What is Vitamin D?

Vitamin D is an essential nutrient that plays a crucial role in various aspects of our health. It aids in the absorption of calcium, which is necessary for maintaining healthy bones. Additionally, Vitamin D helps boost our immune system, fight off viruses, and combat fatigue. It has even been linked to good mood, with a deficiency potentially leading to anxiety and depression.

Vitamin D is a fat-soluble vitamin that our bodies produce when the skin is exposed to sunlight. It can also be obtained from certain foods or supplements. This vitamin exists in several forms, but the two most important ones are Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol). Vitamin D3 is the form that our skin produces naturally in response to sunlight.

How Much Vitamin D Do You Need?

The recommended daily intake of Vitamin D varies depending on age, sex, and certain health conditions. The following are the general guidelines for Vitamin D intake:

  • Infants (up to 12 months): 400 to 1,000 IU (International Units) per day
  • Children (1 to 18 years): 600 to 1,000 IU per day
  • Adults (19 to 70 years): 600 to 1,000 IU per day
  • Adults (over 70 years): 800 to 2,000 IU per day

It’s important to note that these are general recommendations, and individual requirements may vary. 

How to Get Vitamin D From the Sun

Getting Vitamin D from the sun is a natural and effective way to maintain adequate levels of this essential nutrient. Here are some tips on how to get Vitamin D from the sun:

  • Sun Exposure Time: Aim for moderate sun exposure. Spending around 10 to 30 minutes in the sun between 10 AM and 3 PM, at least twice a week, is generally sufficient for most individuals to produce enough Vitamin D. The exact time needed depends on factors such as skin type, latitude, altitude, and season.
  • Skin Exposure: Expose a large area of skin to the sun. The more skin that is exposed to sunlight, the more Vitamin D your body can produce. For instance, wearing shorts and a tank top can help maximise sun exposure.
  • Avoid Sunscreen for a Short Time: If possible, avoid applying sunscreen for the first 10 to 30 minutes of sun exposure. Sunscreen with SPF (sun protection factor) can block the UVB rays that stimulate Vitamin D synthesis. After the initial sun exposure, you can apply sunscreen to protect your skin from harmful UV rays.
  • Face and Arms: If you have limited time for sun exposure, try to expose your face, arms, and hands to the sun. These areas are more sensitive to sunlight and can produce Vitamin D more efficiently.
  • Avoid Overexposure: While moderate sun exposure is beneficial, prolonged sun exposure without protection can increase the risk of skin damage and skin cancer. Be mindful of the intensity of the sun, especially in hot climates, and seek shade or use protective clothing when necessary.
  • Latitude and Season: The angle of the sun’s rays varies with latitude and season. In regions farther from the equator, Vitamin D synthesis may be reduced during the winter months when the sun is at a lower angle. If you live in higher latitudes or experience long winters, consider alternative Vitamin D sources during these times.
  • Vitamin D Production through Glass: Note that sunlight exposure through glass windows does not stimulate Vitamin D production, as UVB rays, the ones responsible for Vitamin D synthesis, are blocked by glass.
  • Individual Variability: Keep in mind that Vitamin D production from sun exposure can vary based on individual factors, such as skin pigmentation. People with darker skin may require more sun exposure to produce the same amount of Vitamin D as those with lighter skin.

It’s important to strike a balance between getting enough sunlight for Vitamin D synthesis and protecting your skin from sunburn and skin damage. 

A woman in hat and sunglasses getting Vitamin D from the sun on the beach

How Does Your Skin Make Vitamin D?

When sunlight (specifically UVB rays) reaches our skin, a chemical reaction occurs that converts a cholesterol compound in the skin into Vitamin D3. This form of Vitamin D is then further converted into its active form in the liver and kidneys.

However, it’s essential to strike a balance when it comes to sun exposure. While sunlight is an excellent source of Vitamin D, prolonged or unprotected exposure can increase the risk of skin damage and skin cancer. Therefore, it’s recommended to spend a brief period (around 10 to 20 minutes) in the sun without sunscreen between 10 am and 4 pm, when the sun’s rays are strongest. 

If planning to stay in the sun for longer, it’s advisable to use sunscreen to protect the skin.

What Are the Symptoms of A Vitamin D Deficiency?

When the body doesn’t get enough Vitamin D, it can lead to a deficiency, which can manifest through a range of symptoms. Here are some additional informative points about the symptoms of a Vitamin D deficiency:

If you’re feeling any of these symptoms, you could be low in vitamin D:

  • Fatigue – a feeling of constant tiredness.
  • Weak immunity – easily catching coughs and colds.
  • Low mood. 
  • Aches and pains in muscles and joints.

