Would you like to know how to identify a possible vitamin D deficiency? How to have your vitamin D levels determined? How much vitamin D you need to take to achieve your desired healthy vitamin D levels? We’ve compiled the most important information about vitamin D for you so you can raise your vitamin D levels to an optimal level, alleviate any existing illnesses, and reduce your risk of future illness.
Maintain a healthy vitamin D level
Vitamin D isn’t actually a vitamin at all. The body can naturally produce vitamin D and maintain healthy levels with adequate exposure to sunlight. However, only insignificant amounts of vitamin D can be absorbed through food – unless you prefer to eat fatty fish. Therefore, the need for sunlight is inevitable.
Vitamin D deficiency can contribute to the development of diseases – and in existing diseases, a vitamin D deficiency can exacerbate them or prevent relief. Conversely, this means that well-adjusted vitamin D levels can at least improve almost any disease.
And so it is no surprise that studies are being published almost daily which show that patients with one disease or another have particularly low vitamin D levels – regardless of whether it is an increased susceptibility to infections, flu, asthma, osteoporosis, high blood pressure, inflammatory bowel disease, diabetes, arthritis, cancer, ADHD, dementia, thyroid nodules or simply “just” tooth decay, hair loss, high cholesterol or chronic exhaustion.
However, there are also quite a few people who initially exhibit no symptoms at all but still have low vitamin D levels. Cancer, diabetes, arthritis, osteoporosis, and other serious diseases don’t develop overnight, but rather over many years, if not decades.
So find out whether you have a vitamin D deficiency or not!
Is your vitamin D level too low?
Before you measure your vitamin D level yourself using a test kit, or have it measured by a doctor or alternative practitioner, you can use the following questions to determine whether your vitamin D level may be too low and whether you are a candidate for vitamin D deficiency or not.
1. Are you getting enough sun?
If you don’t get enough sunlight, your body won’t be able to produce sufficient vitamin D. As mentioned above, your body is normally able to absorb all the vitamin D it needs through regular direct sunlight through your skin.
So, if you spend a lot of time in the sun during the summer, you may be able to produce enough vitamin D—enough that your body can store enough to last even through the winter. However, many people don’t spend enough time in the sun—either in the summer or in the winter—simply because they spend too much time indoors.
2. Do you apply sunscreen when spending time in the sun to protect your skin?
When some people are outside in the fresh air or when they go to the seaside or the mountains in summer, they use sunscreen . However, these prevent or reduce the body’s production of vitamin D in the skin—at least, sunscreens with a higher SPF do.
3. Do you live in the southern half of Australia?
In southern parts of Australia—such as Melbourne, Hobart, or Adelaide—UVB radiation is only strong enough to support adequate vitamin D production during the warmer months, typically from around October to March. During autumn and winter, the sun sits too low in the sky, and UVB levels are insufficient for your skin to produce enough vitamin D.
4. Do you take a vitamin D supplement?
If you answered “No,” “Yes,” and “Yes” to the above three questions, then you are not getting enough vitamin D. If you are not taking a vitamin D supplement, there is a high risk that your vitamin D levels are very low, meaning you have a vitamin D deficiency. Furthermore, if you belong to a risk group for vitamin D deficiency, then it is very likely that you have a vitamin D deficiency:
Who’s at Risk of Vitamin D Deficiency?
Certain groups are more likely to develop vitamin D deficiency due to reduced sun exposure, skin type, age, or lifestyle. If you fall into one or more of the categories below, it’s worth considering a vitamin D test to assess your levels accurately.
High-Risk Groups for Vitamin D Deficiency:
People with obesity
Vitamin D is fat-soluble, meaning it gets stored in fat tissue. Those with higher body fat may need increased levels of vitamin D to maintain optimal blood concentrations.
People with darker skin tones
Higher melanin levels reduce the skin’s ability to produce vitamin D from sunlight. This means individuals with naturally darker skin require more sun exposure to generate adequate levels.
