A complete safety, timing, and dosage guide for combining Fish Oil (Omega-3: EPA / DHA) with Vitamin B1 (Thiamine) — including how the two supplements interact, the best time of day to take each, and which populations should be careful.
Yes, you can safely take vitamin B1 (thiamine) and fish oil (omega-3 EPA/DHA) together, as these two supplements do not interact in any meaningful way.
There is no significant interaction between vitamin B1 (thiamine) and fish oil (omega-3 EPA/DHA). These two supplements work independently in the body, so combining them is safe. You can take both together as part of your daily routine.
Thiamine is a water-soluble vitamin absorbed primarily in the jejunum through both active transport and passive diffusion, depending on dose. Fish oil fatty acids are fat-soluble and require bile salts and micelle formation for absorption in the small intestine. Because they rely on different absorption pathways, they do not compete for transporters or receptors. Fish oil does not affect thiamine phosphorylation or the activity of thiamine-dependent enzymes, and thiamine does not alter omega-3 incorporation into cell membranes. In short, there is no known biological reason for a negative interaction.
For best results, take vitamin B1 and fish oil once daily together with a meal that contains a little fat, such as breakfast or dinner. If you use extended-release or benfotiamine forms, you can still take them with the same meal. A standard dose of thiamine is 1.1–1.2 mg for most adults, while a typical omega-3 dose is 250–1000 mg combined EPA/DHA, depending on your health goals. If you miss a dose, simply take it at your next scheduled time—do not double up. Consistency matters more than exact timing.
If you use benfotiamine, a fat-soluble derivative of thiamine, it may be absorbed with dietary fat just like fish oil, but this does not create a negative interaction—it may actually be convenient to take them together. Thiamine hydrochloride and thiamine mononitrate are water-soluble and typically absorbed with or without food. Fish oil is better absorbed when taken as triglycerides rather than ethyl esters, but this affects only the fish oil itself, not thiamine. Choose a quality fish oil with EPA/DHA in triglyceride form if you want optimal absorption, but neither form affects thiamine status.
This pair is commonly included in daily multivitamin plus omega-3 bundles, and both are often part of energy-support stacks alongside vitamin B12 and magnesium.
Yes, you can take vitamin B1 and fish oil at the same time. They use different absorption pathways and do not interfere with each other. I usually recommend taking them together with a meal to support fish oil absorption.
Yes, it is safe to combine these two every day at recommended levels. The daily reference intake for thiamine is about 1.1–1.2 mg for most adults, and up to 1000 mg of combined EPA/DHA is generally considered safe for supportive use. Extensive evidence does not show any adverse interactions.
You do not need to wait at all. Since there is no known interaction, you can take them together or at any time that is convenient for you.
No, they do not compete for absorption. Thiamine is water-soluble and relies on specific intestinal transporters, while omega-3s are taken up as micelles in the presence of bile. Their absorption pathways are completely independent.
Few people need to avoid this combination. If you have a bleeding disorder or take anticoagulant medication, discuss high-dose fish oil with your doctor first. Those with an allergy to fish should choose algae-based omega-3 supplements instead.
I recommend taking them with food, primarily to help with fish oil absorption and to prevent any upset stomach. Thiamine can be taken with or without food, but a meal that contains some fat will make the omega-3 fatty acids easier to absorb.
Reviewed by Caroline M. on April 10, 2026 for accuracy against the sources listed above. This page is educational and is not a substitute for professional medical advice.
The matrix has 86 supplements and 7310 pairwise interactions. Click any cell to see the full breakdown.