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Getting Back to Basics - Selenium Iodine and Vitamin B12



It often seems to me, in clinical practise, that patients are not aware of the importance to normal body functioning of trace nutrients, vitamins and minerals.   Our diets are often below par nutritionally so we don’t get all the vitamins and minerals from the foods we eat.  If the soils the crops are grown in are also deficient,  then we get even less of those essential nutrients.

From time to time I intend to write a blog piece filling in some of those gaps for you.  Forewarned is forearmed and all that!  If you have any natural health subject you would particularly like to know more about please do email me at and I will see what I can do!

So, let’s get back to the basics of selenium, iodine and Vitamin B12.


What is it?

Selenium is an essential antioxidant mineral that provides support for cell production and healthy immune function.  It’s  a trace mineral, found in soil, water, and some foods.  In New Zealand, soils are low in selenium, so the selenium content of the food is often low – and we  New Zealanders have some of the lowest blood levels of selenium in the world.

While soil conditions affect plant foods directly, they also affect animal foods,  because  most animals depend upon plants for their diet – so you can see how that deficiency progresses up the food chain.  Interestingly, A study showed that New Zealanders, particularly those in the South Island, may have adapted to lack of selenium  by thriftiness in urinary excretion of selenium, in that their bodies have adapted to using less selenium (Robinson, 27 APR 2009)

What does it do?

Selenium is important for  biological function, and a deficiency of it  may affect thyroid function and cause conditions such as Keshan disease. (Keshan disease is a congestive cardiomyopathy caused by a combination of dietary deficiency of selenium and the presence of a mutated strain of Coxsackievirus).  Low levels of selenium are also  linked to a higher risk for cancer, cardiovascular disease and inflammatory diseases.  I don’t think we would know if we were low in selenium as it’s use is part of  our biological processes, and any symptoms you experience are part of a greater picture. Still, it is an important mineral.


Where can you find it?.

Brazil nuts are the most highly concentrated source of selenium. Just a handful a day will provide all the selenium you need.  So that’s pretty easy to do, unless you have a nut allergy!  Multivitamin supplements often have selenium as a part of their ingredients too.

 I think if you include some of these foods in your diets, vary them around a little, you will be getting a good dose of selenium –  brewer's yeast, wheat germ, butter, garlic, grains, sunflower seeds, walnuts, raisins, liver, kidney, shellfish (lobster, oyster, shrimp, scallops), fresh-water and salt-water fish (red snapper, salmon, swordfish, tuna, mackerel, halibut, flounder, herring, smelts), pork, button mushrooms, kelp, molasses, sesame seeds, shellfish, yeast, egg, ham, lamb, beef, bacon, veal, brown rice and red grapes.


The current Recommended Dietary Allowance (Nutrient Reference Values, Australia and New Zealand)

Men = 70 mcg per day

 Women = 60mcg per day

Pregnancy =  65 mcg per day


Which herbs contain it?

Herbal sources of selenium are burdock root, alfalfa, fenugreek, fennel seed, catnip, chamomile, garlic, cayenne, nettle, oat-straw, yarrow, peppermint, sarsaparilla, lemongrass, ginseng, hawthorn berry, rose hips and raspberry-leaf.  You will note that some of our Puraty tea formulations contain selenium rich herbs!



What is it?

Although only required in very small amounts, Iodine is one of the more important trace nutrients as it is needed to make thyroid hormones – essential for proper thyroid functioning -  which helps control metabolism and also for growth and development of body and brain.

It is important that the unborn baby  and young children have adequate intakes too as very severe iodine deficiency, stunted growth and mental retardation can occur.  A number of studies have reported that hearing capacity, motor and cognitive function is affected  in children who have  moderate and severe iodine deficiency.

 An iodine deficiency can cause symptoms such as fatigue, high cholesterol, lethargy, depression, and swelling of the thyroid gland.

One of the serious health effects of iodine deficiency is goitre (enlargement of the thyroid gland leading to a swelling of the neck).

According to the Ministry of Health, evidence of iodine deficiency has been observed in New Zealand since the late 1800s and in the early 1900s goitre was very common.  In order to decrease this effect table salt was iodised at a low level from 1924. The level was increased to 40-80mg of iodine per kilogram of salt in 1938. The iodine content of food is affected by soil, irrigation, fertilisers and cooking.

Recent evidence from a number of studies has indicated that the iodine status of New Zealanders is now declining to the point where intervention is again being discussed by the Government .  I don’t know about you but I would rather deal with it myself than have additives put into my food!

What does it do?

As well as being important for thyroid and metabolic health, many people don’t realize that female breast tissue has a greater concentration of iodine and  therefore, a special need for iodine. When breast tissue has low iodine levels, problems can follow.

