Folic Acid Deficiency

Folic acid — also called folic acid vitamin B9 — belongs to the water-soluble vitamins. It primarily supports vital metabolic processes in the body. In its natural form, folic acid occurs mainly as folate, while the term folic acid usually refers to the synthetic, more stable version. This form is mainly found in folic acid supplements and fortified foods.

The body must receive folic acid through the diet. It is actively absorbed in the small intestine and then converted into its biologically active form. It plays a central role in cell division, DNA synthesis, and blood formation. An adequate supply of folic acid is therefore particularly important during growth phases, folic acid in pregnancy, and in old age.

Folic acid plays an important role in cell growth and regeneration. It is essential for cell division and the synthesis of DNA and RNA — the genetic information of every cell. Beyond that, folic acid also plays a decisive role in the formation of red blood cells, which transport oxygen throughout the body.

Folic acid is especially important during embryonic development. It is necessary for the correct closure of the neural tube — the precursor to the brain and spinal cord. A deficiency during this phase of pregnancy can cause severe birth defects. An adequate folic acid supply during pregnancy is therefore critically important. Women who are planning a pregnancy are usually advised to start taking folic acid early — ideally with prenatal vitamins with folic acid.

A folic acid deficiency occurs when the body receives too little folic acid over a prolonged period or cannot absorb or utilize it sufficiently. It is usually detected by a low folic acid level in serum or red blood cells. Doctors distinguish between a latent deficiency, where stores are already depleted, and a manifest deficiency, where physical symptoms have already appeared.

Folic acid folate deficiency often occurs alongside other nutritional deficiencies — particularly a vitamin B12 or iron deficiency — since these nutrients are closely linked in metabolism. Because folic acid plays a key role in cell division, DNA synthesis, and blood formation, a deficiency especially affects rapidly dividing tissue. This includes blood cell production in the bone marrow, mucosal regeneration in the digestive tract, the skin, and the nervous system.

An untreated folic acid deficiency can lead to anemia, mucosal changes, neurological symptoms, and increased susceptibility to infections. A folic acid deficiency during pregnancy can be especially dangerous, as it is associated with an increased risk of birth defects — particularly neural tube defects. An adequate folic acid supply is therefore essential for health and the function of numerous bodily processes.

A folic acid deficiency can manifest in different symptoms in women and men. Hormonal differences, metabolic processes, and individual circumstances influence folic acid needs. In women, a deficiency primarily affects fertility, pregnancy, and hormonal metabolism. In men, it tends to show changes in performance and metabolism. In both cases, symptoms develop gradually and are often nonspecific, which can make diagnosis difficult.

Since folic acid is involved in numerous processes — including cell division, blood formation, and tissue regeneration — a deficiency often affects multiple organ systems. Blood formation, mucous membranes, skin, and the nervous system are particularly sensitive to a deficiency. Typical folic acid deficiency symptoms can therefore include fatigue, difficulty concentrating, paleness, or digestive problems.

Many of these symptoms can also resemble signs of other vitamin deficiencies — especially a vitamin B12 deficiency — since folic acid and B12 are closely linked in metabolic processes. A thorough medical evaluation is therefore important to identify and treat the exact cause of symptoms.

Because folic acid also plays an important role in blood formation, a folic acid deficiency can lead to a condition known as megaloblastic anemia. This is a form of anemia in which the production of red blood cells in the bone marrow is disrupted. Due to the folic acid deficiency, precursor cells in the bone marrow cannot divide properly. This results in large, immature red blood cells called megaloblasts. They have limited function and can no longer transport oxygen adequately.

The result is typical anemia symptoms such as paleness, fatigue, difficulty concentrating, shortness of breath, and general weakness. All of these symptoms arise because oxygen delivery to the tissues is reduced.

These symptoms closely resemble those of a vitamin B12 deficiency, since both vitamins are closely connected in folate metabolism. While folic acid is mainly responsible for cell division, vitamin B12 is needed to convert folic acid back into its active form. If either vitamin is lacking, similar changes appear in the blood count. However, unlike a pure folic acid deficiency, a vitamin B12 deficiency can also cause additional neurological symptoms, since vitamin B12 is also essential for maintaining nerve cells.

