How to increase your Vitamin D levels? 3 ways to boost your immune system and skin health

What is vitamin D?

Endogenous and exogenous sources of vitamin D

What is vitamin D for?

Low Vitamin D: possible causes

Vitamin D Skin Booster, give your skin a boost

How do I apply Freshly’s Vitamin D Skin Booster?


You’ve no doubt heard about vitamin D and how important it is for our health. Spoiler alert: it’s much more important than you think! In this post, we’ll tell you everything you need to know about vitamin D and ways that’ll help you achieve optimal levels.

Did you know that more and more people have low vitamin D levels or vitamin D deficiency? Several studies show that low levels of vitamin D are becoming more common among the general public with a prevalence of more than 80% in over 65s and around 50% in young people aged between 25 and 35 years, regardless of skin colour, gender or country of residence.

Almost a billion people in the West have low levels of vitamin D, which is related to the appearance of disorders that affect the immune system. These include respiratory infections, type 2 diabetes, neurodegenerative diseases, allergies, cancer or autoimmune disorders (we’ll leave a screenshot from an extensive study on vitamin D). Our skin can also be affected by autoimmune issues, causing conditions such as eczema, psoriasis, vitiligo or acne.

Niveles Vitamina D baja

Now you know just how important vitamin D is for our bodies. Achieving optimal levels isn’t difficult: by adopting some simple strategies, you can boost your levels in just a few months. Let us remind you that the content on this blog post is for information purposes only and in no way intended to replace medical advice. If you would like to find out your vitamin D levels, we recommend you make an appointment with a trusted health practitioner. What’s more, the content of this post does not express an opinion, but consists of evidence-based information from scientific papers.

What is vitamin D?

Even though  it’s called vitamin D and it’s known as the “sunshine vitamin”, it actually acts as a hormone. Both the vitamin D receptor (VDR) and vitamin D metabolites are expressed by various types of immune cells. Research shows that the immune response is very weak in people with low levels of vitamin D (less than 30 ng/mL). In fact, people that develop conditions that affect the immune system, such as autoimmune diseases, often have vitamin D deficiency. The immune system’s cells are full of vitamin D receptors and without vitamin D, they stop working effectively, causing the body’s defences to reduce.

As we’ve already seen, the number of cases of vitamin D deficiency is increasing every year, and you’ve no doubt asked yourself: how can I check my vitamin D levels? You can ask your general practitioner for a blood test to check your vitamin D (25-hydroxycholecalciferol) levels, which are usually measured in nanograms per millilitre (ng/mL).

According to the Institute of Medicine, deficiency is when vitamin D levels are below 20 ng/mL and insufficiency is when the levels are below 30 ng/mL. Studies state that optimal levels would be between 40-90 ng/mL. Many people are afraid of surpassing 60 ng/mL so don’t take action and end up having a deficiency. Bear in mind that hypervitaminosis D is very rare and it could only happen when taking supplements over 50,000 IU a day for months when the minimum daily recommended dose is 1,000 IU and the optimal dose is 4,000 IU.

Endogenous and exogenous sources of vitamin D

There are two source types for obtaining vitamin D: endogenous (i.e. what our bodies can synthesise, but take note, in this case, there’s an external factor that must be present: the sun) and exogenous (what we obtain externally through food). Endogenously, our skin produces vitamin D when it’s exposed to sunlight, and in turn, UVB radiation. When it comes to exogenous sources, we’re talking about diet (but so you know, there are actually very tiny amounts of vitamin D in food) and/or supplements.

Controlled sun exposure is our main source of vitamin D. That’s why we shouldn’t demonise the sun but improve our relationship with it to make the most of all the benefits it can give us. In fact, there are sun exposure tracker apps that show the day’s UV index and how many international units (IU) of vitamin D we’d synthesise if we went out in the sun. Generally, UVB radiation starts to have an effect from 9 am. With 10-20 minutes of sun exposure (across the whole body, if possible), we can produce up to 5,000 IU of vitamin D, which would be enough to maintain healthy levels. Here are some tips: for those 10 minutes, don’t use sun protection as you’ll be stopping vitamin D production. Also, make sure you go outside, as windows can block out part of the light spectrum.

Potenciador Booster Vitamina D

Ten minutes of controlled sun exposure at 9-10 am or 6-7 pm is never going to be bad for your skin or health. To date, there are no scientific studies that prove that it would be harmful. That’s why we always talk about balance. We cannot pigeonhole the sun as being bad or good. It has its functions and we need to understand and respect them if we want to enjoy good health.

We know what you're going to say – you can’t go out in the sun at that time because you’re working or busy doing other things. And that, my friend, is why we have vitamin D deficiency.

To counteract this deficiency many people take vitamin D supplements of between 2,000 IU and 4,000 IU every day. Vitamin D absorption is better when taken as oil capsules (liposome), such as Vitamin D in extra virgin olive oil (avoid sunflower oil), and at mealtimes. This format allows the active (in this case, vitamin D) to travel through your body inside a type of membrane and arrive at the place where it is being sent intact, optimising absorption and efficiency.

One thing is sure: experts recommend avoiding the so-called monthly “supra” doses, which have not been proven to significantly increase vitamin D levels in the body. It’s much better to take a daily supplement than one single dose per month, as your body will make better use of it, improving your levels gradually.

If you do consider taking supplements, make sure you receive advice from a health professional and check your vitamin D levels beforehand to make sure you take the right dose, especially if you want to boost your levels to 40-60 ng/ml.

What is vitamin D for? 

Vitamin D provides our bodies with many benefits and specialists believe that it is an essential nutrient for our health.

