B12 while pregnant

Vitamin B12 metabolism and status during pregnancy, lactation and infancy

Review

. 1994;352:173-86.

doi: 10.1007/978-1-4899-2575-6_14.

L H Allen¹

Affiliations

Affiliation

¹ Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017.

PMID: 7832046
DOI: 10.1007/978-1-4899-2575-6_14

Review

L H Allen. Adv Exp Med Biol. 1994.

. 1994;352:173-86.

doi: 10.1007/978-1-4899-2575-6_14.

Author

L H Allen¹

Affiliation

¹ Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017.

PMID: 7832046
DOI: 10.1007/978-1-4899-2575-6_14

Abstract

This overview of vitamin B12 metabolism and requirements during the continuum of pregnancy and lactation has identified several gaps in our knowledge. More information is needed concerning the roles of the different transcobalamins during pregnancy and lactation, including their impact on placental and mammary transfer of cobalamin and their effect on intestinal absorption in the infant. Knowledge is needed about the relative importance of maternal stores and current dietary intake on fetal storage of the vitamin, and on its concentration in breast milk. Because there is some evidence that infant's urinary methylmalonic acid excretion is reduced by intakes slightly higher than the current RDA, the adequacy of the current RDA for vitamin B12 during infancy should be verified. Finally, it is possible that vitamin B12 deficiency is more common in pregnant and lactating women and their young children in developing countries than has been recognized previously, due primarily to malabsorption. It is important to confirm whether or not this is the case, in view of its potential impact on infant neurobehavioral development and the relative ease with which supplements of the vitamin could be provided.

PIP: Vitamin B12 metabolism and requirements during pregnancy and lactation are reviewed. Pregnant women who have been strict vegetarians for only a few years, and even those who consume low amounts of animal products, are more likely to become vitamin B12 deficient during pregnancy and lactation, to give birth to an infant who develops clinical or biochemical signs of B12 deficiency, and/or to have low levels of this vitamin in their breast milk. Populations that consume large amounts of animal products ingest 3-32 mcg/day, compared to 0-0.25 mcg/day for strict vegetarians. Changes in B12 metabolism during pregnancy affect intestinal absorption, changes in plasma concentrations, and placental transport. The recommended dietary allowance (RDA) during pregnancy is an increase from 2.0 mcg/day to 2.2 mcg/day to cover fetal storage. The World Health Organization (WHO) advises an increase of 0.4 mcg/day to a total of 1.4 mcg/day. Vitamin B12 metabolism during lactation involves the mechanism of secretion and forms in milk. For lactating women the WHO recommends that intake be increased by 0.3 mcg/day to a total of 1.3 mcg/day, while the RDA is increased from 2.0 to 2.6 mcg/day. There is some evidence that the infant's urinary methylmalonic acid excretion is reduced by intakes slightly higher than the current RDA, therefore the adequacy of the current RDA for vitamin B12 during infancy should be verified. More information is needed concerning the roles of the different transcobalamins during pregnancy and lactation, including their impact on placental and mammary transfer of cobalamin and their effect on intestinal absorption in the infant. Knowledge is also needed about the relative importance of maternal stores and current dietary intake on fetal storage of the vitamin, and on its concentration in breast milk. It is possible that vitamin B12 deficiency is more common in pregnant and lactating women and their young children in developing countries than has been recognized previously, primarily because of malabsorption.

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Vitamin B12 during pregnancy | BabyCenter

Vitamin B12 during pregnancy is essential for your baby's developing brain and spinal cord. It also helps make healthy red blood cells and DNA. Vitamin B12 is only found naturally in animal foods (fish, meat, poultry, eggs, and dairy) and fortified plant foods. If your prenatal vitamin doesn't include vitamin B12, and you're vegetarian or vegan, check with your doctor or midwife about taking a supplement.

Photo credit: iStock /mphillips007

Why you need vitamin B12 during pregnancy

Vitamin B12 is essential for the development and function of your baby's brain and spinal cord, and for forming healthy red blood cells. Vitamin B12 also helps make DNA, the genetic material in all your baby's cells.

