Folic Acid Deficiency Symptoms: Signs and Causes

Feeling persistently tired, weak or short of breath are experiences many people dismiss as the result of a busy lifestyle. However, these sensations can sometimes point to an underlying nutritional shortfall — including a lack of folate. Understanding folic acid deficiency symptoms and what causes low folate levels is an important first step towards seeking the right assessment and professional support.

This article explains what folate deficiency is, the signs that may suggest low folate, its relationship with anaemia and vitamin B12 deficiency, and how blood testing is used to assess folate levels. It is intended as educational information only and is not a substitute for professional medical advice.

What Is Folate Deficiency?

Folate is the naturally occurring form of vitamin B9, found in a wide range of foods. Folic acid is the synthetic form of vitamin B9, used in dietary supplements and to fortify certain foods. Although the two terms are often used interchangeably in everyday conversation, they are technically distinct.

Vitamin B9 is essential for the production of healthy red blood cells. It also supports DNA synthesis and cell division, which is why it is particularly important during periods of rapid growth, including pregnancy and foetal development. When the body does not have enough folate, red blood cell production can be disrupted — leading to a range of symptoms and, in some cases, a type of anaemia.

Folate deficiency occurs when folate intake is consistently too low to meet the body's needs, when absorption is impaired or when demand is elevated. It is distinct from vitamin B12 deficiency, though the two conditions share some characteristics and are frequently investigated together.

Folic Acid Deficiency Symptoms

The symptoms associated with low folate tend to develop gradually. They are not unique to folate deficiency and can be caused by a wide variety of other conditions, which is why symptoms alone cannot confirm a deficiency. Only appropriate testing and clinical assessment can do that.

Commonly recognised folic acid deficiency symptoms include:

Persistent tiredness and lack of energy — often one of the earliest and most noticeable signs, caused by the body's reduced capacity to produce functioning red blood cells

Weakness — a general physical fatigue that may feel disproportionate to activity levels

Shortness of breath — particularly during light exertion, related to reduced oxygen-carrying capacity when red blood cell production is compromised

Headaches — frequently reported alongside other symptoms of nutritional deficiency

Pale skin — reduced haemoglobin production can lead to pallor, particularly around the face, lips and inner eyelids

A sore or red tongue (glossitis) — the tongue may appear smooth, inflamed or unusually red

Mouth ulcers — recurrent or slow-healing ulcers in the mouth can be associated with low folate

Difficulty concentrating — some people report problems with memory and focus

Irritability or low mood — mood changes have been reported in association with folate deficiency, though the relationship is complex and not fully understood

It is important to emphasise that these symptoms overlap considerably with those of many other conditions, including vitamin B12 deficiency, thyroid disorders, iron deficiency anaemia and other health issues. If you are experiencing persistent or worsening symptoms, seeking a professional assessment is advisable rather than attempting to self-diagnose.

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What Causes Low Folate Levels?

A range of factors can contribute to low folate levels. Understanding the possible cause is important, because it influences the most appropriate approach to management.

Inadequate Dietary Intake

Folate is found naturally in dark green leafy vegetables (such as spinach, kale and broccoli), legumes, liver, eggs, nuts and fortified breakfast cereals. A diet consistently low in these foods is one of the most common causes of low folate in otherwise healthy adults.

Increased Nutritional Requirements

Certain life stages and health conditions increase the body's demand for folate. Pregnancy significantly elevates folate requirements, as does breastfeeding. People recovering from illness, or those with certain blood disorders, may also have higher requirements.

Malabsorption

Conditions that affect the small intestine can impair the absorption of folate from food. Coeliac disease and inflammatory bowel conditions are examples where malabsorption may play a role. If a malabsorption condition is suspected, investigating the underlying cause is an important part of management.

Certain Medicines

Some medications can interfere with folate metabolism or absorption. These include methotrexate, certain anticonvulsants and some medicines used to treat infections. If you take regular prescription medicines and are concerned about folate levels, discussing this with your prescribing doctor is advisable.

Alcohol Use

Regular heavy alcohol consumption is associated with reduced folate absorption and increased excretion, making it a recognised risk factor for low folate levels.

Folate Deficiency and Anaemia

One of the most significant consequences of untreated folate deficiency is megaloblastic anaemia — a type of anaemia characterised by the production of abnormally large, poorly functioning red blood cells. These oversized cells are unable to perform their role of transporting oxygen around the body effectively.

The symptoms of folate deficiency anaemia overlap considerably with those of other forms of anaemia: tiredness, weakness, pallor and breathlessness are all common. A full blood count is often one of the first blood tests performed when anaemia is suspected, as it can identify changes in red blood cell size and number that may point towards a megaloblastic pattern.

If you are concerned about symptoms that may suggest anaemia, a full blood count test can provide useful information as part of a broader clinical assessment.

It is worth noting that folic acid in anaemia management requires careful investigation to identify the underlying cause, as treatment will depend on the specific form of anaemia and contributing factors.

