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Nutritional contribution of rice and impact of biotechnology and biodiversity in rice-consuming countries - G. Kennedy,a B. Burlingame b and V.N. Nguyen c

a Consultant and b Senior Officer, Nutrition Planning, Assessment and Evaluation Service, and
c Agricultural Officer, Crop and Grassland Service, FAO, Rome, Italy

Rice is the predominant staple food in at least 33 developing countries, providing 27 percent of dietary energy supply, 20 percent of dietary protein and 3 percent of dietary fat. Rice can contribute nutritionally significant amounts of thiamine, riboflavin, niacin and zinc to the diet, but smaller amounts of other micronutrients. Many factors influence the nutrient content of rice, including the cultivar, agricultural practices, post-harvest conditions and handling. Traditional breeding, genetic engineering, fortification and compositional analysis of lesser-known rice cultivars, together with nutrition education and promotion, are all strategies used to improve the nutrient contribution of rice.

RICE CONSUMPTION IN MAJOR RICE-CONSUMING COUNTRIES

Rice is the predominant staple for 15 countries in Asia and the Pacific, ten countries in Latin America and the Caribbean, one country in North Africa and seven countries in sub-Saharan Africa (FAO, 1999). In developing countries, rice accounts for: 715 kcal/caput/day, 27 percent of dietary energy supply, 20 percent of dietary protein and 3 percent of dietary fat. Countries in Southeast Asia are heavily reliant upon rice: in Bangladesh, the Lao People’s Democratic Republic, Viet Nam, Myanmar and Cambodia, rice supplies more than 50 percent of the dietary energy and protein supply per caput and between 17 and 27 percent of dietary fat. Rice is an important staple for several countries in Africa. In Guinea, Guinea-Bissau, Gambia, Liberia, Senegal and Côte d’Ivoire, rice supplies between 22 and 40 percent of dietary energy and between 23 and 39 percent of dietary protein (Table 1).

TABLE 1
Contribution of rice (rice-milled equivalent) as percentage of total dietary energy, protein and fat

Country

Supply
(g/day)

Dietary energy
(%)

Protein
(%)

Fat
(%)

Bangladesh

441.2

75.6

66.0

17.8

Brazil

108.1

13.5

10.2

0.8

Cambodia

448.6

76.7

69.6

17.3

China

251.0

30.4

19.5

2.5

Costa Rica

170.4

21.0

16.0

1.4

Côte d’Ivoire

193.1

25.2

27.1

3.2

Dominican Republic

116.7

17.8

16.2

0.9

Ecuador

129.9

16.6

15.5

0.8

Gabon

78.5

11.4

7.8

0.7

Gambia

246.9

32.9

31.3

1.7

Guinea

185.4

31.3

31.6

4.7

Guinea-Bissau

258.0

40.9

39.2

2.2

Guyana

231.8

31.0

20.9

2.6

Haiti

95.3

17.9

15.7

3.0

India

207.9

30.9

24.1

3.6

Indonesia

413.6

51.4

42.9

8.1

Jamaica

76.3

11.0

9.2

1.5

Japan

165.6

23.3

12.5

1.8

Korea, Rep. of

259.0

33.5

21.0

3.2

Lao PDR

470.0

70.6

66.1

25.5

Liberia

123.7

22.1

25.1

3.5

Madagascar

251.5

46.6

43.6

11.8

Malaysia

245.2

29.8

20.4

2.2

Myanmar

577.9

73.6

68.1

19.9

Nepal

262.3

38.5

29.4

7.2

Panama

125.2

17.7

13.3

1.0

Papua New Guinea

101.6

16.1

13.6

1.8

Peru

127.8

18.8

14.7

1.7

Philippines

267.4

40.9

30.1

4.6

Senegal

186.7

29.2

28.7

1.6

Sierra Leone

258.4

44.1

33.5

2.9

Sri Lanka

255.3

38.4

37.0

2.7

Suriname

189.5

24.7

19.7

1.7

Thailand

285.3

43.0

33.4

4.6

United Arab Emirates

158.4

18.0

10.6

1.1

Viet Nam

464.7

66.7

58.1

14.4

Note: Figures are 1997-99 average per caput.
Source: FAOSTAT, 2001.

FIGURE 1
Global dietary energy supply from rice (milled equivalent) energy/caput/day (kcal), 1961-1999

FIGURE 2
Factors influencing the nutrient composition of rice

Rice production has increased greatly since the 1960s. Globally, the amount of energy per caput supplied by rice has increased from 411 kcal/caput in 1960 to 577 kcal/caput today - an increase of 40 percent (Figure 1). At regional level, the dietary energy supplied by rice has increased by 90 percent in sub-Saharan Africa and by 28 percent in Asia and Latin America (FAOSTAT, 2001).