Recognising the symptoms of a Vitamin D deficiency is important for addressing potential issues. If you experience any of these symptoms, it’s possible that you may be lacking sufficient Vitamin D. This can have long-term implications like:

Diminished Bone and Muscle Health

Vitamin D is essential for the proper absorption of calcium, a vital mineral for maintaining bone strength. A deficiency in Vitamin D can lead to weakened bones, increasing the risk of conditions like osteoporosis in adults and rickets in children. Additionally, inadequate Vitamin D levels can cause muscle weakness and contribute to muscle pain and discomfort.

Impaired Wound Healing

Vitamin D plays a role in promoting proper wound healing and tissue repair. A deficiency can slow down the healing process of injuries, wounds, and surgical incisions.

Decreased Cognitive Function

Emerging research suggests that Vitamin D may have a role in cognitive function and brain health. Some studies have linked low Vitamin D levels with an increased risk of cognitive decline and neurological disorders like dementia and Alzheimer’s disease.

Increased Susceptibility to Infections

Vitamin D is known to modulate the immune system, helping the body defend against infections. A deficiency in this vitamin may result in a compromised immune response, making individuals more susceptible to infections such as respiratory tract infections and flu.

Weakened Cardiovascular Health

Emerging evidence suggests that Vitamin D deficiency might be associated with an increased risk of cardiovascular diseases, including hypertension, heart disease, and stroke. However, more research is required to establish a definitive link.

Depression and Mood Disorders

Vitamin D is believed to influence serotonin levels in the brain, which can impact mood regulation. Studies have shown an association between low Vitamin D levels and an increased risk of depression and other mood disorders.

Excessive Sweating

Some individuals with a Vitamin D deficiency report experiencing excessive sweating, especially around the forehead.

Impaired Gut Health

Certain gastrointestinal conditions, such as Crohn’s disease and celiac disease, can impair the absorption of Vitamin D from the diet, leading to deficiencies in affected individuals.

3 Ways to Quickly and Effectively Increase Your Vitamin D Levels

To restore Vitamin D levels quickly, there are several effective methods you can consider:

The three best and fastest ways to increase your Vitamin D level are:

  • Go outdoors and feel the sun on your skin
  • Eat Vitamin D-rich foods
  • Take Vitamin D supplements
  • Get a Vitamin D shot

Go outdoors and feel the sun on your skin

Vitamin D is known as the ‘sunshine vitamin’ because our bodies can create it when our skin is exposed to direct sunlight. The UVB rays from the sun kickstart a chemical process that produces D3 – a form of Vitamin D that our bodies can store.

Protect your skin with SPF protection, sunglasses and a hat and get some Sunny D!

Eat Vitamin D-rich foods

Omnivorous Sources of Vitamin D

Increasing Vitamin D levels through omnivorous sources can be achieved by incorporating a variety of foods that naturally contain Vitamin D or are fortified with it. Here are some omnivorous sources of Vitamin D that can help boost your intake:

  • Fatty Fish: Fatty fish such as salmon, herring, mackerel, tuna, trout and sardines are excellent sources of Vitamin D. Consuming these fish regularly can provide a significant amount of this nutrient.
  • Shellfish: Oysters and prawns are the highest in Vitamin D if you frequently eat shellfish.
  • Cod Liver Oil: Cod liver oil is one of the richest sources of Vitamin D. A small daily dose of cod liver oil can supply a substantial amount of this essential nutrient. This is also often taken as a supplement.
  • Beef Liver: Organ meats, particularly beef liver, are a good source of Vitamin D. Incorporating beef liver into your diet occasionally can contribute to your Vitamin D intake.
  • Egg Yolks: While egg whites contain little to no Vitamin D, egg yolks are a natural source of this nutrient. Including eggs in your diet, especially those from pasture-raised chickens, can be beneficial.
  • Fortified Dairy Products: Many dairy products, such as milk, yoghurt, and certain cheeses, are fortified with Vitamin D. Check the product labels to ensure you are choosing fortified versions.
  • Pork: Pork contains small amounts of Vitamin D, and incorporating lean cuts of pork into your diet can contribute to your overall Vitamin D intake.

Top Vegan and Vegetarian Sources of Vitamin D

  • Fortified Plant-Based Milk: If you prefer plant-based options, some plant-based milk alternatives, like soy milk and almond milk, are fortified with vitamin D to match the levels found in cow’s milk.
  • Fortified Cereals and Breakfast Foods: Certain breakfast cereals and instant oatmeal may be fortified with Vitamin D. Checking the labels can help you identify Vitamin D-fortified options.
  • Fortified Orange Juice: Some brands of orange juice are fortified with Vitamin D, making them another potential source of this nutrient.

You can see that vegetarians and vegans need to be particularly mindful of where their Vitamin D comes from, and supplementation is often recommended.

Mushrooms – The Ultimate Dietary Source to Increase Vitamin D Levels Quickly
A bowl of vitamin-d-rich shiitake mushrooms.

While most dietary sources of Vitamin D come from animal products, mushrooms have the unique ability to synthesise this vitamin when exposed to sunlight, much like human skin. 

