifestyles Research Center, School of Nutrition and Health Promotion,
Arizona State University, Phoenix. S. S. Angadi is a postdoctoral scholar, Exercise and Metabolic Disease Research Laboratory, Translational
Sciences Section, UCLA School of Nursing, Los Angeles, CA.
Address correspondence to: Glenn A. Gaesser, PhD, Healthy Lifestyles Research Center, School of Nutrition and Health Promotion, Arizona State
University, 500 N 3rd St, Phoenix, AZ 85004. E-mail: [email protected]
STATEMENT OF POTENTIAL CONFLICT OF INTEREST
G. A. Gaesser is chairman of the Grain Foods Foundation Scientific Advisory Board.
FUNDING/SUPPORT
Preparation of this article was supported in part by a grant from the Grain Foods Foundation.
September 2012 Volume 112 Number 9
JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS
1333