How do I know if I my vitamin D levels are low?

A common question that I’m asked is “How do I know if I’m deficient in vitamin D?”

The only sure way to find this out is to get your vitamin D levels tested.

A medical laboratory blood test 25(OH)D (also called 25-hydroxyvitamin D) is accepted to be the best test of overall D status in the body. 25(OH)D levels are most strongly associated with overall health.  There are several types of vitamin D tests, so make sure you specify that the 25(OH)D test is the one you’d like to use.  The test is quick and involves a small sample of blood to be drawn from the arm with a syringe.

Getting your 25(OH)D levels tested is pretty straight forward.  Interpreting your results is a bit trickier.  Optimal vitamin D levels are controversial.

  • The Australian and New Zealand Bone and Mineral Society, Osteoporosis Australia, The Australasian College of Dermatologists and the Cancer Council Australia recommend that for healthier bones the level of vitamin D – 25-hydroxy vitamin D – should be over 75 nmol/l.
  • The Vitamin D Council recommends much higher levels.  Their research indicates that for proper health, serum vitamin D levels should be a minimum of 125 nmol/L, with optimal levels falling between 125-200 nmol/L.
  • Other Vitamin D experts such as Dr Vieth also agree that optimal 25(OH)D levels should be higher than 100 nmol/L.
  • In my opinion research shows that there are clear benefits in having 25(OH)D levels of at least 100 nmol/L.  This is the level that I’d recommend

Note: To convert your test results in nmol/L into ng/ml divide by 2.5 – i.e. 100 nmol/L = 40 ng/ml

 blood testing


To further answer the question – it’s quite likely that you are vitamin D deficient.

While the optimal vitamin D levels in the body are controversial it is very clear that there are epidemic levels of vitamin D deficiency.

Green and colleagues (2004) showed that 31% of New Zealand children aged 5–14 years whose bloods were sampled in 2002 had a serum 25(OH)D concentration indicative of vitamin D insufficiency.For adolescents at or above 15 years and adults a staggering 28% were defined as vitamin D deficient.  Note that deficiency was defined as lower than a mere 37.5 nmol/L in these studies!

Several studies in Australia and New Zealand have shown high rates of deficiency in the older population with restricted access to sunlight, many of whom live in institutions.  Estimates of deficiency range up to 50% in Australia (Flicker et al. 2003, Inderjeeth et al. 2000).  Similar levels were reported in NZ by Ley et al in 1999.  Keep in mind that the researchers used a low benchmark of <37.5 nmol/L to define deficiency so the problem is much worse than the research shows.

Bottom line is that vitamin D deficiency is rampant in our community.  Vitamin D levels are especially concerning in the 70yr+ population

In future articles I’ll be going through vitamin D  recommendations and dosages to combat deficiencies

How much vitamin D do I need?

Unfortunately this isn’t a straight forward question.  There is a wide range of recommendations

The Nutrient Reference Values for New Zealand are:

Age AI (Adequate Intake)
0-50 yr 200 IU
51-70 yr 400 IU
71+ yr 600 IU


The Institute of Medicine’s Food and Nutrition Board (FNB) have the following recommendations for Vitamin D intake. 

Note that these are considerably higher than the recommendations above.

Infants 0-12 months 0 IU/day
1-18 years 600 IU/day
19-50 600 IU/day
51-70 600 IU/day
Over 70 years old 800 IU/day
Pregnant women aged 14-50 600 IU/day

The New Zealand and the FNB’s recommendations are to achieve a 25(OH)D level of 50 nmol/L – which as I mentioned in this article is just far too low.  
Many experts have publically criticised these recommendations.  My personal belief is that these recommendations will increase dramatically over the next couple of years to be more in line with current research that shows the beneftis of higher levels of vitamin D.

Dr Mercola – Who has one of the largest health websites has the following vitamin D intake recommendations.  Dr Mercola goes into detail on his site to justify these levels.  These are around 10x higher than the recommendations above!

Age Dosage/day
Below 5 16 IU per kg per day
Age 5 – 10 2500 IU
Adults 5000 IU
Pregnant Women 5000 IU


The Weston A Price Foundation – an organisation that provides health and nutrition education, recommendations are:

Children age 3 months to 12 years 500-1000IU/day
Children over 12 years and adults 1000-2000IU/day
Pregnant and nursing women 2000-4000 IU/day


Putting all this information shows the large variety in recommendations.  It’s also important to note that the amount of vitamin D required for the individual will vary depending on their vitamin D status – which can only be determined by a 25(OH)D test – see this article.  Illness and medical conditions can also increase the vitamin D requirement.

