A few years ago a study by the University of Maryland showed that asthmatics are more likely to have low levels of selenium, an essential mineral that can help reduce inflammation in the airways. It is found naturally in meat, fish and eggs.
Researchers gave daily selenium supplements or a placebo to 24 patients with asthma. Those taking the supplement had reduced symptoms.
But while too little selenium can cause serious health problems, too much selenium can also be toxic.
The recommended daily amount of selenium for anyone over 14 is 55 micrograms. Women who are pregnant or breastfeeding need up to 60 mcg per day.
Which foods provide the most selenium?
1. Brazil Nuts.
One of the best sources of selenium is Brazil Nuts. Enjoying six to eight nuts would give you about 544 mcg.of selenium. So make sure you only eat a serving of Brazil nuts a few times a week to avoid selenium toxicity.
Some pastas, wholewheat breads, and wholegrain cereals, are enriched with selenium and other minerals. The amount of selenium in these products varies, but you can typically get up to 40 mcg per serving of noodles or cereal, and about 16mcg from 2 slices of wholegrain toast.
85g (3oz) of lean pork contains about 33mcg of selenium.
The amount of selenium in beef depends on the cut, but rump steak will provide you with about 33 mcg. Mince beef offers about 18mcg.
You can get 31mcg of selenium from 85g of boneless turkey. Eaten as a turkey sandwich on fortified wholewheat bread will give you extra selenium.
Chicken will give you about 22 to 25mcg of selenium per 85g of white meat.
9. Cottage cheese
162g of cottage cheese provides about 20mcg, or 30 percent of your daily recommended intake of selenium.
Eggs, cooked any way are a good source of selenium. One hard-boiled egg provides about 20mcg of selenium.
11. Brown rice
200g of cooked long-grain brown rice will provide you with 19mcg of selenium, or 27 percent of the recommended daily amount. If you eat rice with 85g of chicken or turkey you'll get up to 50 mcg of selenium , almost the entire recommended daily amount for adults.
12. Sunflower seeds
Snacking on 33g of sunflower seeds will give you almost 19 mcg of selenium.
an 80g helping of porridge will give you 13 mcg of selenium. Follow with a couple of eggs for breakfast to get 53 mcg.
You'll get about 8 mcg of selenium per 250 ml (8 fl oz ) of milk or yogurt . That's 11 percent of your needs per day. Add some milk to your enriched cereal to up your intake.
198 g of cooked lentils provides about 6 mcg of selenium, plus a healthy dose of protein and fibre. If you add them to a soup with mushrooms you'll have a vegan-friendly meal full of selenium.
It may not seem that much, but a handful (1 oz/28g) of dry roasted cashews (not the salted ones) will give you 3 mcg of selenium, making them a good choice of snack when you're in the pub!