When Should I Start Taking Vitamin D Again?

Unfortunately, the sun’s rays are now diminishing for the winter months. This change in season is a bit of a marmite topic. But, whether or not you like autumn and winter, your vitamin D levels will likely not thank you for the lack of sunlight. Vitamin D is famous, primarily for bone health in the mainstream media, but it does so much more for us than we could ever imagine.

Many people find that vitamin D supplementation starting earlier on in autumn will prevent any unwanted health issues that come with insufficient levels. These include issues like lowered immunity, hormone imbalances and low mood, to name a few. But, there still remains much debate around what levels of vitamin D we should opt for, what dosages are correct and when exactly we should be supplementing with vitamin D in the calendar year.

Approaching the winter months, it's a reminder to consider the importance of supplementing vitamin D. Vitamin D is undeniably linked to the health of our bones by helping the body absorb calcium from the foods we eat. Without enough of the active form of vitamin D, calcium absorption drops to about 12.5%, which can weaken bones over time.

One fascinating fact about vitamin D is that it influences the expression of over 1,000 genes. So, in reality, it acts on almost every cell and every organ of the human body with far-reaching effects on our health beyond just bone density concerns.

To really grasp this concept, it is worth understanding that the body obtains vitamin D from two sources; our diet (or supplements) and from sunlight on our skin. It is this sunlight exposure method that drives the natural production of vitamin D within the body. The reality is, if we had plenty of sun, every day, all year round — supplementing vitamin D or obtaining it from our diet wouldn’t be so important. But this is simply not the case. Vitamin D deficiency is incredibly commonplace in countries with little sunlight in the winter months and it contributes to a vast array of health issues.

As many as 60% of the UK population is thought to have insufficient levels of vitamin D. Some experts are concerned to the extent that they consider vitamin D deficiency to be classed as a major ‘lifestyle risk’ which may fall under the same category as smoking, alcoholism, obesity and sedentary lifestyles.

Here are just a few examples of the body systems that benefit from optimal vitamin D levels:

Immune system

Vitamin D enhances the body's defence against bacterial and viral infections by promoting the activation of immune cells like macrophages, neutrophils, and dendritic cells, which are responsible for identifying and eliminating harmful invaders. A deficiency in vitamin D has also been linked to a higher risk of developing autoimmune diseases.

Cardiovascular health

The research clearly points toward lower serum vitamin D levels being linked to a higher risk of cardiovascular disease incidence, including heart failure, heart attacks and stroke.

Energy levels

Vitamin D helps mitochondria, the energy producers in cells, to function properly. When vitamin D levels are low, the mitochondria can’t generate energy as efficiently, which can leave you feeling more tired and sluggish.

Blood sugar regulation

Low levels of vitamin D are associated with increased insulin production, a condition called hyperinsulinemia.

Mental health

Vitamin D plays a role in the production of serotonin, a hormone that regulates mood. Low levels are associated with depression and feelings of low motivation.

Drops in vitamin D levels can leave you feeling tired, lower your immunity, and even contribute to conditions like Seasonal Affective Disorder (SAD). With less sunlight, the body struggles to produce enough vitamin D. These effects become more noticeable as daylight hours shrink.

Winter in the Northern Hemisphere

In winter, sunlight is not just limited, but also weaker due to the Earth’s tilt. From November to February in the Northern Hemisphere, the sun sits lower in the sky, so its rays spread over a wider area, losing intensity. December and January are the darkest months, with December 21st marking the winter solstice, the shortest day of the year. Therefore, cases of deficiency are thought to be higher in the winter and the spring. 

When exposure to sunlight decreases, the level of vitamin D in the blood drops gradually, as it is stored in fat tissue and is gradually released. This way, the body maintains levels of the vitamin for a few months before supplementation becomes critical. However, to stay in the optimal range for vitamin D, it is worth taking action before levels get too low.

The optional levels of vitamin D require a 25 (OH) D reading above 75 nmol/L. It must be stressed that this is the ‘optimal’ reference range, and a reading lower than this does not necessarily constitute a deficiency. Levels below 25 nmol/L are generally classified as deficient and below 50 nmol/L is an insufficient level. While opinions may vary on what the ‘optimal’ vitamin D levels are, regular supplementation during winter is often suggested to maintain that levels do not drop too low.

Opting for bioavailable vitamin D means your body absorbs it more effectively, giving you better results. Cheaper supermarket brands often include fillers or synthetic ingredients, which can lower the supplement's quality and impact on our health.

When should I take Vitamin D?

It depends on your needs. Since vitamin D is fat-soluble, your body can store it for longer periods compared to water-soluble nutrients, but regular intake is still important, especially in winter months.Nutritional Therapist, Sally Duffin states "Daily or weekly supplementation is really personal preference. You can take a larger dose once a week, or smaller doses on a daily basis - either option will support your vitamin D levels.”

What else should Vitamin D be taken with?

Several other nutrients improve the action of vitamin D in the body.

Vitamin K is often involved in a lot of vitamin D products due to the proven synergistic effect of vitamin K (specifically K2) and vitamin D in the areas of both cardiovascular health and bone health. What’s more, evidence from studies suggests that regular intake of vitamin K is required in order to achieve optimal calcium regulation. Yet, in some individuals, this isn't always necessary.

Magnesium plays a vital role in helping the body produce vitamin D and is also important in moving it through the bloodstream to where it's needed. Ultimately, without enough magnesium, vitamin D can't be effectively processed or transported.

Vitamin D is a fat-soluble (lipophilic) vitamin, meaning it dissolves in fat. Consuming it with dietary fat therefore improves its absorption, which is why Nutritional Therapist, Eleanor Hoath advises clients "take Vitamin D3 supplement in conjunction with their omega-3 or alongside a meal containing fats".

Editors Picks:

To keep your vitamin D levels optimal over the darker, winter months, try to work vitamin D into your routine. You can focus on a mix of diet, lifestyle choices, and supplements. Try to get out into the daylight too, as much as possible, as this will allow your circadian rhythm to benefit from natural light. It’s also a good idea to check your blood levels so you can adjust your intake of vitamin D to what works best for you.

Is too much Vitamin D a bad thing?

It is possible to overdo it. Therefore, it's important to be mindful and test your vitamin D levels at least once a year to keep an eye on them.