Asthma is a chronic inflammatory disorder of the respiratory system, which usually affects children's 10%. The 50% of its etiology is genetic, but the remaining 50% can be influenced and controlled in some way.
Is there a cure for asthma?;
To date, there is no known cure for asthma. However, most people with this condition are able to manage the symptoms effectively in supportive ways. Asthma cases seem to have an increasing trend, and this is worrying experts. In Greece 6.6% of the population has been diagnosed with asthma, a rate slightly higher than the European average (5.1%).
Methods of asthma prevention
In looking for reasons for this increase, and possible ways to prevent it, attention has turned to factors such as allergies. Others, however, blame strong odours, anxiety disorders or even nutritional factors such as vitamin D deficiency.
What is the role of vitamin D?;
One of the reasons that asthma has been booming in recent years may be a lack of vitamin D. Vitamin D is a fat-soluble vitamin and one of the vitamins that our bodies can synthesize on their own, from the cholesterol under our skin and the effects of sunlight.
Children are now playing less in the sun and spending more time at the computer or watching TV, resulting in insufficient vitamin D. Vitamin D has known effects on lung development and the immune system and may be important in the development, severity and onset of allergic diseases such as asthma, eczema and food allergies. Many studies suggest that vitamin D has a protective effect against asthma flare-ups.
What did the research show about asthma and vitamin D?;
Research found that children with asthma who took a vitamin D supplement3 at 500-1000 IU per day halved asthma attacks, perhaps because this reduced the frequency of respiratory infections by increasing immunity, while at the same time reducing the physical effects of inflammation.
Most suggest that higher blood levels of vitamin 25(OH)D are associated with a reduced risk of asthma attacks. Of course, these findings need to be confirmed through clinical trials and studies. For another possible explanation, it may be that people with severe asthma spend more time indoors out of fear, and therefore have lower levels of the vitamin.
Dairy products
We know that dairy products are very rich in vitamin D. Dairy has often been implicated as a common trigger for asthma, but there is very little scientific evidence to support this myth. A brief review of the existing literature showed that there is not enough evidence to directly link dairy consumption to asthma.
National asthma organisations such as Australia's do not recommend the systematic avoidance of dairy products for asthma management and advise that dairy does not increase mucus as is believed. Even in people with lactose intolerance - the main sugar in milk, because this is not considered a food allergy but a food intolerance for which an enzyme deficiency is responsible, the triggering of asthma symptoms is not affected. It is usually food allergies that trigger the onset of asthma symptoms such as coughing, sneezing or mucus. Dairy allergy is more common in children, but this ceases as their digestive system matures in most cases.
Finally, people who have food allergies, such as to dairy, seafood, wheat and nuts, may also have asthma or are more likely to develop it. They should check with their doctor to see if a food is causing their allergy through special tests, which also affects the occurrence of an asthma attack. Asthma patients are at a higher risk of developing osteoporosis due to the use of steroid medications, so they should consume calcium-rich dairy products for better skeletal health. These should only be avoided on doctor's orders and if replaced with other sources of calcium.
Antioxidants and asthma
In another study of adolescents, there was a reduction in asthma symptoms when consumption of calories from rice, nuts, starch and vegetables was increased. Research has shown that if these results are generalised and consumption of these foods is increased, it is possible that a significant reduction in asthma symptoms can be achieved. We know that oxidative stress is important in the pathophysiology of asthma, contributing negatively to its onset and exacerbation. This can be counteracted through antioxidants such as vitamins E and C, carotenoids, lycopene and flavonoids, which we ingest from the diet through fruits and vegetables.
What do the surveys show?;
Vitamin E, which is mainly found in vegetable fats, is associated with a lower incidence of asthma symptoms. Furthermore, vitamin C, found mainly in citrus fruits and green vegetables, helps keep airways open, boosts the immune system and reduces the inflammation that occurs in allergic asthma. The same study showed that people with asthma had lower levels of antioxidants, such as carotenoids, in their blood compared to a healthy population.
