This week we are going to look at the trace mineral Selenium in our series on minerals that are essential to our health.
Selenium has a number of crucial functions within the body including playing a part in healthy growth and reproduction. It is also needed to keep some of your major organs healthy including the liver and the heart. More importantly; recent research is suggesting that it may protect you against cancer. Part of its power comes from the ability to act as an antioxidant, clearing the body of free radicals, which are the unstable oxygen molecules that cause DNA damage to cells, leading to tumours. It works best in conjunction with a group of nutrients including vitamin E, vitamin C and Vitamin B3. Most of the success has been in the laboratory where selenium has broken down carcinogens and encouraged damaged cells to self-destruct before they become cancerous. It is hoped that the selenium in our daily diet also provides this affect.
The selenium works by activating an antioxidant enzyme called glutathione peroxidase. Apart from its possible affect on cancers, selenium is also essential for a healthy functioning immune system by stimulating the activity of white blood cells, the primary component of the immune system. Our immune system like any essential function within the body is likely to become stressed and cease to function as efficiently as it should. Selenium is therefore an important part of our daily diet and for men in particularly it may be very important in the prevention and treatment of prostate cancer.
Selenium may not only be a preventative, but also could help survival rates for those patients who are already suffering from cancer. However, as with any naturally occurring nutrient it must only be supplemented in large doses under the supervision of a medical professional. The recommended daily dose is 55mcg per day for adults but the usual supplement for preventative and therapeutic benefits is between 200mcg and 400mcg.
A normal diet should provide more than enough selenium to keep you healthy and you should be getting around 100mcg of the mineral per day from your food.
One of the main concerns for nutritionists is that the soil that nourishes the food that we eat may be losing its selenium content along with a number of other essential minerals. When tests have been carried out on rheumatoid arthritis sufferers and heart patients, selenium is one of the minerals that’s levels are depleted. Many of these people show indications of following a healthy diet including those foods that should contain adequate levels of selenium. Again we have to question the nutrient quality of the fresh food we are consuming or our ability to process that food. My inclination is to the depletion of the naturally occurring minerals in the soil of our crop growing areas.
Some of the health areas that selenium may be associated with other than cancer are asthma, depression, skin problems, heart disease, infertility, and reduced thyroid function. Symptoms of deficiency are weakness or pain in muscles, changes in the colouring of hair and skin and whitening of the bottom of the fingernails.
There are some cases of toxicity from exposure to excessive selenium in our environment and from over supplementation. It is rare but symptoms of toxicity would be nausea, vomiting, hair loss, skin lesions and abnormalities in the bed of the fingernails. If these symptoms are present it is more usually environmental exposure through industrial or soil pollution. The foods that contain selenium usually have levels of around 30 – 50mcg per serving except for Brazil nuts that contain 70-90mcg per nut.
The best food sources of selenium are liver, fish such as halibut, cod, salmon and tuna. Mushrooms particularly Shitake mushrooms, are a great source and very important if you are vegetarian. Brazil nuts are a great snack and taking one or two a couple of times a day will provide you with adequate amounts in addition to your other nutrient rich foods.
Sally Cronin Just Food for Health 2007.
For the other vitamins and minerals in the series. Essential Nutrients
Coming up this week – Skin health…
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