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vitamin deficiencies and the associated symptoms

Symptoms of the most common vitamin deficiencies

29 Jul 2021 • 2 min read

Most people can get the vitamins they need from a healthy and varied diet. However, there are a few reasons why someone might become deficient in a vitamin or mineral.

Illness, medication or an ultra-busy lifestyle are common reasons why people run low on certain vitamins. Simply getting older can also be a cause. As we age, our body’s ability to absorb vitamins and minerals naturally drops.1

No single food or even food group can provide everything we need, so extremely picky eaters might find themselves with low levels of certain vitamin groups.

Common vitamin deficiencies

Learning to spot symptoms of a vitamin deficiency could help you take control of your health. Watch out for the following:

Iron deficiency

Iron is an essential mineral that’s needed for making haemoglobin and plays a key role in supporting the immune system.

Signs and symptoms

Are you fit and well but find yourself short of breath after minimal exertion? Or experiencing unexplained bouts of tiredness and fatigue?

The most common nutritional deficiency in the world is iron deficiency, also known as iron deficiency anaemia.2 

Iron deficiency can be caused by heavy periods, pregnancy, a stomach ulcer, or a diet low in high-quality food sources of iron. It’s more common in females.


Leaving iron deficiency untreated can affect your body’s immunity, making you more likely to get ill. Luckily, iron deficiency is easily addressed by upping your intake of iron.

Add iron-rich foods such as meat, fish, pulses, legumes and green leafy vegetables to your diet. Avoid too much tea and coffee as this can hinder iron absorption.3

An iron supplement is a sure-fire way of getting enough iron.

The amount of iron people need is:4

  • 7mg a day for men over 18
  • 8mg a day for women aged 19 to 50
  • 7mg a day for women over 50

The daily dose to treat iron-deficiency anaemia is 100 to 200 mg daily.5 However, too much iron when you’re not deficient can be harmful, so this dosage is only advised if you have had your iron deficiency confirmed by a doctor (usually following a blood test).

Vitamin D deficiency

Vitamin D is vital for keeping bones, teeth and muscles healthy. It also helps the immune system function normally and is important for the development of the foetus in pregnant women.6

Signs and symptoms

Tiredness, low immunity (always catching bugs) and lower back pain might be signs of a vitamin D deficiency.7


Although most people in the UK get all the vitamin D they need from sunlight and diet during summer, taking a 10mcg supplement daily is recommended for everyone by Public Health England during the winter months.

Breastfed babies and children up to the age of four should take a vitamin D supplement of between 8.5mcg and 10mcg daily.8 

For very low vitamin D levels the NHS recommends 25-50mcg of cholecalciferol daily. To address a serious vitamin D deficiency, your doctor might prescribe InVita D3, which delivers a high dosage of vitamin D via an oral solution.9

Magnesium deficiency

Magnesium is a mineral that helps us convert food to energy, among other important functions.

Signs and symptoms

As magnesium plays a role in energy production, symptoms of low magnesium include tiredness and low energy.

Symptoms of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue, and weakness.10


The recommended amount of magnesium is:11

  • 300mg a day for men (19 to 64 years)
  • 270mg a day for women (19 to 64 years)

Magnesium can be found in green leafy vegetables, nuts, seeds, whole grains and legumes. Most people can get what they need from their diet, but absorption can be interrupted by type 2 diabetes, alcoholism, gastrointestinal issues such as Crohn’s disease or coeliac.

It’s considered safe to take up to 400mg magnesium daily in a supplement.12

Folic acid deficiency

Folic acid deficiency – a lack of folic acid in the blood – is more accurately known as folate deficiency anaemia.13 

Folate and folic acid are essentially the same thing. They’re a type of B vitamin.

Folate is the naturally-occurring version found in foods such as broccoli, and folic acid is the man-made version found in supplements and in fortified foods such as breakfast cereals and plant milks.

Signs and symptoms

Folate, or folic acid, helps your body make red blood cells. Red blood cells carry oxygen around the body, so if you’re deficient in them, you may feel tired, weak and exhausted.

Other symptoms of folic acid deficiency symptoms in adults include pins and needles, mouth ulcers and even memory problems.14 

Folate deficiency is more common in older people, affecting around 1 in 10 people aged 75 or over, and 1 in 20 people aged 65 to 74.15


Adults need 200mcg of folate a day. It can be found in leafy green vegetables, chickpeas and fortified foods.

Those with a diagnosed deficiency should take folic acid tablets for four months or as advised by a GP.16 

Developing foetuses need lots of folate/ folic acid. Women of childbearing age who have any possibility of becoming pregnant should take 400mcg folic acid tablets daily.17

Vitamin C deficiency

Vitamin C helps the production of collagen, supports immunity and helps your nervous system to work.

Signs and symptoms

Symptoms of vitamin C deficiency include weakness, irritability, joint pain and muscle pain.18 

A severe vitamin C deficiency is also known as scurvy. This is rare but can happen when someone doesn’t get any vitamin C for at least three months.19

Vitamin c deficiency symptoms go away quickly on you start getting vitamin C, whether through diet or supplements.


Adults need a minimum of 40mg of vitamin C a day.20 This is easy to get through a healthy diet with lots of fruit and vegetables, including red peppers and oranges.

However, many people take much more than this in supplement form. Vitamin C is well-tolerated by the body up to 1000mg daily. As vitamin C is water-soluble, any excess is secreted via urine every day.

Last updated: 29 July 2021



Author: Bhupesh PanchalSenior Regulatory Affairs Associate

Joined Holland & Barrett: Apr 2019

Masters Degree in Toxicology and BSc Hons in Medical Biochemistry

Bhupesh started his career as a Clinical Toxicologist for Public Health England, advising healthcare professionals all around the country on how to manage clinical cases of adverse exposure to supplements, pharmaceuticals, cosmetics, industrial chemicals and agricultural products.

After 7 years in this role and a further year working as a drug safety officer in the pharmaceutical industry, Bhupesh joined Holland & Barrett as a Senior Regulatory Affairs Associate in 2019.

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