Diet and the lungs

Our diet can negatively affect our lung health by causing:

• Inflammation of the airways
• Allergic responses
• Oxidative stress
• Obesity, which can contribute to breathing problem

Our diet can positively impact on our lung health by:

• Combating oxidative stress
• Having an anti-inflammatory effect
• Helping us to maintain a healthy weight
• Helping our airways to relax
• Helping to reduce the risk of cancer

Oxidative stress

We breathe in an incredible 15 cubic metres of air each day. Within the air that we breathe there are many factors that can affect our lungs, such as cigarette smoke, air pollution and infections. These factors can damage our lungs through a process called “oxidative stress”. As part of the process of generating energy from oxygen by the cells in our body, we naturally produce chemicals called free radicals. Sometimes the body’s immune system’s cells purposefully create them to neutralise viruses and bacteria. However, environmental factors, such as pollution, cigarette smoke and infections, can also give rise to free radicals. If too many of these free radicals build up in our bodies they can damage cells, tissues or organs, and it is this process that is termed oxidative stress.

How can diet negatively affect our lungs?

Salt 

The recommended daily intake for salt is around 5–6 grams per day. But most people far exceed this amount. High levels of salt have been shown to affect asthmatics by causing muscles in the airways to tighten, reducing blood flow to the lungs and affecting some of the normal processes that go on in the lungs.

High salt intake also leads to fluid retention, which can contribute to difficulties breathing in some people.

Sources:

A lot of salt may already be included in many of the foods that we eat, especially in processed and tinned foods.

Trans- and omega-6 fatty acids

Over the last 15 years, there have been many changes in the diet of European people. The most obvious change is in the amount of omega-6 and trans-fatty acids that are eaten. Trans-fatty acids (or trans-fats) result from the industrial processing of unsaturated fats, which enables the fat to withstand food production and gives the food a longer shelf-life. Trans-fatty acids are neither essential nor beneficial for our health. It is well known that trans-fatty acids contribute to heart disease. Omega-6 fatty acids, although essential in our diet, are consumed at too high a ratio compared with omega-3 fatty acids. Excess omega-6 in our diet also contributes to heart disease. Trans-fatty acids and excess omega-6 fatty acids can also affect the lungs by changing the body’s response to inflammation and making our bodies more open to infection.

Sources:

• Trans-fatty acids – Baked goods: biscuits and cakes Fast food

• Omega-6 fatty acid – Plant oils: sunflower oil, maize oil, peanut oil

Food additives

Some common food additives may trigger an attack in people with asthma. These include tartrazine (a commonly used yellow food colouring), monosodium glutamate (an additive to enhance flavour in savoury snack foods) and sulphites (a preservative commonly used in processed foods).

Sources:

• Tartrazine – Coloured fizzy drinks, soups, sauces and sweets

• Sulphites – Wine, fruit juices, canned fish and dried fruit

• MSG – Gravy, soy sauce and packet soups

Being overweight

People who are obese or overweight have a much greater chance of becoming asthmatic. It is estimated that 15–38% of cases of asthma could be prevented in adults who are obese. Being overweight or obese also increases the risk of having obstructive sleep apnoea. Apnoea means temporary cessation of breathing. And in obstructive sleep apnoea frequent pauses in breathing occur during sleep due to closure of the airways. This is due to the restrictions that are made on the airways because of excess fat around the neck.

How can diet positively affect our lungs?

We can fight the damage done by oxidative stress in our bodies by eating foods rich in antioxidants. Antioxidants effectively “mop up” free radicals and so prevent them from causing damage.Antioxidants

Sources:

• Vitamin C- Citrus fruits (oranges, lemons, grapefruits), kiwi fruit, broccoli and green peppers

• β-Carotene – Apricots, mango, carrots, peppers and spinach

• Vitamin E- Grains, wheatgerm, almonds and peanuts

• Lycopene – Tomatoes and processed tomato products

• Selenium- Grains, brazil nuts, animal products, especially organ meats and seafood

Magnesium

Magnesium is the fourth-most-abundant mineral in the body and is essential for good health. Magnesium helps enzymes to work. Enzymes are biological catalysts that speed up the chemical reactions in our bodies. Magnesium may also help the muscles in our airways to relax and help control our body’s response when fighting an infection.

