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How Long Does It Take to Raise Vitamin D Levels?

How long vitamin D supplements take to work depends on body weight and skin pigmentation, and whether you take the recommended dosage. Rectifying deficiency can take 10 days in order to raise your vitamin D intake to sufficient levels. Learn how to supplement effectively with our guide.

Table of Contents:

How Long Does It Take Vitamin D to Work?

To raise a person’s vitamin D levels to a sufficient level, the intake will vary depending on age and body weight. Our vitamin D research into how much is enough with the Sandwell and Birmingham NHS Trust has shown the average adult may require 2000 - 3000 IU daily (50-75 μg) to maintain healthy serum levels (amount in your blood) of vitamin D.

In our experience, the spray increased vitamin D serum levels within 3 days for both replete and deplete participants, with a significant increase within 10 days. Using a daily spray supplement, vitamin D deficiency can be easily turned into an optimal level within 10 weeks.

How long it takes vitamin D to work will depend on the method of supplementation. Our oral spray technology offers a fast, convenient way to improve your daily intake of vital nutrients.

BetterYou’s vitamin D supplements can help to raise your levels, ensure you are not missing out on the nutrient, and help to avoid the side effects which accompany deficient levels.

The Importance of Vitamin D Supplements

Vitamin D is known as the “sunshine vitamin” because our bodies make it from sunlight. Ultraviolet light (UVB) converts 7-dehydrocholesterol in the epidermis, into vitamin D. This is our primary source of vitamin D, so naturally it can be difficult to rely on this method of synthesising vitamin D in the UK.

In the UK, there is not always reliable amounts of sunlight, especially between October - March, and so a supplement may be considered to improve your intake of winter vitamins. Not only that, but our modern lives keep us increasingly indoors, meaning we may not be exposed to enough sunlight during the summer months to synthesise enough vitamin D.

Who is Most At-Risk of Low Levels?

Those in the “at-risk” groups may consider a supplement to help raise their levels, as they are more likely to suffer low levels of vitamin D:

  • People who are pregnant or breastfeeding
  • Infants and young children under 5 years of age
  • Older people aged 65 years and over
  • People who have low or no exposure to the sun
  • People who have darker skin

Those who follow a vegan or plant-based diet, or exclude certain food groups due to allergies, intolerances or lifestyle may miss out on the nutrients in their diet. Vegan supplements can help to bridge the gaps left in diets which exclude animal products.

Once you know whether you should take a supplement, how long it takes to work, you then need to supplement the recommended amount in order to see the essential benefits of vitamin D.

How Much Vitamin D Do You Need?

You need a recommended amount of vitamin D per day in order to maintain the processes the nutrient contributes to within your body.

According to the NHS:


How Much Vitamin D Per Day? (μg - micrograms)

Infants (Up to 12 months)


Children (1-17 years)


Adults (18+ years)


There are upper limits of vitamin D which you should not exceed in order to avoid “vitamin D toxicity” or supplementing too much. Adults should not have more than 100μg / 4000 IU per day, children should not exceed 50μg / 2000 IU, and infants up to 12 months should not exceed 25μg / 1000 IU to stay within these safe limits. Always read the Nutrient Reference Value (NRV) guidelines of vital nutrients.

How to Test At Home

You can test your vitamin D levels with our at-home vitamin D test to determine if your supplements are working, or whether you need to increase your intake. If you are concerned about your nutritional intake you should consult your Doctor, who may arrange for a test for you.

The UK Department of Health advises the following measurement guidelines:

  • ≥50 nmol/L = adequate
  • 25 - 50 nmol/L = insufficient
  • <25nmol/L = deficient

BetterYou’s test identifies the stored D3 and D2 levels in your blood, to identify your risk of deficiency. Our at-home health test kits are simple to follow, and make it easy to check your dosage by following these steps:

  1. Order your vitamin D test online
  2. Once received, place four blood spots onto the collection card from a quick and simple prick of the finger.
  3. Use the prepaid envelope to send the collection card to City Assays, who analyse the sample for Sandwell and West Birmingham trust.
  4. Receive your results via email within 10 working days of the lab receiving your sample.
  5. We will provide you with a bespoke supplementation plan to help increase vitamin D levels or or maintain them.

The Best Vitamin D Supplements

At BetterYou, our vitamin D supplements are formulated to provide effective and hassle-free nutritional support without the need to take a tablet. Thanks to our vitamin oral sprays, you can simply spray into your mouth, and the nutrient is delivered directly into the bloodstream. This means, the pill-free supplements bypass the gastrointestinal system, for an effective supplementation.

Our vitamin supplements provide different strengths for different ages or needs.


Vitamin D Dosage

Who Is It For?

Vitamin D 4000IU 

4000 IU / 100μg


Vitamin D 3000IU 

3000 IU / 75μg


Vitamin D 1000IU

1000 IU / 25μg

Teens/ Adults

Vitamin D 400IU Junior

400 IU / 10μg


Vitamin D 400IU Infant

400 IU / 10μg


Vitamin D 1000IU Vegan Spray

1000 IU / 25μg (vegan D3V®)


How long it takes your vitamin D to work will depend on the dosage you take and your baseline vitamin D level. Since sunlight is the key source of vitamin D, you may need supplements to support your intake. Government advice is that everyone should consider taking a daily vitamin D supplement during the autumn and winter.

Support Your Health with BetterYou

We pioneered pill-free nutritional supplementation and combined it with our mission for sustainability. We use plant-based plastic for our packing. From men’s health supplements to women’s health supplements, support your diet with BetterYou today.

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