What is rice bran oil, and what does it contain?

Rice bran oil is the oil in rice bran, the brown outer layer of the rice grain that is removed when brown rice is milled into white rice. Most of it is a mix of monounsaturated and polyunsaturated fat: per 100 g, US Department of Agriculture data list about 39 g of monounsaturated fat (mostly oleic acid), 35 g of polyunsaturated fat (mostly linoleic acid) and 20 g of saturated fat (mostly palmitic acid). Rice bran oil also contains small amounts of other compounds, such as γ-oryzanol, a mixture of ferulic acid esters of plant sterols that is found mainly in rice bran. A Thai study found 741 to 1,370 mg of γ-oryzanol per 100 g in crude rice bran oils, and another found that simple refining lowered it from 2.8% to 2.2% of the oil.

In short:

• Where it comes from: the bran removed when rice is milled; bran is 12% to 23% fat
• Fatty acids: oleic, linoleic and palmitic acid make up most of the oil
• γ-Oryzanol: ferulic acid esters of plant sterols and triterpene alcohols; 0.20% to 2.72% of the oil in a review
• Other minor compounds: vitamin E (tocopherols and tocotrienols) and phytosterols
• Processing: the extraction method and refining change the amounts of γ-oryzanol and other minor compounds in the oil
• Thai RDI: none for γ-oryzanol; total fat 65 g, vitamin E 9 mg α-TE

This article explains what rice bran oil is made of and how processing changes it. It does not discuss what it does in the body. For how rice bran oil compares with palm, coconut and soybean oil, see How do cooking oils differ, and what fats do they contain?, and for the forms of vitamin E in Thai rice, see Which foods are high in vitamin E, and how much?

What is rice bran oil?

A grain of brown rice has an outer bran layer, a small germ (embryo) and a large starchy inside, the endosperm. Milling removes the bran and germ to make white rice, and the bran is a by-product of every rice mill.

How much oil is in rice bran?

A 2024 review from the Heilongjiang Academy of Agricultural Sciences in China gives a fat content of 12% to 23% for rice bran. The review notes that rice bran deteriorates rapidly and that hydrolytic rancidity, in which fat is broken down into free fatty acids, is the main obstacle to using it. Bran therefore has to be stabilised or processed soon after milling, and the review reports that delayed stabilisation seriously affects the overall quality of the oil.

How is the oil taken out of the bran?

There are two main routes: pressing the bran mechanically, or dissolving the oil out with a solvent such as hexane. Newer methods use supercritical carbon dioxide or liquefied dimethyl ether. The amount of oil recovered differs a great deal between methods. A 2023 study from Naresuan University extracted oil from white rice bran (Khao Dawk Mali 105) and red rice bran (Riceberry) obtained from a community enterprise in Phitsanulok.

Source: Wongwaiwech et al. 2023. Pressing recovers less oil than solvent extraction. A 2011 study from Pibulsongkram Rajabhat University in Phitsanulok found that heating organic rice bran to 60 °C in a hot-air oven before screw pressing raised the yield from 4.8% to 8.3% (w/w).

What fatty acids are in rice bran oil?

Rice bran oil is built mainly from three fatty acids: oleic acid (a monounsaturated fatty acid with 18 carbons and one double bond, written 18:1), linoleic acid (an omega-6 polyunsaturated fatty acid, 18:2) and palmitic acid (a saturated fatty acid, 16:0).

Fatty acids per 100 g and as a share of the oil

The two columns use different units (grams per 100 g of oil, and percent of fatty acids) and different samples, so they are not expected to match exactly.

The international standard for rice bran oil

The Codex Alimentarius standard for named vegetable oils sets the expected fatty acid ranges for each oil. A 2020 report from Thailand's National Bureau of Agricultural Commodity and Food Standards analysed 90 samples of refined rice bran oil from Thailand and India and 40 samples of crude rice bran oil from Thai refineries. Some samples fell outside the Codex ranges, and Codex agreed to amend the standard: linoleic acid (18:2) to 21% to 42%, myristic acid (14:0) and behenic acid (22:0) to not detected up to 1.0%, and lignoceric acid (24:0) to not detected up to 0.9%. The report also widened the ranges for two groups of plant sterols, based on the Thai crude oils.

What is γ-oryzanol?

γ-Oryzanol (gamma-oryzanol) is a group of compounds found mainly in rice bran.

