Selenium Rich Diet
by Sue Kira, Naturopath & Clinical Nutritionist
Selenium is a very important essential mineral, even though it is only needed in very small amounts. It works closely with vitamin E in some of its metabolic actions and with the promotion of normal body growth and fertility. Selenium is a natural antioxidant that appears to preserve the elasticity of tissue by offsetting oxidation, thereby keeping our skin looking more youthful.
Selenium helps to preserve healthy blood pressure and improve certain energy producing cells, including those of the heart by ensuring adequate oxygen supply.
Because selenium binds with toxic metals and minerals, people with heavy metals in their system may need more selenium than others. But the bonus is that selenium helps to bind to and clear heavy metals including mercury, cadmium, silver and thallium, and also protects the body against radiation exposure.
Sperm contains high levels of selenium (and zinc) and high amounts of selenium are lost during intercourse, meaning that selenium may need to be higher in men than women.
Benefits of selenium at the right dose may include improved energy levels, arthritis relief, preventing cataracts, and slowing down the aging process by attacking free radicals. It can help protect against heart attack, stroke, high blood pressure and hypertensive kidney damage.
Selenium with vitamin E has been used to reduce and prevent angina attacks, with improved results showing on electrocardiograms for heart patients. It may also improve the condition of people with cystic fibrosis or muscular dystrophy.
Benefits of selenium
Let’s look at more of the benefits…
Probably one of the main reasons that people like to take selenium is because it is a great antioxidant which helps to lower free radical damage and inflammation, and therefore enhance the body’s resistance against diseases and stress.
A powerful antioxidant to help protect against oxidative stress
Selenium has a synergistic (works together) effect with other antioxidants like vitamins A & E, to support the body to fight against the effects of oxidative stress, which in turn protects our cells.
Selenium is needed to make glutathione, which is a very powerful antioxidant that protects lipids (fats) in the cell membranes (delicate walls). As an antioxidant, selenium helps to protect against cellular mutation and DNA damage that can lead to disease.
Regulates Thyroid Function
Selenium supports the production of thyroid hormones and there is a strong link between low selenium and thyroid abnormalities. Without adequate selenium, the thyroid simply cannot function properly.
The thyroid gland controls many different body functions including appetite, sleep, temperature, weight, energy and so much more. A poorly functioning thyroid can result in irritability, fatigue, weight gain or loss, trouble sleeping, muscle weakness and many other reactions. Adequate amounts of selenium can benefit the thyroid and body in many important ways.
Selenium also helps to regulate the production of reactive oxygen (oxidation/free radicals) within the thyroid thereby protecting it from antibodies that can create auto-immune thyroid disease.
For these reasons, selenium is being investigated to see if it can help people with Hashimoto’s and Grave’s diseases (auto-immune thyroid diseases) and in pregnant women with thyroid antibodies to help reduce antibody production.
Selenium is required for proper sperm motility (along with zinc) as well as increase blood flow to the genitals, two important components necessary for healthy conception. Selenium is incorporated in the sperm mitochondria affecting how well the sperm move through the vagina.
Both low and high sperm selenium concentrations are reported to have a negative influence on the number of sperm, therefore meeting the recommendation but not exceeding it is important for fertility. Between 70-150mcg of selenium a day is considered a good level for optimal sperm health and fertility, preferably from food sources (but supplements for male fertility can help too).
Helps to protect from cancer
Selenium goes into the nucleus of the cells where the DNA and genome are stored and looks for any damage. It attaches to protective antioxidants like glutathione and then works to reduce and repair any damage to DNA, which left uncontrolled could lead to cancerous cell mutation and tumour growth.
Selenium activates selenoproteins (selenium bound to protein) acting in an enzymatic role (breaks things down) that helps antioxidants to do their job. There is evidence that selenium can not only reduce cancer risk, but it can also help to slow down existing cancer progression and tumour growth.
Studies have shown that a high dose of 200mcg a day of selenium can be effective in protecting DNA which can reduce the risk for cell mutation and cancer development. Other studies have shown that in areas of the world where the soil is lowest in selenium, cancer risk has increased, compared to areas which have higher levels of selenium naturally available.
Improves heart health
It is thought that selenium can help heart health by its ability to reduce inflammation, increase blood flow, reduce free radical oxidative stress and help with antioxidant activity. Low levels of selenium have been observed in those who have coronary heart disease, compared to good levels for those who have no heart disease. More research needs to be done, but why wait for proof when we already know it is a great mineral.
May help reduce the severity of asthma symptoms
According to studies, when people with asthma took selenium supplements, they experienced less asthma related symptoms than those who took a placebo. Experts think that selenium rich food consumption may be a useful add-on treatment to medication for patients with chronic asthma.
