Can Gluten Cause Eye Problems?
Before discussing whether or not gluten can cause eye problems, let’s address some important background information. Celiac disease is often thought of as a disease that only affects the small intestine, creating symptoms like diarrhea, intestinal pain, cramping, weight loss, and malabsorption. While that is true, approximately half of all celiac disease patients present with extra-intestinal (non-gastrointestinal) symptoms, such as anemia, osteoporosis, neurological disorders, infertility, skin concerns, and vision or eyesight problems. Ocular (eye) symptoms caused by gluten can vary according to a person’s genetic predisposition, immune status, gender, and age at onset.
This piece will focus on how non celiac gluten sensitivity and celiac disease can manifest as ophthalmic concerns, which can be derived from both malnutrition or malabsorption and immune alterations.
Gluten Induced Eye Diseases Related to Malnutrition/Malabsorption
Ophthalmologic manifestations related to malnutrition stem from low levels of vitamin A, vitamin D, and calcium, which are common in celiac disease patients. These include retinopathy, cataract, dry eye, and pseudotumor cerebri:
- Retinopathy: characterized by yellowish to white lesions studded with tiny holes in the peripheral retina. It is typically caused by a deficiency in vitamin A. The vitamin A deficiency can also lead to night blindness (nyctalopia). Typically, visual function improves after one to four months of vitamin A supplementation.
- Cataracts: marked by the clouding of the lens of the eye, most cataracts develop slowly over time and cause blurry vision. Cataracts can be caused by a vitamin D deficiency, as a vitamin D deficiency interferes with the absorption of calcium and the resulting hypocalcemia (low blood levels of calcium) contributes to the development of cataracts. In addition, diarrhea common in undiagnosed celiac patients can lead to dehydration. Dehydration can alter the composition of the lens and lead to low levels of calcium in the aqueous humor. This leads to hypocalcemia which can then lead to cataracts.
- Pseudotumor cerebri: also known as idiopathic intracranial hypertension is characterized by increased intracranial pressure of unknown cause. It is thought to be caused by nutritional, metabolic, endocrinological or hematological disorders. In particular, it is linked with both vitamin A poisoning and vitamin A deficiency, although the mechanisms by which vitamin A deficiency and poisoning results in increased intracranial pressure is still not fully understood. Vitamin A deficiency is a common manifestation of gluten induced intestinal damage.
- Dry eye: just as it sounds, dry eye results in uncomfortably dry eyes and sometimes small spots present on the whites of the eyes called Bitot’s spots. Vitamin A deficiency is often the root cause behind this condition as well, and research has shown it is more common in celiac disease patients.
Ophthalmologic Manifestations Due to Immune System Dysfunction
The manifestations related to immune system dysfunction stem from chronic inflammation in the body, a characteristic in autoimmunity and celiac disease. These include orbital myositis, uveitis, thyroiditis associated with orbitopathy and brain occipital calcification.
- Orbital myositis: characterized by diplopia (the perception of 2 images of a single object), pain with eye movements and exophthalmos (a bulging of the eyes). This condition generally stems from inflammation in the body and has been associated with celiac disease and research has found an association between celiac disease and inflammatory myopathies like orbital myositis.
- Uveitis: uveitis is an inflammation of the uvea (the colored layer of the eye). It can lead to vision loss, so early diagnosis and treatment is critical to protect vision. A recent study showed an association between idiopathic uveitis and patients with celiac disease.
- Thyroiditis associated with orbitopathy: otherwise known as autoimmune thyroid disease or Hashimoto’s thyroiditis, the cause (or causes) of Hashimoto’s disease is unknown. However, we know that patients usually have a genetic predisposition to autoimmune thyroid disease, and gastrointestinal immune diseases, such as celiac disease, are more prevalent in patients with Hashimoto’s thyroiditis. The anticipated link between thyroid disease and celiac is again related to chronic inflammation, as pro-inflammatory cytokines, tumor necrosis factors, and interleukin-6 are present in both Hashimoto’s thyroiditis and celiac disease.
- Brain occipital calcification: this condition manifests as a result of inflammatory changes in the region of the eyes and brain caused by immunological dysfunction. It results in low vision, and more research is needed to understand the full relationship between neuro-ophthalmologic conditions and celiac disease.
Gluten induced autoimmune diseases that affect the eyes
Gluten is the most well documented cause of autoimmune disease in medical research. In addition, celiac disease increases a person’s susceptibility to multiple forms of autoimmune disease. The coexistence of celiac disease and other autoimmune diseases have been shown in many studies.
There are also a variety of autoimmune diseases directly related to gluten exposure that can affect the eyes. For example, dry eye syndrome has been reported in gluten related autoimmune disorders such as Sjogren’s syndrome, rheumatoid arthritis (RA), and scleroderma.
Approximately 25 percent of patients with RA will have ocular manifestations. These may include keratoconjunctivitis sicca (dry eye, as mentioned previously), scleritis, episcleritis, keratitis, peripheral corneal ulceration. Less commonly, they can also include choroiditis, retinal vasculitis, episcleral nodules, retinal detachments, and macular edema.
Exophthalmos, or bulging eye occurs in approximately half of patients with thyroid disease – both hypothyroid or Hashimoto’s thyroiditis, and hyperthyroid or Graves disease. Thyroid disease is strongly linked with gluten ingestion and celiac disease.
Finally, there is a suspected link between celiac disease and lupus. Ocular disease occurs in 20 percent of patients with systemic lupus erythematosus (SLE). External ocular manifestations include keratoconjunctivitis sicca, conjunctivitis, uveitis, episcleritis, scleritis, keratitis, and a discoid lupus rash over the eyelids that is often confused with blepharitis.
