Vitamin D – Vital ‘Sunshine’ Hormone That 1 Billion Are Deficient In

5 min read


Key Takeaways:

  1. Nearly 1 billion people have insufficient Vitamin D levels – causing comprised health
  2. Vitamin D helps with Immune, Heart & Brain health, in addition to preserving insulin sensitivity and guarding against cancer
  3. RNI of 400 IU will lead to Vitamin D deficiency
  4. Prioritise UVB ray sunshine exposure whenever you can, as this produces significant Vitamin D
  5. 4,000-5,000 IU taken in the morning is considered an optimal level to supplementing darker months

Why Is There Such Widespread Deficiency?

The biggest reason for such widespread Vitamin D deficiency is that we’re not getting adequate all-round sun exposure to our skin, due to our clothed and indoor modern lifestyles.

You cannot adequately synthesise Vitamin D within your body. By design, the primary source of Vitamin D for humans is through sun exposure on our skin, with diet playing a small role comparatively.

But, as modern societies have developed, we spend almost all of our time inside buildings and with most of our skin covered up. Plus when deliberate out in the sun many put suncream on that blocks Vitamin D synthesis. We simply are not getting the sun exposure necessary for the natural process of producing adequate Vitamin D to occur.

It’s not widely understood that it’s really tough to get adequate amounts of Vitamin D from our diets alone, and the RNI (Reference Nutrient Intake set by governing bodies) is considered the absolute minimum level to sustain life – not be vibrantly healthy.

Lastly, those with darker skin living in cooler darker climes, suffer with increased deficiency of Vitamin D on average. The above issues are exacerbated by their pigment. As human migrated from Africa into the Northern Hemisphere, they lost their protective pigment to allow for increased Vitamin D Synthesis at lower levels of sun exposure. Meaning, dark skin needs more sun to get the same effect.

RNI vs Optimal Health Intake

The daily RNI in the UK is set to 400IU, but many scientists are claiming at these levels it will lead to Vitamin D deficiencies, especially without sufficient exposure to the sun.

A growing body of research shows that 2,000 IU per day is the minimum needed to maintain vitamin D sufficiency, but for optimum Vitamin D status within the body you should be looking to consume/produce closer to 5,000 IU daily, on top of adequate sun exposure.

Can you overdose on Vitamin D? It’s very difficult – you would need to be at 40,000 IU per day over the course of months, or somehow consume 300,000 IU in a single day.

Why Is Vitamin D So Important?

Without trying to geek out too much, Vitamin D is not actually a vitamin – it’s a vital hormone. Hormones are the bodies chemical messengers, providing instructions to cells, tissues and organs to take the necessary action dependant on the circumstance. And with Vitamin D in particular, nearly every type of tissue and cell in the body has vitamin D receptors, meaning that it has significant influence over a large number of physiological processes.

Vitamin D regulates genes that control immune function, metabolism, and even cell growth and development.

As a result, if you have symptoms that suggest distress, inflammation or a lowered immune system, it is often recommended to significantly increase your Vitamin D intake.

Vitamin D deficiency has been linked to an increased risk in a number of diseases, such as Osteoporosis, Heart disease, Stroke, Cancers, Type 1 diabetes and Tuberculosis. Low vitamin D status is also strongly correlated with lower respiratory diseases such as Influenza and COVID-19:

Vitamin D and Influenza
Seasonal Correlation between Flu Season Influenza Infections and Vitamin D Status (source: Ivor Cummins)
COVID-19 Case Severity and Vitamin D Status
COVID-19 Case Severity and Vitamin D Status

The Biggest Vitamin D Benefits:

#1 – Helps Maintain Immune Health – Immune cells rely on vitamin D to regulate how they respond to threats in the body, first by attacking and destroying, followed by cleaning up and returning to a state of readiness.

#2 – Keeps Your Brain Healthy – Insufficient Vitamin D levels dramatically increase the risk of cognitive decline, including Alzheimer’s disease and Dementia. The brain relies on Vitamin D to combat various destructive processes. Vitamin D also supports learning and memory, as it helps create new nerve cells and maintaining brain plasticity.

#3 – Helps Preserve Insulin Sensitivity – Vitamin D deficiency nearly doubles your risk of reaching a “pre-diabetic” level of insulin resistance. And preserving insulin sensitivity not only helps maintain optimal overall health but also helps with building muscle by magnifying the muscle-building effects of proteins.

#4 – Supports Heart Health – The heart is jam packed with Vitamin D receptors, indicating the importance of Vitamin D for optimal health and function. Vitamin D helps with cardiovascular health by reducing the fats in your blood that increase risk of heart disease, by relaxing blood vessels that in turn improve blood pressure/flow, and by improving your cholesterol profile.

#5 – Guards Against Cancer – Studies suggest that breast, thyroid and bladder cancer is strongly correlated with chronically low levels of Vitamin D. This is due to the fact that Vitamin D receptors control a number of processes regarding the immune response to cancer cells, tumour growth, and inflammation.

Issues with low Vitamin D
Issues arising from low Vitamin D Levels (source: Ivor Cummins, D is for Debacle)

When & How To Get Sufficient Vitamin D

As above, you cannot rely solely on a modern diet to get sufficient levels of Vitamin D.

That said, a real-food nutrient dense diet with good amounts of animal fats will amplify your Vitamin D status. That looks like a diet diet rich in fatty fish like salmon, tuna, and mackerel, eggs, mushrooms, pork, beef, liver and cheese. Furthermore, as Vitamin D is used up to fight inflammation, minimising processed foods, refined carbs and seed oils will not deplete what you have.

Cod liver oil is by far the best food source with over 1,300 IU per tablespoon.

By far the best way to keep Vitamin D levels high, is to get your skin exposed to the sunshine. The more skin that is exposed to the sun, and the stronger its rays, the more Vitamin D you produce. For example, with only 25% of our skin exposed, our bodies can produce upwards of 400 IU’s of vitamin D in just 3-6 minutes of exposure to midday sun in a warm climate.

A couple more examples. 30mins of midday summer sunshine in Oslo produces 10,000-20,000 IU. In the UK, 13mins of midday summer sunshine with arms, legs and face exposed three times a week would be sufficient to maintain healthy levels in Caucasian adults.

As a general guide, get out and walk as much as you are able during the day when the shadow is shortest. Expose as much of your skin as is appropriate and possible. Even in overcast days, you still produce some Vitamin D through your skin.

Vitamin D in my life
Grabbing the rare chance for some winter sunshine exposure in the UK. In the darker winter UK months, taking 4000IU in the morning is. good practice.
Supplementing is therefore key

Knowing we are not all fortunate enough to live in year-round sunny climates, nor get adequate time outdoors due to mostly indoor work during the day, then we have to rely on supplementation to fill the Vitamin D gap.

Look to pick up a Vitamin D3 supplement from a reputable company, and aim to take 4,000 to 5,000 IU’s worth a day during the seasons with minimal sunshine. Unlike the other fat-soluble vitamins, A, E and K, the sunshine vitamin is absorbed well without food, so it can be taken alone or alongside food. I strongly recommend taking it in the morning, as Vitamin D temporarily pauses the production of melatonin, the sleep hormone and therefore could disrupt sleep if taken too late.


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