Folk healers advise: take it when your body can make the best use of it. And that’s the key point. Vitamin D is not an ordinary vitamin that you just wash down with water and forget about. Its effectiveness is strongly connected to food, daily rhythm, and even sleep.
What exactly is vitamin D
Vitamin D is a substance that helps the body absorb calcium and phosphorus from food. These are minerals that ensure strong bones and teeth. But its role doesn’t end there. Research from 2020–2024 shows that vitamin D also affects:
- muscle function,
- the immune system,
- mood,
- quality of sleep.
The word supplement means dietary supplement and refers to adding something to your diet when you don’t get enough of certain substances through food. Vitamin D is often taken in this form, because it is hard to get enough of it just from food.
Why do we almost always get too little from food
In nature, vitamin D is produced in the skin when it is exposed to sunlight. The problem is that between October and April in most of Europe, the sun isn’t strong enough for our bodies to produce sufficient amounts. In 2020, measurements showed that as many as 7 out of 10 people had too low a level of vitamin D in their blood during winter.
There’s relatively little of it in food. We find it in fatty fish, eggs, and full-fat dairy products, but you’d have to eat a lot of these foods to meet daily needs. That’s why dietary supplements have become almost essential.
Why it does matter how you take it
Vitamin D is fat-soluble. This means it doesn’t dissolve well in water, but needs fat to pass from the digestive tract into the bloodstream. If you take it on an empty stomach, with water, your body will absorb much less of it.
One older, but still often cited study with 17 adults showed that vitamin D levels in the blood increased by about 50% when taken with the largest meal of the day, compared to those who took it without food. A similar 2014 study with 50 older people showed an increase as much as 32% higher when the supplement was taken with a meal containing fat.
This is also confirmed by the portal Healthline, which regularly summarizes nutritional research and notes that the meal is often more important than the time of day.
Morning – a practical choice for most people
Many people take vitamin D in the morning, mainly for one reason: it’s easier to remember. Morning routines are usually more consistent than evening ones. If you take vitamin D at breakfast, together with an egg, yogurt or a pat of butter, you are already doing a lot for its better absorption.
Research from 2021 showed that people who take dietary supplements at the same time of day are up to 40% less likely to forget their dose. Consistency is key with vitamin D, as its effect builds up slowly, over weeks and months.
From a folk perspective, morning has another advantage. Vitamin D plays a role in regulating the daily rhythm, which means it helps the body distinguish between day and night. Taking it in the morning therefore seems more natural.
Evening – helpful or disruptive for sleep?
Here, opinions are somewhat divided. Some research, gathered around 2021, showed that vitamin D affects the production of melatonin – melatonin being the hormone that tells the body it’s time to sleep. If there’s too much or too little of it at the wrong time, sleep can be disturbed.
There is a theory that taking vitamin D right before bed decreases melatonin production in some people, making it harder to fall asleep. This doesn’t apply to everyone, but it’s common enough to be cautious.
On the other hand, newer analyses from 2024 show that people with low vitamin D levels more often have poor sleep, nighttime awakenings, and feel tired in the mornings. For these people, regular use of vitamin D actually improved sleep quality.
The word individual means that something varies from person to person. And this is crucial when it comes to taking vitamin D in the evening.
What do folk experiences say
In traditional practice, people always observed how their body reacted. If something disturbed sleep, they shifted it to another time of day. The same applies here. If you notice that taking vitamin D in the evening makes it harder for you to fall asleep, move it to the morning. If you don’t notice a difference, then evening is not necessarily a problem.
Folk wisdom here says: don’t take anything in the evening that makes you restless.
So is the ideal time really important?
To sum up research from 2020–2025, there is no single answer. The three most important findings are:
- take vitamin D with a meal that contains fat,
- choose a time that suits you and that you can maintain,
- be consistent.
How much vitamin D do you actually need
Recommendations vary, but most European guidelines suggest 800 to 2000 units (IU) a day for adults during the winter months. In 2025, many countries already started recommending preventive vitamin D supplementation in the cold part of the year, especially for older adults.
On the other hand, too much vitamin D is also not good. Although rare, an excess can cause problems with the body’s mineral balance. That’s why folk practice always advises moderation and long-term, not excessive, use.
The simplest solution is routine. Choose one meal in the day that contains some fat, and take your vitamin D then. This can be breakfast or lunch. If the evening doesn’t interfere with your sleep, dinner is also a good option.
In addition, take advantage of every sunny day. Even 15-20 minutes of sun on your face and hands in summer can create more vitamin D than the average capsule.
What’s worth remembering
Vitamin D is not a miracle pill, but it is one of the most important health allies that most people lack. The key is not what time you take it, but how and how consistently you do it.
If you take vitamin D with a meal at a time that suits you, and do so consistently, you’ve done the most you could do.
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