Helps to increase longevity
Considering the above information, selenium rich foods can have a very positive effect on your life and longevity, if only for its antioxidant abilities. Because selenium is considered to be a trace mineral, we only need very small amounts, but because our body can flush selenium out of our systems quite quickly, we need to have it in our diet on a daily basis, especially as we age.
Testing for selenium deficiency
If you have a condition that puts you at risk of selenium deficiency, such as a thyroid disorder, low sperm count or cancer, you may want to get your selenium levels tested to see if you can benefit by consuming more selenium rich foods.
To find out your current selenium levels, you can have a blood or hair test done by your doctor or naturopath. A blood test only shows the amount of selenium you’ve consumed recently, and the accuracy of hair tests is also not very consistent, since the mineral is stored differently throughout various organs and systems.
My preferred way of testing is with hair analysis, but there is nothing that is highly accurate. To assess whether you need more selenium or not, it’s best to seek expert advice from your health practitioner.
Interactions and side effects of too much selenium
When consumed from food, selenium toxicity is extremely rare and a normal prescription dose doesn’t normally have any negative side effects.
However, toxic doses of selenium may cause:
- bad breath
- fever & nausea
- hair falling out
- weak brittle nails
- liver complications
- kidney and heart problems
- heart attack and respiratory (lung) depression
- death (very high toxic doses)
Selenium may also interact with other medicines and supplements, including antacids, chemotherapy drugs, corticosteroids, niacin (B3), cholesterol-lowering Statin drugs and birth control pills. If you take any of these medications it is best to speak to your doctor before supplementing with any vitamins and minerals, including selenium.
However, selenium from food has not shown to be an issue, but if in doubt please check with your health practitioner.
Note: If you already consume good amounts of selenium from a healthy diet, then additional selenium may actually be harmful, especially if the total dose exceeds 400mcg per day.
Selenium’s benefits work best when daily levels are met from eating selenium rich foods, because supplementing with high doses without consulting a health practitioner could be harmful.
The recommended daily allowance (RDA) in micrograms (mcg) for selenium depends on your age.
- Children 1-3 need 20mcg
- Children 4-8 need 30mcg
- Children 9-13 need 40mcg
- Adults and teenagers 14+ need 55mcg
- Pregnant women need 60mcg
- Breastfeeding women need 70mcg
It is important to know that the amount of selenium in your food depends on how much selenium is in the soil.
For example, in Australia selenium in the soil is generally low, however in organic farms where the soil has been built up naturally by composting, mulching and adding mineral rock powder, selenium levels are normally higher.
The following list of foods shows the amount of selenium acquired from soils with healthy levels of selenium. Yet in soils low in selenium, higher quantities of the same foods may be needed to obtain the optimum levels required.
For example, most of my clients showed low levels of selenium from hair tests, but one husband and wife had good levels because they often drank fresh Brazil nut milk which she made regularly to add to their coffee.
Whole foods are the best sources of selenium, especially when handled and prepared in a delicate way, since selenium may be destroyed during processing and very high heat cooking methods.
- Brazil Nuts: 1 cup = 600mcg (Brazil nut milk is a good option)
- Eggs (medium): 1 = 145mcg
- Sunflower Seeds: 1 cup = 105mcg
- Liver (from lamb, beef or chicken): ½ cup/3oz = 100mcg
- Tuna: ½ cup/3oz = 65mcg
- Chicken: ½ cup/3oz = 35mcg
- Salmon: 3oz/85g = 30mcg
- Turkey: 3oz/85g = 25mcg
- Chia Seeds: 1 Tablespoon = 20mcg
- Mushrooms: 1 cup = 15mcg
As mentioned, hair tests showed that most of my clients were low in selenium. This was generally due to a diet low in selenium, and also because there was insufficient selenium in the soils where their produce etc was sourced from. This is a good reason to consider organic produce, as most organic farmers are very conscious of balancing soil with the right nutrients.
Depending on your dietary intake and any health condition you are supporting, generally a supplement may contain between 100mcg and 200mcg. Higher amounts than this need to be monitored with caution and only taken under prescription from your health care practitioner.
Before you commence your diet, see your medical or health care professional for qualified guidance about what foods and supplements are best for your body. While on the diet do not stop any medications or supplements previously prescribed unless advised otherwise by your medical or health care professional.
During the early stages of a new diet, you may experience symptoms such as fatigue, headaches, or body aches, which may occur because your body is detoxifying. However, if you are unsure about a symptom at any time, check immediately with your medical or health care professional.