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Seeds and nuts are a good source of dietary selenium. [Photo: Bigstock]

Q&A: High selenium foods

Q — I’m interested in getting more selenium into my diet. Can you recommend some high selenium foods that I should be eating regularly?

A — Selenium is a good example of how science can sometimes get it wrong when it comes to health. Up to the late 1950s. But in 1957 scientists discovered that it was actually an essential trace element necessary the prevention of disease. It is required by the body for proper functioning of the thyroid gland, and may help protect against free radical damage and cancer.

Selenium, which belongs to the sulphur family of elements, is found in both vegetable and animal products, particularly seafood, liver, and cereals. It’s concentrations in plants generally reflects its concentration in soils, and many nutritionists are concerned that as our soils become depleted of essential elements such as zinc, potassium, magnesium and calcium, as well as selenium, we may not be getting enough from our food.

By itself, mild selenium deficiency does not usually cause illness, but it can make the body more susceptible to illnesses caused by a variety of other nutritional, biochemical, or stressors.

It can also lead to pain in the muscles and joints, unhealthy hair, and white spots on the fingernails.

Problems of deficiency

Genuine deficiency has been linked with a number of big health problems. In extreme cases it may even lead to Hashimoto’s disease, a condition in which the body’s own immune system attacks the thyroid.

In addition, selenium is widely believed to have anticancer actions. There is an association between low blood levels of selenium and a variety of cancers. But the strongest evidence for the protective effect of supplement comes from a double-blind trial of 1,312 Americans with a history of skin cancer who were treated with 200 mcg of yeast-based selenium per day or placebo for 4.5 years, then followed for an additional two years.

Although no decrease in skin cancers occurred, a dramatic 50% reduction in overall cancer deaths and a 37% reduction in total cancer incidence were observed. There was also a statistically significant 58% decrease in cancers of the colon and rectum.

Adequate selenium has also been associated with a reduce risk of heart disease and depression and, when taken in conjunction with zinc and a multi-vitamin better overall immune function.

And that makes an important point. No nutrient is enough by itself and selenium like all nutrients may work best as part of an overall nutritious and balanced diet.

If you wish to supplement, the current recommended daily value (DV) for selenium is 70µg (micrograms), though health intervention studies have used levels of up to 200 µg daily without harm. One of the best ways to get the selenium you need is as part of a well-balanced multivitamin and minerals supplement.

An excess of selenium is rare except if you have been megadosing and can lead to bad breath, diarrhoea, and even hair loss.

Selenium in your diet

If you want to try and get more selenium from your diet be sure to include more of the following foods:

Brazil nuts     

An ounce (30g) of Brazil nuts (approx 6 nuts) can provide around 8 times your recommended daily intake of selenium, as well as being rich in iron and calcium. Other nuts high in selenium include cashews, walnuts and macadamia nuts.

Oysters

A 100g (3 oz) portion of oysters – raw or cooked, can supply more than double your daily requirement of selenium. Other seafood choices include mussels, octopus, lobster, clams, squid and shrimp.

Tuna

A 100g (3 oz) portion of tuna can supply one and a half times your daily requirement of selenium. This comes with a caution however since tuna and other large predators can be contaminated with mercury and other ocean-borne pollutants. You should only eat tuna on occasion and seek advice from a doctors or nutritionist if you are pregnant.

Other good fish choices include rockfish, swordfish, halibut, mackerel and snapper.

Whole grains

A slice of wholegrain toast can supply more than half your daily recommended value of selenium, as can oatbran bread or bagels. White bread, on the other hand, is a poor source of selenium.  Other whole grains high in selenium include brown rice, barley, oatmeal and quinoa. Any 100g (3 oz) serving of these will supply around 20% of your recommended daily needs.

Seeds

Sunflower seeds are fairly high in selenium, and also have healthy fats that your body needs to stay healthy. Opt for raw or dry roasted to keep the saturated fat count down. Other seeds high in selenium include chia seeds, sesame seeds, flax seeds (linseed) and pumpkin seeds.

Meat

A 100g (3 oz) serving of meats like beef lamb and pork can provide more than half your daily requirements. Opt for grass fed and preferably organic meats to get the best combination of nutrients and healthy fats. If you are concerned about eating too much red meat a 100g serving of chicken can provide around a third of your daily requirement. Again choose organic to get the best quality meat.

Mushrooms

Whatever your favourite mushroom is it is likely to be a good source of selenium. Mushrooms can be added to plenty of dishes to boost their nutritional quality or simply be eaten raw on their own or in a salad. Shiitake, Portobello, chestnut and white mushrooms are all good choices and a 100g (3oz serving can supply around 20% of your daily needs.