However, there is no documented evidence that a diet rich in antioxidants affects asthma. However, research that reduced the antioxidant intake of asthmatic patients to one serving of fruit and two servings of vegetables per day - as is the usual intake in Western-style diets - has shown that it made asthma symptoms and attacks worse. This and other studies in the same vein suggest that Western-style diets contribute to worsening lung function and worse asthma control.
At the same time, studies examining the improvement in respiratory function after increasing fruit and vegetable consumption as opposed to consuming dietary supplements showed positive results only in the first case. This may be due to the fact that fruits and vegetables contain a combination of antioxidants and achieve better absorption of these by the body, compared to dietary supplements which usually contain single nutrients or few combinations of them.
Fat and asthma
Finally, the good polyunsaturated fatty acids, omega-3, found in oily fish, seafood, nuts and green leafy vegetables, act as anti-inflammatory agents and lead to a reduction in asthma cases. Of course, the ratio between omega-3 and omega-6 fatty acids is very important, because omega-6 are the ones that increase inflammation, while omega-3 are the ones that reduce it. Most studies do not come to firm conclusions about their effectiveness, but they do report an improvement in symptoms when the diet is enriched with them.
How does junk food affect asthma and eczema?;
Fast food was also shown to be linked to childhood asthma. A study involving 500,000 children in 51 different countries around the world found that poor eating habits lead to an increase in the incidence of asthma and eczema. It also showed the protective effect of eating fruit and vegetables.
Teenagers who eat fast food 3 times or more per week have 40% greater chance of developing severe asthma
Professors from the University of Nottingham in England and Auckland in New Zealand reported that for children aged 6 or 7 years the rate reaches 27%.
The same well-known scientists point out that eating three or more servings of vegetables and fruit reduces the risk of asthma by about 11%. They record that if the link appears to be causal, then this evidence has a significant impact on public health.
Food preservatives and asthma
Sulfites and tartrazine are the most common additives that cause allergies. Sulphates are salts used to preserve processed foods and are often found in products such as pickles, wine, lemon brine and dried fruit. Tartrazine is a yellow food colouring. Nitrites occur naturally in some foods such as fruits and vegetables, but are added to cured meats such as ham, salami and sausages to make them safe to eat for longer periods of time. There is no evidence that eating foods containing synthetic nitrites can cause asthma symptoms.
Although rare, some people with asthma may be sensitive to salicylic acids found in tea, certain herbs and spices. It is also found in painkillers and aspirin, which are usually blamed more than food for triggering asthma attacks.
In addition, asthma attacks can be triggered by gas-containing foods, including legumes, cabbage, soft drinks and garlic and onions. Furthermore, when consuming large meals, these put pressure on the diaphragm, especially in people with gastric reflux. This pressure can cause chest pressure and trigger an asthma attack.
Herbs and asthma
A survey by the British Asthma Campaign Committee found that 60% of people with moderate asthma and 70% of those with severe asthma have used alternative treatments to improve or cure their condition.
Study showed that gingko biloba extract acts as an anti-inflammatory and reduces bronchospasm in asthmatic patients within 8 weeks of use compared to the control group. In recent years marijuana has also been used to treat asthma. Research shows that its use brings about a significant reduction in airway resistance and has an active bronchodilator effect in asthmatic patients. Furthermore, Chinese herbs are the most popular in the alternative treatment of asthma.
Of course, there is no repeated evidence for the use of herbs or herbal treatments for asthma. Considering how popular such treatments are, more clinical research, more rigorously designed, would need to be done to confidently recommend such treatments.
Irini Kontopidou (Clinical Dietitian - Nutritionist, M.Sc), Mary Micheli (Dietitian - Nutritionist, MSc) and Georgia Georgiou (Clinical Dietitian - Nutritionist, M.Sc).