With early diagnosis, symptoms can usually be reduced through folic acid supplementation, and blood formation can return to normal.

A folic acid B9 deficiency can also affect the nervous system. Folic acid plays an important role in amino acid metabolism and in the production of neurotransmitters. If a deficiency persists over a longer period, nerve signal transmission can be impaired. This may lead to difficulty concentrating, irritability, and depressive moods.

In more severe cases, symptoms such as memory problems, confusion, or a general decline in mental performance can occur. Unlike a vitamin B12 deficiency, which can cause permanent nerve damage, the neurological symptoms of a folic acid deficiency are usually reversible — provided the deficiency is detected and treated in time.

A folic acid deficiency can also cause symptoms such as loss of appetite and unintended weight loss. Because folic acid plays an important role in regenerating the mucous membranes of the digestive tract, a deficiency often leads to gastrointestinal problems. Symptoms include a feeling of fullness, nausea, or digestive irregularities. These issues can reduce food intake and lead to weight loss.

In addition, chronic conditions such as inflammatory bowel diseases, cardiovascular diseases, or cancer can increase folic acid turnover. In such cases, reduced appetite is further worsened by the increased nutrient demands of the disease. Early diagnosis and targeted folic acid supplementation can help stabilize metabolism, support mucosal function, and stop unintended weight loss.

Weight gain is not a direct symptom of a folic acid deficiency. It can, at most, be an indirect consequence of accompanying symptoms. Since a deficiency often leads to pronounced fatigue, lack of motivation, and rapid exhaustion, many affected individuals become less physically active. If daily energy expenditure drops while dietary intake stays the same, this can lead to slight weight gain over time. However, this is not a metabolism-driven fat accumulation — it is a result of a changed lifestyle. Normalizing folic acid levels often helps restore vitality and the desire to stay active.

Muscle pain is rather uncommon with an isolated folic acid deficiency. Instead, general muscle weakness or rapid fatigue tends to be more prominent. Since folic acid is important for blood formation and thus for oxygen transport to the muscles, a deficiency can cause muscles to fatigue more quickly or feel weak under exertion. If actual pain occurs, it is usually functional — for example, due to poor posture resulting from weakness — and typically resolves completely once the deficiency is corrected.

Excessive sweating is not a primary sign of a folic acid deficiency. However, it can sometimes occur as an accompanying symptom when the body is under stress due to anemia-related oxygen deprivation. To compensate for the lack of oxygen in tissues, the cardiovascular system has to work harder. This can lead to circulatory strain and occasional sweating episodes or hot flashes. These symptoms almost never occur in isolation but are usually accompanied by noticeable paleness, heart palpitations, and exhaustion.

Tingling or numbness in the hands or feet can occur in rare cases with a folic acid deficiency. This usually happens when the metabolism of the nervous system is affected. Folic acid plays an important role in neurotransmitter production and nerve cell regeneration. A prolonged deficiency can therefore lead to mild impairments in nerve function.

Unlike a vitamin B12 deficiency, where nerve damage can be irreversible, the neurological symptoms of a folic acid deficiency are often reversible. The tingling is typically caused by a temporary disruption of nerve signal transmission and resolves after folic acid intake is restored.

Hair loss can be a possible consequence of a long-standing folic acid deficiency — especially when it occurs as part of malnutrition or an absorption disorder. Since folic acid plays an important role in cell division and tissue renewal, a deficiency can negatively affect hair root growth and regeneration.

As a result, hair may become thinner, more brittle, or fall out more frequently. Folic acid deficiency–related hair loss often affects people with a one-sided diet, chronic bowel diseases, or increased nutrient needs — such as during pregnancy.

In most cases, hair loss is also reversible. With adequate folic acid intake, hair roots can recover and hair growth can return to normal.