Dietary intake surveys from China and India reveal an average adult intake of about 300 g of raw rice per day (Popkin et al., 1993; FAO, 1998). Based on an average consumption of 300 g of rice for an adult male and 250 g of rice for an adult female, Table 2 shows the quantities of micronutrients supplied by rice. For a male aged between 19 and 50, consuming the cooked equivalent of 300 g of raw rice per day, white rice supplies: 2-5% of the recommended nutrient intake (RNI) of calcium, folate and iron; 9-17% of the RNI of riboflavin, thiamine and niacin; and 21% of the RNI of zinc. Rice provides no vitamin C or A. With brown rice the RNI is increased for all nutrients except riboflavin: the RNI of iron, thiamine and niacin is increased by more than 10 percent. Due to the greater quantity of phytate in brown rice, the bio-availability of many nutrients decreases, particularly iron, zinc and calcium (to which it chemically bonds). Further analysis is required in order to gain a full understanding of the difference between brown and white rice in terms of the bio-availability of nutrients. Rice supplies a smaller proportion of the RNI of all nutrients for women, due to the smaller portion consumed and the greater requirements for certain nutrients, particularly iron.

TABLE 2
Amount and percent of recommended nutrient intake (RNI) of certain micronutrients supplied from an average rice intake (300g male/250 g female)

Ricea

Calcium
(mg)

Ironb
(mg)

Thiamine
(mg)

Riboflavin
(mg)

Niacin
(mg)

Zincb
(mg)

Folate
(mcg)

Male








White rice

20.9

1.4

0.1

0.11

2.8

2.9

13.9

(% RNI)

(2)

(5)

(12)

(9)

(17)

(21)

(3)

Brown rice

78.9

4.2

0.8

0.09

10.5

4.9

31.6

(% RNI)

(8)

(15)

(67)

(7)

(66)

(35)

(8)

Female








White rice

17.4

1.16

0.1

0.1

2.32

2.4

11.6

(% RNI)

(1.7)

(2)

(10.5)

(7)

(17)

(12)

(3)

Brown rice

65.9

3.49

0.67

0.1

8.75

4.1

26.3

(% RNI)

(7)

(6)

(61)

(8)

(63)

(20)

(7)

a Brown rice is medium-grain, cooked; white rice is medium-grain cooked, unenriched (USDA, 2001).
b Lowest % bio-availability assumed for iron and zinc (FAO, 2000).

Note: The figures were obtained from raw rice (300 g for a male and 250 g for a female) converted into its cooked equivalent using the conversion factors of 2.63 for brown and 2.32 for white rice. The percentage requirement was calculated for a 19-50-year-old male and a non-pregnant non-lactating 19-50-year-old female using provisional RNI.

Source: Banjong, 1995.

NUTRIENT CONTENT OF RICE

The different layers of rice seed (outer hull, caryopsis, aleurone, subaleurone and endosperm) and the embryo contain differing amounts of nutrients. Dietary fibre, minerals and B vitamins are highest in the bran and lowest in the aleurone layers; the rice endosperm is rich in carbohydrate and contains a fair amount of digestible protein, with an amino acid profile which compares favourably to other grains (Juliano, 1993). Rice is a good source of the B vitamins, thiamine, riboflavin and niacin, but contains little to no vitamin C, D or bcarotene, the precursor of vitamin A. The amino acid profile of rice is high in glutamic and aspartic acids, but low in lysine (Grist, 1986; Juliano, 1993). The main antinutritional factors, most of which are concentrated in the bran, are phytate, trypsin inhibitor, oryzacystatin and haemagglutinin-lectin (Juliano, 1993).

A number of factors influence the nutrient composition of rice, outlined in Figure 2.

Varietal influence on nutrient composition

Intravarietal differences within rice are often overlooked. However, research by the International Rice Research Institute (IRRI) shows that in reality nutrient composition can differ significantly between varieties (Juliano and Villareal, 1993; Chandrasekhar and Mulk, 1970). The protein content of over 2 000 rice varieties was tested at IRRI; it ranged from 4 to 14 percent in Oryza sativa varieties and from 9 to 14 percent in Oryza glaberrima varieties (Table 3). In O. sativa, Asian rice varieties exhibited the greatest overall variation in protein content (4-14%), while South American varieties had the highest average protein content (7.9%).

TABLE 3
Summary by region of protein content in O. sativa and O. glaberrima

Source

Sample
number

Protein
range
(%)

Protein
mean
(%)

Oryza sativa L.




Asia

1 626

4-14

7.8

Australia

24

5-10

6.7

North America

190

4-13

7.2

South America

301

5-13

7.9

Europe

233

5-13

7.0

Africa

300

5-11

7.3

Total

2 674

4-14

7.7

O. glaberrima

195

9-14

12.0

Source: Juliano and Villareal, 1993.