In my opinion the New Zealand, and FNBs recommendations are far too low.  If I’m asked to quote numbers my recommended intakes would be:

Children <12 yrs 2000 – 3000 IU/day

Adults 3000-4000 IU/day

Pregnant and nursing women 5000 IU/day

If you’re looking to achieve this with Green Pasture cod liver oil the vitamin D levels of our cod liver oil varies from batch to batch.  The latest test data can be found here

If we assume that cod liver oil carries 750 IU/ml.

  • ½ tsp (2.5 ml) = 1875 IU – my recommendation for children <12yr
  • 1 tsp (5 ml) = 3750 IU – my recommended dosage for over 12 yrs
  • 1.5 tsp (7.5ml) = 5625 IU – my recommended dosage for pregnant or lactating women
  • Note that 2 x capsules = 1ml or 750 IU

Cod liver oil and kids

This took a little bribing but the lure of being on on the internet brought my two little starlets out into the spot light.
My two girls – Maia (8) and Ella (5) talk you through the basics of why cod liver oil is important for growing kids

Our most frequent FAQs are about cod liver oil and kids.
Just to clarify a few points:

  • The recommended dosage for under 12s is 2.5 ml
  • As cod liver oil is a food provided by nature you can’t overdose on it

Our experience of using cod liver oil has been fantastic – so good that we decided to share this in business

  • Our girls are very rarely sick. We believe that this is largely due to the immune system boosting effect of cod liver oil.
  • Our girls have excellent teeth. Day to day diet has a massive effect here, but vitamin D also helps with tooth development and repair
  • Omega-3s also support brain development and learning. In a 2.5 ml of our cod liver oil you get at least 250mg of DHA/EPA.

If you’re looking at one food to boost your kid’s health we believe that this is it.
Some of the tips that parents have sent in to us to get their kids into the habit of taking cod liver oil are:

  • Let them use the syringe and be in charge of squirting it in (you’d be surprised how enticing this is)
  • Ask them who wants to go first (again a strange but effective method) – our girls fight for first place
  • Use a chaser if they don’t like the taste – berry and citrus flavours tend togo well – see this article
  • Design a special treat as a chaser – some we’ve heard about are cacao, coconut oil, and strawberries
  • Don’t make a big deal of it. Be casual – don’t build it up. It’s just “what we do at breakfast time”
  • Try some different flavours – Ella likes plain, Maia likes cinnamon tingle and kid’s peppermint
  • Start them young. My girls had cod liver oil as a first food and haven’t stopped.

Here’s to your health and the health of your children


The Death of Commercial Cod Liver Oil

Almost all cod liver oil is sourced from Norway and Iceland. Industrial cod liver oil manufacturing involves alkali refining, bleaching, winterization and deodorization. These processes remove natural vitamin D from the oil. Almost all factories either produce vitamin deficient cod liver oil (vitamin D <900 IU per teaspoon) or add synthetic vitamins back into the oil (the most common procedure eg. Nordic Naturals). Until early 2009 we were able to source cod liver oil from a factory that added the natural vitamins back into the processed cod liver oil. Unfortunately, this factory has now followed the cheaper more commercial path of producing synthetically enhanced cod liver oil.

For those of you that have been using our product lines over the last few years, you will notice that our standard high-vitamin cod liver oil is now “off the menu”. Since we couldn’t source a natural cod liver oil – we couldn’t stock one. The only natural cod liver oil that is high in vitamins A and D on the market is the fermented cod liver oil produced by Green Pasture that we stock. This oil is batch brewed in Nebraska from cod livers using traditional lacto-fermentation and non-toxic methods without using heat and carbon filters that damage vitamins and omega-3 oils. The result is a high vitamin cod liver oil containing 4000-9000 IU vitamin A and 3000-4000 IU vitamin D per teaspoon. Super high-vitamin and exquisitely processed to preserve the natural qualities of cod liver oil.

We refuse to carry inferior products – and if you’re already one of our customers we know that you’ve refused to use inferior products.

Is the change of season making you sneeze?

cold family

Your ability to avoid colds and flu is related to vitamin D. Vitamin D levels in your blood fall to their lowest point during winter due to lack of sunlight. Vitamin D is essential for the body to produce its own antibiotics so a person with a low vitamin D blood level is more vulnerable to contracting colds, influenza, and other respiratory infections. Studies show that children with rickets, a vitamin D-deficient skeletal disorder, suffer from frequent respiratory infections, and children exposed to sunlight are less likely to get a cold. The increased number of deaths that occur in winter, largely from pneumonia and cardiovascular diseases, are most likely due to vitamin D deficiency.


