0808 Rice as a Source of Nutrition and Health

Presenter: Marguerute Uphoff, MD, MPH

IV International Rice Meeting, Havana

1. RICE AS A SOURCE
OF NUTRITION
AND HEALTH
Marguerite Uphoff, MD, MPH
IV. International Rice Meeting
Havana, June 2-6-2008

2. Rice is the staple food
for more than half of
the world’s population
Worldwide, rice provides 20% of total human energy
Rice consumption varies by region -- annual per
capita consumption of rice ranges from 60 kg to 220
kg in Asian countries, to 12 kg per capita in North
America
Rice consumption also varies by income --
dependency on rice is very high among poor people,
in parts of Asia rice provides 50 to 80% of all the
calories of poor households
In Central America and Cuba, rice provides 5 to 10%
of total dietary energy

3. Rice is more than a
source of energy
the major source of energy, but also
the major source of protein, and
a significant source of fiber and of
essential micronutrients
When rice is a large proportion of the diet,
and when the diversity of the diet is limited,
as is true for many living in poverty, rice is:

4. How to make rice
count for nutrition
Use of all of the nutrients that are in
the rice grain
Choose the most nutritious varieties
–traditional cultivars
–conventional breeding
–transgenic engineering
Harness better cultivation techniques
to enhance nutritional value

5. 1. Using all the nutrients:
Grain composition and nutrition
Hull (Husk)—
removed and
discarded in initial
milling
Bran: Pericarp,
Aleurone, Embryo
—removed in
further milling and
polishing
Endosperm: the
white rice that
remains after
milling and
polishing.

6. Milling and polishing:
loss of nutritional value
White rice – milled and polished grains
–contains about 90-94% carbohydrates
–contains 6-10% protein
–contains no significant vitamins or minerals
Brown rice – minimally milled grains
–retains the bran -- pericarp, aluerone, and
endosperm
–contains about 75-85% carbohydrates
–richer than white rice in protein, lipids, fiber,
and vitamins and minerals

7. Bran is the key to
improving rice’s
contribution to
nutrition and health
All rice lipids are in the bran
Rice bran oil has some unique qualities
–80% of the lipids in rice bran are polyunsaturated
fatty acids
–High levels of polyunsaturated fatty compounds
are effective in lowering blood cholesterol levels.

8. Even a little Vitamin E
is beneficial for health
–Rice bran oil is a rich available source
of vitamin E -- which consists of
tocopherols and tocotrienols
–Tocotrienols decrease the synthesis of
cholesterol by inhibiting the activity of
HMG-CoA reductase, an enzyme
involved in cholesterol biosynthesis
–Tocotrienols have been shown to
decrease LDL – the “bad” cholesterol --
by 42-62% in animal studies -- and in
human studies by 20%

9. Rice bran also has value
for its lipid fraction
–Rice bran oil contains linoleic acid, an
essential fatty acid that must be obtained
from the diet because the human body
cannot synthesize it
–Linoleic acid is important for many cell
functions but particularly important for the
brain’s development.

10. Brown rice lowers the
grain’s glycemic index
Brown rice has a lower glycemic index
because it is digested more slowly than
white rice – this is important for diabetes
–Fat content in the bran slows the emptying
of the stomach and also the hydrolysis and
absorption of starch
–Fiber content in the bran slows emptying
time of the stomach

11. Brown rice can help
lower blood pressure
–Brown rice diets have been known for
many years to be effective in reducing
hypertension.
–Rice bran has recently been shown to
decrease hypertension via inhibition of
an angiotensin-1 converting enyzme
(ACE inhibitor).

12. Brown rice contributes
to antioxidants
The micronutrients manganese, selenium and
magnesium are found almost entirely in the
bran of rice
One cup (195 grams) of cooked brown rice can
provide
–66% of the daily requirement of manganese
–27% of the daily requirement of selenium
–20% of the daily requirement of magnesium
These micronutrients facilitate the synthesis of
certain antioxidant enzymes that are protective
for the prevention of cancer and inflammatory
processes, including arteriosclerotic disease

13. Other benefits of
consuming the whole
grain
Eating whole grains such as brown rice
is linked in many studies to protection
against :
–Coronary artery disease and stroke
–Obesity
–Insulin resistance (pre-diabetes)
–Type II diabetes (adult-onset diabetes)
–Celiac disease (gluten intolerance)

14. Intriguing studies
Asthma: One Dutch study found that the
probability of having asthma with bronchial
hyper-responsiveness was significantly less
in children who had a high intake of whole
grains
Gastrointestinal cancer: A British study of
gastrointestinal adenoma found that daily
consumption of a high dose of stabilized rice
bran was associated with an average
reduction of 51% in the number of
precancerous adenomas in the intestinal
tract

15. 2. Choosing the most
nutritious varieties
Benefits from traditional cultivars
–A study of Philippine landraces (traditional
cultivars) demonstrated average lipid content
to be significantly higher than in HYVs collected
in the same area – 2.1% for HYVs compared
with up to 3.2% for some landrace varieties
–Some landraces had a linoleic acid content of
almost 1% of the total grain so that 200 grams
of such rice could supply half of an adult’s daily
requirement

16. Traditional cultivars
and protein quality
Some landraces in the Philippines have
protein content up to 14%; one Chinese
long-grain rice has been reported with a
16% protein content
Average protein content of HYVs is 6-11%
American and Indian rice breeders recently
announced a hybrid with 12.4% protein.

