It’s estimated that around one billion people worldwide have a vitamin D deficiency. This is usually caused by a lack of exposure to sunlight or low intake of vitamin D-rich foods. Though various other factors, including ageing, smoking, and certain health conditions, can also play a role.
Many people aren’t aware that they’re vitamin D deficient, because symptoms can often be very subtle. However, this vital vitamin has some very important functions.
With that said, we’ll be taking a closer look at what vitamin D is, its role in the body, and how to make sure you’re getting enough.
What is vitamin D?
Vitamin D – also known as calciferol – is a fat-soluble vitamin that’s found in a small number of foods, including oily fish and mushrooms. It’s also produced by our bodies when ultraviolet (UV) rays from the sun hit our skin.
Vitamin D is important for health because, among other things, it helps to regulate the amount of calcium and phosphate in the body. These nutrients are required for healthy bones, teeth, and muscles.
What are the health benefits of vitamin D?
Vitamin D has various functions throughout the body and offers a number of health benefits.
We’ll cover some of these below…
Vitamin D can strengthen bones and muscles
Vitamin D helps the gut to absorb calcium and store it in skeletal tissue. From here, it helps to regulate the production of cells that are responsible for building and maintaining bones.
As a result, vitamin D plays an essential role in maintaining bone health and reducing the risk of osteoporosis.
Scientists have also suggested that vitamin D might be able to prevent or delay the onset of rheumatoid arthritis and improve muscle strength and function, which is important for preventing falls as we get older.
Vitamin D can strengthen immune system
Vitamin D helps the body to control and enhance the performance of immune cells, which are the first line of defence against infection and disease.
As a result, vitamin D deficiency is widely regarded by experts as a contributor to autoimmune disease.
Some research has suggested that having healthy levels of vitamin D may be particularly helpful in protecting against viruses such as the flu and respiratory tract infections.
Vitamin D may reduce the risk of depression
Vitamin D is important for oral health
Vitamin D is one of the biggest contributors to our dental health because it helps the body absorb calcium, which is needed for the maintenance of healthy teeth and gums.
Vitamin D and calcium work together to help guard against tooth decay and gum disease, so it’s important to make sure that you’re getting enough of each.
Vitamin D can support healthy weight loss
Obesity is a known risk factor for vitamin D deficiency, so experts have also looked into how vitamin D might support healthy weight loss.
In this study of overweight or obese women who had low calcium levels, those who took a daily calcium and vitamin D supplement were more successful at losing weight than those who took a placebo supplement.
Vitamin D may reduce the risk of cancer
There’s research to suggest that having higher levels of vitamin D may reduce a person’s risk of cancer.
For example, in this study, people with higher levels of vitamin D in their blood were found to have a 22% lower risk of developing cancer – particularly liver cancer.
Additional benefits of vitamin D…
Studies have been conducted that suggest that Vitamin D could also…
- Play an important role in treating high blood pressure (hypertension).
- Help to prevent Type 1 and Type 2 diabetes when combined with a sufficient calcium intake.
What's the recommended daily dose of vitamin D?
In order to protect bone and muscle health, the UK government recommends that adults get 10mcg of vitamin D a day.
From late March through to early September, it’s usually possible to get this from sunlight alone. But in autumn and winter, the NHS advises that everyone should consider taking a 10mcg daily supplement.
The NHS also says that people with dark skin from African, African Caribbean, and South Asian countries may need additional vitamin D year-round, alongside that provided by sunlight
Other people who have limited exposure to the sun – for example, those who cover their skin when they’re outside or live in an institution like a care home – may also find it beneficial to boost vitamin D levels with a supplement.
You can find out more about government guidance on vitamin D intake on the NHS website. However, it’s important to always speak to your GP before adding any supplements to your diet.
Is it possible to get too much vitamin D?
While vitamin D deficiency is fairly common, it’s also possible to end up with vitamin D levels that are too high. This is called vitamin D toxicity or hypervitaminosis D.
Vitamin D toxicity usually results from taking supplements at a much higher dose than the recommended 10mcg a day.
The reason that vitamin D toxicity is more common than other vitamins is largely because it’s fat soluble. This means that it’s much more difficult for the body to break down than water-soluble vitamins, like vitamin C and biotin.
Additionally, vitamin D is also stored in the body, so when levels are too high, we end up with too much spare vitamin D floating around in the bloodstream.
This extra vitamin D can form deposits in arteries and soft tissues, and disrupt and overwhelm biological signalling processes. For example, encouraging the body to absorb more calcium than it needs, which, in extreme cases, can damage the kidneys and nervous system.
Other symptoms of vitamin D toxicity can include high blood pressure, vomiting, poor appetite and bone loss. You can find out more about the symptoms of vitamin D toxicity in this article from Healthline.
