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Folates or folic acid: two terms for two different things
Vitamin B9 comes in two forms, which it is worth distinguishing between, as confusion between the two is the source of several misunderstandings.
- Folates refer to the form naturally present in food; the word comes from the Latin folium, meaning ‘leaf’, in reference to the green vegetables in which they are abundant.
- Folic acid is the synthetic form used in supplements and fortified foods. It is more stable and, paradoxically, is better absorbed than dietary folates.
Both are converted into the same active form by the body. This conversion involves several enzymatic steps, which explains why some formulations provide a so-called ‘methylated’ form directly, which is already activated.
Vitamin B9 has numerous recognised functions. It contributes to the growth of maternal tissues during pregnancy, to the normal synthesis of amino acids, to normal blood formation, to the normal metabolism of homocysteine, to normal psychological functions, to the normal functioning of the immune system, to the reduction of fatigue and to the process of cell division.
This last function is key to everything else: B9 is essential for DNA synthesis. Tissues that renew themselves rapidly (bone marrow, mucous membranes, growing tissues) are therefore the first to suffer from a deficiency.
Symptoms of vitamin B9 deficiency
The symptoms stem directly from this role in cell division and primarily affect rapidly renewing tissues.
- Persistent fatigue, linked to the onset of anaemia
- Paleness and shortness of breath on exertion
- Mouth ulcers and inflammation of the tongue, which becomes smooth and painful
- Digestive problems, diarrhoea and loss of appetite
- Irritability and difficulty concentrating
- Hair loss and brittle nails
Anaemia caused by a B9 deficiency is known as macrocytic anaemia: the red blood cells produced are abnormally large, because the cell has been unable to divide properly due to a lack of available genetic material. This can be detected by a simple blood count.
This is where the first difficulty arises: a vitamin B12 deficiency produces exactly the same type of anaemia. Based on a blood count alone, it is impossible to distinguish between them. This similarity has consequences, which we shall examine, and it is the most important point of this article.
The pitfall of masking a B12 deficiency
Here is the information that explains why one should never take folic acid supplements without first checking one’s vitamin B12 status.
A B12 deficiency has two main consequences: anaemia, which is reversible, and neurological damage, which is far less reversible – including tingling, balance problems, impaired sensation and cognitive impairment.
However, folic acid corrects the anaemia caused by a B12 deficiency, without correcting the neurological damage.
The feared scenario is therefore as follows: a person with a genuine B12 deficiency takes folic acid. Their anaemia improves, their fatigue decreases and their blood count returns to normal. The warning sign disappears whilst the underlying cause persists, and the nerve damage progresses silently for months, until it becomes irreversible.
This mechanism explains why a B12 test must accompany any folate test, and why high-dose folic acid supplementation is a medical decision rather than a personal choice. Our article oninterpreting vitamin B12 levels details the precautions to take when reading these test results.
Causes of a folate deficiency
Unlike B12, for which the liver’s stores last for several years, folate stores are modest: a few months at most. A deficiency therefore develops much more quickly.
The causes fall into three main categories.
Firstly,insufficient intake. Folate is highly sensitive to heat, light and cooking water: a diet low in fresh vegetables, or one that relies on prolonged cooking in plenty of water, significantly reduces actual intake.
Increased requirements: pregnancy and breastfeeding are the main factors, but so too are growth, wound healing and certain blood disorders.
Losses or reduced absorption:
- chronic alcohol consumption, which disrupts both the absorption and utilisation of folates, is a major and common cause
- inflammatory bowel diseases and coeliac disease
- certain medicines: methotrexate, anti-epileptics, sulphonamides
- dialysis
Where to find folate in the diet
Folate is widely found in plant-based foods, but as it is fragile, certain precautions must be taken when preparing them.
The best sources are offal, particularly liver, pulses (lentils, chickpeas, beans), green leafy vegetables such as spinach, lamb’s lettuce and rocket, brassicas – particularly broccoli – asparagus, eggs, citrus fruits and oilseeds.
There are three key steps to ensure you get the most out of these foods:
- Eat some of your vegetables raw. A lamb’s lettuce or rocket salad provides intact folate, whereas prolonged cooking destroys a significant proportion of it.
- Choose steaming over boiling. Folate leaches into the cooking water, which is then poured down the sink.
- Limit how long you store green vegetables, as their folate content decreases over time.
The recommended daily intake for adults is around 330 µg, and rises significantly during pregnancy. Formulations covering the entire B group can be found in the ‘B complex’ category, and our selection of the best B-group vitamin supplements compares the available options.
B9, B12 and iron: distinguishing between the three types of anaemia
Persistent tiredness often leads to a suspicion of iron deficiency. This is just one of three possible causes, and confusing them can lead to taking supplements that do nothing to address the actual problem.
- Iron deficiency causes microcytic anaemia, characterised by small red blood cells. Our guide to iron-rich foods explains this condition in detail.
- Vitamins B9 and B12 cause macrocytic anaemia, characterised by large red blood cells.
A complete blood count immediately distinguishes between these two types, and joint testing for folate and vitamin B12 provides a definitive diagnosis within the second category. It is a simple test, and it avoids months of unnecessary supplementation, which can even be counterproductive in the case of the masking effect mentioned above.
Frequently asked questions
What are the signs of a vitamin B9 deficiency?
Persistent fatigue, pallor, recurrent mouth ulcers, a smooth and painful tongue, irritability and digestive problems are the most common symptoms. These are accompanied by anaemia, which is evident from a blood count.
These signs alone are not sufficient to distinguish a B9 deficiency from a B12 deficiency, as the symptoms are virtually identical. Only a blood test for both vitamins can provide a definitive diagnosis.
What is the difference between folates and folic acid?
Folates are the natural form, found in food.Folic acid is the synthetic form found in supplements and fortified foods.
Contrary to what one might expect, folic acid is better absorbed than dietary folates, which are more fragile and sensitive to cooking. Both are converted into the same active form by the body.
Can you take folic acid without medical advice?
In moderate doses as part of a B-complex supplement, this is generally not a problem. However, taking high doses on their own is not recommended.
The reason lies in ‘masking’: folic acid corrects anaemia caused by a B12 deficiency without addressing the accompanying neurological damage. The warning sign disappears whilst nerve damage progresses. Taking both vitamins together removes this uncertainty.
Does cooking destroy folates?
Yes, and significantly so. Folates are among the most fragile vitamins: they are sensitive to heat and light, and soluble in cooking water.
Prolonged cooking in plenty of water can destroy a considerable amount. Eating some green vegetables raw, favouring steaming and reducing cooking times are the three habits that really help preserve the nutritional value.
Should you take vitamin B9 when taking iron?
Not necessarily, and certainly not without knowing what you’re deficient in. Iron and folate treat two different types of anaemia, and taking both ‘just in case’ is tantamount to supplementing blindly.
Certain situations, such as pregnancy, do warrant taking both simultaneously, but only within a defined medical context. Outside of these cases, a blood test provides far better guidance than mere guesswork.
There is one situation where the matter is beyond dispute, and it is fitting to conclude this article with it. For a woman planning a pregnancy, folic acid supplementation is recommended even before conception and during the first few weeks. The embryo’s neural tube closes during the first month (often before the pregnancy is even known) and this closure depends directly on folate status. This is one of the few instances of supplementation on which there is complete medical consensus, and the only case where waiting until symptoms appear would already be too late. If this applies to you, speak to your doctor or midwife as soon as you start planning a pregnancy, not when you get a positive test result.