Folic acid deficiency – what you need to know

Camilla Freinek Camilla Freinek
from Camilla Freinek, BSc MSc
on 07.05.2024
Person with folic acid deficiency Person with folic acid deficiency

Do you recognise this story? The Grimm Brothers’ fairy tale, in which Rapunzel's mother lusted after the prohibited salad leaves in her neighbour’s garden during pregnancy? Her gut feeling was right on the money, since the water-soluble B vitamin that field salad contains is one of the most critical pregnancy nutrients of all. But folic acid is not just important when it comes to family planning. Other people should also keep an eye on their folic acid supplies. Large-scale studies show a deficiency in supply in large parts of the population. But what are the consequences of folic acid deficiency? And how can it be determined?

What is folic acid and what do you need it for?

Folic acid (also vitamin B9) is a water-soluble vitamin that belongs to the B vitamin family. The vitamin is an essential part of human life from the very beginning, because it ensures that our body grows, thrives, recovers and heals thanks to its key position in amino acid metabolism, cell division and cell regeneration.

Folic acid also proves to be active and important elsewhere. An adequate folic acid supply thus supports healthy blood formation and our neurotransmitter metabolism. Folic acid also contributes to the breakdown of the amino acid homocysteine, which can be harmful to the heart and vascular system in increased concentrations.

Find out more about folic acid

Symptoms & signs: How does a folic acid deficiency manifest itself?

If our body lacks folic acid, this deficiency can manifest itself in many ways. Possible deficiency symptoms include:

Physical symptoms

  • Anaemia (folic acid deficiency anaemia)
  • Pale skin, pale mucous membranes
  • Increased bleeding tendency with mucosal bleeding and punctiform skin bleeding
  • Increased susceptibility to infection
  • Loss of appetite and weight loss
  • Inflamed, red tongue, tongue tingling
  • Inflammation of the stomach or intestinal mucosa
  • Increased homocysteine level, increased risk of arteriosclerosis
  • Serious cases: Cardiac arrhythmias, shortness of breath

Neurological and psychological symptoms

  • Irritability, mood swings including depression
  • Fatigue and insomnia
  • Reduced ability to concentrate, forgetfulness, confusion

In unborn babies whose mothers have folic acid deficiency, there is a risk of a developmental disorder of the nervous system, such as spina bifida, in which one part of the spine or back remains open. In addition, the risk of miscarriages or premature births increases.

Consequences & effects on the body of too little folic acid

Poor folic acid supply is particularly evident in the rapidly dividing cells. Thus, this becomes a breeding ground for anaemia. Due to the folic acid deficiency, the precursors of red blood cells in the bone marrow do not mature properly, with the result that fewer red blood cells are formed, but they contain more haemoglobin and are larger than normal. Their ability to transport oxygen in your blood is reduced.

In addition to red blood cells, white blood cells can also be affected by a folic acid deficiency, with the result that the susceptibility to infection increases. Moreover, if the platelets are suffering from a folic acid deficiency, this can also interfere with blood clotting.

Folic acid sets the mood!

Folic acid facilitates a whole range of processes, reactions and compounds in our brain, which resembles a chemical factory. For example, together with vitamin B6, it is responsible for the formation of neurotransmitters such as GABA and serotonin. However, if our body lacks folic acid, this can also affect our neurotransmitter metabolism and promote the development of depressive moods. However, folic acid also plays a role in the drug treatment of depression. For example, studies show that sufficient amounts of the B vitamin can improve the effect of antidepressants.

Folic acid deficiency: Risk factor homocysteine

Although cardiovascular disease is not a direct consequence of folic acid deficiency, a deficiency can have indirect consequences on our vascular system. For example, folic acid together with the vitamins B6 and B12 causes the breakdown of homocysteine, which causes vascular injury. If only one of these vitamins is missing, there may be an increase in homocysteine levels in the blood. And elevated homocysteine levels are in turn considered a risk factor for vascular calcification (arteriosclerosis) and cardiovascular diseases.

Family planning? Not without folic acid!

As soon as women wish to have a child, they should ensure that they have the correct amount of nutrition. This “internal nest building” forms the foundation and offers the best conditions for ensuring that the new life has everything it needs.

The supply of folic acid, which offers protection against premature birth and miscarriages as well as severe malformations such as neural tube defects in the child, is considered particularly critical. Since the neural tube of the foetus already closes between the 22nd and the 28th day – at a time when many women do not know that they are pregnant – the folic acid supply should be ample before conception.

However, sometimes pregnancy does not occur at all, because in order to allow a child to grow, cell division is the most important process and depends on a sufficient maternal nutritional supply (especially folic acid). And male fertility also requires a good folic acid supply for healthier sperm.

Causes: How does a vitamin B9 deficiency develop?

Folic acid deficiency occurs when we lose or consume more folic acid in the long term than we absorb. In addition to an inadequate folic acid supply via the diet, the need for B vitamins may also be increased in some life situations or the supply may be disturbed by certain factors.

People who should keep an eye on their folic acid supply include:

  • Women wishing to have children
  • Pregnant women and breastfeeding mothers
  • People who mainly eat fast foods that contain few fresh vegetables
  • Patients with certain diseases, such as gastrointestinal disorders, hyperthyroidism, psoriasis, tuberculosis, heart failure, liver diseases
  • Patients requiring haemodialysis (blood washing)
  • People who take certain medicines - e.g.
    • the birth control pill
    • Oral antidiabetics (metformin)
    • Antidepressants – SSRIs (e.g. sertraline, fluoxetine)
    • Diuretics (e.g. loop diuretics, thiazides)
    • Folic acid antagonists (e.g. methotrexate, sulphonomid antibiotics)
    • Antiepileptics (e.g. carbamazepine, phenytoin)
    • Tetracyclines (e.g. minocycline)
    • NSAIDs (acetylsalicylic acid, diclofenac, ibuprofen and paracetamol)
  • Smokers
  • People who consume large amounts of alcohol

From wishing to have children to your own child: When it comes to folic acid, play it safe!

