What Causes Vitamin D Deficiency and How Can I Get More Vitamin D?

Essential for maintaining bone health, supporting your immune system, and promoting cell growth, you don’t want to miss out on a regular helping of vitamin D.

However, whether due to long, dark winters, dietary choices or being cooped up in an office all day in the summer, many people are suffering from the effects of vitamin D deficiency – sometimes without even realising!

In this article, we break down the signs of low vitamin D levels, what causes low vitamin D, and how to increase vitamin D levels, regardless of the weather outside.

What are the symptoms of low vitamin D levels?

Are you constantly feeling tired? Do you struggle to sleep at night? Have your bones or muscles been aching?

While low vitamin D may not be the only cause, these are some of the most common low vitamin D symptoms in adults. That’s because, if your body has low levels of vitamin D, your body cannot produce enough calcium, which causes issues with your bones and muscles. This leads to aches, pains, and general fatigue.

Other symptoms of a lack of vitamin D may include:

• Feelings of depression or sadness.

• Hair loss.

• Loss of appetite.

• Increased susceptibility to colds and the flu.

• Paler skin.

What causes low vitamin D levels?

While a lack of exposure to sunlight is indeed a common cause of vitamin D deficiency, it is not the only reason why you may suffer its symptoms.

For example, did you know that we also get lots of vitamin D from food and drink? Oily fish, such as salmon and sardines, are packed full of this vital vitamin, as are eggs and mushrooms. So, if you’re feeling the effects of low vitamin D, you may want to review and tweak your diet accordingly.

Your body might also struggle to naturally absorb vitamin D from sunlight or from your food. It could be that your digestive tract cannot absorb vitamin D properly due to gut health issues, your kidneys cannot convert this vitamin to its active form, or you just have darker skin that struggles to produce high levels of vitamin D from sunlight – all are common causes of low vitamin D levels.

If you’re experiencing low vitamin D symptoms and think it’s a medical issue, we recommend speaking to your GP, who can guide you through the next steps.

How much vitamin D per day do I need?

According to the NHS, everyone needs at least 10 micrograms (mcg) – or 400 International Units (IU) – of vitamin D every day. This includes babies and young children (for more information on vitamins for children and infants please see NHS guidelines).

But what does 10 mcg mean for you? Let’s break it down into practical terms.

To avoid experiencing the effects of vitamin D deficiency, you’ll roughly need to get 30 minutes of midday sunlight, three to four times per week. If your skin is darker, you might need to up your intake slightly – just ensure you’re properly protected with suncream.

For those wanting to address signs of low vitamin D levels with their diet, we’ve provided some examples of different foods and their respective vitamin D units, below:

• Tin of salmon: 100 grams = 13 mcg/526 IU.

• Tin of tuna: 100 grams = 2 mcg/82 IU.

• Boiled eggs: 2 large eggs = 2 mcg/87 IU.

How to increase vitamin D levels all year round

When the days get shorter and the temperature drops outside, you’re much more likely to feel the signs of vitamin D deficiency. That’s because the UV light from the sun is not strong enough on these colder, darker days for our bodies to produce enough vitamin D.

To combat the effects, we’ve pulled together three tips for boosting vitamin D levels all throughout the year, below.  

Spend more time outdoors

Love the feeling of sunshine on your skin? Great news – you can increase your vitamin D levels simply by spending more time in sunlight!

For example, rather than going to the gym every day, you could start exercising outdoors. This could be a long walk, a run around the park, or cycling along a country path – anything that gets your muscles pumping under the sun!

You could also avoid the effects of low vitamin D by altering your commute, where possible. If you live close enough, for instance, think about walking to work to get your vitamin D boost while also enjoying the benefits of daily exercise.

Experiment with vitamin D-rich recipes

Knowing the foods that boost vitamin D levels is only half the work – you should also understand how you can easily add these foods into your weekly diet and reap the benefits.

Our advice? Try new recipes and dishes to delight and entice your palate.

Take salmon and other types of oily fish, for example. These foods help to increase vitamin D levels in your body, but you might be scratching your head for how to add it to your meal plan. That’s where our Cajun honey salmon comes in, offering a fresh twist on a familiar ingredient.

The same goes for our egg-based breakfast ideas that also come packed with fibre and protein, too. It’s just about experimenting with vitamin D-rich ingredients to find that winning meal plan and help boost your energy levels.

Take vitamin D supplements

While it won't directly increase the levels in your body, vitamin K does play an essential role in the absorption and protection of vitamin D in the long-term. What’s more, vitamin K is important for metabolising calcium, helping to strengthen bones and teeth. 

Dark, leafy green vegetables are your best bet for upping your vitamin K intake, with the likes of kale, Swiss chard, spinach, and broccoli all packed full of this amazing vitamin!

If you want to find out more about the other essential vitamins, minerals, and nutrients that could boost your wellbeing, head over to our nutrition page on our Be Healthy hub.

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Medically reviewed in May 2024.