However, unless you have an underlying health condition, it’s generally quite difficult to reach dangerously high vitamin D levels through sunlight and diet alone.
Though vitamin D toxicity is quite rare, it’s always a good idea to be aware of the risk and to speak to your GP before adding any supplements to your diet.
3 easy ways to boost your vitamin D intake
1. Spend more time outside or sitting by a window
The majority of people can get enough vitamin D by exposing their hands, forearms, or lower legs to sunlight for short periods of time each day – especially between 11am and 3pm from late March/early April to the end of September.
It’s difficult to determine exactly how much sunlight a person needs to meet their body’s vitamin D requirements, because this can vary. Factors such as skin tone and how much skin is exposed to the sun, can all play a role.
However, generally speaking, it’s a good idea to make getting outside for some fresh air a daily habit. This could involve going for a walk or bike ride, or simply sitting and relaxing in your garden or at a local park.
During the winter, our vitamin D production levels are generally much lower, because there are fewer sunlight hours. But even on a gloomy day, it’s possible to get some of the UV rays needed to produce vitamin D, so it’s still worth getting outside during daylight hours.
If you’re unable to get outside or if you’d just like to maximise your sunlight exposure as much as possible, you could also spend some time each day sitting by an open window. It’s important that it’s open, so that the window panes don’t block the UV rays from hitting your skin.
Note: While sunlight exposure is incredibly important for the synthesis of vitamin D, too much time in the sun can also come with significant other health risks, including sunburn and an increased risk of skin cancer.
It’s important to always protect your skin with sunscreen. For more information, have a read of our article; 11 tips to protect your skin from sun damage.
2. Eat more vitamin-D rich foods
Diet can also play an important role in making sure you’re getting enough vitamin D. Some of the richest dietary sources of vitamin D include…
Fatty fish and seafood
Fatty fish and seafood are some of the richest natural food sources of vitamin D.
For example, 100g of tuna contains more than half of the recommended daily intake of vitamin D. Other sources of fatty fish and seafood include…
- Cod liver oil
- Mackerel
- Tinned sardines
- Salmon
- Prawns
- Anchovies
- Oysters
When cooking fatty fish, steaming or baking it and avoiding frying it in oil can help to preserve the vitamin D content. John West has a great selection of fatty fish recipes that you might like to try.
Egg yolks
If you’re partial to a scrambled, fried, or poached egg, you might be pleased to know that egg yolks are packed with vitamin D.
Free-range or pasture-raised chickens and/or those which have been fed vitamin D-enriched grain, can have up to four times more vitamin D – meaning they’ll usually produce eggs with a higher vitamin D content.
Why not check out our article, 10 quick and easy egg recipes, to get started? Just be careful not to eat too many egg yolks, as they’re high in cholesterol.
Mushrooms
Mushrooms produce vitamin D when exposed to sunlight, which makes them one of the few plant-based sources of vitamin D.
Wild mushrooms, like shitake mushrooms, are generally higher in vitamin D because of their exposure to sunlight. But many commercial varieties found in supermarkets, such as chestnut mushrooms and portobello mushrooms, are treated with UV light to naturally enhance their vitamin D levels.
To find out how you can incorporate more mushrooms into your diet, check out this list of mushroom recipes from BBC Good Food.
Vitamin D-fortified foods
As well as eating food sources where vitamin D is naturally occurring, it can also be beneficial to add some vitamin-D fortified foods to your diet.
Cow’s milk, soy milk, fat spreads, orange juice, cheese, yoghurts, tofu, and breakfast cereals are often fortified with vitamin D, although this will vary depending on the brand.
It’s always worth checking the packaging of these foods to get a clearer idea about their vitamin D content.
3. Consider taking a vitamin D supplement if you need a boost
If you’re concerned about your vitamin D intake – particularly during the autumn and winter months – you might like to consider taking a vitamin D supplement.
There are two main types of vitamin D supplements: vitamin D2 (produced by plants) and vitamin D3 (produced by animals).
Some experts believe vitamin D3 is absorbed better by the body, so if possible, it can be best to look for a supplement in this form. Vitamin D3 is usually suitable for vegetarians, although it might not always be suitable for vegans, so it’s always best to check.
Supplements are usually sold in capsules or tablet form. It’s important to only buy supplements from reputable sellers, such as Holland and Barrett.
Note: It’s important to always speak to your GP before adding any supplements to your diet, as they may not be suitable for everyone.
Final thoughts...
Vitamin D is essential for keeping our bones, teeth, and muscles healthy – and without it, we might not feel at our best.
The good news is that the majority of people are able to get enough vitamin D through diet and sunlight alone. However, if you’re concerned about your vitamin D intake, it’s important to speak to your GP, who’ll be able to advise you on supplements.
For further reading, head over to the diet and nutrition section of our website. Here you’ll find other essential vitamin and mineral guides, as well as various healthy diet tips.