What to know about vitamin and mineral deficiency blood tests

What are vitamins and minerals?

Vitamins and minerals are types of micronutrients, a type of nutrient your body needs in tiny amounts. They influence nearly every process in your body and are essential for your health.

You can usually get enough through food, but sometimes, you may need to take a supplement. For example, people who follow vegetarian and vegan diets can have a harder time getting enough of certain vitamins and minerals.

Causes of vitamin and mineral deficiencies

A varied and balanced diet usually provides you with enough vitamins and minerals for optimal health. However, deficiencies can happen for several reasons.

Some common causes include:

• poor absorption of nutrients - for example, if you have coeliac disease or Crohn’s disease
• a diet low in fruits and vegetables
• a poorly planned vegan or vegetarian diet
• excessive amounts of alcohol
• certain medications, like proton pump inhibitors (PPIs)
• pregnancy, due to higher micronutrient needs

It's a good idea to check your vitamin and mineral levels regularly, especially if you’re at risk of deficiency. Speak with a doctor if you think you may have a deficiency.

If you're confirmed to have a deficiency, you can manage it with vitamin and mineral supplements.

Signs and symptoms of vitamin and mineral deficiencies

As there’s such a wide range of vitamins and minerals, the symptoms of a deficiency can vary. Here are some of the most common signs of vitamin and mineral deficiencies:

Iron deficiency

Iron is a mineral that your body needs to make red blood cells. These carry oxygen around your body. If you don’t get enough iron, you may:

• feel weak, tired, and dizzy
• feel short of breath
• get heart palpitations
• get headaches

Because blood loss can cause iron deficiency, women with menstrual cycles have an elevated risk. You might also be at risk of iron deficiency if you follow a vegan or vegetarian diet. This is because plant-based iron sources are harder for your body to absorb.

Learn more about iron deficiency anaemia.

Vitamin D deficiency

Vitamin D is used by every cell in your body and is essential for healthy bones, muscles, and immune system function. If you don’t get enough vitamin D, you might:

• feel tired
• get sick often
• have weak bones
• have muscle pain
• feel anxious or depressed

You get most of the vitamin D you need from sunlight, but it’s also found in foods like eggs, oily fish, liver, and dairy.

However, it's hard to get enough from diet alone. In the UK, low vitamin D levels are common because you don’t get enough sun exposure during winter, so supplemental vitamin D is recommended in the autumn and winter months.

You can prevent or treat a deficiency with vitamin D supplements.

Learn more about vitamin D deficiency.

Folate (vitamin B9) deficiency

Folate is a B vitamin that’s required to make red blood cells. The synthetic (man-made) version is called folic acid.

If you don't get enough folate, you might:

• feel tired
• feel weak
• feel short of breath
• get heart palpitations
• get headaches
• feel irritability
• have difficulty concentrating

It's particularly important if you're pregnant because it plays a key role in foetal development.

Learn more about folate deficiency.

Vitamin B12 deficiency

Vitamin B12 (cobalamin) plays a crucial role in red blood cell production and helps your nervous system to function properly. If you don't get enough vitamin B12, you might:

• feel tired
• feel weak
• get pins and needles
• get mouth ulcers
• have a swollen and sore tongue
• have blurry vision
• have difficulty remembering things
• experience low mood

The most common cause of vitamin B12 deficiency is an autoimmune condition called pernicious anaemia. Other causes include following a vegan or vegetarian diet, certain medications, and stomach or gastrointestinal conditions.

Learn more about vitamin B12 deficiency.

How to test for vitamin and mineral deficiencies

A blood test can be used to diagnose a vitamin or mineral deficiency. There are two types of blood tests you can have:

• Capillary blood test: You can collect your own sample at home by using a finger-prick lancet or an autodraw device on your arm.
• Venous blood test: A trained nurse or phlebotomist can collect your sample in a clinic.

Home blood tests for vitamin and mineral deficiency

You can use an autodraw device to collect your sample at home.

A doctor will review your results and compare them to reference ranges. Then, they'll write you a customised report based on our results.

Learn more about types of blood tests and what to expect.

When to take a vitamin and mineral supplement

Most people can get the nutrients they need from their diet alone. If you don't have a deficiency, you don't need to take a supplement just for the sake of it.

Taking supplements you don't need, especially in high doses, can carry risks.

A good approach is to monitor your vitamin and mineral levels with a blood test. If you’re low in a certain nutrient, you can up your intake of foods rich in these nutrients or take a supplement if needed.

Vitamin D supplements

The UK National Health Service recommends adults take 10 micrograms (mcg) per day in the autumn and winter. People at a higher risk of deficiency are advised to take supplemental vitamin D year-round.

Vitamin B12 supplements

Vegans and vegetarians are at a higher risk of B12 deficiency because dietary B12 is primarily found in animal products.

If a blood test shows that you’re deficient or you follow a strict vegan diet, then it’s recommended that you take a supplement.

Folic acid supplements

Because of its importance in foetal development, people are advised to take a folic acid supplement in the first 12 weeks of pregnancy.

It’s also important to ensure your vitamin B12 levels are normal when starting a folic acid supplement. Folic acid supplements can mask the symptoms of vitamin B12 deficiency, which left untreated, can damage your nervous system.

Takeaway

Vitamins and minerals are essential micronutrients that your body needs in small amounts to function properly, and most people can get enough through a varied, balanced diet.

You can monitor your levels with blood tests, and home blood tests are a convenient option. It's a good idea to only take supplements when needed, with vitamin D recommended for everyone in the UK during the autumn and winter months.