TABLE 4
Iron and zinc content of selected varieties grown in greenhouse conditions

Variety

Iron
(mg/100g)

Zinc
(mg/100g)

Ganjay Roozy

2.64

5.89

Zuchem

2.34

5.10

YR 4194

2.32

5.40

Banjaiman

2.27

5.30

Xue Bue Nuo

2.25

4.66

IR 64446

2.22

5.35

Kinmaze

2.17

5.17

IR 60864

1.50

4.11

Heibao

1.49

3.16

Alan

1.40

3.92

IR 63877

1.31

3.64

IR 74

1.30

3.64

IR 72

1.17

3.25

IR 36

1.01

3.14

Note: Figures are the average of three replications.
Source: Senadhira, Gregorio and Graham, 1998 (adapted).

TABLE 5
Estimates of the quantitative losses of rice for each stage in the post-harvest system in Southeast Asia

Stage

Losses (%)

Min.

Max.

Harvest

1

3

Handling

2

7

Threshing

2

6

Drying

1

5

Storage

2

6

Transport

2

10

Total

10

37

Source: De Lucia and Assennato, 1994.

Since the early 1990s, IRRI in cooperation with the University of Adelaide has been analysing variations in iron and zinc content in different rice varieties. Rice grown under uniform conditions at the IRRI research centre ranged in iron content from 0.75 to 2.44 mg/100 g, with a mean of 1.21 mg/100 g. Zinc content ranged from 1.59 to 5.84 mg/100 g with a mean of 2.54 mg/100 g (Graham et al., 1999). A sample of varieties grown under greenhouse conditions at IRRI is presented in Table 4. Some traditional rice varieties contain two-and-a-half times more iron than commonly grown high-yielding counterparts, while four of the top five varieties richest in iron and zinc are traditional rice varieties and those with the lowest iron and zinc density are the popular, modern high-yielding varieties.

Influence of agricultural factors on nutrient composition

Studies show that agricultural practices can influence the nutrient composition of the rice grain. Controlled experiments have found that soil nitrogen, solar radiation, degree of plant maturation, application of fertilizer and shorter maturation periods all influence protein content (Juliano and Bechtel, 1985; Iwata, 2002; Graham et al., 1999). Iron and zinc content are also influenced by nitrogen application and soil quality (Senadhira et al., 1998).

Influence of post-harvest factors on nutrient composition

Once rice has been harvested, storage, processing, washing and cooking practices can all influence its nutritional quality; nevertheless, post-harvest losses are rarely taken into account in nutritional assessment. Post-harvest losses do not affect the nutrient composition directly, but the magnitude of rice lost during this period can have a profound impact on food security.

Post-harvest losses

Post-harvest loss is defined as a measurable quantitative and qualitative loss in a given product (De Lucia and Assennato, 1994). The loss can occur at any point during harvest, threshing, drying, storage or transport. An estimated 10 to 37 percent of total rice production is lost due to post-harvest factors (Saunders and Betschart, 1979). During harvest, depending on the type of machinery or manpower used, small amounts of the grain are left in the field. Similarly, losses may occur during the drying process, which in developing countries commonly takes place on the roadside. Further losses are incurred during the storage process due to mould, insects and rodents. Estimates from sub-Saharan Africa show that rodents can consume or contaminate up to 20 percent of a stored harvest (FAO, 1994). Estimates of post-harvest rice losses in Southeast Asia are provided in Table 5.

In some regions of Africa and Latin America, postharvest losses of up to 50 percent have been documented. (De Lucia and Assennato,1994); losses of this magnitude can clearly affect food security.

TABLE 6
Energy in 100 g raw and cooked rice

Type of rice

Energy
(kJ/100g)a

Energy
(kcal/100g)a

Brown raw

1 506

360

White raw

1 519

363

Parboiled raw

1 544

369

Brown cooked

498

119

White cooked

456

109

Parboiled cooked

444

106

a Conversion: 1 kcal = 4.184 kJ.
Source: Saunders and Betschart, 1979 (adapted).

Milling

Once harvested, rough rice or paddy rice is dried, either mechanically or in the open air; dried rice is then milled to remove the inedible hull. Hulled rice is also called “brown” rice and its average weight is composed of: 6-7% bran, 90% endosperm and 2-3% embryo (Chen et al., 1998). Further milling and removal of the bran layer gives white rice. On average, paddy rice produces: 25% hulls, 10% bran and 65% white rice (Saunders and Betschart, 1979). Following industrial milling, 100 kg of paddy yields (approx.): 60 kg white rice; 10 kg broken grains; 10 kg of bran and flour; and 20 kg hulls (FAO, 1994).