Folate and Vitamin B12 Deficiency: Understanding the Overlap

Folate deficiency and vitamin B12 deficiency are two distinct conditions, but they are frequently discussed together because:

Both are involved in red blood cell production

Both can cause megaloblastic anaemia

Both can produce overlapping symptoms, including fatigue, weakness, mouth soreness and pallor

Both are routinely assessed when deficiency in either is suspected

However, vitamin B12 deficiency carries additional risks that are not associated with folate deficiency alone — most notably neurological effects, including numbness, tingling and problems with balance. These neurological complications do not typically arise from folate deficiency in isolation.

This distinction is clinically important. Treating folate deficiency with high-dose folic acid supplements without first checking vitamin B12 status can mask a coexisting B12 deficiency — particularly by correcting the blood count changes — while allowing neurological damage to progress unaddressed. For this reason, healthcare professionals commonly check both folate and B12 levels when investigating either deficiency.

If you are experiencing symptoms that could suggest either condition, or low B12 alongside low folate, a combined assessment is likely to be more informative than a single test in isolation.

Low Folate in Women

There is a specific and well-established reason why folate is of particular importance to women — especially those who are pregnant or planning a pregnancy. Folate plays a critical role in the early development of the neural tube, the structure that forms the baby's brain and spinal cord, in the first weeks of pregnancy — often before a woman knows she is pregnant.

Current NHS guidance recommends that women who are trying to conceive or who are in the first 12 weeks of pregnancy take 400 micrograms of folic acid daily as a supplement, in addition to obtaining folate from their diet. Women considered at higher risk may be advised to take a higher dose under medical supervision.

Outside of pregnancy, the symptoms of low folic acid in women are broadly similar to those in men — including tiredness, weakness, pallor, mouth ulcers and a sore tongue. However, women of reproductive age may be at greater risk of folate deficiency due to the increased requirements associated with menstruation, pregnancy and breastfeeding.

If you are concerned about your folate levels, have symptoms suggesting deficiency or are planning a pregnancy, discussing this with a healthcare professional and considering appropriate testing is a sensible step.

Can Low Folate Be Dangerous?

Persistent, untreated folate deficiency can have meaningful health consequences. The development of megaloblastic anaemia can significantly impair quality of life and physical function over time. In pregnancy, insufficient folate is associated with an increased risk of neural tube defects, including spina bifida, which is why preconception supplementation is so strongly recommended.

That said, it is important to maintain perspective. Many cases of folate deficiency are identified and managed effectively through dietary change, supplementation and, where relevant, treatment of an underlying cause. The key is not to allow concerning symptoms to go unaddressed for a prolonged period.

If you are experiencing symptoms that may suggest folate deficiency — particularly if they are persistent, worsening or accompanied by other health concerns — seeking a professional assessment rather than waiting and hoping symptoms resolve on their own is the prudent course of action.

Folic Acid Blood Test: How Folate Levels Are Assessed

A folic acid blood test (also referred to as a folate blood test or serum folate test) measures the level of folate in the blood. It is a straightforward blood draw, typically taken from a vein in the arm.

Folate levels may be measured as:

Serum folate — the amount of folate circulating in the fluid component of the blood at the time of testing. This can fluctuate with recent dietary intake.

Red blood cell folate — sometimes measured in addition to serum folate, as it reflects folate stores over a longer period.

A single test result should always be interpreted in the context of your symptoms, medical history, dietary habits, any medications you are taking and other relevant test results. A result that appears low does not automatically confirm a clinical deficiency, and a result within the reference range does not rule out all nutritional concerns.

Folate testing is often performed alongside:

Full blood count — to identify changes in red blood cell size or number

Vitamin B12 levels — given the overlapping symptoms and the clinical importance of assessing both

Other relevant tests — depending on suspected causes or associated conditions

A health screening package may incorporate several relevant markers and provide a broader picture of nutritional and general health status. If you would like to understand your options for private blood testing in London, you can review available tests and blood test prices online.

What Does a Low Folate Result Mean?

Receiving a low folate result on a blood test can understandably prompt concern, but it is important to understand what that result does and does not tell you on its own.

A low folic acid level suggests that the body may not have adequate stores of folate. However, the clinical significance of that result — and the appropriate next steps — depends on several factors:

The degree of reduction below the reference range

Whether symptoms are present and consistent with deficiency

Dietary history and recent food intake

Current medications that may affect folate levels

Whether other results, including B12 and full blood count, show any abnormalities

Any underlying conditions that may affect absorption

A healthcare professional is best placed to interpret your results in the context of your overall clinical picture. If you have received a low folate result and are unsure what it means, discussing it with your GP or another qualified clinician is an important next step.

