5 Nutritional Deficiencies: Signs, Food Sources & Support

Vitamins help your body carry out everyday tasks, from making red blood cells to maintaining bones, skin and nerves. Understanding nutritional deficiencies starts with knowing what each nutrient does, where to find it and when a possible shortfall needs attention.

This guide explores the same five vitamins as our original article: vitamin D, vitamin B12, vitamin C, folate and vitamin A. It brings together food sources, possible signs of deficiency and practical ways to review your intake.

Food sources of these five vitamins

A varied diet provides a useful foundation. This quick reference includes both animal and plant foods; fortified foods can help where suitable options are limited.

1. Vitamin D deficiency

Vitamin D helps regulate calcium and phosphate, supporting healthy bones, teeth and muscles. It is often called the sunshine vitamin because the body makes it when sunlight reaches the skin outdoors.

In the UK, sunlight is not strong enough for adequate vitamin D production during autumn and winter. People who spend little time outdoors, cover most of their skin or have darker skin may also need to pay attention to their intake throughout the year.

Food and seasonal support

Oily fish, egg yolks and fortified foods contribute vitamin D. Seasonal changes, time spent outdoors and individual circumstances are useful parts of a whole-person review. Consider these alongside the foods you regularly eat.

For more background, see our vitamin D guide. Our Vitamin D3 & K2 liquid has its own serving information: compare the label with your individual requirements.

2. Vitamin B12 deficiency

Vitamin B12 is important for red blood cell formation and normal nerve function. Meat, fish, eggs and dairy supply B12; people following a vegan diet need reliable fortified foods or an appropriate supplement.

Food intake is only part of the picture. Problems absorbing B12, including pernicious anaemia, can cause deficiency even when a diet contains animal foods. Older adults and people taking certain medicines may need particular attention.

Possible signs to investigate

Persistent tiredness, a sore tongue, weakness, numbness or pins and needles can occur with B12 deficiency. These symptoms have other possible causes, so assessment matters. Nerve symptoms should be checked promptly because some damage can become lasting if treatment is delayed.

If you are comparing formats, our Vitamin B12 oral spray lists its ingredients and serving information. A retail supplement should not replace a prescribed treatment plan for an absorption problem.

3. Vitamin C deficiency

Vitamin C supports collagen formation, healthy skin and wound healing. It also helps the body absorb iron from plant foods. Regular fruit and vegetables are the main dietary sources.

Severe deficiency, called scurvy, is rare in the UK. Risk increases when someone eats a very restricted diet with little fruit or vegetables for a prolonged period. Smoking and difficulties maintaining adequate food intake can also be relevant.

Adding variety to everyday meals

Try peppers with lunch, broccoli with dinner or fruit as a snack. Citrus is useful, but it is not the only option. Bleeding gums, easy bruising or poor wound healing alongside a very limited diet need medical assessment rather than a guess at the cause.

Explore our vitamin C article for further reading, or view the ingredients and directions for Liposomal Vitamin C Liquid.

4. Folate deficiency

Folate, or vitamin B9, helps the body make healthy red blood cells and supports cell growth. Folate and folic acid are related but not identical terms: folate occurs naturally in foods, while folic acid is used in supplements and fortified foods.

Green vegetables, chickpeas, peas and fortified cereals are useful sources. Low folate can lead to anaemia, with symptoms such as tiredness and weakness. A restricted diet or problems absorbing nutrients can contribute.

Making room for folate-rich foods

Try chickpeas in a warming stew, peas with a main meal or broccoli alongside dinner. Small, regular additions can make a food routine more varied. Pregnancy and preparation for pregnancy need individual nutritional planning; food ideas here are not a complete prenatal plan.

Do not use high-dose folic acid to self-treat unexplained tiredness: it can mask signs of B12 deficiency. If you are comparing a B-complex supplement, check the actual nutrients, forms and amounts on its label.

5. Vitamin A deficiency

Vitamin A supports normal vision, immune function and healthy skin. The body obtains it from preformed vitamin A in animal foods and from certain plant pigments, including beta-carotene.

This means avoiding liver or eggs does not automatically mean you lack vitamin A. Carrots, sweet potatoes, spinach and other colourful vegetables can contribute through beta-carotene. A problem absorbing fats can also affect vitamin A status and needs individual assessment.

Getting enough without overdoing it

Difficulty seeing in dim light is one possible sign of deficiency and should be assessed. Dry skin alone is not a reliable diagnostic sign.

More is not always better: excessive preformed vitamin A can be harmful. If you are pregnant or planning pregnancy, avoid liver and supplements containing retinol unless specifically advised by your clinician. Check multivitamins and fish liver oils for overlapping vitamin A.

Practical steps if you are worried about a deficiency

1. Look at your usual week. Write down the foods you regularly eat and any whole food groups you exclude. A typical week is more useful than judging one meal.
2. Check fortified foods. Plant drinks and breakfast cereals vary. Read the nutrition panel for the particular vitamin rather than assuming all products contain it.
3. List your supplements. Include sprays, liquids, capsules and combination formulas. The same vitamin may appear in several products.
4. Discuss persistent symptoms. A suitably qualified practitioner can help review the wider picture and identify when testing or further assessment is needed. Fatigue can have causes beyond nutrition.
5. Review the cause as well as the result. A food gap, an absorption problem and an increased requirement may need different approaches.

Bring product labels or photographs of them to an appointment. That makes it easier to see what you are already taking and avoids relying on a product name alone.

Comparing vitamin supplements at Crystal Health & Beauty

Once you know what you are looking for, compare the amount per serving, ingredients, directions and suitability. Liquid, spray and capsule formats offer different practical options; the format alone does not establish that a product is right for you.

Liposomal Vitamin C Liquid

View ingredients, serving information and current options.

Vitamin B12 Oral Spray

View ingredients, serving information and current options.

Check the full label before combining products. Supplements can help meet particular needs, but they do not replace a varied diet or the investigation and treatment of a confirmed deficiency. Ask a pharmacist or clinician about suitability if you take medicines, are pregnant or have an ongoing condition.

Frequently asked questions

Can tiredness tell me which vitamin I need?

No. Several deficiencies can cause fatigue, but so can poor sleep and other health conditions. Persistent tiredness is a reason to look into the cause, rather than automatically adding several supplements.

Can a balanced diet always prevent a deficiency?

A varied diet is an important foundation, but absorption problems and individual circumstances can still cause a shortfall. B12 absorption problems and limited winter sunlight for vitamin D are examples.

Are folate and vitamin B12 the same?

No. Folate is vitamin B9 and B12 is a separate vitamin. Both are involved in healthy blood cell production, but they have different food sources and treatment requirements.

Is a stronger supplement always better?

No. Compare the amount with your needs and any professional advice. A high number on the label is not a reason to take more, especially when combining several formulas.

Updated 7 October 2026. A food-first guide to understanding five vitamins and reviewing your everyday nourishment. Individual requirements vary.