Home Immunity Vitamin D – ideal levels, and how much we should take

Vitamin D – ideal levels, and how much we should take

Vitamin D levels associated with avoiding disease

Vitamin D is increasingly being recognised as an incredibly important nutrient (actually a pro-hormone) having multiple health benefits. It is also becoming widely obvious that most, if not all people have less than ideal blood levels of vitamin D3 or are outright deficient.

This recent article from the New York Times covers the subject well.
“What Do You Lack? Probably Vitamin D”

I have had a number of clients ask questions about Vitamin D recently, which I will answer in this post.

  • What does my Vitamin D blood test mean?
  • What should my Vitamin D levels be? (my doctor thinks they are okay – are they?)
  • How much Vitamin D to I need to take per day?
  • My Doctor prescribes a Vitamin D tablet for me – how do I know it is enough?
  • My multi-vitamin has vitamin D in it – is this enough?
  • Can I take too much Vitamin D? What level is toxic?
  • Can I get Vitamin D from the sun or do I need to take a supplement?
  • Are there added benefits to getting vitamin D from the sun?
  • Can I get Vitamin D from cod-liver oil?
  • My doctor says I don’t need a vitamin D test – it is too expensive, what can I do?
  • I have a broken bone – what can I do to help it heal well and as fast as possible?
  • Important co-factors for Vitamin D

What do my blood tests mean?
The vitamin D test is a measurement of 25 OH Vitamin D, also called 25 hydroxy vitamin D, 25(OH)D or Calcidiol. It measures the amount of vitamin D circulating in the blood stream.
New Zealand / European measurements are in nmol/L (nanomoles per litre). US measurements are in ng/ml (nanograms per milliliter)
Many websites with information about vitamin D use ng/ml.

Here is a summary of ideal Vitamin D levels in both ng/ml and nmol/L

The following 25(OH)D blood serum levels are now generally accepted – NZ measurements are highlighted:

Blood levels below 20 ng/ml or 50 nmol/L constitute a serious deficiency
Blood levels above 32 ng/ml or 80 nmol/L is the lowest optimal level. Below this is now considered deficient.

Blood levels of 40 ng/ml – 50 ng/ml or 100 nmol/L – 125nmol/L is considered a safe  optimum level
Blood levels of 60 ng/ml or 150 nmol/L are now considered an upper optimum level (note there is debate around keeping your level above 50ng/ml all year round, especially without supplemental vitamin K2 to control calcium in blood vessels)
Blood levels of 80 ng/ml or 200 nmol/L are now considered a safe upper limit (although some specialists would consider this too high, and may cause excess calcium absorption)

When you get a blood test, request the results from your Doctor. Check your result against the ideal levels above. Doctors will merely look to see if your blood levels are above 50nmol/L and below 150nmol/L. Most Doctors do not realise that there are many health issues associated with having blood levels below 100nmol/L

Here is a chart from Grassroots Health showing the Vitamin D levels required to avoid a number of diseases.

There are also other common health issues where vitamin D levels are important that are not listed on this chart:

Insulin resistance is linked with low levels of vitamin D. Insulin resistance: insulin receptors on cells do not respond to insulin properly so that blood sugar is unable to be transferred properly into cells. Levels under 50nmol/L give an increased risk insulin resistance and type 2 diabetes. Insulin resistance is the cause of the “deadly quartet”: abdominal obesity, high blood pressure, high triglycerides, and high insulin levels. If you have these you are at much greater risk of developing heart disease. In this New Zealand Study insulin resistance decreased when Vitamin D levels reached 80 – 119nmol/L


Calcium absorption: Vitamin D is necessary for calcium and phosphorus absorption from the gut, studies show absorption is not optimised until vitamin D levels reach 80 nmol/L. Calcium is critical for bone strength.

Vitamin D and pain relief: Most people are completely unaware of this amazing benefit of Vitamin D supplementation:

Weight problems: Low levels are linked with body fat, particularly abdominal fat.

Muscle Strength: A number of studies show muscle pain and weakness occurs with Vitamin D deficiency, however this recent study showed a significant association of vitamin D levels with muscle power and force in adolescent girls.
Vitamin D Status and Muscle Function in Post-Menarchal Adolescent Girls
Recently the Chicago Blackhawks made history when they came from nowhere to get to the Western conference final. They had been taking 5000iu per day of vitamin D per day, which was credited with improving their performance. The Chicago Blackhawks are the First Vitamin D Team in Modern Professional Sports History

Immunity: A recent study showed those with vitamin D deficiency had an almost 40%  increased rate of colds and flu’s compared to those who had levels above 30ng/ml or 80nmol/L. Asthma patients with the lowest vitamin D levels had five times the risk for respiratory infection. Recent evidence shows that vitamin D plays an important role in innate immunity, particularly through the antimicrobial peptide cathelicidin.
Article: Too Little Vitamin D May Mean More Colds and Flu
Study: Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey

And yet another study shows taking a vitamin D supplement is more effective than a flu vaccine.
Vitamin D better than vaccines at preventing flu, report claims

This recent article explains how vitamin enables us to fight infection.
How Sunshine can help your body fight disease

To avoid most health issues we need a minimum vitamin D levels of 80nmol/L, and 120 to 150 nmol/L is now considered optimal, although there is debate around this upper level.

