Make wheezing and puffing a thing of the past with advice on beating asthma from top integrated general practitioner Dr Sarah Brewer.
Make wheezing and puffing a thing of the past with advice on beating asthma from top integrated general practitioner Dr Sarah Brewer.
Asthma is an inflammatory disease of the lungs that affects five and a half million people in the UK. The incidence has doubled over the last 25 years, and the number of asthma attacks sufferers experience is also increasing. Why we have one of the highest incidences of asthma remains unknown, but it is thought to result from ill-understood interactions between our genes, immune system and our 21st century diet, lifestyle and environment.
Diet comes first
Inflammatory diseases such as asthma may be linked with an imbalance of dietary fats. Our ancestors evolved on a Stone Age,hunter-gatherer diet of green plants, wild animals and fish which supplied equal amounts of omega 6 fatty acids (from natural vegetable oils) and omega 3s (from oily fish). Our modern diet now supplies seven times more omega 6s than omega 3s. This increases the production of inflammatory chemicals in the body and may partly account for the increased incidence of asthma.
Tip
Consume more omega 3s, found in:
Oily fish (two to four portions per week) such as mackerel, herring, salmon, trout, sardines, pilchards, fresh tuna (not tinned).
Wild game meat such as venison and buffalo.
Grass-fed beef.
Omega 3 enriched eggs.
Omega 3 fish oil supplements.
Cut out excess omega 6s by consuming less:
Omega 6 vegetable oils such as safflower oil, grape-seed oil, sunflower oil, corn oil, cottonseed oil or soybean oil. Replace with healthier oils such as rapeseed, olive, walnut, almond, avocado, hempseed or macadamia oils.
Margarines based on omega 6 oils such as sunflower or safflower oil.
Convenience foods and fast-foods.
An apple a day…
People with a high intake of fruit and vegetables have better lung function and are less likely todevelop asthma than those who eat little.
Apples, for example, are a rich source of powerful antioxidants , including quercetin, which reduces histamine release and promotes bronchial relaxation. Those who drink apple juice from concentrate at leastonce a day, or who eat five or more apples per week are up to half as likely to experience asthma as non-apple eaters.
Tip
Eat plenty of raw fruit and vegetables for their vitamin, mineral, antioxidant and fibre content. Antioxidants can help to strengthen lung tissue, reduce inflammation and improve asthma symptoms. Eat fruit andvegetables raw or steamed where appropriate.
Did you know?
Coffee and dark chocolate are plant extracts containing caffeine and theobromine which suppress coughs and reduce airway spasm. A regular coffee intake can reduce the chance of asthma symptoms by 30 per cent compared with non-coffee drinkers.
Food intolerances
Avoid any foods to which you know you are sensitive, and which act as triggers for your asthma. If you can’t pinpoint the cause, try excluding the foods that are the most common triggers for a few weeks to see if this helps. Eg cow’s milk, eggs, peanuts, wheat, citrus fruits and food additives, especially sulfites, tartrazine, benzoates and monosodium glutamate.
Tip
If excluding food groups for more than a few weeks, seek nutritional advice to avoid nutrient deficiencies.
Sulfites
As many as one in 10 people with asthma have a sulfite hypersensitivity. Sulfites are antioxidant preservatives (numbered E220 to E229) used in foods and drinks to preserve colour.
People with a sulfite sensitivity may develop wheezing and chest tightness when they consume food or drinks containing sulfites, or when inhaling sulfite fumes. The most likely reason is that sulfites dissolve in the mouth during chewing to form sulfuric acid and release sulfur dioxide gas, which acts as an irritant.
Another possibility is that sulfites readily stick to proteins, and may alter them sufficiently that they are seen as ‘foreign’. The body then mounts an attack against the foreign protein by producing an antibody called IgE. This can trigger the release of histamine, causing an allergic reaction. To eliminate sulfites, check labels and avoid foods in which they occur naturally such as fermented beverages and wines.
