Low vitamin D: what are the health consequences?

What is vitamin D?

Vitamin D is a fat-soluble vitamin that is essential for the body to function properly.

Synthesised by the skin through exposure to the sun (1), it is also present in certain foods, particularly oily fish, eggs and fortified products.

In practice, vitamin D intake is often inadequate in a large proportion of the population (2).

Lack of exposure to the sun, particularly in winter or among people who live mainly indoors, is a major contributory factor.

Vitamin D contributes to a number of important bodily functions, including:

• normal functioning of the immune system
• maintenance of normal bone health
• maintenance of normal muscle function
• normal absorption and utilisation of calcium and phosphorus

A level that is too low can therefore have repercussions on various balances in the body.

Low vitamin D: possible signs and consequences for the body

Too low a level of vitamin D can be accompanied by diffuse symptoms or more marked effects on certain physiological functions.

Persistent fatigue and reduced energy

Too low a vitamin D level may be associated with a persistent feeling of tiredness.

This may be partly explained by its contribution to normal muscle function and the normal functioning of the immune system.

Indeed, an imbalance in these levels may be associated with reduced physical capacity or slower recovery, particularly in sportspeople.

Some research also suggests a link between low-grade inflammation and fatigue, in which vitamin D may play an indirect role (3).

Bone fragility

Vitamin D contributes to the absorption and normal use of calcium, a mineral essential for strong bones.

If vitamin D levels are too low, this mechanism can become less effective: calcium is then less well assimilated and less available for bone mineralisation (4).

Over the long term, this situation could be associated with a progressive reduction in bone density.

Possible impact on the immune system

Vitamin D contributes to the normal functioning of the immune system.

Too low a level could therefore be associated with a less optimal immune response.

Some studies also suggest that vitamin D is involved in modulating inflammatory responses and activating certain immune cells (5).

These mechanisms remain complex, but they tend to suggest an overall role for vitamin D in immune balance.

Muscle and joint discomfort

Low vitamin D levels can sometimes be accompanied by feelings of discomfort, with no obvious cause (6).

This phenomenon could be explained by vitamin D's contribution to normal muscle function.

By helping to regulate calcium, it plays an indirect role in the mechanisms by which muscles contract and relax.

When this function is less optimal, some people may experience tension, increased sensitivity or more marked muscular discomfort.

Of course, these symptoms can vary greatly from one individual to another.

Some people whose vitamin D levels are too low experience no particular symptoms.

In all cases, only a blood test can confirm insufficient vitamin D status and assess its significance.

If in doubt, it is advisable to speak to a health professional.

When and why consider vitamin D supplementation?

In certain situations, the body may not produce enough vitamin D.

This is particularly the case for the elderly, in winter (when exposure to the sun is reduced), when there is little daily exposure to the sun or when dietary intake is inadequate.

In these situations, vitamin D supplementation may be considered to maintain adequate status.

However, the adjustment of intakes must always take account of the individual context, and medical advice is still recommended to determine the specific needs of each person.

The form chosen can also influence absorption: as vitamin D is fat-soluble, it is generally better absorbed when combined with lipids or formulated in a suitable matrix (7).

Vitamin D3 is the form most commonly used for supplementation, as it is close to the form naturally synthesised by the body (8).

Discover Vitamin D3 1000 IU, a bioavailable form of vitamin D that contributes to normal immune system function, normal bone structure and normal muscle function.

It is also possible to take supplements in spray form, for absorption via the oral mucosa, making them easier to use for some people.

Vitamin D3 Spray 2000 IU offers practical sublingual administration, with precise dosage.

For higher needs, a 5000 IU version may be considered in a suitable setting.

Discover Vitamin D3 5000 IU, a highly dosed vitamin D3 dietary supplement.

People following a specific diet can also opt for a vegan alternative.

Vitamin D3 Vegan is a 100% plant-based dietary supplement made from non-GMO, pesticide-free algae.

As vitamin D contributes to the normal absorption of calcium, it is sometimes combined with vitamin K2, which helps maintain normal bone structure.

This combination is being studied for its role in calcium metabolism.

In particular, vitamin K2 plays a role in activating proteins involved in calcium binding in the bone, such as osteocalcin (9).

Discover Vitamin K2 MK-7 + Vitamin D3, a combination studied for its role in calcium metabolism and the maintenance of normal bone structure.