Vitamin D – How to Know Whether You Need To Supplement

Vitamin D how much do you need

I recently received a call from Gary and Robbo from The Mojo Radio Show asking me about Vitamin D, in particular who should take it, how much you should take, and how do you know if your deficient in Vitamin D. This article will give you the lowdown on Vitamin D so that you will know if you need to supplement or not.

If you have not listened to The Mojo Radio Show, they have some awesome interviews, and you can check it out on iTunes or on Google Play.

Vitamin D is also one of the most common supplements that I see people taking, yet most people are taking it because they have heard that it is good for you, or they have been diagnosed as deficient but are often not taking the right dosage.

We will discuss why Vitamin D is important, what happens if your deficient, the negative consequences of taking too much, and what are the best test options to do, so that you know if and how much Vitamin D that you need.

What is Vitamin D

Vitamin D is a fat-soluble vitamin (which means if you eat a low fat diet you may not absorb vitamin D very well). The Vitamin D that we get from the sun, supplements and food sources is converted into the active form of Calcitriol in the liver and kidneys, and Calcitriol is a steroid hormone.

Vitamin D is well known for helping bone quality and preventing osteoporosis, but it also controls the expression of over 1,000 genes in our body, nearly every cell has a receptor for Vitamin D, this means it is important for everything.

Vitamin D is also important for:

  • Promotes calcium absorption in the intestines and maintains calcium and phosphate levels in the blood
  • Regulates immune function, Vitamin D levels are often low in autoimmune conditions and cancer
  • Regulates cell growth
  • Important for neuromuscular function

Your body does very well at adapting to a Vitamin D deficiency, this means that you may not notice short term affects unless your levels are very low, but you will have increased risk of cancer, autoimmune conditions and other chronic health problems as you age.

Where do we get Vitamin D from?

The sun is the best source of Vitamin D, just 15 minutes in the sun between the hours of 11am and 3pm will give you around 10,000 i.u of Vitamin D. The problem is that most people are indoors at this time, or are covered up by clothing, hats and sunscreen to avoid the risk of skin cancer.

Food sources of Vitamin D include fatty fish such as Salmon, Tuna, Sardines and Mackerel, also Cod Liver oil is a good source of Vitamin D. There are small amounts found in grass fed beef, cheese and pasture raised chicken eggs (the yolk not the whites).

Some foods like milk and processed cereals also have Vitamin D added to them, but this would not be my recommended source.

Supplements are a great way to increase your Vitamin D levels, especially if your deficient and you are conscious about spending too much time in the sun, due to the effect that this can have on skin cancer, and premature aging of the skin.

Thorne Research Vitamin D/K2 liquid which is available from Amazon or is a great Vitamin D supplement and it is easy to adjust the dosage depending on your needs.

How to identify if your Vitamin D deficient

The simplest way to test your Vitamin D levels is with a blood test, this test measures your levels of 25-hydroxyvitamin D, this is the same type of Vitamin D that you get from the sun, food or supplements.

The Vitamin D test can be done by your doctor (though many are unwilling to test) or through one of the pathology panels that Planet Naturopath offer.

The reference range varies depending on the pathology lab, but for most labs it is 20 - 80 ng/ml in the U.S and 50 - 250 nmol/l in the rest of the world. But you don’t want to be in the reference range, you want to be in the optimal range which is 40 - 60 ng/ml in the U.S and 100 - 150 nmol/l in the rest of the world.

I recommend testing at the end of summer and at the end of winter for a couple of years to assess how much Vitamin D you need to supplement with to maintain your levels in the optimal range. You may not need to supplement, but with 70% of people below the optimal level of Vitamin D, the chances are you may need to supplement, at least through the winter months.

The Vitamin D blood test is a good indicator of Vitamin D status, and if you are in the optimal range that is great, and you are on the right track with your Vitamin D levels. To maintain these levels you may need a low dose supplement, or get adequate sunshine each day.

