# Thiamine (B1) in the first trimester

Source: https://www.pregnancypowerhour.com/nutrition/thiamine-b1-trimester-1
Last updated: 2026-07-01

> In the first trimester, Thiamine (B1) is vital for energy, and its role becomes especially critical for those experiencing hyperemesis gravidarum.

For those navigating the initial weeks of pregnancy, understanding the role of Thiamine (B1) in the first trimester is particularly important, especially when severe nausea and vomiting are present. Thiamine, a B vitamin, is critical for your body's energy metabolism. It helps convert the food you eat into usable energy, a process that is working overtime as your body begins the incredible work of growing a new life. Unlike some other nutrients, your body cannot store much thiamine, which means a consistent daily intake is important.

During the first trimester, some individuals experience significant nausea and vomiting, sometimes severe enough to be diagnosed as hyperemesis gravidarum (HG). In these situations, maintaining adequate nutrient intake can be challenging. When vomiting is prolonged and severe, there's a heightened risk of thiamine deficiency, which can, in rare cases, lead to a serious neurological condition called Wernicke encephalopathy. This is why care providers pay close attention to thiamine levels in those with persistent HG, often recommending supplementation.

While supplementation might be discussed with your provider, a food-first approach is always a wonderful foundation. Incorporating thiamine-rich foods into your daily diet is a practical step to support your well-being. Good sources include whole grains, such as brown rice or oats, lean pork, various legumes like black beans and lentils, and sunflower seeds. Fortified cereals can also contribute to your daily intake. Focusing on these foods can help ensure you're meeting the recommended daily allowance for pregnancy, which is 1.4 mg/day, as established by the Institute of Medicine (IOM).

When severe vomiting makes eating difficult, your care provider might consider strategies to ensure adequate thiamine, particularly in a hospital setting. For instance, intravenous (IV) thiamine is often given before glucose in patients with HG to prevent precipitating Wernicke encephalopathy. This highlights how crucial this nutrient is when the body is under stress. As you continue to explore your nutritional needs, you might also find it helpful to consider other essential nutrients like [Choline in the first trimester](/nutrition/choline-trimester-1), which supports fetal brain development, or [DHA — Omega-3 in the first trimester](/nutrition/dha-omega-3-trimester-1) for early neurological growth. Your provider is your best resource for your specific situation and can offer personalized guidance.

Navigating early pregnancy can bring many questions about how best to support your body and your baby. Focusing on foundational nutrients like Thiamine (B1) is one way to feel more calm, clear, and confident. As your pregnancy progresses, your nutritional needs may shift, and understanding these changes, much like exploring [Choline in the second trimester](/nutrition/choline-trimester-2), will continue to be a collaborative conversation with your care team. Remember, you get to decide what feels right for your body and your baby, always in conversation with your trusted medical professionals.