25-hydroxyvitamin D

Vitamin D (25-hydroxyvitamin D) is an essential fat-soluble vitamin produced by the body from exposure to sunlight. You can also get vitamin D from certain foods. Vitamin D is vital in your health, from supporting healthy bones and muscles to strengthening the immune system.

The body stores vitamin D in the liver, and it is the only vitamin that can be converted into a hormone. If you aren’t getting enough vitamin D, getting a vitamin D test and opting for ways to increase your vitamin D levels is important.

The role of vitamin D

Vitamin D aids in calcium absorption in the gut and helps maintain phosphate and calcium levels. These nutrients are essential for healthy bones, muscles and teeth. Vitamin D also supports your immune system by fighting off infection and may reduce inflammation.

Low vitamin D levels are also linked to conditions like heart disease, osteoporosis, depression and cancer.

How does vitamin D help muscle recovery?

Some studies have established a link between 25-hydroxyvitamin D and muscle recovery. The studies found that higher vitamin D levels, especially before exercise, result in better recovery after exercise and less muscle fatigue.

Vitamin D deficiencies

About one in five people in the UK have low levels of vitamin D. Many people in the Northern hemisphere have low vitamin D levels. Since the sun is the main natural source of vitamin D, it may be difficult to get enough sunlight, especially in winter.

Deficiency in vitamin D can cause osteoporosis – fragile bones with a high chance of fractures or osteomalacia – softening of the bones, leading to fractures.

What causes vitamin D deficiency?

Your body can produce sufficient vitamin D if you get enough exposure to sunlight. However, in winter and autumn, when sunlight exposure is low, vitamin D levels tend to drop, increasing the risk of vitamin D deficiency.

Other factors, such as sunscreen and smog, can affect how much vitamin D your body will make.  

Symptoms of vitamin D deficiency

In most cases, vitamin D deficiency shows no symptoms, but when symptoms occur, they are usually non-specific. These symptoms include:

• Feeling tired
• Poor wound healing
• Aching joints and bones
• Getting sick often
• Weak bones that result in an increased risk of osteoporosis
• Muscle weakness and pain

Risk factors for vitamin D deficiency

Different factors can increase the risk of developing vitamin D deficiency. They include:

• Staying indoors
• Vegetarian or vegan
• Covering up most of your skin when outdoor
• Darker skin – for example, if you are South Asian, African-Caribbean or African
• Elderly – over 65 years
• Taking certain medications like steroids or antiepileptic drugs
• Digestive disorders such as Crohn’s disease or coeliac disease

How to prevent vitamin D deficiency

Extra sun exposure in summer and spring can help increase your vitamin D levels. Wear sun protection if you are outside for a long time to prevent skin cancer and sun damage. During winter and autumn, healthcare professionals advise taking a 10mcg (400IU) vitamin D supplement daily to prevent low vitamin D levels.

If you are at a high risk of vitamin D deficiency, taking vitamin D supplements all year round is advisable.

The recommended doses include:

• 10 mcg (400IU) daily for children from one yea, all adults, including breastfeeding and pregnant women
• 5 – 10 mcg (340 – 400IU) daily for breastfed babies from birth to one year.

If your vitamin D levels are already low, you can take up to 25mcg (1000IU) daily. Some medical conditions may require taking lower doses of vitamin D.

You can get vitamin D from food. Good dietary sources of vitamin D include:

• Egg yolk
• Liver
• Red meat
• Oily fish
• Fortified food like some breakfast cereal and margarine
• Oily fish

How to measure vitamin D levels

Home vitamin blood tests are available to check your vitamin D level. The test measures 25-hydroxyvitamin D, and the reference ranges include:

• 50 – 200nmol/L normal. The optimal level is 75nmol/L
• 30 – 50 nmol/L is insufficient
• Below 25 nmol/L is deficient

Some inflammatory diseases can make it difficult to interpret vitamin D levels. They include:

• Sarcoidosis – this is a rare condition that results in swollen tissue and small red patches
• A condition that affects the parathyroid glands

You can get a more accurate vitamin D test at our Clinic. Call us on 02071830244 to book an appointment for your vitamin D levels test.