The cardiovascular system also relies on iodine. Hormones in the body regulate the dilation of the blood vessels, in turn, causing blood to flow throughout the body. Without appropriate levels of iodine, this process and several others work at diminished capacity.

In healthy breast tissue, iodine offers antioxidant benefit but studies show that iodine deficient breast tissue is susceptible to lipid oxidation, a contributor to many diseases including cancer.

Where can you find it?

The ocean has a large storehouse of iodine rich foods  including Kelp, Arame, Hiziki, Kombu, and Wakame – “Japanese Vegetables” -  but you can also find it in baked potatoes, milk, seaweed, cod, iodized salt, iodine drops, shrimps, Himalayan salt, turkey, tuna, eggs, yoghurt, banana, navy beans, strawberries, corn, cranberries, green beans, spirulina.


Pregnant and breastfeeding women = 220mcg per day

Men and women  = 150mcg per day

Breastfeeding = 270mcg per day


Which herbs contain it?

Black walnut




What is it?

Vitamin B12, also called Cobalamin, is necessary for the production of red blood cells, plays an essential role in folate metabolism, helps to protect nerve cell health and is involved in the formation of healthy DNA/genetic matter.

It is a water-soluble vitamin and we find it in meat, fish, milk products and eggs. Vegetables alone are an inadequate source of vitamin B12. A Vitamin B12 deficiency is commonly associated with  inflammation, anaemia and impairment of vitamin B12 absorption can cause megaloblastic anemia and neurological disorders/ nerve system damage.

Common symptoms of low B12 are dizziness and fatigue, paleness, shortness of breath, anaemia, and hearing difficulties.

 What does it do?

Vitamin B12 and folate are important for homocysteine metabolism. Elevated homocysteine levels are a risk factor for cardiovascular disease.

Good DNA integrity is dependent on folate and vitamin B12 availability.

Poor vitamin B12 status has been linked to increased risk of breast cancer.

Low maternal vitamin B12 status has been associated with an increased risk of neural tube defects

Vitamin B12 is essential for the preservation of the myelin sheath around neurons and for the synthesis of neurotransmitters, a lack of which may lead to cognitive impairment including dementia in the elderly who are at risk for low B12 levels anyway.

Both depression and osteoporosis have been linked to diminished vitamin B12 levels and high homocysteine levels.

Bacteria in the gut (intrinsic factor) synthesizes B12,  which helps nutrients to be absorbed from food. When intrinsic factor is lacking, vitamin B12 is unable to be absorbed  well and utilised by the body.  So a good probiotic supplement and probiotic and prebiotic foods are helpful in cases of B12 deficiency.  Inadequate absorption or utilisation of B12 because of inflammatory bowel disease is also common.

Other causes of vitamin B12 deficiency include: 

A diet inadequate in vitamin B12 rich foods - particularly so in vegetarians who don’t eat any animal products, meat, fish, milk, eggs, butter, cheese and other dairy products (vegans).

Just a note: Those over 60 are often at risk for low vitamin B12 levels. It’s absorption is commonly impaired past that age.


Where can you find it?

Meat, poultry, fish (including shellfish),  dairy products and eggs contain Vitamin B12.  Strict vegetarians and vegans may  need B12 supplements. Some plant-sourced foods, such as certain fermented beans and vegetables, and edible algae and mushrooms, also contain  vitamin B12 



Men = 2.4 mg per day

Women = 2.4 mg per day

Pregnancy = 2.6mg per day

Lactation = 2.8mg per day


Which herbs contain it?

Natural herbs rich in Vitamin B12 are alfalfa, dandelion, hawthorn berries, hops, bladder wrack, and white oak bark.

For a further in-depth article please click here.


Bone, K. (2007). The Ultimate Herbal Compendium. Queensland: Phytotherapy Press.

Government, N. (n.d.). Nutrient Reference Values Australia and New Zealand. Retrieved from

Michels, A. (2015, August 14). Feeding the Microbiome: New ways that Diet affects your Health. Retrieved October 28, 2015, from Linus Pauling Institue blogs:

Murray, M. P. (2006). The Encyclopedia of Healing Foods. London: Time Warner.

Osiecki, H. (2012). The Nutrient Bible (8th ed.). Queensland: Bio-Concepts Publishing.

Robinson, M. F. (27 APR 2009). Nutrition Reviews. Retrieved from Wiley Online Library:

The Natural Standard Database. (2014, December 04). Retrieved December 04, 2014, from The Natural Standard Database:


By Joanna Vinsen Loveys  BNatMed HbT MNZAMH

Ajay G
Ajay G