Folic acid is one of the widely used vitamin supplements. It is also known as pteroylmonoglutamic acid. Folic acid is found in some processed foods, such as cereals and flour.

Folic acid is the synthesized form of vitamin B9. This type of B vitamin can also be referred to as folate and is found in various foods, including avocados, asparagus, oranges, Brussels sprouts, and many more. Vitamin B9 is needed for cell formation and DNA synthesis. Cerebrovascular accident, birth deformities, heart disease, and certain types of cancer are some of the symptoms of low levels of folate in your blood. Excess circulating folic acid in the blood is not a health threat to adults. However, too much consumption of it can be fatal. This article discusses the main side effects of excess folic acid.

Pathophysiology of Excess Folic Acid

Unlike folic acid, the absorption of folate, which is vitamin B9 present in foods, is fairly poor. Research indicates that about 85 percent of ingested folic gets absorbed while only 50 percent of the ingested folate make it into the blood stream for use by your body. Just after its absorption into the bloodstream, liver breaks down folic acid into smaller compounds. Only smaller portions of these compounds are processed by the liver, at a time. Over time, especially with too much consumption of folic acid form supplements, unmetabolized folic acid (UMFA) will start building up in the blood. This is not the case with folate. It is broken down, and metabolized wholly by the liver. So, none of it can accumulate in your blood. This is not something to be snubbed, as too much of folic acid is the beginning of certain health conditions.

Equivalents of Folate Found In The Diet

The absorption of folic acid in the body is better than that of folate. For this reason, the National Academics of Sciences, Engineering, and Medicine and the Food and Nutrition Board (FNB) came up with a definitive recommendation of folate, known as dietary folate equivalents (DFEs). It is clearly stated that 1 mcg of DFEs is equal to 1 mcg of folate from foods, or 0.6 mcg of folic acid obtained from fortified foods, or 0.5 mcg of folic acid obtained from supplements ingested on an empty gut. As per the DFEs, folate found in foods naturally has no upper limits (UL). That being said, the National Institutes of Health (NIH) suggests that up to 1,000 mcg per day of folic acid in fortified foods and supplements is best for adults above the age of 19 years. According to the NIH recommendations, folic acid UL for children should range between 300 and 800 mcg per day. Higher intake of folic acid is rare considering that most people don’t consume even above the recommended limit. This may only be exceeded if the individual is overusing supplements.

Potential Side Effects of Excess Folic Acid

May Hide Vitamin B12 Deficiency

Too much intake of folic acid may easily hide vitamin B12 deficiency. Vitamin B12 performs various roles in the body, including maintaining healthy nervous system and supporting brain and heart health. Delayed management of vitamin B12 deficiency can lead to permanent nerve damage, making its diagnosis even harder. It is worth mentioning that, both folate and vitamin B12 are used in the same way by your body. Their deficiency also have similar symptoms. In a case where an individual is taking folic acid supplements, detecting vitamin-B12 induced megaloblastic anemia can be hard. Megaloblastic anemia is a blood disorder that presents with difficulty concentrating, general body weakness, and fatigue. It will help checking your levels of vitamin B12 if you start developing the above symptoms.

May Delay Brain Development In Children

Besides promoting fetal brain development, enough intake of folate reduces the likelihood of a child born with birth defects. Folate intake among women is poor. For this reason, pregnant women are always encouraged to supplement with folic acid. That being aid, excess folic acid during pregnancy may reduce cell response to insulin action, leading to delayed brain development in children. According to published studies, increased levels of folate in the blood during pregnancy may increase the likelihood of developing insulin resistance at ages 9 to 13. To avoid these problems, it may be best to stick to the recommended daily intake of folate during pregnancy.

May Increase The Risk Of Cancer Recurrence

There is a closer link between cancer recurrence and the role folic acid plays in precipitating cancer. Studies indicate that taking adequate amount of folic acid may help prevent the development of cancer. Still, excess levels of folic acid may promote the growth or spread of cells which are already cancerous. It has not yet been proven scientifically how high level of folic acid may increase the likelihood of developing cancer. It is claimed that the risk of developing cancer largely depends on the type of cancer. For example, people with previous history of prostate or colorectal cancer are likely to have cancer recurrence if they consume excess folic acid.

People with lower levels of vitamin B12 are at a higher risk of developing age-related mental decline. Published studies found that people above 60 years with UMFA can develop mental decline secondary to vitamin B12 deficiency.

Indications, Uses, and Drug Interaction

Folic acid is mostly used to fortify foods. It is also included in vitamin B complex vitamins, multivitamins, and antenatal supplements. Supplementing with folic acid may help correct low levels of folate in the blood. The supplements are also used by expectant mothers to reduce the risk of birth defects. People above 14 years should take 400 mcg folate per day as their Recommended Dietary Allowance (RDA). Pregnant mothers should not exceed 600 mcg and breastfeeding ones should stick to 500 mcg. Folic acid supplements can interact with medications used to treat rheumatoid arthritis and seizures.


Folic acid is vitamin B9 in the synthetic form. It is often used during pregnancy to prevent birth defects. Excess levels of folic acid in the blood may delay brain development and lead to age-related mental decline. Unless prescribed by a health professional, you need to avoid taking folic acid supplements with antiseizure medications.

Ksenia Sobchak, BA (Hons) Fashion Communication: Fashion Journalism, Central Saint Martins Ksenia Sobchak enjoys blogging on fashion, style, lifestyle, love and CBD areas. Prior to becoming a blogger, Ksenia worked for a renowned fashion brand. Ksenia is a contributing author to leading fashion, lifestyle and CBD magazines and blogs. You can bump into Ksenia at her favourite cafe in South Kensington where she has written most blogs. Ksenia is a staunch advocate of CBD and its benefits to people. Ksenia is also on the panel of CBD reviewers at CBD Life Mag and Chill Hempire. Her favourite form of CBD are CBD gummies and CBD tinctures. Ksenia is a regular contributor at leading fashion, lifestyle as well as CBD magazines and blogs.