Magazine article Nutrition Health Review

Numerous Compounds Found in Whole-Grain Rice Varieties

Magazine article Nutrition Health Review

Numerous Compounds Found in Whole-Grain Rice Varieties

Article excerpt


Whole-grain brown rice contains 15 vitamins and minerals, including B complex vitamins, potassium, magnesium, and iron--all nutrients the body needs to grow and develop normally. In addition to these essential nutrients, there are bioactive phytochemicals in rice, as well as in other whole grains, vegetables, fruits, beans, nuts, and seeds. Although the role of these plant chemicals in terms of human health has not been proven, a body of evidence suggests that some phytochemicals could be nutritionally beneficial.

Studies headed by chemist Ming-Hsuan Chen, with the Agricultural Research Service (A.R.E.) Dale Bumpers National Rice Research Center in Suttgart, Arkansas, have provided information about the chemical composition and potential bioavailability of compounds in a representative group of rice varieties.

Rice is categorized into seven classes based on bran color: white, light brown, speckled brown, brown, red, variable purple, and purple.

Rice bran, an outer layer of whole grain rice, is a rich source of the phytochemical known as gamma-oryzanol and of two forms of vitamin E--the tocopherols and the tocotrienols. These nutritional compounds are linked to preventing oxidative damage in foods and have a wide spectrum of biological activities.

The team used several assays and analytical methods to determine the profiles of tocopherols, tocotrienols, and gamma-oryzanol in five color classes of bran: white, light brown, brown, red, and purple. They found a wide variation in the concentrations of the two forms of vitamin E and of gamma-oryzenol in the bran of all five color classes studied.

Pigmented or darker-colored cereal grains, such as red and purple, have higher amounts of some phytochemical compounds than nonpigmented varieties. The team also analyzed other phytochemicals--specifically phenolics and flavonoids--in the same five color classes of bran. They measured the concentrations of both the extractable and the cell-wall bound amounts in the three lighter rice varieties--white, light brown, and brown--and in the two darker rice varieties--red and purple.

Cell-wall bound phenolics and flavonoids in rice grains are of interest because previous studies by other researchers have shown that-cell-wall bound phenolic compounds can be broken down by digestive enzymes and by microflora in the gut. This liberation from the cell wall may mean that these compounds become available for absorption in the body. In addition, the amount of absorbable phytonutrients in rice may be underestimated because typically the cell-wall bound forms have not been measured, says Dr. …

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