Low folic acid levels can also lead to skin changes, as the skin is one of the tissues with the highest cell turnover. Folic acid is essential for cell division and skin cell regeneration. A deficiency slows these processes. As a result, the skin may appear pale, dry, or flaky because the outermost skin layer is no longer renewing itself regularly.

Redness, inflammation, or eczema can also occur — often in more sensitive areas of the skin. These changes are usually caused by a weakened skin barrier and increased vulnerability to irritation or infection. In combination with the anemia that often accompanies a folic acid deficiency, skin paleness can become even more pronounced.

Adequate folic acid intake supports skin renewal, improves circulation, and can contribute to a healthy complexion.

A folic acid deficiency can also lead to characteristic tongue changes. These often provide a first visible sign of a deficiency. Typical is a smooth, reddened tongue. The tongue papillae recede, giving the tongue a shiny or “lacquered” appearance.

A burning sensation on the tongue, a feeling of dryness, or taste disturbances also frequently occur. These symptoms arise because the tongue’s mucous membrane can no longer renew itself adequately due to disrupted cell division and regeneration. Small cracks or inflammation in the mouth can also develop.

Since tongue changes can also occur with a vitamin B12 deficiency, this symptom should be carefully differentiated during diagnosis. With folic acid supplementation, the mucous membranes can usually regenerate fully, and the symptoms often subside.

A folic acid deficiency can cause a wide range of additional, often nonspecific symptoms. Fatigue, general exhaustion, and increased susceptibility to infections frequently occur with a lack of folic acid, since both blood formation and immune function are impaired. Lack of motivation, concentration problems, and depressive moods are also possible, as folic acid is involved in producing important chemical messengers in the brain.

In women, a prolonged folic acid deficiency can lead to menstrual irregularities, since folic acid also plays a role in hormonal metabolism and cell maturation. In men, a deficiency can impair sperm quality and thus fertility.

A folic acid deficiency affects both women and men, but its significance and effects differ considerably. Folic acid is a vital vitamin involved in central processes such as cell division, blood formation, DNA synthesis, and nerve function. For women, however, folic acid plays a particularly important role, as it is connected to fertility, pregnancy, and hormonal regulation.

For women, an adequate folic acid supply is especially important during childbearing years. Folic acid supports cell maturation and egg cell development. It is essential for the healthy development of the embryo — particularly in the first weeks of pregnancy, when the neural tube closes. A deficiency during this phase can lead to severe birth defects. This is why women who are trying to conceive or who are in the early stages of pregnancy are advised to take additional folic acid for pregnancy.

Even outside of pregnancy, adequate folic acid intake matters for women, as the vitamin supports hormonal metabolism, mucosal regeneration, and overall energy.

Folic acid benefits for men are also significant. Folic acid plays an important role in cell division and sperm production. A deficiency can impair sperm quality and thus fertility. Folic acid is also associated with better vascular health and a lower risk of cardiovascular disease.

During pregnancy, folic acid requirements are significantly higher. The body forms especially large numbers of new cells during this time, and the developing embryo depends on folic acid. Folic acid supplementation in pregnancy plays a central role in cell division, DNA synthesis, and tissue growth — especially in the first weeks. This is when fundamental structures of the child’s nervous system develop.

If a folic acid deficiency occurs in these early stages, serious consequences can follow — including neural tube defects, spina bifida, or brain malformations. These birth defects usually develop within the first 25 days after fertilization, before a woman even knows she is pregnant.

This is why it is often recommended to start taking folic acid before pregnancy. Early and adequate folic acid intake not only protects against nervous system defects but also supports healthy blood formation, placental growth, and the mother’s overall health. Folic acid is one of the most important micronutrients for a healthy pregnancy and optimal child development.

During menopause, a woman’s hormonal balance changes. Estrogen levels drop, which can affect not only metabolism but also how the body utilizes vitamins and minerals. A lower estrogen level can impair the absorption and utilization of folic acid, potentially leading to a functional folic acid deficiency over time.

Folic acid also plays an important role in vascular health during menopause. It is involved in breaking down the amino acid homocysteine, whose concentration in the blood rises when folic acid is deficient. Elevated homocysteine levels are considered an independent risk factor for cardiovascular disease, as homocysteine can damage blood vessel walls and promote atherosclerosis.