What if you are below the optimal range.

If you are below 20 ng/ml or 50 nmol/l you will need to supplement to get back into the optimal range, but if you are just below the optimal range this is a grey area in regards to whether you are truly deficient.

People with darker skin often don’t need high levels of Vitamin D as they are very efficient at converting it into the active form, compared to caucasian people, so skin colour is going to determine whether you may need to supplement.

You can also test your Parathyroid (PTH) hormone levels, if you have adequate levels of Vitamin D your PTH levels will be low, this is a good test to do if your in the grey area just below optimal, it can confirm if you need to supplement or not.

Another test option is to measure your Calcitriol (1,25-dihydroxyvitamin) D levels, this is the active form of Vitamin D, this is not usually available through your doctor but at Planet Naturopath we offer this test.

Why are so many people deficient in Vitamin D

With an estimated 70% of people below the optimal level for Vitamin D you may wonder what everybody did before Vitamin D supplements were available, however there are a number of reasons why Vitamin D deficiency is so common these days

  1. We are spending more time indoors - These days with T.V’s, computers, office jobs and a more sedentary lifestyle, it is not uncommon for people to be inside most of the day.
  2. Skin cancer awareness also encourages people to wear protective clothing to cover up from the sun, and apply sunscreen which prevents Vitamin D being absorbed through the skin.
  3. Overweight population - more and more people are overweight and this reduces your ability to absorb Vitamin D through the skin
  4. Low fat diets - you need fat to absorb Vitamin D, a low fat diet reduces Vitamin D absorption in the intestines.
  5. Digestion problems - Celiac disease, Inflammatory bowel disease, liver and gall bladder issues and IBS all affect our ability to absorb Vitamin D.
  6. Your age - A 70 year old person will absorb 4 times less Vitamin D compared to when they were 20
  7. Gastic bypass - This increasingly popular surgery for weight loss decreases the intestinal absorption of Vitamin D
  8. Genetics - Specific genes like the VDR and CYP2R1 genes determine how well you absorb Vitamin D from the sun and convert it into the active form

What happens if your Vitamin D levels are too high

With 70% of people deficient in Vitamin D which can result in a wide range of health problems you would think that everybody should be dosing up on Vitamin D, just in case!

But there is a sweet spot in the ideal Vitamin D levels, while too little can be a problem, too much Vitamin D can also cause serious health problems. The good news is that you are not going to get too much Vitamin D from the sun, even if you have an outdoor job and get a lot of sun, this is because the body is very good at regulating how much Vitamin D you absorb through the skin.

You can however get too much Vitamin D from long term supplementation of 5,000 i.u a day and above, and with high dose Vitamin D supplements available this is not uncommon.

High levels of Vitamin D leads to hypercalcemia, this is too much calcium circulating in the blood. This can lead to calcium deposits accumulating in the kidney and blood vessels, leading to kidney and cardiovascular disease.

How to increase your Vitamin D levels

The first step is to try and increase your sun exposure, this only needs to be 15 minutes in the middle of the day, and the important thing to remember is to not get burnt. If you are very sensitive to the sun then start with only 5 minutes a day and slowly build up.

If your Vitamin D levels are below 20 ng/ml or 50 nmol/l then you are going to need to supplement with a good quality Vitamin D supplement to get your levels into the optimal range. How much you take will depend on factors like your test results, your age, whether you are overweight or if you have any chronic health problems.

The recommended dose is going to be in the 5,000 to 10,000 i.u a day range, and you should retest your levels every 3 months until you get into the optimal range. Remember to take your supplements with a meal containing fat to improve absorption.

I recommend the Thorne Research Vitamin D/K2 liquid which is available from Amazon or There are other quality practitioner brands available, these can only be prescribed once you have had a consultation with Planet Naturopath.

Vitamin D is super important for your health, and with 70% of people not having optimal levels of Vitamin D it is important to get your levels assessed!

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