Is it possible to take an overdose of vitamin b12 during pregnancy?
Pregnancy is one of the most exciting (and scary!) times of any woman’s life. There’s so much to plan and prepare for: the nursery, the stacks of diapers, the right stroller, a name…
But there’s one thing that’s much more important than all the baby paraphernalia: your health.
Whether you’re pregnant or just planning to start a family, one of your first priorities should be to make sure you’re getting adequate vitamin B12. Many people have no idea just how important this one vitamin is - especially for moms-to-be.
Unfortunately, there’s a lot of conflicting information out there about the so-called possibility of taking an overdose of B12 during pregnancy. In reality, the risk of a B12 deficiency is both far more prevalent - and dangerous.
What is vitamin B12?
There are eight B vitamins (known as the B complex) and every one of them has an important role in our daily function. The complex includes thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9) and cobalamin (B12).
Together, these vitamins help your body break down glucose (blood sugar) and create energy in the form of ATP molecules. ATP is like the ‘fuel’ that powers the tiny engines within every one of your body’s cells.
So, why is B12 so important?
Like the other B vitamins, B12 is also required for energy production and mental alertness. It’s responsible for the body’s metabolism of fats and carbohydrates, and is often promoted for boosting athletic performance and endurance. It plays a major role in maintaining the health of the nerves and blood cells. It’s absolutely crucial for the making of DNA and RNA, the genetic material in all cells.
B12 is also the only B vitamin synthesized by bacteria rather than by plants. To absorb B12, your gut must produce a substance called intrinsic factor, a glycoprotein made by the parietal cells of the gastric mucosa. During digestion, the hydrochloric acid in your stomach releases B12 from protein, where it then combines with intrinsic factor.
This rather complex metabolic pathway means two things: first, if your body lacks intrinsic factor, you will not be able to absorb B12 properly. This can result in a B12 deficiency.
Second, the only way to ensure proper uptake is by taking the most bioactive form of the vitamin. Bioactive simply means that the B12 has already been converted into a form that can be absorbed and used by the body’s cells immediately. Supplementary B12 should require minimal breakdown in order to be effective.
Why do women need B12 during pregnancy?
Vitamin B12 is crucial for normal cell division and differentiation, as well as the development and myelination of the central nervous system. Numerous studies have linked low vitamin B12 status in infancy to poor growth and neurodevelopment, plus many other health risks.
These are some of the many reasons B12 supplementation during pregnancy is so important...
- Taking B12 helps prevent deficiency
Research suggests that B12-deficiency is highly prevalent among pregnant women, affecting three-quarters of pregnancies in some populations. This is very concerning because B12 deficiency has been associated with both lower birth weight (<2,500 g) and preterm birth (length of gestation <37 weeks).
- B12 is required for brain development
- Brain development starts from conception, and a baby’s brain undergoes rapid growth while in the womb.This is also the period when most of the myelination of the brain occurs. Even moderate vitamin B12 deficiency has been associated with demyelination
- and brain atrophy. Numerous case studies have shown the harmful effects of severe vitamin B12 deficiency on the developing infant brain, such as decreased cognitive performance.
- B12 helps prevent neural tube defects
Children born to mothers who have low blood levels of vitamin B12 both before and after conception may have an increased risk of a neural tube defect. Neural tube defects affect the brain and spinal cord. They include conditions such as spina bifida (which can result in partial paralysis) and anencephaly, in which the brain and skull are severely underdeveloped. One study showed that women with the lowest B12 levels were five times more likely to have a child with a neural tube defect.
- B12 reduces homocysteine
Homocysteine is an amino acid that has been implicated in the risk of complications involving the placenta, such as preeclampsia, placental abruption, fetal growth restriction, and miscarriage. High serum levels of homocysteine and low serum levels of B12 have been associated with reduced cognitive function.
B12 works alongside folate and vitamin B6 to maintain normal concentrations of homocysteine in the bloodstream. Supplementation of B12 or folic acid helps to reduce homocysteine and may help in increasing birth weight and length of gestation.
- B12 supports healthy mood during pregnancy
Sufficient vitamin B12 is required for methylation, which in turn is necessary for the production of serotonin as well as other monoamine neurotransmitters and catecholamines.
How much B12 should I take during pregnancy?
The National Institute of Health recommends that women who are pregnant or breastfeeding take at least 2.8 micrograms (mcg) of B12 per day. However, studies have shown that high doses of oral B12 supplements (up to 2 mg or 2,000 mcg) are safe and effective, especially when treating B12 deficiency.
This is because your body will only absorb as much B12 as it needs. Any excess will be flushed out in your urine.
In any case, it’s always important to speak with your doctor before taking additional B12 during pregnancy.
It is possible to take an overdose of vitamin B12 during pregnancy?
There is no upper limit on B12 because of its “low potential for toxicity”. As mentioned above, any excess will be flushed out. Very small amounts are stored in body tissues and most vitamins - including B12 - don’t have an upper-level limit.
This amount of B12 you absorb depends on a number of factors:
- the form of the B12
- the efficacy of your genetic enzymes, and
- the production of intrinsic factor in your stomach
So, what type of B12 should I take during pregnancy?
- A B12 supplement should be sublingually absorbed via the mucous membranes in the mouth. Look for B12 spray or tablets that are placed under the tongue and allowed to dissolve.
- B12’s complex metabolic pathway means that the only way to ensure proper uptake is by taking the most bioactive form of the vitamin. Bioactive simply means that the B12 has already been converted into a form that can be absorbed and used by the body’s cells immediately.
Most B12 supplements are available in two primary forms: methylcobalamin or cyanocobalamin. The less well-known types of B12 include Hydroxocobalamin and Adenosylcobalamin.