How much B1 is in white rice?

January 2, 2026 •

4 min read

White rice, a global dietary staple, is produced by removing the nutritious bran and germ layers from the whole grain during the milling process. This refining process strips away most of its natural thiamine, or Vitamin B1. To combat the resulting nutrient deficiency, most white rice in countries like the US is now enriched, with minerals and B-vitamins, including B1, added back in.

Quick Summary

The refining process removes most of the natural B1 from white rice, but most commercially sold white rice is enriched to restore this nutrient. Enriched white rice provides a notable amount of B1, whereas unenriched varieties contain only trace amounts, a key difference for overall health.

Key Points

Enriched White Rice Contains Added B1: Most commercial white rice is fortified with thiamine (B1) to compensate for nutrients lost during milling, making it a source of this vitamin.
Unenriched White Rice Has Almost No B1: The polishing process removes the outer layers of the grain, stripping away nearly all of its natural thiamine content.
Milling Strips Nutrients: The act of turning brown rice into white rice removes the bran and germ, which are the main sources of B1 and other essential nutrients.
Brown Rice is Naturally Rich in B1: As a whole grain, brown rice retains its natural thiamine, offering a more nutritious alternative to unenriched white rice.
Cooking Methods Matter: To preserve the added thiamine in enriched rice, avoid excessive rinsing and use cooking methods where the water is fully absorbed.
B1 Deficiency Can Cause Beriberi: Historically, diets high in unenriched white rice led to beriberi, a severe thiamine deficiency disease.

The Drastic Difference: Enriched vs. Unenriched White Rice

When rice is milled and polished to become white rice, the fibrous outer bran and the nutrient-dense germ are removed, leaving only the starchy endosperm. This polishing process results in the loss of a substantial portion of the rice's vitamins and minerals, particularly thiamine (vitamin B1). Historically, relying on polished white rice as a staple food without supplementation led to outbreaks of the thiamine deficiency disease known as beriberi.

To prevent such health issues, food manufacturers began the process of enrichment. Today, most white rice sold in many countries, including the United States, is fortified with iron and B-vitamins, including thiamine. The amount of B1 in white rice is therefore highly dependent on whether it is enriched or not.

How Much Thiamine (B1) Is in Enriched White Rice?

An enriched, cooked, medium-grain white rice contains a significant amount of B1. For example, a 1-cup serving (about 185g) of cooked enriched white rice can contain approximately 0.31 mg of thiamine, contributing to a meaningful percentage of the daily value. The specific amount can vary depending on the brand and how the rice is processed. This added thiamine is stable and water-soluble, but a significant portion can be lost if the rice is excessively rinsed or cooked in too much water that is later discarded.

The Negligible Amount in Unenriched White Rice

In stark contrast, unenriched or 'regular' white rice has a very low B1 content. According to the National Institutes of Health, unenriched white rice contains only about one-tenth of the thiamine found in brown rice. The milling process removes 90–98% of the grain's thiamine, concentrating the remaining nutrient in trace amounts within the endosperm. This makes unenriched white rice a poor source of thiamine and an unsuitable staple for a diet without other B1 sources.

The Case for Brown Rice: A Natural Source of Thiamine

As a whole grain, brown rice retains its bran and germ layers, which are rich in natural thiamine and other nutrients. A 100g serving of cooked brown rice may contain approximately 0.177 mg of vitamin B1, making it a naturally superior source compared to either enriched or unenriched white rice. The fiber and other nutrients in brown rice also provide additional health benefits, such as supporting heart health and blood sugar regulation.

Comparison: Enriched vs. Unenriched White Rice Thiamine Content


Feature	Enriched White Rice	Unenriched White Rice
B1 Content	Contains added B1. A typical cooked cup provides a notable percentage of the daily value (e.g., ~15-20%).	Contains negligible B1. The milling process removes most natural thiamine.
Processing	Milled, polished, and then fortified with vitamins and minerals.	Milled and polished with no vitamins added back.
Nutrient Source	Synthetic thiamine added post-processing.	Naturally occurring thiamine, but mostly stripped away.
Health Context	Helps prevent thiamine deficiency in populations that rely on rice as a staple.	Regular consumption can risk thiamine deficiency if no other rich sources are present.
Cooking Consideration	Avoid rinsing or using excess water to retain added nutrients.	Little concern for nutrient loss during rinsing due to already low content.

Cooking and Preservation of Thiamine

Since thiamine is a water-soluble vitamin, cooking methods can impact its retention in rice. For enriched rice, excessive washing or rinsing before cooking can strip away the added vitamins. Cooking in a large pot of water that is later drained, a common practice in some cultures, can also cause significant vitamin loss. The absorption method, where rice is cooked in just enough water to be fully absorbed, is ideal for preserving the nutrient content of enriched rice. Parboiling, a process where rice is soaked and steamed before milling, helps transfer natural thiamine from the husk into the endosperm, resulting in higher thiamine content in the final polished grain.

Conclusion

The amount of B1 (thiamine) in white rice is a tale of two products: enriched and unenriched. While the processing of white rice inherently strips away almost all of its natural thiamine, the common practice of enrichment in many countries has made it a source of this essential vitamin. Unenriched white rice remains a poor source of thiamine and prolonged consumption can lead to deficiency disorders like beriberi. For those seeking naturally high levels of B1, whole grains like brown rice are a far more reliable and nutritious option. Ultimately, a balanced diet including varied food sources is the best way to ensure adequate thiamine intake.

This article is for informational purposes only and is not a substitute for professional medical or dietary advice. Always consult with a qualified healthcare provider or registered dietitian for any health concerns or before making changes to your diet. For more information on the fortification of rice and its public health implications, consider visiting the World Health Organization's page on Thiamine Deficiency.

Frequently Asked Questions

No, while enriched white rice contains added B1 and other nutrients, brown rice is a whole grain that naturally contains higher amounts of fiber, magnesium, and antioxidants, and has a lower glycemic index.

Yes, rinsing enriched white rice before cooking can wash away some of the added water-soluble vitamins, including B1. It is recommended to cook enriched rice without rinsing to retain the nutrients.

Polished rice is another term for white rice after the milling process has removed the bran and germ. Enriched rice is polished white rice that has had certain nutrients, like B1, added back into it.

If you eat only unenriched white rice and your diet lacks other sources of B1, you could develop beriberi over time. The modern practice of rice enrichment helps prevent this in many regions.

Rice enrichment was started to address the thiamine deficiency disease known as beriberi, which became widespread in populations that depended on polished white rice as a staple.

Besides brown rice, other good natural sources of B1 include pork, salmon, legumes (like black beans and lentils), green peas, and whole grains.

Yes, parboiling is a process where rice is soaked and steamed before milling. This helps to transfer nutrients, including B1, from the bran into the endosperm, resulting in a higher B1 content compared to regular white rice.