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Rice is the seed of the monocot plants Oryza sativa (Asian
rice) or Oryza glaberrima (African rice). As a cereal grain,
it is the most widely consumed staple food for
a large part of the world's human population, especially in Asia. It is the
grain with the second-highest worldwide production, after corn, according to data
for 2010.
Since a large portion of maize crops are grown for purposes other than
human consumption, rice is the most important grain with regard to human
nutrition and caloric intake, providing more than one fifth of the calories consumed
worldwide by humans.
Chinese legends attribute the domestication of rice to Shennong,
the legendary Emperor of China and inventor of Chinese agriculture. Genetic
evidence has shown that rice originates from a single domestication
8,200–13,500 years ago in the Pearl River valley region of China.[5] Previously,
archaeological evidence had suggested that rice was domesticated in the Yangtze River valley
region in China. From East Asia, rice was spread to Southeast and South
Asia. Rice was introduced to Europe through Western Asia, and to the Americas
through European colonization.
There are many varieties of rice and culinary preferences tend to vary
regionally. In some areas such as the Far East or Spain, there is a preference
for softer and stickier varieties.
Rice is normally grown as an annual plant,
although in tropical areas it can survive as a perennial and
can produce a ratoon crop
for up to 30 years. The rice plant can grow to 1–1.8 m
(3.3–5.9 ft) tall, occasionally more depending on the variety and soil
fertility. It has long, slender leaves 50–100 cm (20–39 in) long and
2–2.5 cm (0.79–0.98 in) broad. The small wind-pollinated flowers
are produced in a branched arching to pendulous inflorescence 30–50 cm
(12–20 in) long. The edible seed is a grain (caryopsis)
5–12 mm (0.20–0.47 in) long and 2–3 mm (0.079–0.118 in)
thick.
Rice cultivation is well-suited to countries and regions with low labor
costs and high rainfall, as it is labor-intensive to cultivate and requires
ample water. However, rice can be grown practically anywhere, even on a steep
hill or mountain area with the use of water-controlling terrace systems.
Although its parent species are native to Asia and certain parts of Africa,
centuries of trade and exportation have made it commonplace in many cultures
worldwide.
The traditional method for cultivating rice is flooding the fields
while, or after, setting the young seedlings. This simple method requires sound
planning and servicing of the water damming and channeling, but reduces the
growth of less robust weed and pest plants that have no submerged growth state,
and deters vermin.
While flooding is not mandatory for the cultivation of rice, all other methods
of irrigation require
higher effort in weed and pest control during
growth periods and a different approach for fertilizing the soil.
The name wild rice is usually used for species of
the genera Zizania and Porteresia,
both wild and domesticated, although the term may also be used for primitive or
uncultivated varieties of Oryza.
Nutrition and health
Nutrients and the nutritional
importance of rice
|
Rice, white, long-grain, raw
|
|
|
Nutritional value per 100 g (3.5 oz)
|
|
|
1,527 kJ (365 kcal)
|
|
|
80 g
|
|
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0.12 g
|
|
|
1.3 g
|
|
|
0.66 g
|
|
|
7.13 g
|
|
|
(6%)
0.0701 mg
|
|
|
(1%)
0.0149 mg
|
|
|
(11%)
1.62 mg
|
|
|
(20%)
1.014 mg
|
|
|
(13%)
0.164 mg
|
|
|
(3%)
28 mg
|
|
|
(6%)
0.80 mg
|
|
|
(7%)
25 mg
|
|
|
(52%)
1.088 mg
|
|
|
(16%)
115 mg
|
|
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(2%)
115 mg
|
|
|
(11%)
1.09 mg
|
|
|
Other constituents
|
|
|
11.61 g
|
|
|
·
Units
·
μg = micrograms •
mg = milligrams
·
IU = International units
|
|
|
Percentages are roughly approximated usingUS recommendations for adults.
Source: USDA Nutrient Database |
|
Rice
is the staple food of over half the world's population. It is the predominant
dietary energy source for 17 countries in Asia and the Pacific, 9 countries in
North and South America and 8 countries in Africa. Rice provides 20% of the
world’s dietary energy supply, while wheat supplies 19% and maize (corn) 5%.
A
detailed analysis of nutrient content of rice suggests that the nutrition value
of rice varies based on a number of factors. It depends on the strain of rice,
that is between white, brown, black, red and purple varieties of rice – each
prevalent in different parts of the world. It also depends on nutrient quality
of the soil rice is grown in, whether and how the rice is polished or
processed, the manner it is enriched, and how it is prepared before consumption.
An
illustrative comparison between white and brown rice of protein quality,
mineral and vitamin quality, carbohydrate and fat quality suggests that neither
is a complete nutrition source. Between the two, there is a significant
difference in fiber content and minor differences in other nutrients.
Brilliantly
colored rice strains, such as purple rice, derive their color from anthocyanins
and tocols. Scientific studies suggest that these color pigments have
antioxidant properties that may be useful to human health. In purple rice bran,
hydrophilic antioxidants are in greater quantity and have higher free radical
scavenging activity than lipophilic antioxidants. Anthocyanins and γ-tocols in
purple rice are largely located in the inner portion of purple rice bran.