There are several degrees of milling which can take place, depending on consumer preferences and the degree of whiteness or opacity desired. Milled rice is referred to as “polished” or “whitened” and there are various degrees or fractions of polishing - white rice implies between 8 and 10 percent bran removal. In general, the more rice bran is removed from the grain during polishing, the more vitamins and minerals are lost. Protein loss due to milling is estimated at between 10 and 15 percent (Malik and Chaudhary, 2002).

Parboiling

Prior to milling or storing, rice may be parboiled - a process which involves soaking the rice in warm water, steaming and drying. Parboiling rice prior to cooking preserves some of the nutrient content, as micronutrients are transferred from the aleurone and germ into the starchy endosperm (Juliano and Bechtel, 1985). An analysis of six rice varieties (PR 106, PR 108, PR 109, Pb Bas I, Bas 370 and IR 8) grown in India found the content of thiamine and riboflavin in parboiled rice milled to 6 percent to be higher than in parboiled brown rice, parboiled rice milled to 8 percent, raw brown rice and raw milled rice (Grewal and Sangha, 1990).

Washing and cooking

Washing rice prior to cooking is estimated to lead to losses of: protein (2-7%); potassium (20-41%); thiamine (22-59%); riboflavin (11-26%); and niacin (20-60%) (Juliano, 1993). Losses from washing and cooking methods used in India were calculated as follows: protein (10%); iron (75%); and calcium and phosphorus (50%) (Grist, 1986). Cooking in excess water that is discarded can lead to losses of thiamine (30-50%); riboflavin (25-35%); and niacin (25-50%) (Saunders, 1979). High temperature frying can destroy up to 70 percent of thiamine (Saunders, 1979).

Table 6 compares the nutritional value of equal portions of raw and cooked rice. Rice expands during cooking as water is absorbed: 100 g raw white rice yield approximately 232 g cooked white rice, and 100 g raw brown rice yield 263 g cooked brown rice (Banjong et al., 1995).

Storage

As noted in Table 5, between 2 and 6 percent of rice harvest may be lost during storage as a result of infestation by insects, mould and consumption or contamination by rodents and birds. Parboiling rice has been shown to decrease losses during storage due to insects (Bhattacharya, 1985). Similarly, certain traditional rice varieties have proven to be less vulnerable to attack by insects than are high-yielding varieties (FAO, 1994). Vitamin content, particularly thiamine, has been seen to decrease during rice storage (Juliano et al., 1985); however, the loss of B vitamins during storage was found to be less in parboiled rice (Bhattacharya, 1985).

NUTRITIONAL PROBLEMS IN PREDOMINANTLY RICE-CONSUMING COUNTRIES

The largest nutritional problems occurring both globally and in rice-consuming countries are: protein-energy malnutrition; and iron, iodine and vitamin A deficiency. Millions of children are affected by malnutrition, which contributes to half of the 10 million deaths per year of children under 5 years of age (Shrimpton et al., 2001). Globally, there are 3.5 billion people with iron deficiency, 2 billion at risk of iodine deficiency and millions with clinical manifestation of vitamin A deficiency (ACC/SCN, 2000). The highest prevalence of anaemia and vitamin A deficiency is found in South Asia (Mason et al., 1999) - the result of limited dietary diversity, the strict vegetarian diet of part of the population and unfavourable socio-economic conditions (particularly for women).

The widely accepted UNICEF causal model for malnutrition identifies three underlying causes:

Disease and intake of only a limited range of foods are the two primary factors leading to malnutrition.

Basic indicators, such as life expectancy, infant mortality rate and literacy rates of men and women, provide a reasonable picture of the health and sanitation conditions and of gender equality in a given country. A profile of basic health and living standards in predominately rice-eating countries is given in Table 7. Countries with the best life expectancy and under-five mortality rate include: Japan, Costa Rica, United Arab Emirates and Jamaica. Those with the lowest life expectancy and infant mortality rates are: Sierra Leone, Malawi, Guinea and Côte d’Ivoire. It should be noted that during this assessment period, many of these countries experienced civil unrest.

The greatest progress in reducing the under-five mortality rate has been seen in Malaysia, Republic of Korea, Indonesia, Gambia, Ecuador and Bangladesh, and the least in Cambodia, Sierra Leone, Côte d’Ivoire and Papua New Guinea.

MEASUREMENT OF MALNUTRITION IN CHILDREN

There are three key indicators of childhood growth used to assess the prevalence of malnutrition in children under 5 years of age: “stunting”, “wasting” and “underweight”. Stunting is measured in terms of height for age and is considered a good indicator of chronic malnutrition. Wasting is measured in terms of weight for height and indicates acute malnutrition. Underweight is measured in terms of weight for age and is the indicator most commonly used in growth monitoring programmes. All three indicators are assessed using growth reference curves and include all children falling below an established reference cut-off point. (UNICEF, 2001).

