Why Vitamin D Deficiency is So Common

Vitamin D has become one of the most talked-about nutrients in health and wellness, yet 1 in 6 UK adults have low levels. Despite its importance for bone health, immunity, mood, and muscle function, many people still don’t fully understand how we actually make vitamin D, why it’s important and how supplementation could be one of the most effective ways to optimise this important nutrient in the body.

So let me explain…

How We Make Vitamin D

Vitamin D is unique because it behaves more like a hormone than a traditional vitamin. The body can produce it when skin is exposed to ultraviolet B (UVB) rays from sunlight. However, the process depends on several factors one of the most important being that UVB rays must be strong enough to penetrate the atmosphere and reach the skin, which typically only happens when the sun is high in the sky. This is why midday sun is far more effective for vitamin D synthesis than other times of day.

A useful rule of thumb is the “shadow rule”: when your shadow is shorter than your height, UVB rays are more likely to be strong enough for vitamin D production. When your shadow is longer, UVB is weaker and vitamin D synthesis is minimal. Many people assume that when they’re walking the dog in the morning or commuting home at the end of a sunny day they will still be making vitamin D, but it’s unlikely to be the case.

Other factors that influence how much vitamin D we make include whether we are wearing SPF, as this would effectively block the UV rays from penetrating the skin inhibiting vitamin D synthesis.

Skin colour is another variable because darker skin produces less vitamin D from the same amount of sunlight, and age is also a factor, older adults have reduced capacity to synthesis Vitamin D through the skin.

As a nation we are increasingly spending less time outside and more time inside which reduces the opportunity for appropriate sun exposure.

Higher body fat percentage is an interesting one too, because vitamin D is fat-soluble so less may be available to circulate in the body if it’s stored in the fat tissue.

Why Do We Need Vitamin D?

Vitamin D plays a wide range of roles in the body. Most people are familiar with its importance for bone health, as it helps regulate calcium absorption. Without adequate vitamin D, bones can become weaker over time. However, vitamin D is also involved in immune system regulation, inflammation balance, mood, cognitive health and muscle function.

Low vitamin D levels have been associated with increased susceptibility to infections, fatigue, low mood and impaired musculoskeletal function.

Given the varied role of vitamin D in the body, it’s so important to pay attention to your vitamin D levels and try to keep them optimal for overall health not just bone strength.

Why Do Many UK Adults Have Insufficient Levels?

As we have established, vitamin D insufficiency is common in the UK, particularly during autumn and winter months largely due to where the UK is in the world. Between October and March, the angle of the sun in the UK just doesn’t support meaningful vitamin D production in the skin. As a result, many people ether rely on stored levels of the nutrient, or dietary intake, which is often not enough to maintain optimal levels as we actually don’t get that much from our diet, although small amounts can be found in oily fish, egg yolks and beef liver. Some foods are now fortified with it, toosuch as breakfast cereals and plant-based milks.

For this reason, public health guidance in the UK commonly recommends vitamin D supplementation during autumn and winter months however for some people, depending on their base level, supplementing throughout the summer may also be beneficial.

Why is Liposomal Vitamin D Sometimes Used?

Liposomal vitamin D is a form where vitamin D is encapsulated in liposomes, little bubbles of fat that surround the nutrient, and are also made from the same phospholipids as our cell membranes designed to enhance absorption by protecting the nutrient through digestion and potentially improving uptake in the gut.

While standard vitamin D3 is already well absorbed in most people when taken with food containing fat, liposomal forms are sometimes used in individuals who may have compromised absorption or who prefer advanced delivery systems.

Why Combine Vitamin D3 with K2?

Vitamin D and vitamin K2 are often paired together due to their complementary roles in calcium metabolism. Vitamin D increases calcium absorption from the gut, while vitamin K2 helps direct calcium into the bones and teeth rather than allowing it to accumulate in soft tissues.

TRY: Meteron Labs liposomal D3 with K2, delivering 4000ius D3 and 100mcg K2 in 1ml.

Why Supplementing Can Be The Most Precise and Reliable Way

Although sunlight is the most natural source of vitamin D, it is not always a reliable one especially in higher latitudes like the UK.

Seasonal changes, lifestyle factors, skin differences, and behavioural habits all influence how much vitamin D we produce. This makes it difficult for many people to maintain consistent levels through sun exposure alone.

Supplementation can offer a practical and controlled way to maintain optimal vitamin D levelsthroughout the year, particularly during months when UVB exposure isn’t sufficient.

Have You Ever Tested Your Vitamin D Levels?

At-home vitamin D testing can be a valuable tool for understanding individual nutrient status in a more personalised way. Rather than relying on assumptions.

At-home testing also helps bridge the gap between general public health guidance and personal need. For some people, standard supplementation advice may be sufficient, while others may require higher or more tailored dosing to reach optimal levels.

Importantly, testing can also be useful for tracking progress over time. This allows individuals to see whether supplementation, dietary changes, or increased sunlight exposure are effectively improving their vitamin D status.

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