The specific type of Vitamin D found in mushrooms is called ergosterol, a provitamin that is converted into Vitamin D2 when exposed to ultraviolet (UV) light. When mushrooms are exposed to sunlight or artificial UV light during their growth process or post-harvest, their ergosterol content is converted into biologically active Vitamin D2. This process significantly increases the Vitamin D content of the mushrooms, making them a valuable natural source of this nutrient. 

The specific types of mushrooms that have been found to produce significant amounts of Vitamin D2 when exposed to UV light are shiitake and maitake. While other mushroom varieties may contain Vitamin D2 naturally in small amounts, these two species are known to have a higher potential for Vitamin D synthesis.

To create Vitamin D-enriched mushrooms, growers use controlled exposure to UV light either during the growing process or after harvest. This artificial exposure closely mimics the effect of natural sunlight. When you see “UV-exposed” or “Vitamin D-enriched” labels on mushroom packaging, it indicates that the mushrooms were treated with UV light to boost their Vitamin D2 content. This process significantly increases the Vitamin D content of the mushrooms, making them a valuable source of this essential nutrient for vegans and others looking to enhance their Vitamin D intake.

Vitamin D is fat–soluble, which means it is best absorbed when taken with food that contains fat. 

Take Vitamin D Supplements

Vitamin D can be taken on its own or as part of a multivitamin. Both D2 and D3 will help raise your levels, with D3 considered more stable and with a longer–lasting effect.

The NHS recommends that every adult takes a daily 10-microgram supplement, available over the counter at all pharmacists.  This recommendation is particularly important for those over 60 years old as the body’s ability to absorb Vitamin D from the sun and food diminishes as we age. 

How Long Does It Take Vitamin D Supplements to Work?

The time it takes for Vitamin D supplements to work and for you to notice changes in your Vitamin D levels can vary depending on several factors, including your current Vitamin D status, the dosage of the supplement, and individual differences in metabolism and absorption.

In general, some individuals may start to notice improvements in their Vitamin D levels within a few weeks of starting supplementation, while for others, it may take a bit longer. It’s essential to be patient and consistent with your supplement regimen to allow your body to absorb and utilize Vitamin D effectively.

Read more on The Difference Between Vitamin D, D2 and D3.

Get a Vitamin D Shot

Getting a Vitamin D shot means Vitamin D is entering the body via intramuscular injection. This way, it instantly enters the bloodstream for maximum absorption. This makes Vitamin D shots the most potent and rapid doses of Vitamin D you can get.

How Long Does It Take for Vitamin D Shot to Work?

Some patients feel instant results while some feel improvements as early as the next day!

woman and a man sitting on a couch in a clinic

During the pandemic, Vitamin D deficiency was brought to the forefront of the news. Those with deficiencies were urged to get Vitamin B injections from a trusted and registered source.

How Long Does It Take to Restore Vitamin D Levels?

Recipients of Vitamin D shots have attested to feeling better almost immediately or as soon as the next day.

Sunshine will raise levels of active Vitamin D within about 8 hours – depending on the sun’s strength and your body’s absorption level.

Vitamin D3 supplements are thought to raise vitamin D levels in the bloodstream in around 24 hours. However, it takes up to 7 days for this to be converted into the active form of vitamin D – which is what a blood test will pick up.

The time it takes for Vitamin D levels to rise after taking it in food form is harder to calculate. However, as Vitamin D is stored in the body, it follows that a diet rich in this vitamin will be beneficial to keep levels steady.

What Is a Healthy Vitamin D Level?

Vitamin D is measured as the concentration of the active form – hydroxyvitamin D – in the blood serum. 


Sun, diet, and supplements combined should normally be enough to keep optimal Vitamin D levels for most of us.  However, if you’re seriously deficient in Vitamin D, you may need further help to raise your levels quicker.

We can help you boost your health and well-being with Vitamin D Shot available in our clinic in central London.

This treatment can only be done on prescription and by suitably qualified GMC-registered practitioners.  Here is what you can expect in 3 simple steps:

  1. A blood test to determine Vitamin D levels.
  2. Medical consultation with a GMC-registered doctor – to establish whether the treatment is needed.
  3. The treatment will only take 5-10 minutes.

Some of our patients report feeling a lot better almost immediately; others feel the improvements later or the following day.

For further information call our friendly team on 020 3095 0002 or email info@ivboost.uk

IVBoost UK’s Own Dr Joshua Berkowitz

Dr Joshua Berkowitz has been practising medicine for over half a century. He has practised in South Africa and the UK. He is an advocate for using IV drips to support healing and does so in his practice to optimise nutrition and the patient’s ability to cope during the healing process.

All the content published on ivboost.uk is either written or reviewed by Dr Joshua Berkowitz who is an expert in Aesthetic Medicine and Nutritional Support.