There is a “high” to “very high” prevalence of stunting (30-40%), wasting (10-15%) and being underweight (20-30%) (Dean et al., 1995). The highest rates of prevalence of children suffering from stunting are seen in Korea, Bangladesh, Cambodia and Nepal. In twelve countries, the rate is above 30 percent - considered high. Wasting or acute malnutrition is most severe in Bangladesh, India, Cambodia and Suriname; a total of seven countries show a high to very high rate of wasting. Bangladesh, Cambodia and India have the highest prevalence of underweight children; 16 countries have high to very high prevalence rates.

STRATEGIES TO PREVENT AND ALLEVIATE MALNUTRITION

There are several broad categories of intervention that can alleviate malnutrition. Improvements in the quality of and access to health care, increased literacy rates, access to clean water and higher women’s status all contribute to a fall in the number of malnourished. There are four categories of direct intervention believed to be successful in the reduction of micronutrient malnutrition: supplementation, fortification, dietary diversification and disease reduction (Bouis, 1996). While all of these strategies are important, the remainder of this paper will focus on the potential for improving malnutrition, primarily micronutrient malnutrition through agricultural improvement of rice.

Recently, research has looked towards improving the nutritional status of populations through the improvement of staple crops. While it is understood that a variety of foods are needed to meet nutrient requirements, the rationale for improvement of the nutrient content of staple foods is based upon the premise that staple foods are widely available and affordable for the majority of the world’s population, particularly the poor. Foods naturally rich in micronutrients - i.e. animal products and vegetables - are generally more expensive than staple foods, they are subject to seasonal availability and cannot be stored for long periods. Additionally, the diets of the most economically disadvantaged contain a greater proportion of calories from staple foods; therefore, increasing the micronutrient density of these foods is seen as a strategy for improving their nutritional profile.

TABLE 7
Basic indicators of health and well-being

Country

Life
expectancy
(years)

Under-5 mortality
ratea

Infant
mortality
rateb

% population with improved drinking water source

Adult literacy
ratec

GNP per caput
(US$)d

1999

1999

1999

1995-99

1999

M

F

Bangladesh

59

89

58

97

63

48

370

Brazil

67

40

34

83

86

85

4 420

Cambodia

54

122

86

30

79

58

260

China

70

41

33

75

91

77

780

Costa Rica

76

14

13

98

95

95

2 740

Côte d’Ivoire

47

171

102

77

63

37

710

Dominican Republic

71

49

43

79

82

81

1 910

Ecuador

70

35

27

71

91

86

1 310

Gabon

52

143

85

70

74

53

3 350

Gambia

48

75

61

62

38

24

340

Guinea

47

181

115

48

50

22

510

Guinea-Bissau

45

200

128

49

48

16

160

Guyana

65

76

56

94

99

97

760

Haiti

54

129

83

46

47

42

460

India

63

98

70

88

71

44

450

Indonesia

66

52

38

76

90

78

580

Jamaica

75

11

10

71

69

81

2 330

Japan

80

4

4

n.a.

n.a.

n.a.

32 230

Korea, Republic of

73

5

5

92

99

98

8 490

Lao PDR

54

111

93

90

74

48

280

Liberia

50

235

157

n.a.

36

18

490*

Madagascar

58

156

95

47

50

44

250

Malaysia

72

9

8

95

89

79

3 400

Myanmar

61

112

79

68

88

78

220*

Nepal

58

104

75

81

63

28

220

Panama

74

27

21

87

93

92

2 070

Papua New Guinea

59

112

79

42

81

63

800

Peru

69

52

42

77

96

89

2 390

Philippines

69

42

31

87

94

94

1 020

Senegal

53

118

68

78

43

23

510

Sierra Leone

39

316

182

28

45

18

130

Sri Lanka

74

19

17

83

91

79

820

Suriname

71

34

27

95

95

91

1 660*

Thailand

69

30

26

80

96

92

1 960

United Arab Emirates

75

9

8

n.a.

85

93

17 870

Viet Nam

68

40

31

56

95

88

370

a Probability of dying between birth and 5 years of age expressed per 1 000 live births.

b Probability of dying between birth and 1 year of age expressed per 1 000 live births.

c Percentage of persons aged 15 and over who can read and write.

d Figures marked * refer to years or periods other than those specified, differ from the standard definition, or refer to only part of the country.

Source: UNICEF, 2001.

The proceedings of the Nineteenth Session of the International Rice Commission called for increased emphasis by rice scientists on strategies to combat malnutrition (Swaminathan, 1999). Historically, improvements in rice breeding have focused on increasing the quantity of the food source; however, the importance of the quality of the food source for reducing micronutrient deficiencies is now coming to the forefront (Ruel and Levin, 2000). There is greater recognition of the global prevalence of many forms of micronutrient malnutrition, such as iron, vitamin A and zinc deficiency. Improvements in rice technology include a variety of approaches, namely: enhancing nutritional quality through plant breeding; increasing micronutrient content of the grain through genetic modification; and improving rice fortification techniques.