So can’t I just eat more vitamin D rich foods to avoid colds this winter?

It is very difficult to get adequate amounts of vitamin D from your diet unless you are eating large amounts of offal, oily fish and seafood. Some estimates have been made on food composition with daily intakes of vitamin D between 2-3 μg /day (80-120 IU) for adults (Baghurst & Record 2002). This is well short of the 4000IU that we’d recommend for adults to achieve optimal levels of vitamin D (see here for how we justify this dose)


I thought I could still get my vitamin D dose by getting outside in the sun?

Sun exposure on the skin is the other option for boosting your vitamin D levels. Vitamin D is produced by your skin in response to exposure to ultraviolet B rays from the sun. But these rays cannot penetrate glass, sun tan lotion, clothing, or dark skin to effectively generate vitamin D in your skin. In most parts of Australia a “vitamin D winter” occurs for around 4-6 months in which weather conditions make it impossible to produce enough vitamin D from sunlight.

The largest study of its kind (with over 19,000 subjects) from the Archives of Internal Medicine (2009) gave a summary:
“The findings of our study support an important role for vitamin D in prevention of common respiratory infections, such as colds and the flu. Individuals with common lung diseases, such as asthma or emphysema, may be particularly susceptible to respiratory infections from vitamin D deficiency.”

If you’re looking to optimise your vitamin D levels to reduce your risk of colds and flus this winter make sure you keep up your cod liver oil.

Dental decay and cod liver oil

Dental Decay and Cod Liver Oil

Dental Caries are a Real Problem!

tooth 1

Every week we get emails from customers who are using cod liver oil to improve the dental health of themselves or their kids.  Dental caries, also known as tooth decay, is a tooth infection caused by bacteria that leads to a loss of the hard tissues of your teeth. It is one of the most common diseases in the world.  In 2010, 55% of Australian 6-year-olds had experienced decay in their baby teeth and 48% of 12-year-olds had experienced decay in their permanent teeth.  Dental decay is the most prevalent chronic (and irreversible) disease in New Zealand. In 2009, one in three adults had untreated coronal decay, and one in ten had root decay.  50% of children and adolescents aged 2–17 years also had dental caries

What causes dental caries?

Dental caries are caused by bacteria on the surface of teeth that can turn certain sugars into acids, which can demineralize the hard tissues of your teeth. The bacteria form a sticky layer (plaque), which helps protect the bacteria from being removed by your immune system.

Caries develop when your tooth enamel starts to demineralize by acids secreted by bacteria. Enamel is the thin, highly mineralized coating that makes up the visible part of teeth. The damage caused by the acids then spreads into the dentin, which is the softer tissue underneath the enamel. At this point, the tooth develops a cavity.

Before the cavity forms in the dentin, the process is reversible, but after it spreads to the dentin, it is not. The decay then spreads through the dentin to the layer below, called the pulp. The pulp is the part of the tooth that is made up of living connective tissue and its main purpose is to form dentin.

Frequent snacking, sugary foods, not enough saliva, and lack of tooth brushing and flossing all increase your risk of developing dental caries.

How are dental caries treated?

The treatment of caries involves removing the decay and then filling the space with restorative materials, such as porcelain or gold.

How does cod liver oil reduce the risk of dental caries?

Enamel is the most mineralized substance in the human body. It is made up of mostly calcium and phosphate. Vitamin D is important for increasing the absorption of calcium and phosphate from the food you eat.

Increasing the absorption of calcium and phosphate can improve the strength of your teeth and their ability to fight demineralization from bacteria.

Vitamin D increases the amount of good antimicrobial proteins in your body which help to fight the bacteria that cause dental caries.  In addition, vitamin D helps form dentin and enamel in teeth.

Research shows that vitamin D may help reduce the risk of dental caries in infants and younger children.  Studies have shown that children with dental caries have lower levels of vitamin D.  Mothers of children with dental caries  have lower vitamin D levels during pregnancy than mothers whose children don’t have caries

A 2013 review from the United Statesfound that taking vitamin D supplements resulted in a 47% reduced rate of dental caries.

While more experiments are needed to know for sure if vitamin D can help to treat dental caries, the theory and evidence are positive.

How should I get my vitamin D?

You can fulfil your vitamin D requirements by getting safe sun exposure and by eating a nutrient rich diet.  For most – this is difficult to do, especially as the season is changing. 

You have a choice to supplement with artificial supplements or to use nature’s rich source of vitamin D – cod liver oil.

Please see our article on dosage – How much vitamin D do I need?