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Fish Fat May Reduce Children’s Asthma Risk
12/5/2005
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New findings support results of prior research; inhalers may raise risk of severe attacks

by Craig Weatherby



Asthma is a very common, often disabling, and potentially fatal condition. About one in 10 children and one in 20 adults suffer its effects.


Asthma's origins remain somewhat mysterious but its symptoms stem from an inappropriate inflammatory response in the body, triggered by the immune system.


Key Points

  • Asthmatic mothers who eat plenty of oily fish may reduce their children’s risk of asthma, or reduce its severity.
  • Young children who eat plenty of oily fish, whole grains, or dairy may reduce their risk of asthma, or its severity.
  • Short-acting (but not long-acting) inhalers may increase the risk of severe asthma attacks.

One of the chief benefits of long-chain marine omega-3s is their ability to reduce excessive levels of inflammation in the body.  They exert this effect via their influence on the body’s production of a variety of chemicals involved in inflammation, including eicosanoids, platelet activating factor, free radicals, cytokines, and others.


Medical researchers explore the effects of various anti-inflammatory foods and drugs in an effort to deliver relief to asthma sufferers, and help prevent it from developing in children.


Scientists engage in two kinds of studies in this area. Observational studies look for statistical relationships between diet and rates of asthma and/or levels of pro-inflammatory chemicals related to asthma, while clinical trials test various substances versus a placebo, to see if they reduce the risk or severity of asthma, and/or blood levels of pro-inflammatory chemicals.


Mothers’ diets affect children’s asthma risk

The results of two clinical studies published this year—one by US researchers, another by Dutch investigators—indicate that pregnant mothers with asthma who eat oily fish, which are inherently high in omega-3s significantly reduce their children’s risk of developing asthma.


In contrast, mothers who ate fish sticks actually raised their children’s risk of asthma. This is not surprising, since the kinds of fish used in sticks are lean white fish low in omega-3s, while the bread coating typically contains three pro-inflammatory elements: refined flour, omega-6 fatty acids and hydrogenated fatty acids.


It seems safe to assume that the omega-3s in fish fat accounts for preventive and symptom-reduction effects of oil-rich dietary fish, given the findings of research designed to test this hypothesis.  In 2003, Australian researchers published the results of a placebo-controlled clinical study in which pregnant women took omega-3 supplements or a placebo starting five months after conception, until delivery.


In this study, the children of the mothers taking omega-3 supplements produced lower levels of pro-inflammatory chemicals (cytokines) in response to common allergens, and were three times less likely to exhibit an allergic reaction to eggs at one year of age.



The same Australian research team published the results of a related study in 2003. This one tested the effects of maternal omega-3 supplements on children who were deemed at high risk of developing eczema (another inflammatory disorder).  The results showed positive preventive results similar to those seen in their asthma-prevention study.

We should note that the greatest therapeutic effect in eczema is seen when patients take supplemental doses of an anti-inflammatory omega-6 fatty acid called GLA, which some people’s bodies have difficulty making from dietary omega-6 fatty acids.  Nonetheless, the positive effects seen in this study support the anti-inflammatory benefits of marine omega-3s.


Whole grains and dairy may also help

It seems that fish rich in omega-3s aren’t the only foods that might reduce risk of allergies in children. The Dutch team whose findings we cited above also found a comparably strong link between higher consumption of whole grains and reduced allergy risk in children.


Another Dutch team published the results of an observational study in 2003, which indicate that higher consumption of dairy foods or whole grain bread by children yields a lower risk of asthma at age three. This same study found no benefit from higher fish consumption, but the type of fish—a key factor—was not defined.


Note: The belief that dairy foods aggravate or promote asthma is common, and may well be true in some cases, given the varied reactions human bodies exhibit in response to any given food in the context of a health condition. But our search of the medical databases found only evidence that diets relatively high in dairy foods either help prevent asthma, or have no effect one way or the other on its development.


Among the fish highest in omega-3s, the ones lowest in manmade contaminants are wild salmon, sablefish, herring, anchovies, sardines, and young, low-weight tuna.


Inhalers may induce severe asthma attacks

The results of a new study appearing in the current issue of the journal “Nature” indicate that short-acting inhalers used by asthmatics for symptomatic relief might increase the likelihood of an acute attack.


An international team of researchers analyzed daily lung function measurements taken in a large group of asthma patients during a clinical trial in New Zealand.  The results show that regular use of the inhale commonly used by asthmatics for relief can increase the instability of lung function, and increase the likelihood of an acute attack.


Their analysis of the fluctuation of airway obstruction in a population of 80 asthmatics over an 18-month period showed that asthma is a dynamic process that can develop a long- term pattern. It appears that regular use of a long-acting bronchodilator (salmeterol) decreases risk of airway obstruction but a widely used short-acting bronchodilator (albuterol) increases the long-term risk.



Sources


Omega-3s and asthma prevention

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Asthma and inhalers

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Anti-Inflammatory effects of omega-3s

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