Breeding for nutritional improvement

As part of an effort to create nutritionally superior cultivars, scientists at IRRI with the collaboration of the University of Adelaide have been systematically documenting the iron and zinc content of hundreds of rice varieties (Graham et al., 1999). This work has led to the identification of varieties with above average levels of iron and zinc. Trials are currently underway to combine the traits of high zinc and iron content with improved yield. The initial focus is on successfully breeding a rice variety containing higher absolute mineral content. The true test of the success of this strategy will be the bio-availability of the increased nutrient content. In order to achieve higher bio-availability, three approaches are possible: i) increase the concentration of the nutrient in the grain; ii) increase the percentage of bio-availability (by decreasing material which inhibits nutrient uptake); and iii) a combination of these two strategies (Graham et al., 1997). The most feasible strategy currently available is to breed a variety with increased nutrient content in the grain. Decreasing the antinutrient content of the grain is not currently recommended due to the crucial role of the antinutritional factors in plant growth (Bouis, 1996).

Similar research at the West Africa Rice Development Association (WARDA) has had success with breeding for specific traits. While not directly aimed at improving the nutrient content of rice, the WARDA project hopes to improve household food security through use of improved rice varieties, by combining the desirable traits of two very different species: Oryza glaberrima and Oryza sativa. The low yield and tendency towards brittle grains of O. glaberrima have led to its increased marginalization in favour of O. sativa varieties native to Asia. These varieties were introduced in Africa, where they were cultivated and popularized due to their high-yielding potential. The drawback to the cultivation of O. sativa varieties in Africa has been their increased susceptibility to pests and diseases, which over the years has led to the application of increasing amounts of pesticides and fertilizers to maintain high yields.

Using conventional and modern techniques, scientists at WARDA were able to combine the beneficial traits of both O. glaberrima and O. sativa. The new varieties are known as “NERICA” (NEw RIce for AfriCA). By combining the beneficial traits of the African and Asian species, NERICAs have potentially higher yields, better resistance to disease and drought and higher protein content than the O. sativa varieties commonly grown in the region (WARDA, 1999).

Genetic engineering for nutritional improvement

Nutritional genomics is a new term referring to a combination of biochemistry, genetics, molecular biology and genome-based technologies to investigate and manipulate plant compounds with nutritional value (Tian and DellaPenna, 2001). This new technology has been applied to rice in two instances: golden rice and iron-enhanced rice.

In the case of golden rice, an entire biosynthetic pathway for beta-carotene was introduced through the use of a technique called agrobacterium-mediated transformation, resulting in rice grains containing a significant amount of previously non-existent carotenoids, the precursors of vitamin A. The most promising experimental line contained 1.6 µg/g carotenoid - evidence that the goal of achieving provitamin intake of 100 µg retinol equivalent from a daily rice intake of 300 g is attainable (Ye et al., 2000). In a similar experiment, again using genetic modification and a ferritin gene from Phaseolus vulgaris, the iron content of rice grains was doubled (Lucca et al., 2000). Furthermore, in order to boost absorption of the iron by humans, a heat-tolerant phytase from Aspergillus fumigatus was engineered into the rice (Lucca et al., 2000). The role of the phytase is to degrade phytic acid which, when present, inhibits iron absorption.

There is hope that these new technologies will translate into improved micronutrient intakes for large segments of the population currently suffering from deficiencies. Questions remain as to the extent to which the increased levels of micronutrient in the grain will increase levels of bio-availability in humans. Likewise, there remain numerous questions regarding the yield, disease resistance and palatability of these new lines.

Fortification of rice

Fortification strategies, particularly those involving fortification with iron, have had varying degrees of success. The fortification of foods with iron remains technically complex. Those iron compounds with the greatest bio-availability (ferrous sulphate and ferrous fumarate) significantly alter the palatability of food, whereas a significant decrease in the uptake of iron is seen when a more palatable iron compound (elemental iron or ferric orthophosphate) is used (Dary, 2001). There are technical, logistical and practical barriers to be addressed in order to achieve a successful fortification programme. The level of technical difficulty encountered in fortification programmes depends on the nutrient to be added. Logistical and practical elements which contribute to a fortification programme’s success include: ensuring supply of and access to the product; monitoring by and support from the government; and consumer knowledge and demand for the product (Maberly, 2000). The involvement of the appropriate industry sector (millers, in the case of rice) is important. Lastly, on a practical level, the enriched product must not only be available, but affordable and palatable.

In the Philippines, one type of fortified rice has successfully undergone consumer acceptability tests. The iron-fortified rice was tested for effectiveness in a clinical trial of 218 school children. After 6 months, the experimental group showed significantly higher mean haemoglobin levels and a significant reduction in the prevalence of anaemia when compared to controls (Florentino, 2001). A government-sponsored programme is supporting the nationwide production and distribution of the iron-fortified rice, and efforts are also underway to improve the technology by reducing the cost and losses associated with the fortification process.

