Consuming elevated amounts of folic acid supplements may lead to adverse effects, such as hastening cognitive decline in senior citizens and raising the chances of cancer reoccurrence. Folic acid is the synthetic variant of vitamin B9, which is predominantly found in dietary supplements and select fortified foods.

In its natural state within foods, vitamin B9 is referred to as folate. You can obtain folate from a variety of sources, including legumes (dal), oranges, asparagus, Brussels sprouts, avocados, and a range of leafy green vegetables. Whether provided as folate or as folic acid, vitamin B9 plays a crucial role in cellular development and DNA synthesis within your body.

Insufficient blood levels of folate have been associated with a range of health concerns, such as an increased risk of congenital disabilities, cardiovascular diseases, strokes, and specific types of cancer. Conversely, for the majority of healthy adults, elevated blood levels of folate are generally not a cause for alarm. However, excessive intake of folic acid through supplements can pose significant health risks.

Below are four potential side effects linked to excessive consumption of folic acid.

Understanding the Development of Excess Folic Acid

The human body has a more challenging time absorbing folate compared to folic acid. Research indicates that approximately 85% of folic acid sourced from fortified foods or supplements is effectively absorbed, in contrast to only around 50% of natural folate derived from whole foods.

Once folic acid enters the bloodstream, it undergoes a breakdown process into smaller components within the liver. However, the liver can only metabolize a limited amount of folic acid at once. This limitation means that excessive consumption of folic acid through fortified foods and supplements may lead to a buildup of unmetabolized folic acid (UMFA) in the bloodstream, an issue that does not arise when consuming foods rich in folate. This accumulation is alarming as elevated blood levels of UMFA have been associated with several health concerns.

Understanding Dietary Folate Equivalents

Given that folic acid is absorbed more efficiently than folate from food sources, the Food and Nutrition Board (FNB) at the National Academies of Sciences, Engineering, and Medicine established dietary folate equivalents (DFEs) to provide clearer guidelines for folate intake.

One microgram (mcg) of DFEs is equivalent to:

• 1 mcg of folate from food sources
• 0.6 mcg of folic acid from fortified foods or dietary supplements taken alongside meals
• 0.5 mcg of folic acid from dietary supplements consumed on an empty stomach

There is no established upper limit (UL) for folate that occurs naturally in foods. However, the National Institutes of Health (NIH) advises that adults over the age of 19 should restrict their daily folic acid intake from fortified foods and supplements to a maximum of 1,000 mcg. For children, this upper limit is lower, falling between 300–800 mcg, depending on age.

It is important to note that the majority of individuals do not exceed the 1,000 mcg threshold of folic acid on a daily basis unless they are consuming high-dose supplements. According to the NIH, only about 5% of men and women aged 51–70 exceed this intake level daily, primarily due to supplement usage.

In summary, the body absorbs folic acid from fortified foods and supplements more readily than it does naturally occurring folate from traditional foods. An excess of folic acid can result in the accumulation of unmetabolized folic acid (UMFA), which may pose risks to health.

1. Potential to Conceal Vitamin B12 Deficiency

Excessive consumption of folic acid can potentially conceal a deficiency in vitamin B12. This essential vitamin plays a critical role in the production of red blood cells and is vital for maintaining the health of your heart, brain, and nervous system. Without appropriate treatment, a deficiency in vitamin B12 can lead to irreversible nerve damage, making a delayed diagnosis particularly concerning. Both folate and vitamin B12 are utilized in similar ways by the body, which means that a deficiency in one can mimic symptoms associated with a deficiency in the other. As a result, taking folic acid supplements may mask symptoms of vitamin B12-related megaloblastic anemia, potentially allowing an underlying deficiency to go unnoticed.

Megaloblastic anemia is a medical condition characterized by the presence of enlarged red blood cells, which can lead to a range of symptoms including weakness, fatigue, difficulty concentrating, and shortness of breath. If you are consuming folic acid supplements and begin to experience any of these symptoms, it's advisable to have your vitamin B12 levels assessed. High levels of folic acid may obscure a vitamin B12 deficiency, consequently elevating the risk of damage to the brain and nervous system.

2. Potential Acceleration of Age-Related Cognitive Decline

An excessive intake of folic acid may contribute to a quicker decline in cognitive abilities associated with aging, especially among individuals with deficient vitamin B12 levels. Research conducted on seniors aged 60 and above revealed a concerning correlation between elevated blood levels of folate or UMFA and cognitive deterioration in those with insufficient vitamin B12. This association, however, was not observed in individuals who maintained normal B12 levels.