In addition, an adequate folic acid supply can positively influence mood and energy, since the vitamin is involved in neurotransmitter production. Many women therefore benefit from a folate-rich diet and folic acid supplements for women during menopause.

A folic acid deficiency is particularly common in older adults and often goes undetected for a long time. Symptoms develop gradually and may resemble other age-related conditions. Folic acid remains crucial in old age for cell renewal, blood formation, nerve function, and overall well-being. A deficiency can contribute to physical and mental exhaustion in older people.

The causes of folic acid deficiency in old age are usually multifaceted. As people age, nutrient absorption in the small intestine declines — for example, due to age-related changes in the intestinal lining or reduced stomach acid production, which is needed to release and activate folic acid. Chronic diseases and regular use of certain medications, such as proton pump inhibitors, can also impair folic acid absorption and metabolism.

Even with a balanced diet, a so-called functional folic acid deficiency can develop in old age. This means that enough folic acid is consumed, but the body can no longer convert it into its active form or transport it into the cells. This is usually caused by disruptions in folate metabolism, oxidative stress, or impaired liver function.

An untreated folic acid deficiency in old age can lead to anemia, neurological changes, cognitive impairment, and increased susceptibility to infections. Regular monitoring of folic acid levels and supplementation are therefore especially important to support the health and quality of life of older adults.

A folic acid deficiency can be traced back to various causes that often occur simultaneously and in combination. Since folic acid is needed for numerous metabolic processes, a deficiency often has noticeable health consequences.

The most common causes include:

A one-sided diet low in fruits, vegetables, and whole grains is one of the most common causes of folic acid deficiency. Processed foods in particular contain only small amounts of folate. Furthermore, folic acid is heat-sensitive and is partially destroyed by cooking, frying, or prolonged warming.

Chronic alcohol consumption significantly impairs folic acid absorption and storage. Alcohol damages the intestinal lining, inhibits folic acid absorption in the small intestine, and depletes the liver’s folic acid stores.

Malabsorption in the small intestine — as seen in celiac disease, Crohn’s disease, or chronic gastritis — can prevent the body from absorbing enough folic acid. A disrupted gut flora after prolonged antibiotic therapy can also impair absorption.

Certain medications directly interfere with folate metabolism or reduce its absorption. These include methotrexate and folic acid interactions, antiepileptics, some antibiotics, oral contraceptives, and proton pump inhibitors. These medications disrupt folic acid activation and often lead to a deficiency with prolonged use.

In certain life situations, folic acid requirements rise. Pregnant and breastfeeding women need more folic acid. Chronic inflammation, cancer, or wound healing processes also increase consumption.

In people with chronic kidney disease — especially dialysis patients — folic acid is increasingly removed from the blood. Because it is water-soluble, it is lost with every treatment, further promoting deficiency.

A folic acid deficiency can have diverse causes, including dietary habits, diseases, or medication effects. Precise identification of the cause is therefore crucial to treat the deficiency effectively and restore affected metabolic processes.

Folic acid and B12 are closely connected and jointly involved in central metabolic processes. Both vitamins are necessary for producing genetic material in cells and for breaking down the amino acid homocysteine. A deficiency in either vitamin can therefore cause very similar disruptions in cell metabolism and produce the same symptoms.

Both a folic acid deficiency and a vitamin B12 deficiency lead to megaloblastic anemia, in which large, immature red blood cells are produced. These cells can only transport oxygen to a limited extent, leading to typical symptoms such as fatigue, paleness, weakness, and difficulty concentrating.

While folic acid is primarily needed for cell division, vitamin B12 is additionally essential for maintaining nerve cells and forming the myelin sheath that surrounds nerves. An isolated vitamin B12 deficiency can therefore lead to irreversible neurological damage, manifesting as tingling, numbness, or coordination problems.

A vitamin B12 deficiency can also be mistakenly treated with folic acid. This may temporarily mask blood count changes, but neurological damage continues to progress. For this reason, both vitamins should always be checked when anemia is present.

