What is Vitamin D?
Vitamin D is needed by our bodies to support many important functions - including balanced mood, immune health, bone, joint and muscle integrity. Vitamin D is one of the fat-soluble vitamins and is a precursor to an important steroid hormone called calcitriol, the active form of vitamin D required by our bodies to regulate overall health.
The two forms of vitamin D available to us are vitamin D2 (Ergocalciferol) and vitamin D3 (Cholecalciferol). Vitamin D2 is the form produced by plants, while vitamin D3 is produced naturally by our bodies when our skin is exposed to direct sunlight.
Vitamin D benefits
What is Vitamin D good for? This important nutrient supports:
- Bone health: supports the absorption of calcium – an essential mineral for strong, healthy bones and teeth. It’s important in all stages of life – from development in the womb to our twilight years.
- Immune health: adequate levels of vitamin D are needed for our general, everyday health – including immune function.
- Balanced mood: studies show that sunlight exposure is good for our mood, which comes at no shock. Vitamin D deficiency is often associated with insufficient sunlight exposure and research indicates a link between low mood and low levels of vitamin D.
- Muscle health: supporting muscle strength and function, its role is particularly important as we age – for balance and stability, which lowers the risk of falls and fractures.
Vitamin D sources
Sun exposure is the primary source of vitamin D. When the skin is exposed to sunlight, it produces vitamin D
The main food sources of vitamin D include fatty fish such as salmon, mackerel and sardines.
Cod liver oil is a natural, rich source of vitamin D.
Food sources of vitamin D are relatively limited. The primary source of this essential nutrient is liver, while egg yolks also contain small amounts of vitamin D. In New Zealand, certain dairy products like milks, yogurts and margarines, along with other foods, are fortified with vitamin D.
Vitamin D deficiency
Are you getting enough Vitamin D? As mentioned, we produce vitamin D through exposure to sunlight. Varying factors such as the distance from the equator, time of day and length of time spent in the sunlight, the season, age and skin pigmentation all have an influence on how much vitamin D can be produced through the skin. Also, while we do need to protect ourselves from the sun’s UVA and UVB rays - the use of high SPF sunscreens may reduce the natural synthesis of vitamin D in the skin, contributing to deficiency.
The New Zealand Nutrition Foundation (NZNF) recommend a minimum daily intake of vitamin D of:
- 5mcg (200 IU) for infant, children and adults.
- Increasing up to 15mcg (600 IU) for over adults 70+.
During winter, even the strong New Zealand sun isn’t enough for some people to generate adequate vitamin D.
It’s important to note that the minimum daily intake, is set by the NZNF as the minimum daily intake needed to avoid being Vitamin D deficient. Which means it may not necessarily be the optimal amount, it’s simply the amount needed to avoid showing symptoms of a deficiency. As a naturopath, I think of the minimum intake as the ‘bare minimum’ needed.
Factors that increase Vitamin D deficiency risk:
- Lack of exposure to natural sunlight
- Similarly, populations in colder climates who have minimal sun exposure during winter months are likely to be deficient in this sunshine vitamin.
- People with more melanin pigment and olive skin tone may be more at risk due to absorbing less UV light.
- The use of certain medications that may affect Vitamin D levels.
- Breastfed infants with mothers who have high risk of vitamin D deficiency.
What happens if I don’t get enough Vitamin D?
Considering that studies have shown around 30% of Kiwis have sub-optimal levels of Vitamin D, it’s definitely something to consider. If you are concerned about your Vitamin D levels, it’s best to consult with your health professional to determine whether you may have low levels. They can do a blood test, and they will also assess you based on the factors that increase your deficiency risk - as listed above.
When safe sun exposure is not possible - consuming vitamin D containing food and supplementing with vitamin D or cod liver oil capsules is worth considering. A daily dose of 1000 IU of vitamin D is what most people aim for to support adequate intake from April to November.
Naturopath tip:
One great thing about Vitamin D is that your body can store it – so unlike the water-soluble vitamins, (like the B complex vitamins and Vitamin C for example) you may not need to ensure you have it every day (unless you have confirmed low levels). You can take a 1,000 IU Vitamin D supplement, every few days or once a week if you’re taking it as a ‘insurance policy’ to avoid low levels.
What do we know about Vitamin D levels in relation to other health conditions?
Optimal levels of Vitamin D are essential to support a healthy kidney, heart and digestive system – as well as a balanced mood and hormones, strong bones and optimal immune health. It really is essential for everyday wellbeing.
Getting safe and adequate Vitamin D supplementation:
Vitamin D synthesised in the body through exposure to sunlight is self-regulating and the ideal way to ensure you’re getting enough Vitamin D. Toxicity is only possible from supplemented vitamin D at very high doses. In case of severe deficiency, a doctor can prescribe a monthly dose of up to 50000 IU. When treating symptoms that come with deficiency, an initial blood test to check serum levels (through a qualified professional) is recommended, followed by a second blood test a few months after supplementation has begun to help monitor progress towards optimal levels. Be sure to adjust your dosage accordingly during this time.
Vitamin D for babies and children
Vitamin D is crucial for babies' growth and development, particularly in the formation of strong bones and teeth. Babies require vitamin D for proper absorption of calcium and phosphorus, which are essential minerals for bone health.
The primary sources of vitamin D for babies is breast milk or formula. Paediatricians often recommend that babies who are exclusively breastfed receive a vitamin D supplement, typically in drop form, starting shortly after birth. This supplementation supports adequate amount of vitamin D for a baby’s growing needs.
Adequate intake of vitamin D is important for children and toddlers to support immune health, healthy teeth and strong bone development.
What is the best source of vitamin D?
There are two forms of vitamin D supplement:
- Vitamin D3 (Cholecalciferol) is the most absorbable form of supplementation to take.
- Vitamin D2 (Ergocalciferol) and derived from plants.
You may also like to read about Your daily dose of Vitamin D: Our top picks for every season. It includes options for every preference, including Vitamin D capsules, dissolvables, Vitamin D for babies and vegan Vitamin D.
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