What Is Parboiled Rice, and Is It Healthy?

Parboiled rice, also called converted rice, is partially precooked in its inedible husk before being processed for eating.

In some Asian and African countries, people have been parboiling rice since ancient times as it makes the husks easier to remove by hand.

The process has become much more sophisticated and is still a common way of improving the texture, storage, and health benefits of rice.

This article reviews parboiled rice, including its nutrition, benefits, and downsides.

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Parboiling happens before rice is milled, that is before the inedible outer husk is removed to yield brown rice but before brown rice is refined to make white rice.

The three main steps of parboiling are (1, 2):

1. Soaking. Raw, unhusked rice, also called paddy rice, is soaked in warm water to increase the moisture content.
2. Steaming. The rice is steamed until the starch converts into a gel. The heat of this process also helps kill bacteria and other microbes.
3. Drying. The rice is slowly dried to reduce the moisture content so that it can be milled.

Parboiling changes the color of rice to a light yellow or amber, which differs from the pale, white color of regular rice. Still, it’s not as dark as brown rice (1).

This color change is due to pigments moving from the husk and bran into the starchy endosperm (the heart of the rice kernel), as well as a browning reaction that happens during parboiling (3, 4).

Summary

Parboiled rice is soaked, steamed, and dried in its husk after harvest but before milling. The process turns the rice light yellow rather than white.

During parboiling, some water-soluble nutrients move from the bran of the rice kernel into the starchy endosperm. This minimizes some of the nutrient loss that normally happens during refining when making white rice (1).

Here’s how 5.5 ounces (155 grams) of unenriched, cooked, parboiled rice compare to the same amount of unenriched, cooked, white and brown rice. This equates to about 1 cup of parboiled and white rice or a 3/4 cup of brown rice (5):

Notably, parboiled rice has significantly more thiamine and niacin than white rice. These nutrients are important for energy production. Furthermore, parboiled rice is higher in fiber and protein (6, 7).

On the other hand, some minerals, including magnesium and zinc, are slightly lower in parboiled rice, compared to regular white and brown rice. That said, these values can differ based on variables in the parboiling process (1).

Both parboiled and white rice are sometimes enriched with iron, thiamine, niacin, and folate, which reduces some of these nutrient differences when compared to brown rice. Still, brown rice is the best source of nutrients, overall.

Summary

Parboiled rice is higher in B vitamins compared to unenriched, regular white rice. This is due to the parboiling process, during which some nutrients transfer from the bran into the starchy endosperm. Still, brown rice is the most nutritious.

Parboiling is common, partly due to its beneficial effects on the cooking and storage qualities of rice. Studies also suggest that it may have health benefits beyond the increase in nutritional value.

Improved cooking and storage qualities

Parboiling reduces the stickiness of rice so it yields fluffy and separate kernels once cooked. This is especially desirable if you need to keep the rice warm for a while before serving, or if you plan to reheat or freeze leftover rice and want to avoid clumping (2).

Additionally, parboiling inactivates the enzymes that break down the fat in rice. This helps prevent rancidity and off-flavors, increasing shelf-life (8).

Transfer of plant compounds

When whole-grain brown rice is milled to make white rice, the bran layer and oil-rich germ are removed. Hence, potentially beneficial plant compounds are lost.

However, when rice is parboiled, some of these plant compounds, including phenolic acids with antioxidant properties, transfer to the starchy endosperm of the rice kernel, reducing the loss during refining. Antioxidants protect against cellular damage (9).

In a 1-month study in rats with diabetes, parboiled rice was found to contain 127% more phenolic compounds than white rice. What’s more, eating parboiled rice protected the rats’ kidneys against damage from unstable free radicals, whereas white rice didn’t (10).

Still, more research is needed to explore the plant compounds in parboiled rice and their potential health benefits.

Formation of prebiotics

When rice is steamed as part of the parboiling process, the starch turns into a gel. When it cools, it retrogrades, meaning the starch molecules reform and harden (1).

This process of retrogradation creates resistant starch, which resists digestion instead of being broken down and absorbed in your small intestine (11).

When resistant starch reaches your large intestine, it’s fermented by beneficial bacteria called probiotics and encourages their growth. Therefore, resistant starch is called a prebiotic (12).

Prebiotics promote gut health. For instance, when they’re fermented by bacteria, they yield short-chain fatty acids, including butyrate, which nourish the cells of your large intestine (12).

May affect blood sugar less

Parboiled rice may not raise your blood sugar as much as other types of rice. This may be due to its resistant starch and slightly higher protein content (13).

When people with type 2 diabetes ate about 1 1/8 cups (185 grams) of cooked parboiled rice after fasting overnight, their increase in blood sugar was 35% less than when they ate the same amount of regular white rice (13).

In the same study, no significant difference in blood sugar impact was observed between regular white and brown rice, even though the latter is a more nutritious choice (13).

Similarly, in another study in people with type 2 diabetes, eating about 1 1/4 cups (195 grams) of cooked parboiled rice after an overnight fast increased blood sugar 30% less than eating the same amount of regular white rice (14).

Eating leftover parboiled rice that’s chilled and then reheated may further reduce its impact on blood sugar (15, 16).

Nonetheless, more human studies are needed to explore the potential advantage of parboiled rice for blood sugar control.

If you have diabetes and test your blood sugar at home, you can check for yourself how different types of rice affect your levels. Be sure to compare the same amount of rice and eat them in the same way to have a fair comparison.

Summary

Parboiled rice is less prone to rancidity compared to brown rice and cooks into well-defined kernels rather than clumping. It may also offer more plant compounds, support gut health, and raise blood sugar less than regular white rice.

The main downside of parboiled rice is that it’s less nutritious than brown rice.

What’s more, depending on your texture and flavor preferences, you may not like parboiled rice. Compared to the soft, sticky texture and light, bland taste of white rice, it’s firm and chewy with a somewhat stronger flavor — though not as strong as brown rice (15).

For instance, it would be more difficult to use chopsticks to eat the distinct, individual grains of parboiled rice, compared to sticky clumps of regular white rice.

Parboiled rice also takes a little longer to cook. While white rice simmers in about 15–20 minutes, parboiled takes about 25 minutes. Still, this is less than the 45–50 minutes needed for brown rice.

Summary

Besides its lower nutritional content compared to brown rice, other potential downsides of parboiled rice are taste and texture differences, as well as a slightly longer cooking time than regular white rice.

Parboiled (converted) rice is partially precooked in its husk, which retains some nutrients otherwise lost during refining.

It may benefit gut health and impact blood sugar less than brown or white rice.

Still, though parboiled rice is healthier than regular white rice, brown rice remains the most nutritious option.