Allergy, Eczema | May 8, 2014 | Author: The Super Pharmacist
For many eczema patients a strong connection exists between food allergies and eczema symptoms. The allergic response, which stems from inflammation in the intestinal lining, can arise from a variety of causes, including illness, stress and exposure to allergens. Inflammation that becomes chronic weakens the selective barrier of the intestine, making it more permeable and allowing pathogens and incompletely digested food particles to be absorbed1. Once in the bloodstream the immune system tags these substances as foreign and attacks them, leading to a repeating cycle of inflammation and irritation of the intestinal lining and increased intestinal permeability whenever the offending foods or substances are consumed. The condition that results from increased intestinal permeability is commonly known as “leaky gut.” In eczema the immune response associated with leaky gut syndrome extends beyond the digestive tract to include irritation and inflammation of the skin. One study of patients with adverse food reactionsfound leaky gut present in all participants6. Researchers noted that symptom severity was directly related to degree of permeability and concluded that food sensitizations early in life are likely to contribute to intestinal permeability6.
Certain genetic factors may make eczema patients more susceptible to allergens and other environmental triggers. Some individuals inherit a genetic deficiency in the substance that forms protective seals, known as tight junctions, between intestinal cells2. While a healthy immune system can compensate for leaky gut to some degree, according to preliminary research, intestinal infection or stress, such as from repeated exposure to allergens, may trigger a breakdown in the intestinal barrier2. Another genetic component recently discovered in eczema, though not diet related, involves a skin barrier gene called filaggrin, which regulates fluid loss from the skin. Defects in this gene are associated with increased fluid loss and resultant dry skin that occurs in eczema3,4.
The “western” diet, high in processed foods, sugar, salt, milk products and saturated fat may have a detrimental effect on children's health that contributes to rising eczema rates around the world. An increase in the occurrence rate of eczema was observed in East Germany after adoption of a “western” diet by East Germans following reunification with West Germany. The dietary changes eventually resulted in eczema rates equal to those of West Germany. In Canada, a survey of a population of indigenous children found that, while the rate of occurrence of eczema was 17% out of a worldwide range between 10% and 30%, the number of children with moderate to severe symptoms in the indigenous Canadian population was as much as 54% higher than that reported for Australia and Japan. Processed foods contribute to intestinal permeability, in part because of their high levels of dangerous compounds called advanced glycation end products, or AGE's16. The process of glycation, in which a sugar molecule attaches to a protein or lipid, produces these destructive molecules, which can cause oxidation and inflammation that contribute to leaky gut, allergies and eczema. Glycation also increases the likelihood of your immune system reacting to the affected proteins or lipids as allergens16.
The University of Wisconsin Department of Family Medicine advocates a four-pronged approach for repairing leaky gut and fostering a healthy intestinal immune barrier that includes:
Identifying and avoiding allergenic foods helps reduce stress on the immune system, which quells inflammation and reduces eczema symptoms and flare-ups. The most common food allergens in eczema patients include cow's milk, eggs, peanuts, wheat, soy, nuts and fish7, which account for more than 90% of food allergies in children with eczema7. To further aid in distinguishing culprit foods it is helpful to know that infants tend to react most often to cow's milk, egg, peanut, and soy foods, while wheat, fish, tree nut and shellfish allergies occur predominantly in older children7. Additionally, eczema flare-ups in infants tend to occur following consumption of milk or eggs, while in older children and adults, eating pollen-related foods and exposure to inhaled allergens such as pollen and dust trigger most flareups8. However, though milk allergy is considered common, one study found that milk elimination may be over-prescribed for managing eczema in children. This study showed milk allergy in only 4% of participants, while, according to researchers, in standard practice, approximately 24% of eczema patients are placed on milk elimination diets12. On a precautionary note, elimination diets have been found to cause nutritional deficiencies in some eczema patients. Patients who eliminate milk have been found to have lower levels of calcium, zinc and vitamin B213. Eczema patients with allergies to wheat and soy who eliminate those foods may exhibit lower levels of calcium, phosphorus, iron, potassium, zinc and vitamins B2, B6 and niacin. Those who eliminate beef, pork and chicken might develop lower iron levels but higher levels of potassium, vitamin A and vitamin B2. These findings highlight the importance of careful food selection to maintain a well-rounded diet to offset the nutritional losses of food elimination. Regarding food allergy in adult eczema patients, one study found that in those with severe symptoms, allergy to animal foods occurred at a higher rate than in those with mild to moderate symptoms9. Among participants with severe eczema 51% were sensitive to all animal foods tested. By comparison, 28% of a group with mild to moderate symptoms showed sensitivity to animal foods. Plant-food allergies occurred in 64% of participants regardless of symptom levels. In another study, three weeks of a hypoallergenic diet proved effective for reducing itching and sleeplessness in adults with longstanding chronic eczema averaging 26 years21.