Those who spend little or no time outdoors
This includes people who are housebound, work night shifts, are in hospital care, or simply don’t get outside regularly—even on weekends.
Older adults
As we age, the skin becomes less efficient at synthesizing vitamin D. In addition, older adults may spend less time in direct sunlight.
Infants who are breastfed
Babies rely on maternal vitamin D stores. If the mother is deficient, the infant may also be at risk—especially if they aren’t receiving vitamin D supplementation.
If you identify with any of these groups, it’s advisable to have your vitamin D levels tested. A blood test can help determine whether supplementation is necessary—and if so, what dosage is appropriate to restore healthy levels.
How to measure your vitamin D levels
There are now test kits available online for measuring vitamin D levels. You then immediately send your blood sample to the specified laboratory, which will send you the results—i.e., your personal vitamin D level—within a few days. Of course, you can also visit your family doctor or alternative practitioner for this purpose.
What’s measured isn’t the actual vitamin D3 (cholecalciferol), but rather the storage form of vitamin D. This is called 25-hydroxyvitamin D, usually abbreviated to 25(OH)-vitamin D3, or even simpler: 25(OH)D. Measuring vitamin D3 would only provide a snapshot of the current status. The storage form, on the other hand, provides information about long-term vitamin D supply.
How to Evaluate Your Vitamin D Levels
When your vitamin D test results come in, they may be reported using different units depending on the lab. Here’s how to understand and convert them:
Common Units Used:
- ng/mL = nanograms per millilitre
- μg/L = micrograms per litre (same as ng/mL)
- nmol/L = nanomoles per litre
Conversion Formula:
To switch between nmol/L and ng/mL:
- nmol/L ÷ 2.5 = ng/mL
- ng/mL × 2.5 = nmol/L
For example:
- 75 nmol/L ÷ 2.5 = 30 ng/mL
- 40 ng/mL × 2.5 = 100 nmol/L
Updated Guidelines for Vitamin D Levels
Many labs still use outdated reference ranges. However, current research and clinical experience suggest the following levels are more accurate for optimal health and immune support—especially through winter:
| Vitamin D Status | ng/mL | nmol/L |
| Optimal | 40–60 ng/mL | 100–150 nmol/L |
| Mild Deficiency | 20–30 ng/mL | 50–75 nmol/L |
| Severe Deficiency | Less than 20 ng/mL | Under 50 nmol/L |
A level of 50 ng/mL (125 nmol/L) is often considered ideal for long-term health and resilience during months with low sunlight.
If your vitamin D levels fall below the optimal range, it’s worth speaking with a qualified health practitioner to determine the best supplement dose for you. At Vitalis Health, we recommend testing before and after any supplementation to monitor progress safely.
How to increase your vitamin D levels
There are basically four ways you can increase your vitamin D levels:
- The most natural way: direct sunlight on your uncovered skin
- For emergencies: Visit a tanning salon (if sun and dietary supplements are temporarily not possible)
- The uncertain path: nutrition (uncertain because food contain various amounts of vitamin D and can therefore only contribute a little to meeting the vitamin D requirement, but cannot ensure this on its own)
- The safest way: taking vitamin D supplements
1. Increase vitamin D levels in the sun
As we saw above, this isn’t easy, especially if you live in the “wrong” region. In Central and Northern Europe, you have to take advantage of the summer to replenish your vitamin D stores. On the other hand, it’s precisely in summer that the risk of sunburn looms.
It’s important to note that you don’t need to tan, let alone burn, to produce vitamin D. Vitamin D production starts much earlier. Adequate vitamin D production takes half the time required for a slight tan to appear – assuming, of course, that you haven’t applied sunscreen.
Key Factors That Affect Vitamin D Production
Your body’s ability to make vitamin D from sunlight depends on several environmental and personal factors:
- Season & Time of Day: Vitamin D is best produced around midday in summer. In winter or during early morning/late afternoon, the sun’s angle is too low, reducing UVB exposure. Tip: If your shadow is longer than your height, your skin won’t make much vitamin D.