There is no direct connection between folic acid and vitamin D, yet a deficiency in both vitamins frequently occurs together. An unbalanced diet, chronic diseases, or advanced age can lead to a simultaneous shortfall.

Both vitamins are important for different but closely linked processes in the body. Folic acid is primarily important for cell division and blood formation. Vitamin D is essential for bone metabolism, immune function, and muscle performance.

A combined deficiency can therefore have an especially strong impact on overall well-being. While a folic acid deficiency often causes fatigue, paleness, or concentration problems, a vitamin D deficiency additionally leads to muscle weakness, increased susceptibility to infections, and lack of energy.

A folic acid deficiency frequently occurs together with an iron deficiency, since both nutrients are closely connected to blood formation. Both folic acid and iron are needed to produce red blood cells in the bone marrow. If either nutrient is lacking, the body cannot form enough functional blood cells, and anemia develops.

An iron deficiency leads to microcytic anemia, in which red blood cells are smaller and paler because not enough hemoglobin can be produced. A folic acid deficiency, on the other hand, causes megaloblastic anemia, in which cells remain enlarged and immature due to disrupted DNA synthesis.

In many cases, both deficiencies exist simultaneously — particularly with malnutrition, chronic bowel diseases, or increased blood loss. Symptoms such as fatigue, paleness, dizziness, or decreased performance often appear. Since the symptoms are very similar, targeted diagnostics are essential to determine the exact cause and provide appropriate treatment.

Diagnosing a folic acid deficiency relies on a combination of medical history, clinical examination, and laboratory testing. Since symptoms are often nonspecific, a careful medical history regarding dietary habits, medication use, and possible accompanying conditions is essential. Symptoms such as fatigue, difficulty concentrating, or skin changes can provide initial clues. During the physical examination, the skin, mucous membranes, and tongue are checked for typical changes. A neurological assessment may also be useful to identify accompanying symptoms such as tingling, memory problems, or irritability — and to distinguish these from a vitamin B12 deficiency.

Through a folic acid blood test, serum folate and red blood cell folate are measured. Serum folate reflects the current folic acid concentration in the blood and indicates short-term changes in dietary intake. Red blood cell folate, on the other hand, provides information about long-term folic acid supply and is therefore the more meaningful value — especially in chronic deficiency. Additionally, measuring vitamin B12 and folic acid levels along with homocysteine can be useful, as these values are often altered together and influence each other.

A comprehensive diagnostic workup enables targeted therapy and prevents a combined or hidden deficiency from being overlooked.

Folic acid concentration in the blood can be measured both in serum and in red blood cells. The normal folic acid level in serum typically ranges between 4 and 15 ng/mL, while the red blood cell folate value should be above 140 ng/mL. Values below these reference ranges indicate inadequate supply or a manifest folic acid deficiency.

Since a folic acid deficiency often accompanies anemia, additional parameters such as MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), and hemoglobin are measured in the blood test. An elevated MCV and MCH combined with low hemoglobin are typical signs of megaloblastic anemia, as occurs with folic acid or vitamin B12 deficiency.

The combination of these lab values enables an accurate assessment of folic acid supply and a differentiated distinction from other causes of blood count changes.

If the measured folic acid value falls below the normal range, this indicates a deficit or a manifest folic acid deficiency. A low folic acid serum value usually reflects an acutely reduced dietary intake, while low red blood cell folate points to a chronic deficiency.

Typical signs of a folic acid deficiency include fatigue, paleness, difficulty concentrating, tongue burning, skin changes, or nonspecific digestive problems. Megaloblastic anemia frequently develops, in which red blood cells are enlarged and functionally impaired.

If a folic acid deficiency is suspected, vitamin B12 and homocysteine levels should always be checked as well. Both values help with differential diagnosis, since a vitamin B12 deficiency causes similar symptoms and also leads to elevated homocysteine levels.

Elevated folic acid levels in the blood are rather rare and usually result from excessive supplementation — such as through dietary supplements or medications. A normal diet typically cannot produce excessively high folic acid levels, since folic acid is water-soluble and excess amounts are excreted by the body.