To promote a strong, resilient immune system and minimize risk for food allergies in children the American Association of Allergy, Asthma and Immunology recommends breastfeeding exclusively for the first four to six months10. If that is not feasible, a next-best option is to choose a formula in which the proteins are hydrolyzed – a processing method that partially digests proteins, making them more digestible. Historically, hydrolyzed cow's milk protein has been well tolerated by 90% of allergic children. However, a recent trend indicates increasing numbers of children are unable to tolerate hydrolyzed cow's milk15. In one study, 33% of children with severe eczema showed sensitivity to hydrolyzed proteins; 77% of those were sensitive to the milk protein casein, 18% were sensitive to the group of milk proteins known as whey protein and 5% were sensitive to an amino-acid based formula15. All children in the study showed symptoms of cow's milk allergy. As a precautionary note, since a child can potentially react to any type of hydrolyzed formula, several American and European pediatric medical societies recommend only introducing these formulas with your doctor's supervision15. A child who does not tolerate cow's milk or hydrolyzed cow's milk may require an amino acid formula. These avoid proteins altogether by using simple amino acids, the building blocks of proteins. Amino acids offer an advantage in that they are readily absorbed without needing to be digested first. A retrospective study showed that 36% of children with multiple food allergies who did not tolerate hydrolyzed cow's milk were able to consume an amino acid formula15. Some experts recommend that women avoid cow's milk while nursing, on the assumption that children may be less likely to develop an allergy to cow's milk. In one study, nursing mothers whose infants developed eczema in the first three months of life or who had older children who showed an allergy to milk eliminated cow's milk from their diets11. Results showed lower levels of antibodies to milk proteins in both the mothers and their infants. After the initial phase of exclusive breastfeeding or formula feeding, introduce solid foods one at a time so that you can observe any potential signs of allergic reaction. Delaying the introduction of solid food beyond six months has not been shown to offer any extra measure of allergy prevention10.
Supplementing with probiotics is a safe, potentially effective means for decreasing immune system triggers and improving eczema symptoms. Probiotic bacteria are thought to inhibit inflammation and promote proper development of young, immature intestinal, respiratory and immune cells into healthy, fully mature cells17. Conversely, lack of sufficient probiotics could lead to poorly developed cells and tissues susceptible to developing allergic responses. Starting an infant on probiotics in the first weeks of life may help prevent intestinal permeability, ward off food allergies and prevent eczema. Supplementation with probiotic Lactobacillus bacteria decreased frequency of intestinal inflammation by three times compared to a placebo in children with eczema, in one report19. However, probiotics are only a piece of the puzzle and may not provide the entire solution. A study of Asian infants found that probiotic supplementation of a cow's milk formula proved ineffective at preventing food allergy or eczema22. Supplementing a hydrolyzed protein formula with probiotics also failed to prevent eczema in infants, in another study. Certain species of bacteria may offer greater eczema-prevention benefits than others. Supplementation with the bacteria Lactobacillus rhamnosis from birth to two years of age has been found to decrease the prevalence of eczema by half when the children were two and four years old18. By contrast, the same study found that supplementation with the probiotic Bifidobacterium animalis lactis exerted no beneficial effect on eczema occurrence. A report on adults with moderate to severe eczema noted that a particular strain of Lactobacillus salivarius known as LSO1 demonstrated superior immune-modulating benefits compared to two other strains of the bacteria20.
An important component of cell membranes, certain fats, notably polyunsaturated fats contribute to the structural integrity and elasticity of skin and may provide particular benefits for eczema patients. Fish oil supplementation in the first months of life has been shown to help prevent food allergies in high-risk infants31. Likewise, children of women who consume diets high in omega-3 fatty acids tend to have lower rates of eczema32. Diets high in arachidonic acid, a polyunsaturated fatty acid in meat, eggs and dairy, were found to be associated with lower levels of eczema in a large study of Japanese children30.