Comparative
nutrition studies on red, black and white varieties of rice suggest
that pigments in red and black rice varieties may offer nutritional benefits.
Red or black rice consumption was found to reduce or retard the progression of
atherosclerotic plaque development, induced by dietary cholesterol, in mammals.
White rice consumption offered no similar benefits, and the study claims this
to be due to absent antioxidants in red and black varieties of rice.
Comparison of rice to other major
staple foods
The
table below shows the nutrient content of major staple foods in a raw form. Raw
grains, however, are not edible and cannot be digested. These must be sprouted,
or prepared and cooked for human consumption. In sprouted and cooked form, the
relative nutritional and anti-nutritional contents of each of these grains is
remarkably different from that of raw form of these grains reported in this
table.
Health
Benefits of Rice
While
all whole grains share similar health benefits, each individual whole grain
also offers its own special advantages. Here is some of the recent research
related to rice.
BLACK RICE RIVALS BLUEBERRIES AS
ANTIOXIDANT SOURCE
Scientists
working with Zhimin Xu at the Louisiana State University Agricultural Center
have found that black rice (sometimes called “forbidden rice”) contains
health-promoting antioxidants called anthocyanins, at levels similar to those
found in blueberries and blackberries.
BLACK RICE BRAN PROTECTS AGAINST
INFLAMMATION
S.P.
Choi and colleagues from Ajou University in Suwon, South Korea tested both
black rice bran and brown rice bran for their effectiveness in protecting
against skim inflammation. In mouse tests, they found that the black rice bran
did suppress dermatitis, but the brown rice bran did not. The scientists
suggest that black rice may be a “useful therapeutic agent for the treatment
and prevention of diseases associated with chronic inflammation.”
BLACK RICE BRAN HIGH IN ANTIOXIDANTS
A
team of researchers at Cornell University, including WGC Scientific Advisor Rui
Hai Liu, analyzed the phenolic content and antioxidant activity of 12 diverse
varieties of black rice, and found that antioxidants were about six times
higher in black rice than in common brown/white rice. The black rice bran had
higher content of phenolics, flavonoids and anthocyanins.
SWITCH TO BROWN RICE REDUCES
DIABETES RISK IN MEN AND WOMEN
Scientists
at the Harvard School of Public Health followed 39,765 men and 157,463 women as
part of the Health Professionals Follow-up Study and the Nurses’ Health Study I
and II. They found that those eating several servings of white rice per week
had a higher risk of Type 2 diabetes and that those eating 2 or more servings
of brown rice had a lower risk. They estimate that replacing about two servings
a week of white rice with the same amount of brown rice would lower diabetes
risk 16%.
BLACK/BROWN
RICE MORE EFFECTIVE IN WEIGHT CONTROL
At
the Department of Food and Nutrition at Hanyang University in Seoul, Korean
researchers randomly assigned forty overweight adult women to two groups. For
six weeks, one group ate meals containing white rice, while the other consumed
otherwise-identical meals with a mix of black and brown rice. While both groups
showed significant reductions in weight, BMI and body fat, the whole grain rice
group surpassed the white rice group in all three measures. The whole grain
group also saw an increase in HDL (good) cholesterol and in antioxidant
activity.
BROWN RICE, FOR LOWER BLOOD GLUCOSE
IN HEALTHY AND DIABETIC SUBJECTS
Lower
post-prandial blood glucose response can be important both for preventing and
for controlling diabetes. In a study at the University of the Philippines,
researchers used a randomized cross-over design to compare the effects on blood
glucose of brown rice and white rice on 10 healthy and nine Type 2 diabetic
volunteers. In healthy volunteers, the glycemic area and glycemic index were,
respectively, 19.8% and 12.1% lower with brown rice than with white rice; with
diabetics, the same values for brown rice were 35.2% and 35.6” lower than with
white rice.
PHENOLS IN BROWN RICE MAY INHIBIT
BREAST AND COLON CANCER
Rice
is a staple in Asia, where breast and colon cancer rates are markedly lower
than in the Western world. Scientists at the University of Leicester, UK,
analyzed the phenolic compounds in brown rice, brown rice bran, and white
milled rice (from the same varietal) to look for known cancer-suppressive
compounds. They discovered that several such compounds were present in all
three samples, but were found in much lower levels in the white rice. They postulated
that consuming rice bran or brown rice instead of white rice may be
advantageous with respect to cancer prevention.
The Different Types of Rice
The different types of rice include the following:
Short-grain rice is very starchy and cooks up soft and sticky. It’s used in things like
sushi, paella, and risotto.
Long-grain rice contains
less starch so the cooked grains are drier and more separate. It’s often used
in pilafs or dishes with a lot of sauce.
Jasmine and basmati are long-grain varieties that have been cultivated to bring out
distinctive flavor profiles. They often turn up in Indian and Asian food.
Brown rice—which is
also available in long and short grains—is a lot chewier and heartier than
white rice and takes about twice as long to cook.
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