Gluten induced nutritional deficiencies that can impact the function of the eyes
There is evidence that dietary antioxidants and anti-inflammatory nutrients may help decrease the risk of age-related eye disease. Many of these nutrients are often deficient in those with gluten sensitivity or celiac disease patients.
Beneficial nutrients for eye health that are commonly depleted due to gluten induced intestinal damage include the following:
- Vitamin A: Vitamin A helps to form a compound called rhodopsin which aids in night time vision. As gluten causes inflammatory malabsorption of vitamin A, loss of night vision can occur in those with gluten sensitivity and celiac disease.
- Vitamin C: Vitamin C is a highly effective antioxidant, protecting essential molecules in the body from damage by free radicals and reactive oxygen species that can be generated during normal metabolism as well as through exposure to toxins and such pollutants as cigarette smoke. The eye has a particularly high metabolic rate, and thus has an added need for antioxidant protection. Because it’s absorbed in the jejunum — the primary site of small intestine inflammation — vitamin C deficiency is common in untreated celiac patients.
- Vitamin E: Vitamin E also acts as an antioxidant. Fats are especially vulnerable to destruction through oxidation by free radicals, and the retina is highly concentrated in fatty acids. Vitamin E attacks free radicals to prevent a chain reaction of lipid oxidation. Consumption of gluten proteins leads to disturbances in the immune system as well as secondary deficiency of vitamin E.
- Beta carotene: Beta Carotene is best recognized as the orange pigment found in fruits and vegetables (like sweet potatoes and carrots). Among plant foods, it is the primary dietary source of Vitamin A, which is essential to eye health. As a fat soluble nutrient that requires small intestinal absorption, it is a common deficiency risk in celiac disease patients.
- Zinc: Zinc has been observed as the most common deficiency, with 59.4% of celiac disease patients experiencing a deficiency at diagnosis. Zinc is important in maintaining the health of the retina, is an essential constituent of many enzymes, and needed for optimal metabolism of the eye.
- Lutein and Zeaxanthin: The carotenoids lutein and zeaxanthin protect the eyes by absorbing blue light and quenching free radicals. Celiac disease is known to cause deficiencies in these fat-soluble nutrients due to intestinal malabsorption.
- Omega-3 fatty acids: The omega-3 fatty acids have a number of actions that provide neuroprotective effects in the retina, including modulation of metabolic processes affecting oxidative stress, inflammation, and vascularization. Docosahexaenoic acid (DHA) in particular is a key fatty acid found in large amounts in the retina. Research has shown that DHA is decreased in subjects with active celiac disease. While serum levels increased following a gluten-free diet, they still remained significantly lower than control values (those tested without celiac disease).
- Vitamin B12: Vitamin B12-deficiencies are likely the most common culprit of nutritional optic neuropathies, a gradual loss of vision in the eyes. Deficiencies can occur in diseases that inhibit small intestine absorption. Gluten sensitivity and celiac disease are a common cause of vitamin B12 deficiency.
- Folate: Folate deficiency can also result in optic neuropathies or gradual vision loss, and is common in people with malabsorption concerns due to a number of factors, including gluten sensitivity and celiac disease.
- Copper: Copper deficiency can also result in optic neuropathies or gradual vision loss, and is usually caused by malabsorption syndromes like celiac disease. Less commonly it can be caused by excessive zinc intake, which blocks the absorption of copper.
The Role of Nutrition in Eye Health
Many of these nutrients have been studied with respect supporting eye health and preventing vision decline. Nutrition has gained tremendous respect thanks to the ability of these key nutrients to support long-term eye health. Interestingly, over time, our food system has become flooded with processed foods devoid of nutrients, and our produce has become less nutrient dense thanks to commercial farming practices. While food was once enough for healthy eyes and vision, it is now more difficult to achieve eye health while aging without attention to these key nutrients. Conditions like gluten sensitivity and celiac that can cause malabsorption even further exacerbate the need for attention to nutrition and supplementation in order to support long-term eye health and vision.
One study enrolled 3,640 patients with AMD and declining visual acuity to administer high-dose vitamins C and E, beta carotene, and zinc supplements. Comparison with the placebo group demonstrated a statistically significant odds reduction for the development of advanced AMD by supplementing with the antioxidants plus zinc. The study followed these patients for up to nine years.
Another study evaluated the effect of multivitamin supplements and vitamin E on patients at risk of nuclear opacification. In regular users of multivitamin supplements, the risk of nuclear opacification was reduced by one third. In regular users of vitamin E supplements and persons with higher plasma levels of vitamin E, the risk was reduced by approximately half.
Another large, randomized study found that women taking B vitamins (including folate and vitamin B12) reduced their risk of early macular degeneration by more than a third after seven years.
Celiac disease and non celiac gluten sensitivity can manifest in many ways outside the digestive system. This includes vision problems and eye disease. Immune alterations and nutrient malabsorption are both culprits in this process.
Ophthalmic symptoms should be investigated in both adults and children and taken into consideration as a potential early manifestation of gluten related issues, including celiac disease. Even if digestive symptoms are not present, ophthalmic symptoms may help indicate a gluten related problem, particularly if other root causes of ophthalmic-related issues have been ruled out.
Furthermore, if you have been diagnosed with celiac disease or non celiac gluten sensitivity, it is wise to be vigilant in testing for, consuming, and supplementing as necessary with nutrients needed for eye health, as they are often found to be depleted even in patients who have been strictly following a gluten-free diet.