Moreover, another investigation indicated that individuals exhibiting high folate alongside low vitamin B12 levels could be as much as 3.5 times more susceptible to cognitive impairment compared to those with standard blood parameters. It is crucial to note, however, that the existing studies underscore the necessity for further research before concluding that high-dose folic acid supplementation could adversely affect mental well-being.

In summary, while a notable intake of folic acid may potentially hasten age-related cognitive decline, particularly in those with low vitamin B12 levels, more comprehensive studies are required to establish a definitive link.

3. May hinder brain development in children

Ensuring adequate folate intake during pregnancy is crucial for fostering your baby's brain development and minimizing the likelihood of birth defects. Many women, however, struggle to fulfill their folate requirements through dietary sources alone, leading to recommendations for those in their childbearing years to consider folic acid supplements.

Nevertheless, excessive supplementation of folic acid during pregnancy may inadvertently elevate insulin resistance and impede brain development in children. Research indicates that children aged 4 to 5, whose mothers consumed over 1,000 mcg of folic acid daily during pregnancy, performed worse on cognitive development assessments compared to those whose mothers adhered to a dosage of 400–999 mcg.

Furthermore, another study established a connection between elevated folate levels in the blood during pregnancy and an increased risk of insulin resistance in children aged 9 to 13. While additional research is essential to draw definitive conclusions, it is prudent to refrain from exceeding the advised daily limit of 600 mcg of folic acid supplements during pregnancy unless otherwise guided by a healthcare professional. Folic acid supplements can effectively enhance folate levels during pregnancy; however, caution is warranted, as excessive intake may lead to increased insulin resistance and adversely affect brain development in offspring.

4. Potential to Heighten Cancer Recurrence Risk

The relationship between folic acid and cancer development, as well as recurrence, appears to be quite complex. Numerous studies indicate that when healthy cells are exposed to sufficient amounts of folic acid, this may serve as a protective mechanism against cancerous changes. Conversely, when cancerous cells are subjected to elevated levels of folic acid, this may facilitate their growth or dissemination. However, the findings in this area are inconsistent. While a handful of research efforts suggest a slight increase in cancer risk among individuals taking folic acid supplements, the majority of studies have not established a definitive connection.

It is hypothesized that the risk associated with folic acid may vary depending on the type of cancer and individual health background. For example, some earlier studies indicate that individuals with a past diagnosis of prostate or colorectal cancer who consumed over 1,000 mcg of folic acid daily experienced a 1.7–6.4% increased risk of tumor recurrence. On the other hand, consuming a diet rich in folate does not seem to correlate with a higher risk of cancer; in fact, it may even lower the risk.

In summary, further investigation is essential to fully understand the connections between folate, folic acid supplementation, and cancer risk and recurrence. Excessive intake of folic acid supplements could enhance the proliferation and spread of cancer cells, which may be particularly harmful for individuals with a cancer history. Nevertheless, additional research is warranted to clarify these findings.

Recommended Usage, Dosage, and Potential Interactions

Folic acid, also known as folate, is commonly found in a variety of multivitamins, prenatal supplements, and B complex vitamins. Additionally, it is available as a standalone supplement. In several nations, including India and Australia, certain foods are fortified with this essential vitamin to enhance public health. These supplements are often recommended to prevent or address low levels of folate in the blood. Particularly, individuals who are pregnant or planning to conceive frequently take folic acid to help minimize the risk of congenital disabilities. For instance, in Japan, the emphasis on folate intake during pregnancy is highlighted through public health campaigns.

The Recommended Dietary Allowance (RDA) for folate stands at 400 mcg for individuals aged 14 and older. Pregnant women are advised to increase their intake to 600 mcg, while breastfeeding mothers should aim for around 500 mcg. Supplement dosages typically vary between 400 and 800 mcg, providing flexibility based on individual health needs.

Folic acid supplements can be acquired without a prescription and are generally regarded as safe when consumed in appropriate amounts. Nevertheless, it is important to be aware that these supplements may interact with certain prescription medications, including those prescribed for conditions such as seizures, rheumatoid arthritis, and parasitic infections. Therefore, if you are currently taking other medications, it is wise to consult a healthcare professional prior to incorporating folic acid into your regimen.

In summary, folic acid supplements serve a vital role in reducing the risk of birth defects and addressing folate deficiency. When taken within the recommended guidelines, they are typically safe, yet awareness of potential interactions with other medications is crucial.

The Bottom Line

Folic acid supplements are widely regarded as safe and can serve as a practical method for ensuring adequate folate levels in your diet. Nevertheless, excessive intake of folic acid can lead to various side effects, notably slower cognitive development in children and a hastened cognitive decline in older adults. Although additional research is essential to fully understand these effects, collaborating with your healthcare provider can help clarify your folate levels and ascertain whether supplementation is necessary.