General Approaches to Managing Folate Deficiency

Management of folate deficiency is not one-size-fits-all. The appropriate approach will depend on the cause, the severity of the deficiency and any associated conditions. Under professional guidance, management may include one or more of the following:

Dietary modifications — increasing consumption of folate-rich foods such as leafy green vegetables, legumes, fortified cereals and eggs

Folic acid supplementation — the dose and duration of supplementation should be guided by a healthcare professional, based on individual circumstances

Addressing an underlying cause — if absorption problems or a specific medical condition are contributing to low folate, treating the underlying issue may be an important part of management

Reviewing medications — if a medicine is affecting folate metabolism, a prescribing doctor may consider alternative approaches where appropriate

It is essential that vitamin B12 status is assessed before starting folic acid supplementation, particularly at higher doses, to avoid the risk of masking a coexisting B12 deficiency.

If you are ready to explore private blood testing to assess your folate levels or related markers, you can book a blood test at Private Blood Tests London at a time that suits you.

When to Seek Medical Advice

You should speak to a healthcare professional if:

You are experiencing persistent tiredness, weakness, breathlessness or other symptoms described in this article that do not resolve with rest

You have received a low folate result and are unsure how to proceed

You are pregnant, planning a pregnancy or breastfeeding and have concerns about your folate intake

You have a known condition that may affect nutrient absorption

You are taking medications that may interact with folate

You have symptoms that could suggest vitamin B12 deficiency alongside folate concerns

Private blood testing can be a useful and convenient way to access results, but it does not replace a full clinical assessment by an appropriately qualified healthcare professional. At Private Blood Tests London, results are available to share with your doctor to support further discussion and clinical decision-making.

Frequently Asked Questions

What are the most common folic acid deficiency symptoms?

The most commonly reported symptoms include persistent tiredness, weakness, shortness of breath, headaches, pale skin, a sore or red tongue and mouth ulcers. These symptoms are not exclusive to folate deficiency and can be caused by several other conditions.

What causes low folate levels?

Low folate levels are most commonly associated with an inadequate diet, malabsorption conditions such as coeliac disease, increased requirements (for example during pregnancy), regular heavy alcohol use and certain medications that affect folate metabolism.

Can low folate cause anaemia?

Yes. Folate deficiency is a recognised cause of megaloblastic anaemia, a condition characterised by abnormally large, poorly functioning red blood cells that are unable to carry oxygen efficiently. This can lead to symptoms such as fatigue, pallor and breathlessness.

What is the difference between folate and folic acid?

Folate is the naturally occurring form of vitamin B9, found in foods such as leafy green vegetables, legumes and eggs. Folic acid is the synthetic form used in dietary supplements and to fortify certain foods. Both are forms of vitamin B9, but they are processed slightly differently in the body.

Can folate deficiency cause the same symptoms as B12 deficiency?

There is significant overlap between the symptoms of folate deficiency and vitamin B12 deficiency. Both can cause fatigue, weakness, pale skin, mouth soreness and megaloblastic anaemia. However, vitamin B12 deficiency can also cause neurological symptoms — such as tingling, numbness and balance problems — which are not typically associated with folate deficiency alone.

Why does vitamin B12 status matter when investigating folate deficiency?

Treating folate deficiency with high-dose folic acid supplements without first checking vitamin B12 levels can mask a coexisting B12 deficiency. The folic acid may correct changes visible in the blood count while B12-related neurological damage continues to progress. This is why both are routinely assessed together.

What are the symptoms of low folic acid in women?

Women can experience the same general symptoms of folate deficiency as men, including fatigue, weakness, pallor and mouth ulcers. However, women of reproductive age may face greater risks due to increased folate requirements during menstruation, pregnancy and breastfeeding. During pregnancy, insufficient folate is associated with an increased risk of neural tube defects in the developing baby.

Can low folate be dangerous?

Persistent, untreated folate deficiency can contribute to megaloblastic anaemia and, during pregnancy, is associated with an increased risk of neural tube defects. While many cases are managed effectively when identified, it is important not to leave symptoms unaddressed over a prolonged period. Seek professional advice if you have ongoing concerns.

What does a folic acid blood test measure?

A folic acid blood test measures the level of folate in the blood, most commonly as serum folate. It may sometimes be assessed alongside red blood cell folate for a more comprehensive picture. Results should always be interpreted in the context of symptoms, diet, medications and other test results.

What does a low folate result mean?

A low folate result suggests the body may not have adequate folate stores, but the clinical significance depends on many factors including the degree of reduction, associated symptoms, diet, medicines and other test results. A healthcare professional should interpret the result in the context of your full clinical picture.

How is folate deficiency tested?

Folate deficiency is typically investigated through a blood test measuring serum folate levels, often alongside a full blood count and vitamin B12 measurement. Additional tests may be performed depending on suspected causes, such as tests related to absorption or other nutritional markers.

Can diet alone correct low folate levels?

In some cases, increasing dietary intake of folate-rich foods — such as leafy green vegetables, legumes and fortified cereals — may help improve folate status. However, the appropriate management approach depends on the cause and severity of the deficiency and should be guided by a healthcare professional. Some people may require supplementation or treatment of an underlying condition.

This article is intended for general educational and informational purposes only. It does not constitute medical advice and should not be used as a basis for self-diagnosis or self-treatment. If you have concerns about your health or nutritional status, please seek advice from a qualified healthcare professional.