Low folate: what a low folate blood result means, causes and treatment

A low folate result means the amount of folate in your blood is below the laboratory reference range. Folate is a B vitamin, also called vitamin B9, that the body needs to make red blood cells and to keep the nervous system healthy. The NHS notes that vitamin B12 and folate perform several important functions in the body, including keeping the nervous system healthy.

Low folate is a finding, not a diagnosis in itself. The next question is always why it is low, because the cause decides the treatment. It is also not necessarily accompanied by anaemia. The NHS says some of the problems can happen if you have a deficiency in vitamin B12 or folate but do not have anaemia.

The NHS describes four broad groups of cause. The first is diet. Good sources of folate include broccoli, Brussels sprouts, asparagus, peas, chickpeas and brown rice, and a lack of dietary folate is more common in people with a generally unbalanced diet, people who regularly misuse alcohol, and people following a restrictive diet that does not include good folate sources.

The second is poor absorption, usually from an underlying digestive condition such as coeliac disease. The third is losing folate from the body, which can happen with frequent peeing caused by conditions such as congestive heart failure, acute liver damage or long-term dialysis. The fourth is needing more than usual. The NHS says your body may need more folate than usual if you are pregnant, have cancer, have a blood disorder such as sickle cell anaemia, or are fighting an infection or an inflammatory condition. Premature babies are also more likely to develop folate deficiency.

Medicines are an additional cause. The NHS lists some anticonvulsants used for epilepsy, colestyramine, sulfasalazine and methotrexate. Your GP will be aware of medicines that can affect your folate levels and will monitor you if necessary. Do not stop prescribed medicines without advice.

Low folate may produce no symptoms, particularly early on. When symptoms occur the NHS lists extreme tiredness, a lack of energy, pins and needles, a sore and red tongue, mouth ulcers, muscle weakness, problems with vision, psychological problems ranging from mild depression or anxiety to confusion, and problems with memory, understanding and judgement.

These symptoms overlap with many other conditions, including vitamin B12 deficiency, thyroid problems and iron deficiency, which is why the result is interpreted alongside a full blood count and other tests rather than on its own.

The NHS says folate deficiency can often be diagnosed from your symptoms and the results of a blood test. A GP will typically review your diet, alcohol intake, medicines, digestive symptoms, pregnancy or planned pregnancy and any long-term conditions. A full blood count looks for large red blood cells and anaemia, and a vitamin B12 level is measured alongside folate.

Checking B12 matters because the two deficiencies look alike and are treated differently. The NHS says that before you start taking folic acid, your GP will check your vitamin B12 levels, because folic acid treatment can sometimes improve your symptoms so much that it masks an underlying vitamin B12 deficiency. If a B12 deficiency is not detected and treated, it could affect your nervous system. If your symptoms suggest a digestive cause, further tests such as coeliac blood tests may be arranged.

The NHS says folate deficiency anaemia is treated with daily folic acid tablets to build up your folate levels, and the GP may also give dietary advice to increase your folate intake. Most people need to take folic acid tablets for about 4 months. If the underlying cause continues, you may have to take them for longer, possibly for life.

To check that treatment is working, the NHS says a blood test is often carried out around 7 to 10 days after starting, to check haemoglobin and the number of immature red blood cells, and another may be done after approximately 8 weeks to confirm success. Most people who have had a deficiency do not need further monitoring unless symptoms return or treatment is ineffective.

Where the cause can be dealt with, such as a medicine, alcohol intake or a digestive condition, treating it is the best way to prevent the problem returning.

Complications are uncommon but can occur when a deficiency has been present for some time. The NHS lists problems with the nervous system, temporary infertility, heart conditions, and pregnancy complications and birth defects, and says adults with severe anaemia are at risk of heart failure. Some complications improve with treatment, but others, such as nervous system problems, can sometimes be permanent.

Folate matters especially around pregnancy. If you are pregnant or planning a pregnancy, a low folate result should be discussed with your midwife or GP promptly, because the NHS names pregnancy complications and birth defects among possible complications of deficiency.

The NHS says to see a GP if you think you may have a vitamin B12 or folate deficiency. Seek help sooner if you have numbness or tingling that is spreading, memory or thinking problems, or breathlessness and palpitations, and call 999 or go to A&E for chest pain or severe breathlessness.

The NHS notes that vitamin B12 and folate deficiency are more common in older people, affecting around 1 in 10 people aged 75 or over and 1 in 20 people aged 65 to 74. If you have coeliac disease, drink heavily, take certain medicines or have a restricted diet, a low result is more likely and worth following up.