Pregnancy vitamins are often talked about in terms of supporting your baby’s development. But when you’re dealing with Pregnancy Sickness, the conversation changes.
In the first trimester, many women aren’t worrying about “perfect nutrition” - they’re simply trying to get through the day without vomiting, tolerate a few bites of food, or keep fluids down.
That’s where Vitamin B1 (also called thiamine) becomes especially important.
Vitamin B1 is one of the key nutrients healthcare professionals often discuss alongside severe nausea and vomiting in pregnancy because prolonged sickness can make it difficult to get enough from food alone.
In this article, we’ll explain:
- what Vitamin B1 does
- why it matters during Pregnancy Sickness
- why deficiency can happen more easily during prolonged vomiting
- how supplementation may help support recovery
- why tolerability matters during the first trimester
What is Vitamin B1?
Vitamin B1, also known as thiamine, is a water-soluble vitamin that helps the body:
- turn food into energy
- support normal brain and nervous system function
- maintain healthy muscle and nerve communication
Unlike some nutrients, the body cannot store large amounts of Vitamin B1 for long periods. That means regular intake is important.
Most people get enough thiamine through food, including:
- wholegrains
- fortified cereals
- meat and fish
- legumes
- nuts and seeds
But Pregnancy Sickness can make eating these foods consistently extremely difficult.
Why is Vitamin B1 important during Pregnancy Sickness?
If you are experiencing ongoing nausea and vomiting in pregnancy, you may:
- struggle to eat enough
- vomit frequently
- tolerate only very limited foods
- avoid tablets because they make you gag
Over time, this can reduce Vitamin B1 intake and make stores run low.
This is why healthcare professionals often recommend thiamine supplementation for women experiencing severe or prolonged Pregnancy Sickness.
The concern is not about one bad day of sickness. It’s about sustained vomiting and poor intake over time.
Can low Vitamin B1 levels become serious?
In severe cases, prolonged thiamine deficiency can lead to neurological complications, including Wernicke encephalopathy.
This condition is rare, but it’s one of the reasons Vitamin B1 is discussed so frequently in relation to Hyperemesis Gravidarum and severe Pregnancy Sickness.
The important thing to know is:
- awareness matters
- early supplementation is often recommended
- healthcare teams are familiar with monitoring for this risk
The goal of discussing Vitamin B1 isn’t to frighten women - it’s to highlight the importance of nutritional support during prolonged sickness.
Why are supplements hard to tolerate during pregnancy sickness?
One of the biggest challenges in the first trimester is that many standard pregnancy vitamins can feel impossible to take.
You may find that you struggle with:
- large tablets
- strong smells or tastes
- swallowing capsules
- drinking large volumes of liquid
- supplements that worsen nausea
This creates a difficult cycle:
- sickness makes eating harder
- poor intake can worsen weakness and depletion
- supplements themselves may trigger more nausea
That’s why tolerability matters so much when designing nutritional support for Pregnancy Sickness.
Should you supplement Vitamin B1 during Pregnancy Sickness?
Many healthcare professionals recommend thiamine supplementation for women experiencing prolonged vomiting or poor nutritional intake during pregnancy.
You should always speak to your midwife, GP or healthcare team for individual advice, especially if:
- you are struggling to keep food down
- vomiting is persistent
- you are losing weight
- you feel weak or dehydrated
- you cannot tolerate standard pregnancy vitamins
Early support can make a significant difference.
Why this conversation matters
Too often, pregnancy nutrition advice assumes women can tolerate:
- large tablets
- balanced meals
- regular eating patterns
- multiple supplements every day
But Pregnancy Sickness changes the reality of what feels manageable.
For many women, the first trimester is less about “optimising wellness” and more about finding forms of nutrition and supplementation they can realistically tolerate.
That’s why conversations around Vitamin B1, electrolytes and gentle nutritional support matter so much in Pregnancy Sickness care.
My Final thoughts
Pregnancy Sickness is often treated as something women simply have to “push through”, but prolonged nausea and vomiting can have real nutritional consequences.
Vitamin B1 is talked about so frequently because it plays an important role during periods of poor intake and prolonged vomiting - and because early nutritional support matters.
For women experiencing Pregnancy Sickness, the challenge is not simply knowing what nutrients are important. It’s finding ways to tolerate them during one of the hardest stages of pregnancy.
I hope these articles are helping you find a way to take control and feel more informed about your Pregnancy Sickness, however severe it is for you,
Laura x
If you're like me and you love to geek out on information, head to our page "The Science Bit" to learn even more about some of the ingredients in Replenish.
Frequently Asked Questions About Vitamin B1 and Pregnancy Sickness
Is Vitamin B1 the same as thiamine?
Yes. Vitamin B1 and thiamine are two names for the same vitamin.
Why is thiamine talked about in Hyperemesis Gravidarum?
Because prolonged vomiting and poor intake can increase the risk of deficiency over time.
Can Pregnancy Sickness cause vitamin deficiencies?
It can make it more difficult to maintain adequate nutrition, particularly when food and supplements are hard to tolerate.
Should everyone with morning sickness take Vitamin B1?
Not necessarily. Supplementation advice depends on symptom severity and individual circumstances, so it’s important to speak with a healthcare professional.
Why are pregnancy vitamins so hard to tolerate in the first trimester?
Nausea, vomiting, heightened taste and smell sensitivity, and gag reflex changes can all make tablets and supplements feel overwhelming during Pregnancy Sickness.