Recently I have requested clients get their levels tested, none had a level above 57nmol/L. Even some who took supplements had low levels.

How much Vitamin D do you need to take?

As a general rule 1000 – 2000 iu Vitamin D3 per day is a safe intake. However not all people will reach ideal blood levels with this amount, as metabolism is quite different depending on health issues (e.g. those with auto-immune thyroid disease require more), the amount of body fat you carry, and your genes. I’ve seen some women remain deficient taking 1500iu per day whereas another will have levels of 80nmol/L.

A general rule is to take 1000iu Vitamin D3 per 15 kg of body weight per day. Take this amount for 6 weeks and then get your Vitamin D level tested. If it still measures below ideal add more, and test again.

OR: You could get your Vitamin D level checked  – once your 25(OH)D blood serum level is known it is then possible to calculate how much Vitamin D3 supplementation would be needed to raise your blood levels to a more acceptable level.

Trials have shown that an average adult (taking Vitamin D3 by mouth)
requires the following levels of supplementation to raise their blood levels by the stated amounts:

Daily Vitamin D3
supplement level
Raises blood level
of 25(OH)D by a
maximum of:
1000 IU 10 ng/ml or 25 nmol/L
2000 IU 20 ng/ml or 50 nmol/L
4000 IU 40 ng/ml or 100 nmol/L
5000 IU 50 ng/ml or 125 nmol/L

My Doctor prescribes a Vitamin D tablet for me – how do I know it is enough?

A New Zealand doctor may prescribe Cholecalciferol tabs – these are Vitamin D3 tabs, the dose is 1.25mg per tab, this is equivalent to 50,000iu (international units). This is a high strength tablet compared to the ones you buy from a health shop, which are usually 1000iu tabs. The normal dose prescribed is one per day for 6 days, then 1 per week for 6 weeks. Some doctors will prescribe 1 tab per month.

If you are on a maintenance dose of one tab a month – it may or may not be enough. 50,000iu per month is an average of 1670iu per day. The only way to know if it is sufficient is to ask your doctor to get a vitamin D test. Depending on the results adjust the dose – you may need 2, 3 or even 4 tabs per month to reach ideal Vitamin D levels.

Here is an interesting case study from Dr William Davis who found one client needed 10,000iu per day to get ideal vitamin D levels. Note that taking a lot of vitamin D is not toxic unless it raises your blood levels too high.

My multi-vitamin has vitamin D in it – is this enough?

Most multivitamins contain an RDI (recommended daily intake) amount of vitamin D, e.g commonly 400iu – for many people this will not be any where near enough.

Can you take too much vitamin D?

Yes – if your blood levels are too high – no matter what dose you are taking, reduce your vitamin D. Do not allow your Vitamin D level to go above 150nmol/L. Certain health conditions such as hyperparathyroidism mean you may be especially sensitive to vitamin D, in which case do not take vitamin D without talking to your Doctor.

What happens if you take too much vitamin D?

Excess vitamin D increases calcium absorption. You will get a hypercalcemia, excess blood calcium. This is dangerous. You may get calcium in arteries and calcium stones in kidneys. Taking calcium supplements with vitamin D can also lead to excess blood calcium. Do not take calcium supplements when you are taking vitamin D. Read this article from Dr Davis “Increased blood calcium and vitamin D”

Also read this article from Chris Masterjohn “Are Some people pushing their Vitamin D Levels too High”

He notes that lifeguards in Israel have levels of 50ng/ml and have a greater incidence of kidney stones. Adequate vitamin K2 is essential to supplement with Vitamin D. It may be best to keep your levels in the winter at 32 – 50ng/ml (80 – 125nmol/L) for Europeans and 30 -40ng/ml (75 – 100nmol/L) for those of African descent.

Can I get Vitamin D from the sun or do I need to take a supplement?

Yes you can get vitamin D from sun exposure. A single session in the summer sun can manufacture 10,000 – 20,000 iu. When studies have looked at vitamin D levels in young people with a lot of sun exposure, such as surfers they found levels of 105 – 163nmol/L. Vitamin D manufacture from sunlight is self-limiting, so we don’t ever get toxic levels.

As we age – we start to manufacture vitamin D poorly, so many older people, even with sun exposure may not get ideal levels without taking a supplement.