For women who are somewhere between the desire to have children and the realisation of their wish, a healthy diet is particularly important. Since folic acid is an extremely sensitive nutrient and sufficient care for the mother/child is particularly critical, women who wish to have children, as well as pregnant and breastfeeding mothers, should already use a folic acid product with a high enough dosage.

Folic acid deficiency during menopause and in old age

Folic acid is not just a must-have for expectant mothers and those planning a family. Folic acid remains a (female) topic even in and after the menopause. For example, initial studies indicate that the targeted intake of folic acid (for four weeks, 1 mg daily) can lead to a subjective improvement in hot flushes (Bani p. et. al. 2013).

Mature women not only benefit from this water-soluble vitamin from a “female” perspective. Other health issues are also determined by folic acid. For example, scientists observed decades ago that postmenopausal women with low folic acid levels had a higher risk of heart disease (Brattström, L.E. et. al. 1985). This observation can be traced back to the main role of folic acid in the breakdown of homocysteine. Accordingly, a folic acid deficiency can lead to an increase in homocysteine. This in turn can have a negative effect on the heart and the blood vessels.

An adequate folic acid supply for mature women can also be recommended in terms of mental fitness. Studies suggest that the supplementation of B vitamins, especially folic acid, can have a positive effect on delaying and preventing the risk of cognitive decline (Martínez V.G. et al. 2022).

Diagnostics: Detect folic acid deficiency via blood values

Although typical symptoms of folic acid deficiency can occur, these symptoms can also be caused by other diseases or nutrient deficiencies and are therefore not considered to be “evidence”. If you want to know the exact state of your folic acid supply, a laboratory blood test is recommended.

Folic acid concentrations of >5.38 ng/ml in serum are considered ideal values.

When do you talk about folic acid deficiency?

Folic acid levels below 2.0 ng/ml are referred to as folic acid deficiency. 

In the course of routine medical examinations, the folic acid value is not always necessarily determined. Nevertheless, a serious folic acid deficiency can lead to abnormal deviations in the blood count and can be revealed through them. Thus, in folic acid deficiency anaemia, the red blood cells are enlarged and more intensely discoloured.

Practice tip from Biogena Diagnostics ®:

"In order to obtain a good overall picture about the respective metabolic situation, the additional determination of vitamin B6, B12 and homocysteine (as control parameters) is useful in a folic acid check. Vice versa – in the case of elevated homocysteine levels ideally a laboratory diagnostic investigation of the three homocysteine-degrading vitamins B6, B12 and folic acid should be carried out.”

Rectify the deficiency – what can you do about it?

The most promising strategy for quickly and successfully correcting a folic acid deficiency is temporary supplementation of the vitamin. Thus, acute folic acid deficiency is generally "history" after just over one month.

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In order to prevent a folic acid deficiency in the future, the doctor and patient should also carry out a bit of causal research together. If the folic acid deficiency was triggered by a low-folic acid diet, the affected person must be encouraged to introduce a dietary change (more plant-based, fresh, natural, whole). If alcohol is involved, this should be avoided in the future. In the case of disease-related folic acid deficiency, on the other hand, the disease itself must be treated. In addition to a diet rich in folic acid, an additional nutritional supplement may also be useful – your trusted specialist will be happy to advise you on this.

Because folic acid is found primarily in a natural, plant-based diet, those who mainly eat fast food (no fresh vegetables or salads) are at risk.

Although folic acid is found naturally in numerous foods (= dietary folate), it is not so easy to absorb the recommended 300 μg daily – because the water-soluble vitamin is very sensitive and is destroyed by storage, industrial processing and heating. This is also reflected in analyses that show that the folate content of spinach decreases by half when stored for 4 days at room temperature.

Another factor that plays into our respective folic acid supply is the availability of dietary folate. How well folic acid can be absorbed by humans from their diets depends on the form it is presented. While the so-called “monoglutamate” contained in the product can be almost completely absorbed, the absorption rate for “polyglutamate” is approx. 20%. According to the experts, on average only about 50% of food folate can be reasonably exploited.

Nutrition & food: What is rich in folic acid?

The word folic acid derives from the Latin “folium” or “leaf”. According to the motto “Nomen is Omen” (the name speaks for itself), the vitamin is actually abundant in dark green leafy mixtures, such as lamb’s lettuce, chard, spinach and kale. Notable amounts of natural folic acid (= folate) are also found in other types of cabbage as well as in whole grain products, tomatoes, oranges, egg yolks and nuts. Particularly high concentrations are found in yeast, liver, wheatgerm and bran.


Folic acid in μg



Lamb’s liver


Sunflower seeds










Chicken egg






Table: Folic acid content of food (according to Prof. Dr Friese K, 2014.)

How long does it take for your folic acid supplies to be refilled?

Our body can only store small amounts of folic acid, half of which is located in the liver. In order to refill empty supplies a period of approx. four weeks should be anticipated with a supplementation of 800 μ g folic acid daily.


The versatile substance folic acid is often lacking in our diet. Women who wish to have children should therefore supplement with folic acid as a preparation for pregnancy. However, for people who eat a low-vegetable diet or do not feel very fit, it is quite useful for them to look closely at their own folic acid level and to remedy any deficit with an adequate folic acid preparation, if necessary.

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