CONCLUSIONS

Rice is a good source of carbohydrates and B vitamins, and thanks to recent technological breakthroughs, it may have the potential to also supply greater amounts of other nutrients. Caution however should be exercised when promoting any single food source. One food, no matter how modified, cannot provide all the necessary nutrients required to maintain good health. In addition to a sufficient dietary supply of energy, protein and fats, adequate nutrition requires the consumption of a wide range of vitamins and minerals. In predominantly rice-based diets, adequate nutrition can only be achieved through the addition of other nutritious foods. Animal foods, such as poultry, meat, fish, eggs and milk, can supply the necessary amounts of protein, fat, vitamins and minerals, particularly vitamin A and iron. Similarly, green leafy vegetables and fruits can provide substantial amounts of vitamin A, vitamin C and iron.

Numerous factors influence the nutrient composition of rice. They may be classified into:

Both agriculture and nutrition scientists should work towards understanding the ways in which nutrient composition is affected and, more importantly, they should work together to optimize the nutrient composition of the final product for consumption. One step towards this goal is to increase awareness in the nutritional and agricultural communities of the factors influencing nutrient composition. Greater documentation of the influence of variety on nutrient composition should be produced and disseminated. All new rice varieties should, at the very least, undergo complete nutrient analysis. This basic information is essential for the assessment of the adequacy of nutrient intake and in order to provide a benchmark for assessing the impact of new varieties.

A large number of people living in predominantly rice-eating countries suffer from various forms of malnutrition. Understanding the causes of malnutrition is the only way to bring about sustained improvements in overall health and well-being. Current advances in rice technology may be able to alleviate the severe malnutrition currently experienced. These advances must also be accompanied by actions which alleviate the core causes of malnutrition, namely, improvements in health care, sanitation and hygiene and education.

REFERENCES

ACC/SCN. 2000. Fourth Report on the World Nutrition Situation. Geneva, ACC/SCN in collaboration with IFPRI.

Banjong, O., Viriyapanich, T. & Chitchang, U. 1995. Handbook for dietary evaluation. Institute of Nutrition, Mahidol University, Thailand.

Bhattacharya, K. 1985. Parboiling of rice. In Juliano, B. ed. Rice chemistry and technology, p. 289-348. St. Paul, MN, USA, American Association of Cereal Chemists.

Bouis, H. 1996. Enrichment of food staples through plant breeding: a new strategy for fighting micronutrient malnutrition. Nutrition Reviews, 54: 131-137.

Chandrasekhar, U. & Mulk, M. 1970. Nutritive value ofhighyieldingricevarieties Jaya, Padma and Hamsa. Indian J. of Nutrition and Dietetics, 7: 240-242.

Chen, H., Siebenmorgen, T. & Griffin, K. 1998. Quality characteristics of long-grain rice milled in two commercial systems Cereal Chemistry, (75)4: 560-565.

Dary, O. 2001. Technical and practical barriers to cereal food fortification (wheat flour, maize flour and rice). In Proceedings of Conference on Forging Effective Strategies to Combat Iron Deficiency, Atlanta, Georgia, 7-9 May 2001.

Dean, A., Dean, J., Coulombier, D., Brendel, K., Smith, D., Burton, A., Dicker, R., Sullivan, K., Fagan, R. & Arner, T. 1995. Epi-Info, Version 6. A word processing database and statistics program for public health on IBM compatible microcomputers. Center for Disease Control and Prevention, Atlanta.

De Lucia, M. & Assennato, D. 1994. Agricultural engineering in development post-harvest operations and management of foodgrains. FAO Agricultural Services Bulletin No. 93, Rome, FAO. Available online at www.fao.org/inpho/vlibrary/t0522e/t0522e00.htm. Accessed 11 May 2001.

FAO. 1994. African experience in the improvement of post-harvest techniques. Synthesis based on the Workshop held in Accra, Ghana, 4-8 July 1994 Agricultural Support Systems Division, Rome.

FAO. 1998. FAO-Nutrition Country Profiles India. Rome.

FAO. 1999. The state of food insecurity in the world. Rome.

FAO. 2000. FAO Rice Information, Vol. 2. Rome.

FAOSTAT. 2001. FAO Statistical Databases. Available online at http://apps.fao.org/. Accessed 2 May 2001.

Florentino, R. Experiences on Rice Fortification in the Philippines. In Proceedings of Conference on Forging Effective Strategies to Combat Iron Deficiency, Atlanta, Georgia, 7-9 May 2001.