Getting Vitamin D from the sun:
During summer, UVB rays – the type that you need to make vitamin D from cholesterol in the skin are highest at midday. UVA is high all day long, and although it wont burn – it causes deeper skin damage and can cause faster aging and more dangerous skin cancers like melanoma. The best time to get UVB is sunbathing is late morning or midday. Usually 5 minutes is enough for fair skins and up to 30 minutes for darker skins – no sunscreen. Do not get burnt. In winter, longer periods are required, around 30 minutes per day near midday in the North of the country, with those people living in the south island of New Zealand will not be able to get enough. When the sun is below 45 degrees above the horizon, nobody can make any D3 -tip: your shadow has to be shorter than your height.

Older people, those with higher body fat and those with darker skin, or different genetic types that make less, may not get adequate vitamin D from sun exposure and may still require supplements in the summer. If you have regular summer sun and a short winter of non exposure you might be able to keep your levels adequate, although they will fall during winter. Only by testing will you know.

Here is a useful tool to work out how much sun to get to raise your vitamin D levels Calculated Ultraviolet Exposure Levels for a Healthy Vitamin D Status

Is it better to take supplements or get vitamin D from the sun?

There are added benefits from getting sunlight on your body and being in the sun. Sunlight normalises your  circadian rhythm, and increases daytime hormones – seretonin. Which when the sun goes down gets converted to melotonin. Sunlight can therefore improve sleep. This study showed that sunlight was better than vitamin D supplements Sunlights ability to protect against MS goes beyond Vitamin D More here too: Beneficial effects of UV radiation other than via vitamin D production

Jamie Scott also wrote that sunlight on the skin may be important for clearing or recycling cholesterol, and therefore be important for heart health. Taking Vitamin D supplements won’t do this. This is because sunlight changes the cholesterol in your skin into Vitamin D. High Cholesterol and sunlight deficiency

Can I get Vitamin D from cod-liver oil?

Yes you can – however I don’t recommend you aim to get all your vitamin D from cod liver oil. Why? Lets have a look at what is in a dose of cod liver: Thompsons Cod liver oil plus,

Each Capsule Contains:

Cod Liver Oil 500mg
Vitamin A (120mcg) 400IU
Vitamin D (1.25mcg) 45IU
Vitamin A (513 mcg) 933IU
Vitamin D (1.375 mcg) 55IU

So in order to get 1000iu Vitamin D you would need to take 22 capsules! And along with this you would get a possibly toxic dose of 20,000iu vitamin A. A high intake of Vitamin A appears to negate the benefits of vitamin D. Vitamin D Council, Vitamin A, Vitamin D and Cancer.

Getting enough omega 3 from Cod liver oil is also a problem for the same reason, taking enough capsules to get a good dose of Omega 3 can give you excess vitamin A. I recommend taking Fish oil omega 3 – from the flesh of the fish which does not contain Vitamin A or D and then taking Vit D separately. Alternatively take a little codliver oil and add either an omega 3 supplement or eat plenty of oily fish.

My doctor says I don’t need a vitamin D test – it is too expensive, what can I do?

I’d suggest you pay for a test yourself, it’s about $50.00. (NZ)

I have a broken bone – what can I do to help it heal well and as fast as possible? Important co-factors for Vitamin D in the body.

Make sure your vitamin D is at ideal levels, that way you will absorb maximum calcium and phosphorus from your food.

Calcium- Ensure you have a diet that is alkaline. This will ensure you don’t pull calcium from your bones to buffer an acid diet. Eat vegetables and fruit with your protein and good fats.  (Dont skimp on protein though – adequate protein is critical to bone healing) See Paleo diet, acid alkaline foods. I would not recommend calcium supplement as you may get excess when taking vitamin D. Or keep the dose to about 500mg per day only while your bone is healing.

Make sure you have co-factors for bone construction, especially the minerals that our soils are deficient in.

Vitamin B-complex. The paleo diet is high in B vitamins, however some people do not absorb Vitamin B12 from the stomach. Get your vitamin B12 and folic acid levels tested. If low and you are eating good amounts in your diet you may need a B12 injection. Folic acid in high in green leafy vegetables.

Silicon 8mg
Zinc 10 – 20mg
Boron 3 mg
Magnesium 200 – 400mg
Vitamin K1 from foods like kale
Vitamin K2 100mcg
Vitamin A 250iu (found in calf’s liver)
Selenium 150mcg (2 -3 brazil nuts per day will give you selenium)

Vitamin D from New Zealand Zone Nutrition Shop (Australian and NZ customers)

Listen to this BBC discussion for current views on Vitamin D
BBC talk Vitamin D

Sources and further reading:
American Journal of Clinical Nutrition, Vol. 69, No. 5, 842-856, May 1999
“Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety” Reinhold Vieth
Vitamin D Council
Linus Pauling Institute, Vitamin D
DougCuk, Vitamin D resource

Vitamin D found to influence over 200 genes, highlighting links to disease

Gibson Research Corporation, Vitamin D Research

Vitamin D testing in Primary Care

Vitamin D and adult bone health in Australia and New Zealand:
a position statement
(Working Group of the Australian and New Zealand Bone and Mineral Society, Endocrine Society of Australia and Osteoporosis Australia*)

Studies showing very high vit D levels may not be safe

Medscape Review article Vitamin D, Vitamin D: A Rapid Review

My Doctor prescribes a Vitamin D tablet for me – how do I know it is enough?


