B1 Supplement Guide
Evidence-based information on B1 benefits, dosage, safety, and food sources — sourced from NIH, FDA, and PubMed.
Our assessment
The evidence shows that B1 (thiamin) is a well-tolerated vitamin with a clear role in energy production. Our assessment: for most people, getting enough B1 through diet or a standard supplement is safe and supports basic cellular function. However, the data does not support using high-dose B1 supplements for boosting energy or treating specific conditions unless you have a known deficiency NIH ODS ↗.
How it works
Think of B1 as a key that unlocks energy inside your cells. It works by enhancing mitochondrial efficiency and biogenesis, which means it helps the power plants of your cells run more smoothly. B1 also supports cellular ATP synthesis and mitochondrial energy output, providing the fuel your body needs for daily activities NIH ODS ↗.
Safety profile
Thiamin has not been shown to cause any harm NIH ODS ↗. Data on specific side effects from FDA reports is not available. However, you should be aware that some medicines can lower thiamin levels in your body. Examples include furosemide (Lasix), which is used to treat high blood pressure and swelling NIH ODS ↗. If you take this medication, discuss your B1 status with your doctor.
Our recommendation
For most adults, a balanced diet provides adequate B1. If you choose a supplement, a standard dose from a reputable brand is safe. There is no need for high doses unless you have a confirmed deficiency or a medical reason, such as taking a diuretic like furosemide NIH ODS ↗. Always consult your healthcare provider before starting a new supplement, especially if you take prescription medications.
AI-assisted analysis based on NIH ODS, FDA, and PubMed data. Citations are linked to original sources.
Recommended Dosage
| Life Stage | Recommended Amount |
|---|---|
| Birth to 6 months | 0.2 mg |
| Infants 7–12 months | 0.3 mg |
| Children 1–3 years | 0.5 mg |
| Children 4–8 years | 0.6 mg |
| Children 9–13 years | 0.9 mg |
| Teen boys 14–18 years | 1.2 mg |
| Teen girls 14–18 years | 1.0 mg |
| Men | 1.2 mg |
| Women | 1.1 mg |
| Pregnant teens and women | 1.4 mg |
| Breastfeeding teens and women | 1.4 mg |
Source: National Academies of Sciences, Engineering, and Medicine. Always consult your healthcare provider for personalized dosage recommendations.
Drug Interactions
Yes. Some medicines can lower thiamin levels in the body. Here are a couple examples: Furosemide (Lasix), which is used to treat high blood pressure and swelling caused by excess fluid in the body Fluorouracil (5-fluorouracil and Adrucil), which is used in chemotherapy treatments for some types of cancer Tell your doctor, pharmacist , and other health care providers about any dietary supplements and prescription or over-the-counter medicines you take. They can tell you if the dietary supplements might interact with your medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients such as thiamin.
Check All InteractionsFood Sources
Thiamin is found naturally in many foods and is added to some fortified foods. You can get recommended amounts of thiamin by eating a variety of foods, including the following: Whole grains and fortified bread, cereal, pasta, and rice Meat (especially pork) and fish Legumes (such as black beans and soybeans ), seeds, and nuts
Complete food source guideHealth Goals This Supplement Supports
Frequently Asked Questions
How much B1 should I take daily?
Refer to the Recommended Dosage table above. Individual needs vary by age, gender, and health status. Always follow the dosage on your supplement label and consult your healthcare provider.
What are the side effects of B1?
Thiamin has not been shown to cause any harm.
Can I get enough B1 from food alone?
Thiamin is found naturally in many foods and is added to some fortified foods. You can get recommended amounts of thiamin by eating a variety of foods, including the following: Whole grains and fortified bread, cereal, pasta, and rice Meat (especially pork) and fish Legumes (such as black beans and
Does B1 interact with medications?
Yes. Some medicines can lower thiamin levels in the body. Here are a couple examples: Furosemide (Lasix), which is used to treat high blood pressure and swelling caused by excess fluid in the body Fluorouracil (5-fluorouracil and Adrucil), which is used in chemotherapy treatments for some types of c