Constant brain fog, nagging headaches, and severe fatigue that never seems to go away—it’s easy to dismiss these symptoms as nothing more than not sleeping enough, eating too much fast food, or just getting older.
But experts think this could be a sign of a little-known vitamin deficiency: folic acid.
Folic acid, also known as vitamin B9, is crucial for helping the body produce and repair DNA, and forming red blood cells that carry oxygen to major organs.
It also helps break down the amino acid homocysteine, which circulates in the blood and at high doses increases the risk of blood clots and heart attacks.
However, the body cannot produce folic acid itself and must obtain the vitamin from foods such as dark leafy greens and Brussels sprouts. Fortified grains and supplements contain the synthetic version of vitamin B9 called folic acid.
Folate and folic acid are especially crucial for pregnant women, as a nutrient builds the baby’s neural tube that eventually develops into the brain and spinal cord.
Although estimates suggest that a true folic acid deficiency is rare, one in five Americans don’t get enough, including men, non-pregnant women and older adults.
Experts told the Daily Mail that a folic acid deficiency can lead to fatigue, brain fog and shortness of breath
Experts told the Daily Mail that inadequate folate levels prevent the body from making red blood cells, leading to the blood disease megaloblastic anemia, which causes extreme fatigue, shortness of breath, numbness in the hands and feet and ulcers around the mouth.
It is also crucial for sperm production in men, and a deficiency can potentially increase the risk of fertility problems.
“The human body needs folates for DNA synthesis, cell division and healthy red blood cell production,” Dr. Robert Thompson, a family physician and medical associate at Care Point Boston, told the Daily Mail.
‘It is therefore important to consume folic acid throughout your life, and not just during pregnancy.’
Natural folic acid is found in dark leafy greens such as spinach and kale, beans, peas, nuts and citrus fruits such as oranges.
Folic acid, meanwhile, is a synthetic form of folate that is added to fortified foods such as bread and cereal.
It is also an important part of prenatal vitamins intended for women who are pregnant or trying to become pregnant.
“Folic acid intake is unique because of its importance at the extremely early stages of embryonic growth,” said Dr. Thompson.
‘Taking enough folic acid before you are pregnant or during your first trimester significantly reduces the chance that your fetus will develop a neural tube defect.’
Neural tube defects include spina bifida and anencephaly, a fatal condition in utero that occurs when parts of the brain, skull and scalp do not develop properly.
The American Academy of Pediatrics recommends women of childbearing age take a prenatal product containing 400 to 800 micrograms (mcg) of folic acid per day.
Folic acid is especially crucial during pregnancy as it can prevent neural tube defects in the fetus, such as spina bifida
Outside of pregnancy, folic acid is a vitamin that is needed regularly in everyone’s diet, Dr. James J Chao, plastic surgeon and chief medical officer and co-founder of VedaNu Wellness, told the Daily Mail.
‘Many of the cells we need most depend on folic acid. These include red blood cells, cells lining your digestive tract and white blood cells,” he said.
‘It also works with another B vitamin, B12, to help lower blood levels of the amino acid homocysteine by converting it to another amino acid, methionine.’
Methionine serves as a building block for the production of proteins and is further converted into antioxidants that fight inflammation.
Chao explains that folic acid is necessary “for optimal sperm production” because it protects sperm cells from DNA damage and allows them to repair themselves.
Low folic acid levels increase the risk of sperm DNA becoming fragmented, reducing sperm quality and movement.
Women with heavy periods may also benefit from folic acid because it supports the production of red blood cells that can combat anemia caused by menstrual blood loss.
Chao also notes that folic acid “deserves attention in older adults” because they naturally “absorb it less well” due to aging and lower food intake.
Folic acid can be found in leafy vegetables and citrus fruits, as well as fortified breads and breakfast cereals
Alcohol can also interfere with the absorption of folic acid by damaging the cells lining the digestive tract and inhibiting the expression of proteins needed to transport folic acid along the intestinal wall. Chronic alcohol use also reduces the liver’s ability to store circulating folic acid.
Federal health authorities recommend that men, older adults and adult women who are not pregnant or trying to become pregnant consume 400 mcg of folic acid each day. While most groups can reach that level through food sources, older adults or those with alcohol addiction may benefit from additional supplementation, Chao notes.
“Signs and symptoms of folic acid deficiency depend on the stage of the deficiency, but may include fatigue, headache, shortness of breath, irritability and poor appetite,” he said.
‘Brain fog, forgetfulness and confusion can occur. These symptoms are often overlooked and treated as a normal age-related decline in cognition.”
Folate deficiency can also affect brain health in the long term. A 2022 study in the European Journal for Clinical Nutrition found that low folate levels were associated with faster decline in cognitive function in older adults.
Other red flags that may warrant a folic acid supplement or increased dietary sources include a red, swollen, or sore tongue, mouth ulcers, palpitations, and shortness of breath.
Despite the benefits of folic acid, it is possible to get too much of a good thing. Health authorities recommend that adults consume no more than 1,000 mcg per day because high doses can cause nausea, cramps and diarrhea.