A mixture, not one compound

A 2025 review from the University of Camerino in Italy describes γ-oryzanol as a complex mixture of ferulic acid esters of phytosterols and triterpene alcohols, found predominantly in rice bran, and notes that its composition and concentration vary significantly between rice varieties. Researchers at the Tokyo University of Technology likewise describe it as a group of phytosterol ferulates contained as a minor component in rice bran oil. Each component is a sterol or triterpene alcohol joined to ferulic acid.

A dash means the formula is not given here.

Where γ-oryzanol forms in the rice plant

A 2022 study from the Indian Agricultural Research Institute followed γ-oryzanol through the growth of six rice varieties. Cycloartenyl caffeate, a related ester, was predominant in the leaf blades, leaf sheaths and other non-seed tissues but was totally absent in the mature grains, while 24-methylenecycloartanyl ferulate, campesteryl ferulate and β-sitosteryl ferulate increased as the grain matured. The authors report that ferulate esters were predominant in the seed tissues.

Milling and cooking

The same study measured how much γ-oryzanol stayed in the rice after processing. Milling removed a large part of it, and cooking removed more.

Source: Ghosh et al. 2022 (six indica varieties, four of them basmati). The study also separated mature grains into husk, embryo, bran and endosperm to compare where γ-oryzanol accumulates.

How much γ-oryzanol is in rice bran oil?

The amount depends on the rice variety, the extraction method and whether the oil is refined.

Crude oils from Thai rice bran

The Naresuan University study measured γ-oryzanol in crude oils extracted by four methods from white rice bran (Khao Dawk Mali 105) and red rice bran (Riceberry). It found 741.13 to 1,370.43 mg per 100 g (dry basis), depending on the rice and the method. Each compound measured varied in its own way with the method: in the same study, total phytosterols and policosanols were highest with dimethyl ether extraction.

Figures from other sources

The Rice Department study analysed 101 local varieties grown in the 2016 wet season in north-eastern Thailand and found γ-oryzanol in all of them. Its figures are for the rice grain, not the oil, so they are much lower than the figures for oil.

What else does rice bran oil contain?

Vitamin E

In FoodData Central, 100 g of rice bran oil has 32.3 mg of alpha-tocopherol. Rice and rice bran also carry tocotrienols, the other family of vitamin E. The Thai Reference Daily Intake (Thai RDI) for vitamin E is 9 mg α-TE a day. For the forms of vitamin E in Thai rice varieties and rice bran oils, see Which foods are high in vitamin E, and how much?

Other minor compounds in rice bran oil

FoodData Central also lists phytosterols, plant sterols that are close relatives of the sterol part of γ-oryzanol (table below). The Naresuan University study also measured policosanols, a group of long-chain alcohols.

How does refining change rice bran oil?

Crude rice bran oil is dark and contains gums and waxes. Refining steps include removing free fatty acids (deacidification), removing colour (bleaching) and removing odour (deodorisation).

A Thai study of simple refining

The Pibulsongkram Rajabhat University study tested three simple refining steps on organic crude rice bran oil: filtering through filter paper, settling with 4% (w/v) fuller's earth, and passing the oil through a column of activated carbon.

The oil became lighter and lost most of its gum and wax, while γ-oryzanol fell slightly.

γ-Oryzanol in by-products

By-products of rice bran oil processing can hold a lot of γ-oryzanol. A 2019 Naresuan University study found that rice acid oil, a residue from solvent-extraction processing, contained up to 3,829.65 mg of γ-oryzanol per 100 g, along with up to 120.59 mg of tocopherols and tocotrienols per 100 g. The Heilongjiang review reports that with a deacidification method using an immobilised enzyme (lipase), the γ-oryzanol remaining in the oil was at least 40% higher than with traditional alkali refining. The Tokyo University of Technology researchers note that some methods used to measure γ-oryzanol in crude oil are not sensitive enough for refined oil, and developed a method for refined oil.

Is there a recommended daily amount?

γ-Oryzanol is not a nutrient with a Thai Reference Daily Intake (Thai RDI), so there is no recommended daily amount for it in Thailand. Rice bran oil counts towards total fat: the Thai RDI for total fat from all foods is 65 g a day, and for saturated fat 20 g. For the other Thai reference amounts, see What are the Thai daily reference amounts for each nutrient?

Why the figures differ

The figures in this article come from different rice varieties, regions, extraction methods and laboratories. The Naresuan study used bran from one community enterprise, and the Rice Department study one region and one season. They are best read as ranges rather than as the content of every bottle of rice bran oil.

Who should talk to a doctor or pharmacist?

If you are pregnant or breastfeeding, or take medication regularly, talk to a doctor or pharmacist before taking dietary supplements.

Dietary supplements are not intended to prevent, treat or cure any disease.