Pregnancy and Thiamine (Vitamin B1) Deficiency

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Here on The Pulse, we have discussed a lot about vitamin D and about vitamins overall during pregnancy, but not so much about thiamine (thiamin) deficiency, also called vitamin B1, and about deficiency of this vitamin, so let’s make thiamine deficiency our topic for today. Thiamine deficient can develop for several reasons, including alcoholism (this is fairly common) and a lack of thiamine in the diet. There also are important connections between thiamine deficiency and diabetes, because of the role that thiamine plays in the metabolism of sugars. During pregnancy, your need for thiamine increases, and thiamine deficiency can develop as a complication of hyperemesis gravidarum (HG), a condition that features severe nausea and vomiting, with weight loss and liver problems.

Other than in alcoholics, thiamine deficiency is rare in the developed world, but the simple lack of thiamine in the diet has been associated with certain diets, especially those dominated by polished rice in various developing countries. However, thiamine deficiency is possible in those in developed countries who follow the popular “gluten-free” diet, which avoids whole grains (a good source of thiamine) yet is appropriate, only for those who suffer from celiac disease, but not for everybody else. Other factors that put you at risk for thiamine deficiency include HIV/AIDS, bariatric surgery, diuretic medication (medication to increase water excretion through he kidneys). Diabetes type 2, which is characterized by a reduced ability of the body to respond to insulin entails an increased need for thiamine, so it is both a cause of thiamine deficiency and a condition that thiamine deficiency can exacerbate.

Mild thiamine deficiency is very difficult to diagnose, because symptoms are mild and not specific to the condition. Consequently, the index of suspicion for thiamine deficiency tends to be very low for non-alcoholics, so doctors have no reason to order tests, such as for levels of thiamine in the blood and urine. As the deficiency worsens, however, various symptoms develop that collectively are characteristic of a disease called beriberi, which is characterized by various symptoms involving both the nervous system and the cardiovascular system. Additionally, various metabolic abnormalities often emerge, including lactic acidosis. The combination of effects provides a hint of possible thiamine deficiency, leading to tests for thiamine levels in blood and urine samples. Most importantly, thiamine deficiency can be assessed by measuring the activity of an enzyme called erythrocyte transketolase (EKTA), which requires thiamine to function, and which is vital to connecting biochemical pathway that break down glucose (blood sugar) to release energy with pathways that build up various biochemical compounds from glucose. Thus, if EKTA activity is low, this supports a diagnosis of thiamine deficiency.

Symptoms of beriberi include tingling (paresthesia) and loss of sensation (anesthesia) in the hands and feet, breathing difficulty, vomiting, and cardiovascular problems that may include a rapid heartbeat and collection of fluid throughout the body (edema). Ultimately, the cardiovascular effects (known classically as “wet beriberi”) can lead to heart failure, and the nervous system effects (“dry beriberi”) can reach the point of two very severe complications. One such complication is called Wernicke encephalopathy (WE). Typically triggered by the administration of intravenous fluids with glucose (sugar), WE is characterized by three neurological abnormalities, all of which occur in most cases: One is weakness of the muscles that move the eyes (ophthalmoparesis) with rapid, repetitive movement of the eyes back and forth (nystagmus). Another abnormality is lack of full control of voluntary muscles and coordinated body movements (ataxia) and the third abnormality is confusion. The other neurological complication is Korsakoff syndrome, which is a psychotic disorder that begins with memory loss, followed by what is called confabulation, in which the person unwittingly invents information to fill in the memory gaps. The combination of WE and Korsakoff syndrome is known as Wernicke-Korsakoff syndrome (WKS).

As for the baby, thiamine deficiency increases the risk of bad outcomes of pregnancy, including spontaneous abortion (miscarriage), fetal death, and stillbirth. However, thiamine deficiency is easily treated with 50-100 mg of thiamine administered intravenously (IV) and then smaller amounts (such as 10 mg) injected daily intramuscularly (IM) for a week. Thiamine therapy must begin before the woman is given any glucose (dextrose). Otherwise, there is great danger that the glucose can trigger the development of WE.

As in the case of pregnancy, breastfeeding increases your need for thiamine, due to the thiamine needs of the baby. Rather being a risk for a nursing baby, thiamine supplementation is vital to assure that your milk supplies the baby with adequate thiamine. If your doctor determines that your thiamine status is not good, then you may need to feed your infant with formula.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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