- Geographic Location: The closer you are to the equator, the more consistent your UVB exposure year-round.
- Altitude: Higher altitudes receive stronger UVB rays—vitamin D production is easier in the mountains than at sea level.
- Weather & Pollution: Cloud cover and air pollution block UVB rays, significantly lowering vitamin D synthesis.
- Skin Exposure: The more skin exposed (e.g., arms, legs, back), the more vitamin D your body can produce.
- Skin Tone: Fair skin produces vitamin D faster than darker skin, which requires more sun to reach the same levels.
Why dark skin types need more sun
The more melanin—the so-called skin pigment—your skin has, the darker it is and the longer it needs to be exposed to UV light to produce enough vitamin D. Melanin also protects your skin from UV damage, which is why people with dark skin are less prone to sunburn than those with lighter skin. For this reason, if you have dark skin, you need to stay in the sun for a relatively longer time to build up the necessary vitamin D than people with lighter skin.
Glass blocks UV radiation
Don’t forget that glass blocks UV light. Therefore, your vitamin D production isn’t particularly high in a car, in a bright office space behind a closed window, or under a glass roof.
Vitamin D and the risk of skin cancer
If you are concerned about a possible risk of skin cancer, here is what to do:
Exposing your skin to the sun for too long and causing frequent sunburns can increase your risk of skin cancer. However, the moderate but regular sunbathing we’ve described is not only healthy, it’s vital and can even reduce your risk of cancer.
Once you’ve spent the time in the sun needed for vitamin D production, you should move to the shade. If this isn’t possible, e.g., during a hike, a sailing trip, etc., you should apply a natural sunscreen.
2. Increase vitamin D levels in the tanning salon
Your skin can also produce vitamin D when you lie on a tanning bed in a solarium. The required vitamin D can often be produced within just a few minutes. So, there’s absolutely no need to “sizzle” under the tanning bed for so long that you’ve achieved a certain tan.
If you decide to use a tanning bed, be just as careful there as you would when sunbathing outdoors. That is, half the time it takes your skin type to blush is sufficient for vitamin D production.
Look for high-quality tanning salons with regularly maintained equipment that not only uses UVA radiation but also UVB radiation, which is necessary for vitamin D production. Otherwise, you’ll only get a tan but not vitamin D.
However, the tanning salon should only be an emergency solution if you are unable to spend time outdoors and you have not yet taken a suitable vitamin D supplement.
3. Increase vitamin D levels through food
Our bodies can easily obtain most of the vitamins and minerals we need daily from food. However, the situation is quite different with vitamin D. There are very few (ethical) foods that naturally contain vitamin D. And those that do, generally contain very small amounts of the vitamin. For these reasons, it’s almost impossible to obtain the daily required amount of vitamin D exclusively through food.
Foods without vitamin D
There is no vitamin D in vegetables, salads, fruits, cereals and legumes.
Foods low in vitamin D
Dairy products, eggs, and liver contain little vitamin D. One liter of milk or yogurt contains just 1 µg of vitamin D, which is extremely low even when considering the—officially—far too low daily requirement of 20 µg.
Eggs are often cited as a good source of vitamin D. However, you would need to consume 100 g of egg yolk (i.e., just the yolk) to get just 5 µg of vitamin D.
Beef or lamb liver also provides only a small amount of vitamin D (around 2 µg per 100 g), so you would have to eat a kilogram of it every day to at least come close to meeting your minimum requirements.
Foods rich in vitamin D
Mushrooms and fish contain high levels of vitamin D. Some mushrooms (wild mushrooms) can contain around 3 µg of vitamin D per 100 g. Cultivated mushrooms grown without UV radiation (commonly the case with button mushrooms) contain significantly less vitamin D, but can be placed in the sun, where they produce abundant vitamin D within a few hours.