Sources:

• Nuts
• Cereals
• Seeds
• Carrots and spinach
• Seafood

Omega-3 fatty acids

Omega-3 fatty acids are essential for good health but are deficient in most people’s diets. Omega-6 fatty acids are also essential but are over eaten. The ideal omega-6 to omega-3 ratio in our diet is 4 to 1. However, in the average modern diet the ratio is closer to 20 to 1. Omega-3 fatty acids help to control the growth of cancer cells. They also have an anti-inflammatory effect by reducing the production of cells that are involved in asthmatic and allergic reactions.

Sources:

• Oily fish and shellfish
• Soy
• Leafy vegetables

A balanced diet

A balanced diet with a high intake of fruit, vegetables and fish reduces the risk of developing lung diseases, especially asthma and COPD. Although diet and its affects on our lungs is an area that is still being studied, it is clear that by doing the following we can help maintain good lung health:

• Eat a balanced diet with a lot of fruit, vegetables and fish.
• Reduce salt intake.
• Restrict the amount of trans- and omega-6 fatty acids in our diet.
• Maintain a healthy weight.
• Do moderate exercise.

Diet and asthma

Asthma is a common, life-long chronic disease in which the lung airways become inflamed and narrow, causing problems breathing. Asthma affects both children and adults and can develop at any age. Symptoms include wheezing, shortness of breath, chest tightness and cough. The causes of asthma are not completely understood, although environmental factors (allergens and pollutants) can trigger asthma attacks.

• Some foods can provoke symptoms in some asthma patients by causing an allergic reaction (milk, eggs, and nuts).
• Some foods can provoke asthma by promoting inflammation (fatty foods).
• Some foods control inflammation because they contain anti-inflammatory components (onions).
• People who have asthma and are obese show improved lung function when they lose weight. This is in part due to increased space in the chest cavity which allows the lungs to expand fully.
• A well-balanced nutritional diet helps to keep the immune system strong, and wards off colds and flus which are common asthma triggers.
• Drinking lots of water is important as it
  • helps the production of watery thin mucus which may make coughing easier, and because
  • dehydration is sometimes linked to asthma attacks.

Diet and COPD

Chronic obstructive pulmonary disease (COPD) used to be referred to as chronic bronchitis and/or emphysema. In this disease, the sufferer’s airways become smaller, causing them to have difficulty breathing. Although it is very common, not many people know about COPD. The symptoms of the disease include cough, sputum (mucus) production, shortness of breath (especially with exercise), wheezing and chest tightness. Smoking is the main cause of COPD, and passive smoking and indoor and outdoor pollution have also been shown to play a role.

• Salt intake can lead to fluid retention which can interfere with breathing in COPD.
• Being overweight will make the symptoms of COPD worse, as carrying the added weight requires more work for the body and keeps the lungs from expanding fully.
• Some people with COPD may have serious problems maintaining their normal weight, as additional calories are needed to make up for those they burned with the act of breathing.

Diet and cystic fibrosis

Cystic fibrosis (CF) is a common genetic disease, which mainly affects the respiratory and digestive systems in children and young adults. CF causes the production of thick, sticky mucus that clogs the air passages of the lungs, leading to persistent infection and permanent lung damage due to scarring. Some 94% of CF deaths are due to respiratory failure. Currently, individuals with CF have an average lifespan of approximately 30 years.

• Extra calories may be needed to compensate for the poor absorption of nutrients in CF. These extra calories also help to meet the greater energy needed for breathing.
• A high-calorie, high-fat diet is vital for normal growth and development in children with CF.
• “Fat-soluble” vitamins (A, D, E and K), are not absorbed properly in CF so these should be taken daily.

Author

This material was compiled by the ELF office with the help of ERS expert Dr Isabella Romieu. The factsheet was reviewed by the ERS Advisory Board.

Information sources

The following article from the ERS publication “Breathe” was used as a basis for this factsheet:

Romieu I, McKeever K. Diet in respiratory disease. Breathe 2005 Volume 2, Pages 155-168.