Vitamin B1 · Grain to table · Food literacy
Thiamin
What went into the flour?
Thiamin, or vitamin B1, helps enzymes carry out reactions involved in energy metabolism. [1]
A slice of toast connects that cellular role to an everyday food question: what remained after milling, and what was added afterward? Whole grain, enrichment and cooking describe different stages in the nutrient’s journey to the plate.
Meet the vitamin
One familiar name. Several chemical forms.
Thiamin, thiamine and vitamin B1 name the same water-soluble vitamin. It supports energy metabolism and normal cellular function. Foods can contain it naturally or have it added during manufacture. [1]
Inside the body, its main active form is thiamin diphosphate (TDP), also called thiamin pyrophosphate (TPP). It helps enzymes carry out reactions involving glucose, amino acids and fats. Think of a coenzyme as a working partner for an enzyme, rather than as fuel itself.
Supplement labels commonly name thiamin mononitrate or thiamin hydrochloride. Benfotiamine is a synthetic derivative converted to thiamin in the body, not simply another spelling of the vitamin. These names should remain distinct when reading a study or ingredient list. [1]
The distinction is chemical, not just typographic. TDP has an attached diphosphate group that plain thiamin does not. Mononitrate and hydrochloride are salt forms, not names for this phosphorylated coenzyme. A source specifying one form has supplied information that the broad label “B1” leaves out. [2]
From kernel to flour
Whole grain and enriched answer different questions.
A whole grain retains bran, germ and endosperm. Refining removes the bran and germ, taking nutrients with them. Enrichment adds certain B vitamins and iron back after processing; it does not rebuild the kernel or restore its fiber. [3]
That is why “whole grain” and “enriched” are not interchangeable descriptions. One concerns the grain’s components; the other concerns additions. Reading both the grain description and the ingredient list is more informative than judging the loaf by appearance.
On the plate
Keep the food description attached to the number.
Whole-wheat bread
0.126 mg per 32 g slice, commercially prepared, not toasted. [4]
Cooked brown rice
0.360 mg per 202 g cup, long-grain. [4]
These are USDA Standard Reference Release 28 entries, in a report dated January 2016. They describe reference foods and specified portions, not an analysis of the manuscript’s bread or a current branded product.
The rice amount is for cooked rice. A cup of dry rice has a different weight and yields a different quantity after cooking. Similarly, a database slice is not automatically the size of the slice on your plate.
Preparation matters
Added to the food does not mean unchanged by cooking.
Heat can reduce thiamin content. Its water solubility also means some can leave food in discarded cooking water. These are separate routes of loss. [1]
A measured rice experiment
In a 2017 laboratory study, Silveira and colleagues compared fortified rice after stir-frying, boiling, microwave cooking and boiling in a food-service setting. They measured thiamin and folic acid using high-performance liquid chromatography, a method that separates compounds for analysis. [5]
The microwave condition had the highest thiamin retention in that experiment: 65.4%. This is a measured result for the tested fortified rice and procedures, not a universal retention factor to apply to every saucepan or grain.
How to interpret the rice experiment
The accessible abstract does not give the complete cooking protocols or sample-level results. The study measured vitamin content in food, not human absorption or skin outcomes. Its useful lesson is that a fortification amount and a post-cooking amount answer different questions.
Read the label
Milligrams and Daily Value.
Which parts of the kernel remain?
What was added during manufacture?
What was measured after cooking?
Those questions should travel together. An ingredient name can establish that a vitamin was added, but does not by itself give the vitamin amount in a cooked portion. Likewise, a rice experiment cannot determine the thiamin content of a different loaf.
Sources to follow
Revised October 25, 2026. Sources below distinguish chemical identity, food composition and the particular preparations or populations studied. Research methods and interpretation remain alongside the findings.
- NIH Office of Dietary Supplements: Thiamin.
- Chemical identity: ChEBI thiamin diphosphate; FDA hydrochloride and mononitrate.
- USDA: Healthy Eating with MyPlate, grain-kernel explanation.
- USDA: Thiamin by household measure, Release 28.
- Silveira and colleagues: Cooking fortified rice, original research abstract.
Recipe provenance: Eat for Your Skin, “Strawberry Basil Toast w/ Burrata.”