Common dietary sources of sulfites
Very high level
Bamboo shoots, coconut (desiccated), coleslaw (commercial), dehydrated fruits and vegetables, dried fruits and vegetables, fruit juices, ginger (dried, preserved), grapes and grape juice, lemon juice (bottled), lime juice (bottled), molasses, pickled onions, red cabbage etc, potatoes (frozen sliced, processed, instant), preserved cut fruit or vegetable salads, sauerkraut, sun dried tomatoes, tomato pastes, ketchup, purée, trail mix, wines
High level
Citrus peel, dried potatoes, fruit fillings and toppings, glace fruits, maraschino cherries, sauces such as mint sauce/jelly, wine vinegars
Moderate level
Alcoholic cordials, breakfast cereals containing dried fruit and/or coconut (eg muesli, granola), cheeses, cider, cider vinegar, clams (tinned or bottled), corn starch, corn syrup, dextrose, fruit juices and soft drinks, gelatine, glucose syrup, gravies, guacamole,jams and jellies (not all), maple syrup, mincemeat, mushrooms (sliced and frozen), pectin, pickles and relishes, pastry shells (frozen), pizza dough (frozen), potatoes (frozen), potato crisps, sausages, burgers, pork pies and other preserved meats, seafood (processed shrimp, prawns,crab, lobster, crayfish, squid) eg seafood soup, tuna (canned), vegetables (dehydrated)
Salicylates
One in five adults with asthma has a sensitivity to aspirin (a salicylate) which can trigger an attack. Salicylates block the action of an enzyme, COX-1, which is involved in the breakdown of a fatty acid called arachidonic acid. When aspirin switches off COX-1, arachidonic acid is instead broken down to produce leukotrienes. These are powerful inflammatory chemicals that cause inflammation in the nose, sinuses and lungs, to trigger a runny nose, airway spasm and wheezing. The result is a worsening ofasthma and accelerated growth of nasal polyps.
Salicylates similar to aspirin are also present in many foods. Although it is not proven that salicylates in food can trigger asthma, it is worth following a low-salicylate diet to see if this helps your asthma if no other dietary approach has helped.
Tip
Tartrazine, an azo-dye used as a yellow food colouring, can also inhibit COX-1, to increase production of leukotrienes. Up to one in four people with salicylate-exacerbated asthma are also sensitive to tartrazine, so you may wish to check labels for it too.
Monosodium glutamate (MSG)
Some people with asthma are sensitive to this flavour enhancer which provides building blocks for making a nerve chemical, acetylcholine, which is believed to trigger symptoms. In those who are sensitive, symptoms typically start one to two hours after ingestion and may come on as long as 12 hours afterwards. In one study involving 32 people with asthma, 14 reacted to MSG, while in another only two out of 30 people experienced respiratory problems. These discrepancies may be because symptoms only occur in those with a vitamin B6 deficiency, or when consuming MSG on an empty stomach, or with alcohol, which hastens MSG absorption.
Tip
MSG is commonly used in Asian cooking. It may be listed on food labels as monosodium glutamate, sodium glutamate, 2-aminoglutaric acid or as additive number E621. It is also present in flavourings described as: hydrolysed vegetable protein (HVP), hydrolysed plant protein (HPP) and ‘natural flavour’.
Common dietary sources of salicylates
Exceptionally high level
Asparagus, cardamom, cayenne, celery seed, cinnamon, cloves, cumin, dill, fenugreek, ginger, liquorice, mace, marjoram, mint, mustard seed, oregano, paprika, pepper, prunes, raisins, raspberries, rosemary, sage, tarragon, thyme, turmeric.
Very high level
Almonds, apricots, basil, tomato sauces, honey, oranges, pineapple, tea
High level
Cantaloupe melon, Champagne, coffee, cranberries, grapes, green peppers, endive, courgette, peanuts, pineapple,radish, strawberries
Moderately high level
Aubergine, avocado, broadbeans, broccoli, cherries, chillies, cucumber, grapefruit,okra, peach, pine nuts, pistachios, potatoes, squash, spinach, watercress
Benzoates
Some people with asthma are hypersensitive to benzoates used as food preservatives (numbered E210 to E219). Those who are most at risk are those who are also aspirin sensitive. The way in which benzoates can trigger asthma is unknown, but may involve the production of inflammatory chemicals in a similar way to aspirin and other salicylates.
Tip
The number of people affected is likely to be small (although one study found one in six were affected), but if you are one of those who are susceptible to benzoates, eliminating them from your diet may help to reduce the frequency of your attacks.
Common dietary sources of benzoates
Apples, avocado, black tea, blackberries, blackcurrants,blueberries, cranberries, greengages, nectarines, peaches, papayas, plums, prunes, raspberries, redcurrants, strawberries, pumpkins, kidney beans, red beans, soybeans, spinach, anise, cassia bark, cinnamon, cloves, nutmeg
