Persistent brain fog, recurring headaches and a crushing tiredness that lingers day after day are often blamed on poor sleep, a fast-food-heavy diet or the natural effects of aging.
Yet health specialists warn these common complaints may point to a lesser-known nutritional problem: folate deficiency.
Folate, or vitamin B9, plays a vital role in the body, supporting DNA production and repair while helping create red blood cells needed to deliver oxygen to key organs.
The nutrient is also involved in breaking down homocysteine, an amino acid found in the bloodstream that, when levels climb too high, has been linked to an increased risk of blood clots and heart attacks.
Because the body cannot make folate itself, it must come from the diet, including foods such as dark leafy greens and Brussels sprouts. Fortified cereals and dietary supplements provide folic acid, the synthetic form of vitamin B9.
Folate and folic acid are especially crucial for pregnant women, as the nutrient builds the baby’s neural tube that eventually grows into the brain and spinal cord.
While estimates suggest that true folate deficiency is rare, one in five Americans doesn’t get enough, including men, non-pregnant women and older adults.
Experts told the Daily Mail that folate deficiency can lead to fatigue, brain fog and shortness of breath
Experts told the Daily Mail that insufficient levels of folate prevent the body from making red blood cells, leading to the blood disorder megaloblastic anemia, which causes extreme fatigue, shortness of breath, numbness in the hands and feet and sores around the mouth.
It’s also crucial for sperm production in men, and a deficiency may potentially raise the risk of fertility problems.
‘The human body requires folates for DNA synthesis, cell division and healthy red blood cell production,’ Dr Robert Thompson, family medicine physician and medical contributor at Care Point Boston, told the Daily Mail.
‘Therefore, it is important to consume folate throughout one’s life and not just during pregnancy.’
Natural folate is found in dark leafy greens such as spinach and kale, beans, peas, nuts and citrus fruits like oranges.
Folic acid, meanwhile, is a synthetic form of folate added to fortified foods such as bread and cereal.
It’s also a major component of prenatal vitamins meant for women who are pregnant or trying to conceive.
‘The intake of folic acid has a unique place due to its importance at an extremely early stage of embryonic growth,’ Dr Thompson said.
‘Taking sufficient folic acid before you are pregnant or during your first trimester will greatly reduce the chance of your fetus developing a neural tube defect.’
Neural tube defects include spina bifida and anencephaly, a fatal condition in the womb that occurs when parts of the brain, skull and scalp fail to properly develop.
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The American Academy of Pediatrics recommends women of childbearing age take a prenatal containing 400 to 800 micrograms (mcg) of folic acid per day.
Folate is especially crucial in pregnancy, as it can prevent neural tube defects in the fetus such as spina bifida
Outside of pregnancy, folate is a vitamin 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 rely on folate. These include red blood cells, cells lining your digestive tract, and white blood cells,’ he said.
‘It also works in concert with another B vitamin, B12, helping to lower blood levels of the amino acid homocysteine by converting it to another amino acid, methionine.’
Methionine serves as a building block for creating proteins and further converts into antioxidants that fight inflammation.
Chao explains that folate is necessary ‘for optimal sperm production’, as it protects sperm cells from suffering DNA damage and allows them to repair themselves.
Low levels of folate raise the risk of sperm cell DNA becoming fragmented, reducing the sperm’s quality and movement.
Women with heavy periods may also benefit from folate because it supports red blood cell production that can combat anemia caused by menstrual blood loss.
Chao also notes that folate ‘deserves focus in older adults’ because they ‘absorb it less well’ naturally due to ageing and lower food intake.
Folate can be found in leafy greens and citrus fruits, as well as fortified breads and cereals
Alcohol can also interfere with folate absorption by damaging cells lining the digestive tract and inhibiting the expression of proteins needed to transport folate past the intestinal wall. Chronic alcohol use also makes the liver less able to store circulating folate.
Federal health authorities recommend men, older adults and adult women who are not pregnant or trying to conceive consume 400 mcg of folate each day. While most groups can reach that level through food sources, older adults or those with alcohol use disorder may benefit from additional supplementation, Chao notes.
‘Signs and symptoms of folate deficiency depend on the stage of deficiency but can include fatigue, headache, shortness of breath, irritability and poor appetite,’ he said.
‘Brain fog, forgetfulness and confusion can occur. These symptoms are commonly missed and treated as normal age-related decline in cognition.’
Folate deficiency may also impair brain health in the long term. One 2022 study in the European Journal for Clinical Nutrition found that low folate was associated with faster cognitive function decline in older adults.
Other red flag signs that may warrant a folate supplement or increased dietary sources include a red, swollen or painful tongue, mouth ulcers, heart palpitations and shortness of breath.
Despite folate’s benefits, it is possible to get too much of a good thing. Health authorities recommend adults get no more than 1,000 mcg each day, as high doses may cause nausea, cramps and diarrhea.