© FG Trade - Getty ImagesVitamin D deficiency symptoms and when to take a supplement.
Vitamin D is one of thirteen essential vitamins that the body needs to function normally. It's well known that vitamin D is important for bone health but there's increasing evidence that it also plays a role in many other areas of good health including the immune system, the cardiovascular system and mental health. It may also be protective against certain types of cancer. There are still many unknowns, some controversy and lots of ongoing research into exactly what vitamin D does and how much of it we need.
It's estimated that as many as 50 per cent of the world's population are deficient in vitamin D. In the UK, approximately 25 per cent of people have low levels of vitamin D and could be at risk of developing a deficiency. Such was the concern that in 2016, Public Health England published advice that everyone should consider taking a vitamin D supplement during the winter months and that those in at risk groups should take one all year round. This advice was expanded in April 2020, during the coronavirus global pandemic, to suggest that everyone should consider supplementation due to the lockdown restrictions.
Award-winning author and running health expert Dr Juliet McGrattan looks at Vitamin D deficiency symptoms, risk factors and the latest research:
What is vitamin D?
Vitamin D is a fat soluble vitamin. There are two forms:
- D2 (ergocalciferol) which we obtain from plants in our diet.
- D3 (cholecalciferol) which is made in the skin and also obtained in animal products in our diet.
Vitamin D is needed for healthy bones, teeth and muscles. It controls calcium and phosphorus levels in the body, both of which are needed for a healthy skeleton. Insufficient vitamin D means that not enough calcium and phosphorus can be absorbed from your intestines.
© Baac3nes - Getty ImagesVitamin D deficiency
Where do you get vitamin D?
Most of your vitamin D stores come from sunlight and the rest is obtained through your diet:
?? Vitamin D from sunshine
The body's largest and most important supply of vitamin D comes from sunlight. It's often known as 'the sunshine vitamin'. When UVB light shines on skin, cholesterol in skin cells starts the process of making vitamin D. It's transformed to its active form in the liver and kidneys and can then be used by the body.
The sunlight needs to hit the skin directly when you are outdoors and must be of a UV index which is equal to or higher than three. During the spring and summer months in the UK this means being outside in direct sunlight, with some of your skin exposed and sunscreen free, for 10 to 15 minutes, three times a week, between the hours of 11am and 3pm. People with darker skin need longer than this because their skin contains more melanin which absorbs the UV rays.
In the winter months, the UV rays are not strong enough so we rely on our stores of vitamin D from sunshine earlier in the year and what we can obtain from our diet. This is why supplements of vitamin D are recommended in autumn and winter.
?? Vitamin D from your diet
You obtain around 10 per cent of your vitamin D through your diet. It's not present in a wide variety of foods but you will find it in the following:
- Oily fish eg salmon, mackerel, pilchards and sardines
- Eggs
- Red meat
- Fortified foods including some dairy products, cereals, margarines and spreads
How much vitamin D do I need to take?
The recommended daily intake (RDI) of vitamin D varies between countries. Many experts believe that the recommended amounts are significantly lower than they should be. It isn't possible to know how much vitamin D your skin is making so, in the UK it is currently advised that:
- Everyone over the age of one-year-old should take 10 micrograms (400 IU) daily between October and March.
- People over the age of one, who are at risk of vitamin D deficiency should take a daily 10 microgram supplement.
- Children under one year of age should have 8.5 to 10 micrograms of vitamin D unless they are drinking more than 500mls of infant formula per day (formula milk is already fortified).
Supplements can be bought in pharmacies and supermarkets and are available free of charge for low income families in the UK.
Who is at risk of vitamin D deficiency?
Certain people have a higher risk of low vitamin D levels and are therefore more likely to develop a deficiency. These are largely linked to reduced exposure to sunlight and they include:
- Residents of care homes.
- Housebound people or people with frailty who do not regularly leave the house.
- People over 65.
- People who wear clothes that cover their skin, often for cultural reasons.
- People of African, African-Caribbean or south Asian background because darker skin requires more prolonged sun exposure to make vitamin D.
- Pregnant and breastfeeding women.
- Babies and children under the age of five.
- People who follow a vegan diet.
- People with conditions that affect the absorption of nutrients from their gut eg cystic fibrosis and Crohn's disease.
- People taking certain medications including corticosteroids.