Some studies suggest that babies born to women with low levels of vitamin B12 during pregnancy may have an increased risk of neural tube defects.

How much vitamin B12 do pregnant women need?

When you're pregnant or breastfeeding, you need slightly more vitamin B12 than usual.

Pregnant women: 2.6 micrograms (mcg) per day

Breastfeeding women: 2.8 mcg per day

Nonpregnant women: 2.4 mcg per day

Best foods with vitamin B12 during pregnancy

Vitamin B12 is only naturally found in animal foods (fish, meat, poultry, eggs, and dairy products). Plant foods don't have vitamin B12 unless they're fortified. If you're looking for foods fortified with B12, breakfast cereals as well as some soy and other plant milks are good bets. Check labels to be sure.

Here are some good food sources of vitamin B12:

3 ounces Atlantic salmon, cooked: 2. 6 mcg
3 ounces ground beef, 85-percent lean, pan browned: 2.4 mcg
8 ounces 2-percent milk: 1.3 mcg
6 ounces plain, fat-free yogurt: 1.0 mcg
1 serving breakfast cereal fortified with 25 percent of the daily value for vitamin B12: 0.6 mcg
1 1/2 ounces cheddar cheese: 0.5 mcg
1 large egg, cooked: 0.5 mcg
3 ounces turkey breast meat, roasted: 0.3 mcg

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(Note that a 3-ounce serving of meat or fish is about the size of a deck of cards.)

Do you need a vitamin B12 supplement during pregnancy?

You may need a vitamin B12 supplement if you're a vegan or vegetarian during pregnancy, you don't eat B12-fortified foods every day, and your prenatal vitamin doesn't include B12. Check with your doctor or midwife to make sure you're getting enough vitamin B12 from your pregnancy diet or prenatal vitamin.

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Eva Dasher

Eva Dasher writes, researches, and edits content on a wide variety of subjects, including parenting, medicine, travel, natural history, science, business, and the arts. Her favorite pastimes include experimenting with new foods, libations, and restaurants, as well as traveling the world with her two college-age children, husband, extended family, and friends.

Vitamin B12 deficiency during pregnancy as a consequence of the development of type 2 diabetes in babies

August 27, 2018

According to a study presented at the annual meeting of the Society of Endocrinologists in Brighton, vitamin B12 deficiency during pregnancy can cause a child to develop type 2 diabetes.

As you know, vitamin B12 (cyanocobalamin) is found in animal products, including fish, meat, poultry, eggs and milk. Accordingly, the risk groups are starving people and vegetarians. Also, mothers with low levels of cyanocobalamin had a low body mass index (BMI) and a chance of having an underweight baby with high cholesterol. In addition to the above, high insulin resistance was observed in newborns, which is one of the risk factors for developing type 2 diabetes.

A study conducted at the University of Warwick School of Medicine (Coventry, UK) showed that changes associated with vitamin B12 deficiency may be the result of abnormal levels of the hormone leptin. Leptin is synthesized by fat cells of the body and is actively involved in energy metabolism and the regulation of hunger. Obesity is directly related to a violation of the metabolism of this hormone. It is believed that in this case, the standard mechanism of dependence of hunger on the level of leptin fails. The brain simply does not notice this hormone and the mechanism of "sharp starvation" is activated. So high levels of leptin in obesity and increased insulin resistance in combination lead to the development of type 2 diabetes.

Researcher Ponnusami Saravanan says that the processes occurring in the mother's body affect the health of the child. Children whose mothers suffered from vitamin B12 deficiency had elevated levels of leptin, which contributed to an increased risk of developing type 2 diabetes.

But how exactly is an increase in leptin concentration associated with the development of type 2 diabetes? There are two scenarios. The essence of the first mechanism is an increase in the level of leptin, due to a low concentration of cyanocobalamin and the subsequent accumulation of fat cells in the fetus. The second mechanism is the rearrangement of placental genes responsible for leptin production caused by low levels of B12. Since cyanocobalamin is involved in methylation reactions, the second option associated with the inclusion and exclusion of genes is most likely.

