Vitamin D deficient? It’s likely

As the leaves turn and daylight savings beckons, another season of the sunshine vitamin is coming to a close – not that we had too much of it this year, if you live in Ireland/UK.

I’m talking about vitamin D of course. 

This is a vitamin you *should* care about, and rarely do I use the word *should* as I’m a soft sell kind of nutritionist.

To say that vitamin D deficiency is wide spread would be a gross understatement. Evidence suggests that upwards of 35% of the US population are deficient, with similar levels in Europe.

While there isn’t an official definition of deficiency, it’s considered to be less than 50 nmols/litre in Europe and 20 ngram/ml in US. 

Severe deficiency is considered less than 30 nmols/litre or 12 ngrams/ml.

And that’s just deficiency, that doesn’t cover insufficiency, which could be considered even more epidemic.

Insufficiency means that you’re not functioning at your best.

Many consider insufficiency to be between 50-75 nmol/litre or 20-30 ngram/ml.

So, the next time you get a blood test done, please ask your physician to include vitamin D and do make sure that you get the actual number because many physicians have ‘not deficient’ as their reference point as opposed to functioning at your best.

Vitamin D – the basics

Eighty to ninety percent of vitamin D comes from the interaction between your skin and the sun. If you have dark skin pigmentation with high melanin content, you need a lot more sun exposure to create the same amount of vitamin D. 

This leaves ten to twenty percent of vitamin D coming from various animal sources in your diet. 

Plant-based folks get a small amount through mushrooms (technically a fungi, but let’s call it an honorary plant, for now), and maybe some through fortified cereals and such like. If you’re a plant-based eater, please keep reading!

There are two kinds of vitamin D – vitamin D2 and D3. Vitamin D3 is by far the most prevalent. 

Once ingested or absorbed vitamin D has to go through two steps to become biologically active. The first in the liver and the second in the kidneys. 

When you get a blood test, 25-Hydroxy vitamin D or 25 (OH)D is considered the most accurate indication of your vitamin D status.

Why you *should* care about your vitamin D levels

Vitamin D regulates your circulating calcium levels by increasing intestinal absorption. 

Calcium is one of the most tightly regulated nutrients. When systemic levels are low, either through low calcium intake or low vitamin D levels, your body moves quickly to correct it.

Alarm signals are sent to your parathyroid gland, with a resulting increase in parathyroid hormone. 

This has the effect of calcium being resorbed from your bones and teeth to maintain those tightly controlled systemic levels. Over time, your bone mineral density can decrease. If this happens chronically, children can develop rickets and adults, osteomalacia – a softening of the bones.

Vitamin D has other countless roles in the many tissues that have a specialised vitamin D receptor. This makes it more like a steroid hormone than a vitamin. 

For example, it’s one of the most important regulators of immune function. As the light changes and our sun exposure decreases, our risk for infection goes up.

There are strong correlations between low vitamin D levels and the frequency and severity of symptoms, especially in the upper respiratory tract.

Why athletes in particular *should* care about vitamin D levels

The greatest impact to athletic performance is likely through athlete availability – a sick or injured athlete cannot perform!

Vitamin D also has a direct effect on muscle repair and mitochondrial function.

There is mounting evidence to suggest that athletes with low vitamin D levels cannot recover as effectively from post-exercise induced muscle damage, which is a normal part of training.

There is also substantial evidence that low vitamin D levels mean that muscle cells cannot recover high energy phosphates during training. This means that energy creation (ATP – adenosine tri-*phosphate*) is inhibited.

Vitamin D supplementation – yes!

We really *should* supplement during winter in northern latitudes as there is insufficient sun exposure, and dietary intake cannot compensate for that.

A very general dosing strategy should aim to maintain vitamin D levels between 50-120nmols/litre or 20 – 48 ngram/ml.

Fifty nmols/litre or 20 ngram/ml is enough to support bone function, while higher levels (between 75-120 nmols/litres or 30 – 48ngram/ml) confers additional benefits.

Athletes should aim for levels between 75- 120 nmols/litre or 30 – 48 ngram/ml

Athletes living in extremely sunny environments rarely go above 150 nmols/litres with no additional supplementation, indicating that the body naturally calibrates vitamin D levels.

When it comes to supplementation to meet these targets, most recommend between 1000-2000 IU of vitamin D3 per day.  This can be given via drops, sprays or capsules, and there are many plant-based options available.

For athletes, I would suggest a minimum intake of 2000IU per day to gain all the benefits that this unique steroid-like vitamin offers.

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I’m Jill – a nutritionist who works alongside athletes, and non-athletes, to ensure that they perform at their best! There are four different ways to work with me, from a one hour Kitchen table talk to a bespoke Race Package.

If you need some help deciding which package works best for you, I offer a complimentary zoom chat. Contact me today to arrange