Fish is a good source of vitamin D, but only certain types, such as herring (from the Atlantic) or eel, provide this. Just 100 grams of these two fish provide 20 to 25 µg of vitamin D.
Most reliable source of vitamin D: supplements
If exposure to the sun is not possible for whatever reason, vitamin D supplements are the best alternative for safely meeting your vitamin D needs.
They can be used to specifically correct a vitamin D deficiency and ensure vitamin D supply in a reliable and healthy way and without side effects.
4. Increase vitamin D levels with supplements
If you have decided to improve your personal vitamin D status with a dietary supplement, many questions usually arise.
- What is the vitamin D requirement according to official recommendations?
- What is the maximum amount of vitamin D you can take?
- Could there be side effects?
- How much vitamin D do I personally need?
- How much vitamin D do I need to take to achieve healthy levels?
- Which vitamin D supplement should I take?
We will clarify all these questions below.
What is the official vitamin D requirement?
Depending on the organization, recommendations regarding the daily intake of vitamin D supplements vary considerably.
The nutrition societies in Switzerland, Germany and Austria, for example, recommend the following intake amounts:
- Infants (0 – 1 year): 10 µg / 400 IU per day
- Children (1 – 15 years): 20 µg / 800 IU per day
- Adults (including pregnant women, breastfeeding women and the elderly): 20 µg / 800 IU per day
The US health organization National Academy of Medicine (formerly Institute of Medicine (IOM)), on the other hand, finds that the daily requirement of vitamin D for adults is no more than 15 µg / 600 IU.
However, many experts believe that these doses, which have been officially recommended for decades, are far too low, which could possibly be the result of a statistical calculation error, as scientists at the University of California showed in March 2015.
Vitamin D specialists – such as the Vitamin D Council (details below) – have long recommended not only much higher amounts, but also very individualized amounts – logically based on one’s own vitamin D status. The relevant tables, from which you can determine your personal requirements, can be found below: How much vitamin D do I personally need?
What is the maximum amount of vitamin D you can take?
Even according to official opinion, much higher levels than the officially recommended levels would not cause any harm. According to the Institute of Medicine and the EFSA (European Food Safety Authority), the highest amounts of vitamin D that one could take daily for a lifetime without fear of harm ( Tolerable Upper Intake Level ) are in the following ranges (1):
- Infants: 25 µg / 1,000 IU per day
- Children (1 – 10 years): 50 µg / 2,000 IU per day
- Adults: 100 µg / 4,000 IU per day
However, even with these values, it can be assumed that they are set very low and that at least adults can take significantly higher amounts – at least for a short time, namely when a deficiency exists and needs to be remedied.
Why are the recommended amounts so different?
Unfortunately, some researchers still believe there is insufficient evidence to support the benefits of increased vitamin D intake. Many other scientists, however, believe that the officially recommended vitamin D doses do not meet the body’s daily needs, promote vitamin D deficiency, and increase the risk of disease.
When you compare the recommendations of vitamin D experts with the official recommendations, the differences are sometimes quite large, which could lead to some confusion. However, you should always keep in mind that your body can produce between 10,000 and 25,000 IU of vitamin D per day – depending on the weather, season, skin type, and location.
According to vitamin D advocates, vitamin D toxicity, in which the vitamin can have negative effects on your health, could only occur if you consume 40,000 to 50,000 IU per day regularly over a period of several months.
High doses of vitamin D for serious illnesses?
For some conditions, there are now even clear studies showing that higher doses of vitamin D than those normally recommended can have enormous health benefits, such as multiple sclerosis and prostate cancer. If you suffer from such a condition and are considering taking higher doses than recommended, consult your doctor. In this case, you should also have your vitamin D levels accurately measured every three months to ensure that your blood levels are always within a safe and healthy range.
How much vitamin D do you personally need?
The following recommendations for increasing your vitamin D levels come from the Vitamin D Council, a nonprofit organization based in California. The Vitamin D Council was founded in 2003 by Dr. John J. Cannell but is no longer active.
