People with sickle cell disease (SCD) have a higher turnover of red blood cells, which can contribute to anemia. Some people believe it can help to take folic acid, as humans need this nutrient to make more red blood cells.

It is possible that people may feel a benefit from taking this supplement. However, there has not been much research to suggest that folic acid is useful for reducing sickle cell anemia symptoms.

Folic acid may help reduce the risk of certain side effects from taking the SCD drug hydroxyurea.

Read on to learn more about whether folic acid helps with SCD, along with the dosages, potential risks, and side effects.

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Folic acid may help with managing SCD. However, at present, there are few studies on this.

The theory behind taking folic acid for SCD is that it may help with managing anemia. People with SCD are prone to sickle cell anemia because the disease causes the body to make crescent or sickle-shaped red blood cells that are hard and sticky.

These blood cells are less able to transport nutrients and oxygen. They can also get stuck in blood vessels, and they die faster than usual. This leads to a shortage of red blood cells.

Folate, or vitamin B9, helps the body make more red blood cells. Because of this, some people believe taking folic acid can help people with SCD get more folate. Folic acid is the synthetic form of folate and is present in both fortified foods and dietary supplements.

A 2018 review notes that it is a common practice for people with SCD to take folic acid but that there is little scientific evidence for it currently.

There is not much research on the benefits of folic acid for SCD, but it may:

Reduce anemia symptoms

Some people report that folic acid reduces their anemia symptoms, but researchers have yet to verify this via studies.

The 2018 review looked at previous research on the subject to determine whether folic acid could be a beneficial part of SCD treatment. However, only one study from 1983 was eligible for inclusion, and the authors state that this trial had a high risk of bias. This may mean the results are not reliable.

The 1983 trial tested folic acid supplementation in children and found that it significantly increased folate levels in the blood. However, it did not appear to improve hemoglobin levels, and the impact on symptoms is unclear.

Reduce medication side effects

Folic acid may help reduce some of the risks of hydroxyurea.

Hydroxyurea is a medication that doctors can prescribe to children and adults with SCD to keep blood cells round and flexible. However, hydroxyurea can cause macrocytosis, or enlarged red blood cells. These cells can lack the nutrients they need to function.

With regular blood tests, a doctor can detect macrocytosis before it becomes a serious problem. If it does occur, a doctor may recommend taking folic acid to reduce the impact.

Prevent neural tube defects

Unlike some other potential benefits of folic acid, there is strong evidence that folic acid reduces the risk of neural tube defects (NTDs).

NTDs can develop in fetuses during pregnancy. They affect the development of the early brain or spine. Spina bifida is an example of a condition NTDs can cause.

Doctors recommend that all people take a folate or folic acid supplement before and during pregnancy to reduce the risk of NTDs. This is also important for those with SCD.

Children and adults with SCD or sickle cell anemia often take a daily dose of 1 milligram (mg) of folic acid with the aim of reducing symptoms. It is unclear whether this is the best dosage, though.

An ongoing clinical trial that began in 2020 will use a daily dose of 1–5 mg of folic acid in children with SCD, but the results of this research are not available yet. It is best to ask a doctor what dosage to take.

According to the Centers for Disease Control and Prevention (CDC), folic acid typically does not cause harmful effects in doses of 400 micrograms (mcg) or below.

It is water-soluble, meaning if a person has too much of this nutrient, the body should be able to expel it in urine.

Some people may experience digestive discomfort from taking this supplement, such as nausea or diarrhea. If this occurs, a person should speak with a doctor.

Folic acid is generally safe. However, previous research has found some links between folic acid supplements and certain health conditions. These include:

  • B12 deficiency complications: A 2018 review notes that taking at least 5 mcg of folic acid per day could mask a vitamin B12 deficiency by preventing anemia in people with SCD. This could delay a vitamin B12 deficiency diagnosis, which could result in nerve damage.
  • Malaria: Folic acid may increase the risk of severe illness due to malaria. In previous studies of children living in an area where malaria is common, iron and folic acid supplements appeared to raise the risk of severe symptoms from the disease and mortality.
  • Cancer growth: Some studies have found an association between folic acid intakes of 1 mg per day and the increased growth of some types of cancer. However, this only applies to preexisting cancer.
  • Priapism: Folic acid may increase the risk of priapism. Priapism is an erection that lasts longer than usual or is not due to sexual arousal. It is unclear how common or likely this is.
  • Neurodevelopmental issues in fetuses: Due to the high absorption rate of folic acid, taking it in large doses from supplements or fortified foods may lead to high levels of unmetabolized folic acid in the blood. A 2017 review suggests that excessive folic acid supplementation among pregnant people may negatively affect the neurodevelopment of fetuses. However, more research is necessary.

SCD affects millions of people worldwide, including people with ancestors from Sub-Saharan Africa, Central and South America, parts of the Mediterranean, Saudi Arabia, and India.

Despite this, there is a lack of research on some aspects of SCD care. For example, although many clinics have long prescribed folic acid to patients, there are no high quality studies confirming that this is effective.

This may be due, in part, to a lack of research funding. A 2020 study compared funding levels in the United States between 2008 and 2018 for SCD and another genetic disease, cystic fibrosis (CF).

Both conditions received a similar amount of research funding from the government and charitable foundations, even though SCD is three times more common than CF. Additionally, research productivity and drug development were higher for CF.

SCD mainly affects Black, Hispanic, and Asian people, while CF is more common in white people. The authors of the study advocate for more funding for SCD research in order to tackle the disparities this causes.

If a person is considering taking folic acid for SCD, they may want to ask their doctor:

  • Can folic acid help my condition?
  • How does it help?
  • Should I have tests to check my folate levels?
  • How will folic acid supplements affect other treatments?
  • Are there side effects?
  • Can I get the amount of folate I need through my diet?

Some people with SCD take folic acid to try to reduce anemia symptoms. It may also help reduce some risks of taking hydroxyurea, and it is an important supplement to take during pregnancy.

However, there is still a need for more research on whether folic acid can be helpful in the daily management of SCD symptoms. New trials are still ongoing.

Folic acid is generally safe in moderate doses, but people who are considering trying it should speak with a doctor first to ensure it is safe for them.