Graham, R., Senadhira, D. & Ortiz-Monasterio, I. 1997. A strategy for breeding staple-food crops with high micronutrient density. Soil Science Plant Nutrition, 43: 1153-1157.

Graham, R., Senadhira, D., Beebe, S., Iglesias, C & Monasterio, I. 1999. Breeding for micronutrient density in edible portions of staple food crops: conventional approaches. Field Crops Research, 60: 57-80.

Grewal, P. & Sangha, J. 1990. Effect of processing on thiamine and riboflavin contents of some high-yielding rice varieties of Punjab. J. Food Sci Technol., 52:387-391.

Grist, D.H. 1986. Rice (6th edition). Singapore, Longman Singapore Publishers. 599 pp.

Iwata, T. 2002. Breeding, production physiology and quality of the famous Japanese rice variety Koshihikari. In Specialty rices of the world: breeding, production and marketing, p. 243-248.

Juliano, B. & Bechtel, D. 1985. The rice grain and its gross composition. In Juliano, B. ed. Rice: chemistry and technology (2nd edition), p. 17-58. Minnesota, USA, American Association of Cereal Chemists.

Juliano, B.O. 1993. Rice in human nutrition. Rome, FAO. 162 pp.

Juliano, B.O. & Villareal, C.P. 1993. Grain quality evaluation of world rices. Manila, Philippines, IRRI. 205 pp.

Lucca, P., Wunn, J., Hurrell, R. & Potrykus, I. 2000. Development of iron-rich rice and improvement of its absorption in humans by genetic engineering. J. of Plant Nutrition, 23: 1983-1988.

Malik, S. & Chaudhary, P. 2002. Non-conventional tools in the improvement of aromatic rices. In Specialty rices of the world: breeding, production and marketing, p. 207-222.

Maberly, G. 2000. Salt 2000: prospects for global elimination of iodine deficiency disorders. Manila Forum 2000: Strategies to Fortify Essential Foods in Asia and the Pacific. Manila, Philippines, ADB.

Mason, J., Hunt, J., Parker, D. & Jonsson, U. 1999. Investing in Child Nutrition in Asia Asian Development Review, 17: 1, 2.

Popkin, B., Keyou, G., Fengying, Z., Guo, X., Haijiang, M. & Zohoori, N. 1993. The nutrition transition in China: a cross-sectional analysis. European J. of Clinical Nutrition, 47: 333-346. Ruel, M. & Levin, C. 2000. Assessing the potential for food-based strategies to reduce vitamin A and iron deficiencies: a review of recent evidence. International Food Policy Research Institute (IFPRI) and MOST, the USAID Micronutrient Project.

Saunders, R. & Betschart, A. 1979. In Inglett, G.E. & Charalambous, G. eds. Tropical foods: chemistry and nutrition, p. 191-216. NY, USA, Academic Press.

Senadhira, D., Gregorio, G. & Graham, R. 1998. Paper presented at the international Workshop on Micronutrient Enhancement of Rice for Developing Countries, 3 Sept., Rice Research and Extension Center, Stuttgart, AK.

Shrimpton, R., Victora, C., de Onis, M., Costa Lima, R, Blössner, M. & Clugston, G. 2001. Worldwide timing of growth faltering: implications for nutritional interventions. Pediatrics, May 107(5): E75.

Swaminathan, M.S. 1999. Issues and challenges in sustainable increased rice production and the role of rice in human nutrition in the world. Proceedings of the Nineteenth Session of the International Rice Commission-Assessment and Orientation towards the 21st century, p. 7-17. Rome, FAO.

Tian, L. & DellaPenna, D. 2001. The promise of agricultural biotechnology for human health. Meeting report on the Keystone Symposium “Plant foods for human health: Manipulating plant metabolism to enhance nutritional quality”.

UNICEF. 1999. State of the world’s children 1999. United Nations Children’s Fund, NY, USA, Oxford University Press.

UNICEF. 2001. State of the world’s children 2001. United Nations Children’s Fund. Available online www.unicef.org/sowc01. Accessed 2 May 2001.

USDA, Agricultural Research Service. 2001. USDA National Nutrient Database for Standard Reference, Release 14. Nutrient Data Laboratory Home Page, http://www.nal.usda.gov/fnic/foodcomp.

USDA, Agricultural Research Service. 1999. USDA Nutrient Database for Standard Reference, Release 13. Nutrient Data Laboratory Home Page, http://www.nal.usda.gov/fnic/foodcomp.

WARDA. 1999. Rice Interspecific Hybridization Project: Research Highlights 1999. WARDA, Bouaké, Côte d’Ivoire.

Ye, X., Al-Babili, S., Kloti, A., Zhang, J., Lucca, P., Beyer, P. & Potrykus, I. 2000. Engineering the provitamin A (b carotene) biosynthetic pathway into (carotenoid-free) rice endosperm. Science, 287: 303-305.


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