Dr. Cannell believed that vitamin D deficiency is the cause of many diseases and that health problems could be alleviated or even cured with sufficient vitamin D. To disseminate this information to as many people as possible, he founded the Vitamin D Council.
When looking at the following tables, please keep in mind that every organism works differently and therefore not everyone absorbs the same amount of vitamin D in the same way and in the same amount at the same dosage.
The tables therefore only provide average values which are intended to serve as a rough guide and should not be considered as a “guarantee” or “promise”.
If the procedure presented below does not lead to success, a high-dose intake may also be an option, as we explain here: How to Take Vitamin D
It is ideal if you have your vitamin D status checked twice a year so that you can continually adjust the vitamin D dose you personally need.
If the value is between 0 and 10 ng/ml
If your value is in this range, you have a severe vitamin D deficiency.
To increase your vitamin D blood levels (for example, if your current status is 10 ng/ml), you can take the following daily doses to increase your levels (based on an average body weight of 75 kg):
| Your value: 10 ng/ml | desired value | required dose per day |
| 20 ng/ml | 1000 IU | |
| 30 ng/ml | 2200 IU | |
| 40 ng/ml | 3600 IU | |
| 50 ng/ml | 5300 IU | |
| 60 ng/ml | 7400 IU |
If the value is between 10 and 20 ng/ml
Even in this case, you still suffer from vitamin D deficiency. To increase your vitamin D blood levels (for example, if your current status is 15 ng/ml), you can take the following daily doses (based on an average body weight of 75 kg).
| Your value: 15 ng/ml | desired value | required dose per day |
| 20 ng/ml | 500 IU | |
| 30 ng/ml | 1700 IU | |
| 40 ng/ml | 3200 IU | |
| 50 ng/ml | 4900 IU | |
| 60 ng/ml | 7400 IU |
If the value is between 20 and 30 ng/ml
Many people have a level between 20 and 30 ng/ml. If you want to raise this to between 40 and 50 ng/ml, you could proceed as follows:
| Your value: 25 ng/ml | desired value | required dose per day |
| 30 ng/ml | 700 IU | |
| 40 ng/ml | 2000 IU | |
| 50 ng/ml | 3700 IU |
If the value is between 30 and 40 ng/ml
A value in this range is officially considered perfect. The amount of vitamin D present is sufficient for good calcium absorption. Some research studies have also shown that vitamin D levels in this range may reduce the risk of cancer and also have a positive effect on the immune system.
However, some vitamin D experts believe that even vitamin D levels of up to 40 ng/ml are not optimal, especially for getting through the winter well.
Therefore, to increase your vitamin D blood levels (perhaps still in the fall) (with a current status of, for example, 35 ng/ml), you can take the following daily doses (based on an average body weight of 75 kg).
| Your value: 35 ng/ml | desired value | required dose per day |
| 40 ng/ml | 800 IU | |
| 50 ng/ml | 2500 IU | |
| 60 ng/ml | 5800 IU |
If the value is between 40 and 60 ng/ml
If you were to expose your entire body (i.e. naked) to the equatorial sun for a whole year, these would most likely be the vitamin D levels you would achieve as a result.
Today, such a vitamin D status is only found in traditional hunter-gatherer societies (such as those in Africa). If your body has such a supply of the vitamin, almost perfect regulation of parathyroid hormone and calcium in your body is guaranteed.
If you are currently breastfeeding your child , your breast milk will contain enough vitamin D at this level to pass on to your baby.
To further increase your vitamin D blood levels (e.g., if your current status is 45 ng/ml), you can take the following daily doses (based on an average body weight of 75 kg).
| Your value: 45 ng/ml | desired value | required dose per day |
| 50 ng/ml | 900 IU | |
| 60 ng/ml | 4600 IU |
If the value is between 60 and 100 ng/ml
The Vitamin D Council refers to these measurements as the “high-normal range.” Several studies have shown that you can achieve such high vitamin D levels simply by spending a lot of time in the sun. Therefore, it is considered that a vitamin D concentration at this level corresponds to healthy levels intended by nature.