In April 2020, Public Health England advised that everyone should consider taking a daily 10 microgram supplement of vitamin D because of the reduced amount of time we were all spending outdoors due to lockdowns during the coronavirus pandemic.
9 vitamin D deficiency symptoms
The majority of people will be unaware that their vitamin D levels are low. Doctors don't routinely check vitamin D blood tests unless there are specific health concerns, medical conditions or risk factors.
Here are some of the signs and symptoms of vitamin D deficiency:
- Bone and joint pain - usually in the legs or feet.
- Muscle pain and weakness - particularly after exercise and usually affecting the thighs and trunk muscles.
- Bones which fracture easily.
- Difficulty with walking.
- Pins and needles - usually in the hands and feet due to low calcium levels (vitamin D is needed for calcium absorption).
- Recurrent upper respiratory tract infections - vitamin D is required to keep your immune system functioning well.
- Excessive tiredness - this may be a sign of low vitamin D levels but other causes are more common and increasing levels may not reduce fatigue.
- Depression - low vitamin D levels may be linked to low mood but there isn't clear evidence that increasing levels will always relieve symptoms.
- Hair loss - some studies have shown a link between low vitamin D levels and hair loss.
In adults, the first five symptoms can indicate osteomalacia, a condition of the bone caused by vitamin D deficiency. In children the condition is called rickets and may be accompanied by poor growth and skeletal deformities. Rickets is rare in the Western world but cases have started to increase again in recent years.
As we begin to understand more about how vitamin D works in the body and its interaction with different body systems, it seems likely that this list of signs and symptoms will grow.
© PeopleImages - Getty ImagesVitamin D deficiency
Vitamin D deficiency diagnosis
Vitamin D is not routinely checked by doctors. The National Institute for Health and Care Excellence (NICE) indicate that screening should only be done if there are musculoskeletal symptoms that could be caused by vitamin D deficiency, the person is at high risk of deficiency or there is a clinical reason to check it such as a fall or osteomalacia.
Blood tests check the level of 25-hydroxyvitamin D (25-OH Vitamin D) and NICE state that a level less than 25 nmol/l indicates vitamin D deficiency.
If you just want to start taking a supplement in accordance with the general advice, there is no need for you to have your vitamin D levels checked.
Vitamin D deficiency treatment
If you are found to be deficient in vitamin D your doctor may arrange tests to look for an underlying cause.
Treatment of a deficiency involves having a high dose of vitamin D for a few months and then dropping to a lower maintenance dose. The dose and frequency you are given will depend on your individual circumstances and the regime your doctor is using.
You can increase the amount of vitamin D in your diet and also increase your exposure to sunlight (taking care to avoid sunburn of course).
There is lots of research underway to determine if there is a link between vitamin D and Covid 19. Currently there is not enough evidence to support taking vitamin D to prevent or treat coronavirus.
Vitamin D supplements are available to buy over-the-counter as an individual supplement or in combination with other vitamins. You can check the label to find out how much vitamin D is in them and speak to your pharmacist for advice. It's advisable to take vitamin D supplements with a meal or food that contains fat because it is a fat soluble vitamin.
If you have any of the following, check with your doctor or pharmacist before you take a vitamin D supplement:
- High blood calcium levels
- Severe kidney disease
- Heart disease or you take the medication digoxin
- Sarcoidosis
- Allergy to vitamin D or any ingredients contained in supplements eg peanut oil
Can you take too much vitamin D?
It is very unlikely you will have any problems of toxicity from vitamin D if you stick to recommended doses. However, too much over long period of time could lead to high blood calcium levels and cause bone, kidney and heart damage.
Adults shouldn't take more than 100 micrograms daily (4000 IU) per day as it could be harmful. In children from one to 10 years this amount is reduced to 50 micrograms and children under one year, no more than 25mcg (1000 IU).
Vitamin D further research
The full extent of the roles and benefits of vitamin D in the body aren't yet fully established. Research continues in cancer, cardiovascular disease, type 2 diabetes, mental health, respiratory conditions and ageing. It's definitely an area to watch.
If you are at risk or think you may have a vitamin D deficiency, consider taking supplements and speak to your doctor to get your blood levels measured.
?? Dr Juliet McGrattan has worked as a family doctor, health journalist and Master Coach for the 261 Fearless global running network. Her second book Run Well: Essential health questions and answers for runners due to be published by Bloomsbury on 18th March is available for pre-order now.
Last updated: 10-03-2021