A too much folic acid level can be especially problematic when a vitamin B12 deficiency exists at the same time. The elevated folic acid intake could mask the hematological symptoms while the neurological damage from the B12 deficiency progresses unnoticed.

Folic acid supplementation should therefore always be monitored by a doctor — especially in older adults or individuals with unexplained anemia. This is the only way to ensure that a concurrent vitamin B12 deficiency is not overlooked and that a balanced nutrient supply is maintained.

A folic acid test for home use offers a simple way to get an initial impression of your own folic acid status. Typically, capillary blood from the fingertip is applied to a test strip. These tests can provide clues about a possible deficiency but are not as reliable or precise as a laboratory test performed by a doctor.

A self-test can serve as an initial indicator for detecting a deficiency — especially when typical symptoms such as fatigue, paleness, or concentration problems are present. If the test shows abnormal results, a medical evaluation should follow in every case.

The goal of treating a folic acid deficiency is to replenish nutrient stores, address the underlying cause, and prevent further damage. Since folic acid is essential for vital processes such as cell division, blood formation, and nerve health, a deficiency should be treated promptly.

Depending on the severity, treatment involves a combination of dietary therapy and supplementation. In milder cases, a dietary change to foods rich in folic acid — such as dark leafy greens, legumes, and whole grains — is often sufficient. In cases of pronounced deficiency or increased need — such as during pregnancy, breastfeeding, or with chronic diseases — folic acid tablets are required.

At the same time, the underlying cause of the deficiency should always be investigated and treated. Regular monitoring of blood counts and folate values helps assess treatment success and prevent relapse.

Folic acid supplementation is the most important component of treating a folic acid deficiency. The goal is to replenish the body’s folate stores, restore disrupted cell metabolism, and normalize symptoms such as fatigue, anemia, or mucosal changes.

The folic acid dosage depends on the severity of the deficiency and individual factors such as age, existing conditions, or absorption disorders. In most cases, 400 to 1,000 micrograms of folic acid are taken orally each day. In cases of severe deficiency, chronic diseases, or impaired gastrointestinal absorption, a higher dosage over several weeks may be necessary. After a certain period, the dose is reduced to a maintenance dose of approximately folic acid 400 mcg daily.

During pregnancy and breastfeeding, the need for folic acid is significantly higher. Women who are trying to conceive or who are already pregnant are recommended to take at least 400 micrograms of folic acid per day and to continue through the end of the first trimester. For women with certain risk factors — such as diabetes or obesity — the requirement can increase to up to 800 micrograms daily.

Folic acid can be supplemented in various forms. Folic acid pills or capsules are most common. Drops can also be given to those who have difficulty swallowing. For patients with impaired intestinal absorption or after digestive tract surgery, folic acid can also be administered intravenously or intramuscularly.

It is also important to always check the vitamin B12 level, since both vitamins are closely linked in their metabolic pathways. If a B12 deficiency exists simultaneously, folic acid supplementation may correct the anemia — but it can mask the neurological damage caused by the B12 deficiency.

Regular lab monitoring is generally advisable to assess treatment progress and ensure that folic acid levels are normalized long-term.

A folate-rich diet plays a central role in preventing and treating a folic acid deficiency. Since folic acid is water-soluble and sensitive to heat, light, and oxygen, care should be taken during food preparation to avoid folic acid loss.

Especially rich sources of folic acid include dark leafy greens such as spinach, broccoli, kale, and lamb’s lettuce. Legumes, whole grains, and citrus fruits also contain plenty of folic acid. These foods high in folic acid also provide other important micronutrients that support cell metabolism and blood formation.

A diet based on fresh, unprocessed foods can cover daily folic acid needs in most cases. When demand is higher or absorption is limited, the diet should be complemented with a folic acid supplement.

Below we answer the most common questions about folic acid deficiency so you can best understand the importance of folic acid, what a deficiency means, and its relevance for the body.

The information listed contains relevant topics and serves to improve understanding.