However, since there is currently insufficient scientific evidence to show whether such vitamin D levels provide greater health benefits compared to levels of 40 to 60 ng/ml, you do not need to make any effort to achieve levels above 60.
If the value is between 100 and 150 ng/ml
Although these levels of vitamin D in the blood are not yet toxic and generally not dangerous, they are believed to be too high. There are no known beneficial effects of the vitamin that would only be evident at such high concentrations above 100 ng/ml.
A research group at the University of Utah found that vitamin D levels above 100 ng/ml may be associated with a slightly increased risk of cardiac arrhythmia. Therefore, you should take steps to lower your vitamin D blood levels below 100 ng/ml. To do this, stop taking vitamin D supplements. You should have your vitamin D status checked after three months.
Your value is higher than 150 ng/ml
Such a level is definitely too high. It can lead to health problems. Therefore, if you are taking vitamin D supplements, stop taking them and ensure that your vitamin D status drops below 100 ng/ml.
These vitamin D supplements are recommended
Now that you know how much vitamin D your personal vitamin D level needs, all you need now is information about the type of vitamin D supplement that is right for you.
Vegan preparations
Vitamin D3 supplements are often derived from lanolin, the wool wax of sheep. They are therefore not suitable for vegans. However, there are now vegan vitamin D3 supplements available, namely products extracted from lichens or fungi, or obtained with the help of microorganisms.
Capsules or drops
It doesn’t matter what form you take vitamin D3 in—be it capsules, tablets, or drops. They all increase your vitamin D levels, although drops can usually be dosed much more individually.
Cod liver oil
Cod liver oil contains a lot of vitamin D. However, since cod liver oil contains not only plenty of vitamin D but also large amounts of vitamin A, and these amounts could potentially lead to a vitamin A overdose, cod liver oil is not the ideal form of vitamin D supplementation for increasing vitamin D levels.
When should you take vitamin D?
Time of day: It doesn’t matter what time of day you take vitamin D. You can take it at any time of day or night.
Fasting or with food? Vitamin D is a fat-soluble vitamin, so you should take it with a meal—either during or after a meal. If you take drops or fat-containing capsules, they already contain the necessary fat for absorption, and you can also take the vitamin on an empty stomach.
Your vitamin D level also needs vitamin K2 and magnesium
It is also ideal if you choose a combination product that combines * vitamin D3 with vitamin K2 in a capsule or *drops to regulate your vitamin D level .
Vitamin D3 helps you absorb calcium, and vitamin K2 ensures that calcium reaches the bones and doesn’t accumulate in the arteries. Since the body needs vitamin D to utilize it, you should also ensure you’re getting enough magnesium when increasing your vitamin D levels with supplements . Otherwise, you could experience symptoms of magnesium deficiency on the one hand, and vitamin D deficiency symptoms on the other, despite good vitamin D levels.
However, you should be careful with calcium intake. Vitamin D alone ensures better absorption of calcium from food. If you take additional calcium, your calcium levels may rise too high. This is known as hypercalcemia.
How medications affect vitamin D levels
If you are taking (or have to take) medications, such as those for cardiac arrhythmia (cardiac fibrillation), high blood pressure, hyperthyroidism , kidney stones, etc., you should discuss regulating your vitamin D levels with a supplement with your doctor. Furthermore, do not take vitamin D without medical supervision if your blood calcium levels are very high.
Additionally, some medications can interfere with the effectiveness of vitamin D and reduce your vitamin D levels even with supplementation. In this case, you’ll need to take a higher dose of vitamin D. If you’re dependent on medication, discuss this issue with your doctor as well.
The conversion factor for the vitamin D dose
- 1 µg = 40 IU (International Units)
- 1 IU = 0.025 µg
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