Asthma is a chronic condition that affects the airways, causing them to become narrow and inflamed, resulting in symptoms like recurrent attacks of shortness of breath, wheezing, cough and expectoration of mucus.

Research is showing that asthma is on the increase, especially among children. Many reasons have been suggested for this increase, including increased pollution of air, food, and water, a junk food diet, increased stress on the immune system, increased and early vaccination, and the increase of new allergens such as genetically modified organisms.

Its cause isn't completely understood, but asthma is one of a group of allergic conditions, including eczema and hayfever, which can often occur together. The unpleasant symptoms of these conditions can be controlled, and research is continually showing the crucial role of basic nutrients in reducing asthma incidence and severity.

Vitamins and minerals

Many recent studies as well as a review of 40 older studies spanning 30 years and from all over the world, show the crucial role of basic nutrients in reducing the incidence and severity of asthma. These studies show the vital role of vitamins A, C, D, folates, zinc and omega-3 on reducing asthma symptoms.

vitamin D

Researchers from Costa Rica found that 175 out of 616 asthmatic children were, incredibly (considering the sunny climate), deficient in vitamin D, and that these particular children needed hospitalization for their asthma more frequently. Their low vitamin D levels were associated with increased Immunoglobulin E (IgE) levels (markers of allergy) and asthma severity. The study concluded:

Conclusions: Our results suggest that vitamin D insufficiency is relatively frequent in an equatorial population of children with asthma. In these children, lower vitamin D levels are associated with increased markers of allergy and asthma severity.

Research paper details:

Brehm JM, et al. Serum vitamin D Levels and Markers of Severity of Childhood asthma in Costa Rica. Am. J. Respir and Critical Care medicine Vol 179. pp. 765-771, (2009)

Vitamins A and C

Meanwhile, researchers from Nottingham reviewed 40 studies and 30 years of research. They analyzed data from research papers on asthma, wheeze, or airway responsiveness in relation to intakes and serum concentrations of vitamins A, C and E. The researchers concluded that "relatively low dietary intakes of vitamins A and C are associated with statistically significant increased odds of asthma and wheeze."

Research paper details:

Allen S, Britton J, Leonardi-Bee J. Association between antioxidant vitamins and asthma outcomes: Systematic review and meta-analysis. Thorax. Published Online First: 30 April 2009

folate

Two researchers from the US reviewed the medical records of more than 8000 people, collecting data on blood levels of folate (the naturally-occurring form of folic acid, or vitamin B9), respiratory and allergic symptoms, and IgE (Immunoglobulin) levels. They found that higher folate levels were associated with lower levels of the IgE allergy marker, fewer reported allergies, fewer episodes of wheezing, and reduced incidence of asthma. The lowest folate levels were associated with a 40% increase in risk of wheezing, a 30% higher risk of elevated IgE, and a 16% higher risk of having asthma as compared to the highest folate levels.

Research paper details:

Matsui EC, Matsui W. Higher serum folate levels are associated with a lower risk of atopy and wheeze. Journal of allergy and Clinical Immunology 2009. Article in Press

Nutrients Work Together

In addition to these individual vitamins and minerals, many studies have supported the importance of nutrient synergy in reducing asthma risk. For example, a randomised, double blind, placebo-self-controlled trial carried out in Egypt, found that a combined supplement containing omega-3, Vitamin C and zinc was associated with significant improvements in asthma symptoms, lung function, and markers of inflammation in the lungs. This was also found to be the case for each single nutrient alone, but the effects were greater when the nutrients were given in combination.

Conclusion: Diet supplementation with omega-3 fatty acids, Zn and Vitamin C significantly improved asthma control test, pulmonary function tests and pulmonary inflammatory markers in children with moderately persistent bronchial asthma either singly or in combination.

Research paper details:

Al Biltagi M et al. Omega-3 fatty acids, Vitamin C and Zn supplementation in asthmatic children: a randomized self-controlled study. Acta Paediatrica Volume 98 Issue 4, Pages 737 - 742 2009

All of these nutrients can be obtained from a well-balanced diet of good quality whole foods such as fruits, vegetables, and whole grains, and good food sources of these individual nutrients have been given in previous articles.