Vitamin B6 (Pyridoxine) - General
For healthy, uncomplicated pregnancies, the required amount of vitamin B6 during pregnancy can be obtained through a varied diet/prenatal vitamins.
However, vitamin B6 is often prescribed during pregnancy for women suffering with mild to severe nausea and vomiting of pregnancy. More information regarding vitamin B6 for nausea/vomiting is located here.
Vitamin B6 may also be recommended for women who are diagnosed with anemia and in which iron supplementation is either causing distressing side effects or is ineffective at raising hemoglobin levels.
Women should not take vitamin B6 supplements for NVP, anemia, or any other condition without talking to their health care provider (HCP) first, as it can be very easy to take too much of the vitamin, which could cause unwanted (neurological) side effects.
Background
Vitamin B6 (pyridoxine) is an essential water-soluble vitamin that:
Is important for the development and functioning of the nervous system
Makes antibodies needed to fight disease
Keeps blood sugar (glucose) in normal ranges
Breaks down proteins (the more protein eaten, the more vitamin B6 is required for digestion)
Is often prescribed for the treatment of nausea and vomiting of pregnancy
Makes hemoglobin, which transports oxygen in the blood (B6 has been linked to the prevention of anemia during pregnancy)
May reduce the risk of preeclampsia, preterm birth, and birth defects
A healthy and varied diet will provide most individuals with enough B6; deficiency is not common in the United States, but may occur in combination with deficiencies of other B vitamins (such as folic acid).
However, in cases of malabsorption/gastrointestinal disorders (i.e. celiac disease), kidney diseases, and alcohol use, which all impair the body’s ability to absorb B6, supplements are generally required.
Although uncommon, deficiency symptoms include irritability, depression, confusion, peripheral nerve damage (arms and legs/hands and feet), seizures, and anemia.
Pregnancy and Deficiency
In normal pregnancies, a slow, gradual B6 deficiency occurs; however, there is very little information regarding B6's role in pregnancy and fetal development.
It assessed that B6 may play a role in the development of the fetal central nervous system, especially neurotransmitters, but the amount of B6 required for proper fetal development is not known. While some researchers assess that pregnancy may require more B6 than what is currently recommended, research remains inconsistent.
Therefore, the daily requirement for pregnant women is set at 1.9 milligrams, slightly above the recommendation for non-pregnant women of 1.3 mg (accounts for extra weight and fetus/placenta intake of B6).
No increased risk of miscarriage, birth defects, or other neonatal complications have been identified following a fetus’ vitamin B6 exposure; it is currently assessed that doses less than 500 mg/day are unlikely to harm a developing baby.
However, doses above 500 mg (likely for months) can cause potential harm in adults; it is recommended that women remain under the upper tolerable limit of 100 mg while pregnant (supplements only). High intake of B6 through food is not harmful and has never been reported.
Women with moderate to severe nausea and vomiting of pregnancy are usually given a recommendation or prescription of 25 to 75 mg/day, as a possible "treatment" for symptoms. Although this can get some women very close to the 100 mg upper limit, there is also no evidence of harm/nerve damage at doses below 200 mg/day (read Vitamin B6 for NVP).
Symptoms of potential toxicity likely develop at doses in excess of 500 to 1,000 mg/day over a period of months. Too much B6 can cause:
Numbness and difficulty walking (which may be irreversible depending on dose and length of exposure)
A lack of muscle control or coordination of voluntary movements
Painful skin lesions, heartburn and nausea, sensitivity to sunlight, and reduced ability to sense pain or extreme temperatures
Anemia
It is recommended that when HCPs suspect anemia in a pregnant woman, that B6 status should be considered as well as iron, as B6 also assists in the production of hemoglobin. Vitamin B6 deficiency is thought to be a common cause of anemia in pregnancy, with or without a deficiency of iron, and can be taken in place of iron in some instances.
In at least one study, women with anemia who did not respond to iron supplementation had B6 deficiency, and when given B6 supplements, their anemia improved.
It is unclear if B6 supplementation would have any improvement on hemoglobin levels in women diagnosed with anemia, but not with a B6 deficiency.
Food Sources
The best sources of vitamin B6 include meats, poultry, fish, potatoes, non-citrus fruits, legumes (peas and beans), bananas, nuts, whole grains, and fortified cereals.
B6 is present in a variety of foods but may be destroyed in whole or part by heating (cooking, boiling, microwaving, steaming). However, cooking is necessary for food sources such as chicken and meat. Women should vary their diet to also include raw food sources of B6.
Action
Women who are concerned about their nutrition during their pregnancy need to talk to their HCP, especially if suffering from mild to severe nausea and vomiting of pregnancy. Further, speaking with an HCP about their overall nutrition can help HCPs assess women's diets for possible improvement during pregnancy.
Resources
Vitamin B6 Fact Sheet (U.S. National Institutes of Health)