  1. Yes that sounds plausible – but it’s wrong. The huge state of the art July 2010 study Common genetic determinants of vitamin D insufficiency: a genome-wide association study found that none of the genes they identified are linked with skin pigmentation.

    Confirmation of that interpretation in an article Here :- ” the accompanying (Lancet) editorial points out, it is somewhat surprising that none of the genes identified are linked with skin pigmentation”

    A systematic review of the association between common single nucleotide polymorphisms and 25-hydroxyvitamin D concentrations
    “We speculate that recently identified U-shaped relationships between 25OHD concentrations and disease outcomes (i.e. increased risk at both high and low concentrations) may reflect a mixture of genotype-defined subgroups.”

    ‘Genetics to Blame for Vitamin D Deficiency?’
    “Researchers conducted a genome-wide association study (Common genetic determinants of vitamin D insufficiency: a genome-wide association study) that involved almost 34,000 people of European descent from 15 different studies. They used radioimmunoassay and mass spectrometry to determine vitamin D concentrations and found that variants at three genetic sites, or “loci,” were significantly associated with vitamin D concentrations. The presence of harmful alleles at three “loci” more than doubled the risk of Vitamin D insufficiency.”

    Maybe non-whites are the ones who benefit from doubling their vitamin D levels ? Nope – Vitamin D, Adiposity, and Calcified Atherosclerotic Plaque in African-Americans “positive associations exist between 25-hydroxyvitamin D and aorta and carotid artery CP in African-Americans”

    Many people are naturally low in vitamin D, forcing vitamin D levels up by taking supplements can only do harm. If you think you can improve yor health by conforming to the advice of Holick or – God forbid – that of Hollis, Cannel & Co at the vitamin D ‘Council’ who recommend (>50ng/ml) then you are in for an unpleasant surprise.

    Vitamin D and homeostasis

    Mad dogs and ….

    • Interesting points – I will research further.

      However these facts remain:
      -Many people do not get sufficient sun in the summer to increase their Vitamin D levels enough to keep them going through the winter, this may be even more the case for those such as African Americans who evolved living nearer the equator with many hours a day and year round sun exposure.
      The answer of course is that we all get regular sun exposure.
      -For those who don’t get adequate summer sun supplementation or UVB sunbeds is the only way to ensure adequate vitamin D.
      The question is – how much and what are ideal levels if we do take a supplement.
      Also what are the downsides to vitamin D supplementation? Another topic I will explore.

  2. Great stuff, Julianne!

    I’d been planning a Vitamin D post for quite some time, but it’s going to be morphed into a large “resource link” type post—and if you don’t mind, I will include yours, definitely! 🙂

  3. An adequate blood level of vitamin D in older males improves bone density, just as with women. This helps prevent bone related disorders such as arthritis and osteoporosis. A sufficient dose of the vitamin is linked to reducing the incidence of certain types of cancers that older men are prone to such as prostrate and colon cancer.

  4. Hello, I was reading your article, which is so interesting and thorough. I would like to know if what you write about desired blood levels and about desirable intake of vitamin D applies for children. My son is 9 years old, and has 20 ng/ml.

    I don’t trust doctors about it, it seems they know nothing about it, or just don’t care.
    I presonally am diagonsed for 3 years with chronic fatigue syndrom, and only now i read about vitamin D and tested myself (about same amount as my son), and it’s unbelievable any of the many doctors I met for my muscles pain, joint pain, weakness and much more, has never told me to test my vitamin D levels…

  5. Some naturalistic research I read many years ago, followed a village of fisherman whose intake of Vit D was measured regularly. When D levels were over 80nmol\\L their heart health suffered.
    The Westonaprice foundation research suggests that 80nmol\\L is about right. That \’ a long way below 150 nmol\\L as an upper limit.
    Vit D needs are much much higher with age. Probably most of nz elderly will be low to deficient at my guess,
    I measure D levels from sunlight with a UVB meter and it indicates that we have a quite long Vit D winter in nz or anywhere below 34 degrees south.

    • Hi Neil,
      Do you have reference for that study? Recent studies as far as I am aware indicate that 35 to 60 are best – Chris Kresser has just done a very informative post on the topic

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