One of the most known benefits is its ability to help the body absorb calcium and phosphate. As you already know, these are the main minerals that ensure your bone system is strong, preventing bones from thinning and weakening and stopping them from breaking.

However, vitamin D is also present in many other functions. For example, it plays a role in making muscles move and in nerves sending messages between the brain and other parts of the body. What’s more, as we’ve said, our immune system cells have multiple vitamin D receptors (VDRs), which means if there’s not enough or no vitamin D, they don’t work properly.

Furthermore, the fact that it is synthesised in the skin and the relationship vitamin D has with the immune system’s activity have led to many studies on how it affects a variety of skin disorders such as acne, rosacea, scarring, psoriasis, alopecia, vitiligo and atopic dermatitis. In all cases, patients with vitamin D deficiency tend to show more severe symptoms or deterioration in the course of the illness compared to those who have normal levels. Some of the most visible effects are a loss of radiance or dehydration, among others.

Here you can find more technical information about the immune functions of vitamin D if you want to delve a bit deeper:

Antimicrobial and antiviral properties

Modulation of antimicrobial peptides and the immune response.

When an infection is present, activated monocytes and macrophages strongly express CYP27B1, which turns 25(OH) D3 into 1,25(OH) D3. This vitamin D3 activation stimulates the production of cathelicidin LL-37, which acts against invading fungi and bacteria by destabilising microbial membranes. It also exhibits direct antiviral activities, especially respiratory viruses like Covid-19, as it disrupts viral envelopes and alters the viability of host target cells.

Antigen-presenting cells

The 1,25(OH)2D or calcitriol modulates the differentiation and functions of antigen-presenting cells by inducing them to become more immature. This results in a decrease in antigen presentation and the production of interleukin-12 (IL-12) and an increase in the production of IL-10, a tolerogenic cytokine. It has also been proven that 1,25(OH)2D inhibits the production of some inflammatory cytokines such as IL-2, IL-6 and IL-17. These immune responses are related to autoimmune disorders.


Activated T-lymphocytes express CYP27B1, which mediates converting 25(OH)D into 1,25(OH)2D, which stimulates VDR activation.

Studies have shown that reducing the CD4/CD8 ratio, an indicator of increased immune activation, is associated with low levels of 25(OH)D and that giving 5,000 to 10,000 IU of vitamin D3 is associated with an increase in CD4/CD8 ratio, reflecting immune suppression.


Inactive B-lymphocytes have no VDR and only when they become activated to proliferate by mitogens do they upregulate their VDR expression.

1,25(OH)2D inhibits the formation of plasma cells and induces apoptosis of activated B-cells as well as plasma cells.

It is thought that, by controlling B-cell activity and transforming B-cells into plasma cells, 1,25(OH)2D helps reduce the production of autoantibodies, thereby reducing the risk of antibody-mediated autoimmune disorders, such as systemic lupus erythematosus.

Potenciador Booster Vitamina D

Low Vitamin D: possible causes 

Several factors can cause low levels of vitamin D, especially given our current lifestyle: we spend most of our day indoors (during work, school or free time) and use photoprotection when we do go outdoors, which could lead to deficiency. The five most common causes are:

  1. Lack of sun exposure. This is without a doubt the main reason for vitamin D deficiency. The lack of UVB radiation reduces vitamin D production.
  2. Time of year. Some people achieve normal levels of this important vitamin in summer, given their exposure to the sun, but then they lose it because they don’t keep up their sunlight intake during winter.
  3. Skin phototypes. Skin type also influences our ability to synthesise vitamin D. This means that people with darker skin tones, require a higher sun intake to achieve optimal levels of vitamin D. This is because melanin (a natural pigment that gives us our skin colour) competes with active photons to produce vitamin D. So a person with fair skin has a phototype suitable for latitudes where there is less sun and darker phototypes in areas where there is more sun. Evolution has made sure of that.
  4. Age. Skin loses its ability to produce enough vitamin D as the years pass.
  5. Diet. It is not usually a significant cause of deficiency, as only some types of animal oils (fish) contain low concentrations of vitamin D.

Vitamin D Skin Booster, give your skin a boost

What if there was a product that could boost vitamin D synthesis through your skin? Freshly proves its commitment to innovation by launching Vitamin D Skin Booster, which will help you increase your endogenous vitamin D concentration (that’s produced inside your body or cells) topically.

Formulated with actives at the forefront of cosmetic science: D Skin Nectar (optimises vitamin D production), Chicory Root Active (stimulates endogenous vitamin D synthesis and its VDR) and Vitamin D3-Like (stimulates the production of VDRs), you’ll increase vitamin D synthesis in your skin by +119% with sun exposure and +77% without sun exposure. And you’ll improve your skin health too! Other skin benefits include increased skin thickness and improved symptoms of eczema, psoriasis, rosacea and vitiligo.

This solution can help you keep healthy levels of vitamin D in your skin, especially bearing in mind that during autumn and winter we tend to spend even less time in the sun. We must say though that if you were to have vitamin D deficiency, this booster should in no way be used as a replacement for sun exposure and supplements prescribed by a professional.

Potenciador Booster Vitamina D

How do I apply Freshly’s Vitamin D Skin Booster?

You can combine it with any of your usual products, except those that need rinsing, such as gels or cleansers, as you’d rinse the product off and it wouldn’t have an effect on your skin. How?

Add a drop (for facial products) or a whole dropperful (for body products) of Vitamin D Skin Booster to turn any of your usual products into a vitamin D booster. Mix them in the palm of your hand and massage across your face or body.

Potenciador Booster Vitamina D

We hope this post about vitamin D has helped you learn about this important vitamin. Thank you for reading it and being a part of the Freshly family.

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