Expert opinion: is the first study to report a possible association between maternal vitamin B12 deficiency during pregnancy and increased leptin levels in infants. Thus, we can say that the determination of cyanocobalamin plays an important role in the diagnosis of lipid metabolism in children. In addition, risk groups have been identified that require closer attention from the doctor and the appointment of vitamin B12 in accordance with the individual needs of the body.

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Vitamin B12 deficiency in a pregnant woman can lead to the development of metabolic disorders in the fetus

At the UK Society for Endocrinology Annual Conference, held in Brighton, scientists from the University of Warwick, United Kingdom, presented the results of their new study, according to which vitamin B deficiency ₁₂ in a woman during pregnancy can be a factor predisposing to the development of metabolic problems in her unborn child. In particular, they determined that such children have an increased level of leptin, and suggested that the lack of cyanocobalamin in the prenatal period adversely affects the expression of the gene that regulates the synthesis of this hormone.

The main source of vitamin B ₁₂ for humans is food of animal origin - fish, meat, eggs and milk. Therefore, the development of a deficiency of this vitamin is more likely in people who follow a vegetarian diet. Previously, scientists assumed a relationship between cyanocobalamin and the development of metabolic disorders, but no unequivocal evidence was obtained. Thus, the researchers noticed that vitamin B deficiency ₁₂, determined in a pregnant woman at the 28th week of gestation, is associated with the development of insulin resistance in her unborn child. In addition, a low level of this vitamin in combination with a high body mass index (BMI) has often been associated with the birth of a child with low birth weight and / or with high cholesterol levels. Cases of gestational diabetes mellitus in women with a lack of vitamin B ₁₂ were registered 2 times more often than in pregnant women without this deficient condition.

In this study, scientists led by Dr. Ponusammy Saravanan found that about 12% of women of childbearing age in the UK are deficient in vitamin B ₁₂ . Among pregnant women, the prevalence of pathology is 20–30%. The researchers suggested that the level of cyanocobalamin in the expectant mother determines the availability of this vitamin to the fetus, so they evaluated the relationship between the level of vitamin B ₁₂ and leptin in the adipose tissue of a pregnant woman, in the tissues of the placenta and in cord blood. 91 mother-child couples took part in the work. Delivery in all cases was operative. In all couples, samples of cord and venous blood and maternal adipose tissue were taken. In addition, placenta samples were obtained in 83 cases.

After analyzing the obtained samples, the authors of the work came to the conclusion that vitamin B deficiency ₁₂ is an extremely common pathology. It occurs in 39.6% of women and 29% of children. BMI varied among women, but at vitamin B levels ₁₂ <191 ng/l, it averaged 30 kg/m ² , while at the content of this vitamin >191 ng/l, BMI averaged 28, 4 kg/m ² (p<0.05). In addition, the concentration of cyanocobalamin in the blood <191 ng/l was associated with a significant increase in the level of triglycerides and low density lipoproteins.

In the course of the work, scientists assessed the level of leptin in children. Leptin is a peptide hormone that determines the feeling of satiety after eating. Its high level is usually noted in overweight patients, which can ultimately lead to the development of leptin resistance, uncontrolled overeating, an increased risk of developing insulin resistance and type 2 diabetes mellitus.

Researchers have found that children born to women with vitamin B deficiency ₁₂ have higher levels of this hormone than their peers whose mothers were not diagnosed with vitamin B deficiency. The relationship between the level of leptin in the mother and its concentration in cord blood has not been recorded. Initially, these results seemed unexpected to the researchers, but then they came to the conclusion that leptin cannot penetrate the hematoplacental barrier. They suggested that vitamin B 9 deficiency0052 12 in a pregnant woman can negatively affect the leptin gene, changing the level of the hormone as the fetus grows. After the final evaluation of the results, the authors of the study concluded that the level of vitamin B ₁₂ in a pregnant woman is independently associated with leptin levels in her unborn child. In addition, the expression of the gene that controls leptin metabolism was higher in the adipose and placental tissues of women with low levels of cyanocobalamin.

The long-term impact of the identified disorders on children's health is currently unknown. However, scientists once again proved the importance of a rational and balanced diet for a pregnant woman for the normal development of an unborn child.