17. Traditional cultivars
and micronutrients
Commercial varieties of rice usually contain
about 2 mg/kg of iron
Some selected Philippine varieties contain
more than 5 mg/kg of iron
Certain colored traditional rice varieties in
Philippines have 63.5 mg/kg iron.
Some highly-colored landraces in Philippines
and Malaysia can contribute most, but not all,
of a person’s daily requirement of vitamin A
precursors
Remember: iron like other nutrients is in bran!

18. Bio-engineering nutrition
An transgenic rice has been developed
which is iron-rich
– It has an iron content of 38 mg/kg
–This iron is stored as iron-ferritin in the
endosperm
Therefore, it is in principle more bio-
available and is not lost with milling

19. Bio-engineered Iron-
Rich Rice
–The grain has been engineered to have
lower phytate levels
Phytates interfere with iron absorption
–The grain also has a metallothionein-like
protein that enhances iron absorption

–However, field testing and human
absorption studies have yet to be done

20. Golden Rice
Golden Rice is a transgenic engineering
accomplishment that has been heralded in
the popular media as a means of combating
vitamin A deficiency.
Ingo Potrykus from Zurich and Peter Beyer
of Freiburg developed a biosynthetic
pathway that expressed beta carotene in
the rice endosperm.
The first Golden Rice (GR1) developed in
1999 contained 1.6 micrograms of beta
carotene per gram
–This was an order of magnitude more
than most rice but still a small contribution
toward the daily requirement.

21. Golden Rice
GR2, developed in 2005, produces up to
37 micrograms of beta carotene per gram
of milled rice
–This amount theoretically could meet the
daily requirement of someone whose
primary source of dietary energy was rice.
However, how well the carotenoids in
Golden Rice will be converted to vitamin A
in the intestinal tract -- and absorbed into
the blood stream -- has yet to be studied.

22. Golden Rice
Golden Rice may make a significant
contribution to alleviating vitamin A
deficiency diseases
But the contribution of Golden Rice to
human nutrition and health will not be
available for a number of years

23. 3. Modifying cultivation
to improve nutrition
Cultivation practices and environmental
circumstances have been shown to
affect the total protein content of rice
Some factors that increase the protein
content of rice are:
wider spacing
border effects
response to nitrogen fertilizer
various stresses

24. Cultivation practices affect the biological
value (BV) of the rice protein
–BV reflects the completeness of the set of amino
acids that the body needs for protein synthesis
A Bulgarian research project demonstrated
that application of nitrogen-phosphorus
fertilizer increased yield and total protein
–But this protein had a lower biological
value because of the relative decrease in
various essential amino acids: Lysine,
Arginine, Threonine, Valine, Leucine and
Isoleucine – by 5 to 24%
The effect of fertilizer application on amino
acid composition of the rice protein varied
among the cultivars evaluated
Biological Value of protein

25. Cultivation affects BV
A study in Japan showed that application
of nitrogen fertilizer changed the free
amino acid composition of brown rice
 The total amount of some free amino
acids (glutamic acid, aspartic acid,
asparagine, glutamine and alanine)
was higher in grain produced without
application of nitrogen fertilizer

26. The BV of rice protein
makes a difference
Study of nitrogen balance in poor children in
Peru compared high-protein rice (11.4%
protein) diet with conventional rice (7.1%
protein) diet:
–Children on the high-protein rice diet
retained more nitrogen in their bodies
than with the lower-protein rice diet, but
–Less nitrogen was retained per gram of
ingested N for high-protein rice compared
with the lower-protein rice, indicating that
the high-protein rice had lower BV

27. Rice can contribute more to
health and nutrition if we:
–Consume whole grain rice --
do not discard the most
nutrient-rich part, the bran!

28. Rice can contribute more to
health and nutrition if we:
–Utilize the best available varieties
in terms of their nutritional value:
Select and protect a biodiverse
set of existing cultivars that
provide positive nutritional benefit,
and

Continue the breeding and
development of promising
new cultivars

29. Rice can contribute more to
health and nutrition if we:
–Learn more about how
alternative cultivation
practices affect the
nutrient qualities of rice,
e.g. SICA

30. References for “Rice as a
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31. References for “Rice as a
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