tyw
Member
@redred and @Westside PUFAs -- Regarding the Arsenic Issue
To begin, while I like rice from a taste and nutrition perspective, the risks of Arsenic are real. (and yes @Such_Saturation , this is a modern phenomena
)
It's clear that Rice will uniquely concentrate arsenic found in the environment. This makes it very difficult to assess actual risk of arsenic from rice, since where your rice comes from leads to very large variations in arsenic content. More on this later.
To be specific, the arsenic that we are really concerned with is inorganic arsenic (anything with Arsenic not attached to Carbon). Rice is known to concentrate these inorganic compounds in various parts of the plant.
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Brown rice is still the worst offender; most of the arsenic is found in the husk. Details here: http://dspace.lib.kanazawa-u.ac.jp/dspace/bitstream/2297/7368/1/TE-PR-HASEGAWA-H-942.pdf
ie: white rice has half the arsenic content of brown rice.
Suboptimal cooking methods and contaminated drinking water are the culprits in the areas most affected by Arsenic poisoning.
Methods like soaking the rice in arsenic-free water prior to cooking will probably cut out some Arsenic. Some claims are on the order of 20-30%. The mechanism will probably be the same as this research, though less extreme (those researchers cooked the rice in a coffee percolater) -- Rethinking Rice Preparation for Highly Efficient Removal of Inorganic Arsenic Using Percolating Cooking Water
In any case, rinsing / soaking rice in the traditional Asian method is probably preferable.
----
Populations where Arsenic toxicity is a real threat
Regarding the very high arsenic consuming populations -- : http://dspace.lib.kanazawa-u.ac.jp/dspace/bitstream/2297/2866/1/TE-PR-HASEGAWA-H-01.pdf
Note the concentration of arsenic, which is at least 3x higher than averages elsewhere in the world (values cited after this section). This is an environment issue that will vary in severity from location to location
These particular populations are at more Arsenic risk from their drinking water. The high arsenic-concentrating ability of rice makes this even worst.
In most high-rice-consuming populations though (eg: China), the Rice is the bigger factor -- BMC Public Health
----
"Normal" Population Exposure
If you want to compare these values to other populations:
+ European Adult 0.14 to 0.64 μg/kg b.w. per day => if you are 70kg, that is 0.009mg to 0.045mg per day -- http://www.efsa.europa.eu/sites/default/files/scientific_output/files/main_documents/3597.pdf
+ Japanese Adults "total daily InAs intake of adults (21 μg/person/day on a bioaccessible-fraction basis and 24 μg/person/day on a content basis)". That's 0.021 mg per day -- Inorganic arsenic in the Japanese diet: daily intake and source. - PubMed - NCBI
ie: We're talking about huge variations in Arsenic consumption in the most vulnerable regions.
If we're talking about what is a realistic upper limit, say you eat 500g (raw) of Rice (which is a large amount of rice => something like 380g carbs and 1800kcal)
Say that rice is grown in Thailand -- Total and inorganic arsenic in rice and rice bran purchased in Thailand. - PubMed - NCBI . That's an average of 76 nano-gram of Inorganic Arsenic per gram of rice, and therefore 76 * 500 = 38,000 ng = 0.038 mg. We are actually within the realm of "normal European consumption".
Say that rice is grown in Australia -- Assessment of arsenic in Australian grown and imported rice varieties on sale in Australia and potential links with irrigation practises and soil g... - PubMed - NCBI . The average is 0.22mg of Inorganic Arsenic per Kilogram in the short rain varieties. 500g of rice means 0.11mg of inorganic Arsenic. That's more than double the high value we see in European populations.
Clearly we see a different depending on source. This research shows a 7-fold difference in Arsenic levels around the world -- http://pubs.acs.org/doi/abs/10.1021/es802612a
IMO, a 7-fold difference is the difference between "no issue at all", and "toxic in the long run".
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Detox
None of the above even takes into account how efficiently Arsenic is removed via the methylation system in a particular individual.
There will be too many factors to consider here, like genetic propensity toward under- or over-methylation. existing state of liver stress, how much fat and protein are in the diet (both of which compete for methylation), etc .....
We also have no clue as to how well the body can get off already stored Arsenic.
Note that these concerns apply generically to all toxins, and not just arsenic
----
But against these unknowns, we can definitely say that at least in the case of Arsenic, less is probably better.
If you're really concerned about levels of Arsenic, and/or get rice from an area that is arsenic contaminated (do your own research here), then you may choose to avoid rice.
Me personally, I don't really bother. I get varying quantities of Thai sticky rice (and not Aussie rice), buy local root tubers whenever I can (they are available year round), avoid all the other offending arsenic containing items (eg: seaweeds and other grains), and work toward growing my own sweet potatoes one day . My consumption range would probably still be in the "normal" range.
.....
To begin, while I like rice from a taste and nutrition perspective, the risks of Arsenic are real. (and yes @Such_Saturation , this is a modern phenomena
)Sidenote: if you ask me what the "Ideal Starches" are, I'd say properly cooked Sweet Potatoes and Yams any day . I'd love to an isolated farm, and grow sweet potatoes and yams year-round.
. I'd love to an isolated farm, and grow sweet potatoes and yams year-round.It's clear that Rice will uniquely concentrate arsenic found in the environment. This makes it very difficult to assess actual risk of arsenic from rice, since where your rice comes from leads to very large variations in arsenic content. More on this later.
To be specific, the arsenic that we are really concerned with is inorganic arsenic (anything with Arsenic not attached to Carbon). Rice is known to concentrate these inorganic compounds in various parts of the plant.
-----
Brown rice is still the worst offender; most of the arsenic is found in the husk. Details here: http://dspace.lib.kanazawa-u.ac.jp/dspace/bitstream/2297/7368/1/TE-PR-HASEGAWA-H-942.pdf
Arsenic concentrations in parboiled and non-parboiled brown rice of BRRI dhan28 were 0.8±0.1 and 0.5±0.0 mg kg-1 dry weight, respectively while those of BRRI hybrid dhan1 were 0.8±0.2 and 0.6±0.2 mg kg-1 dry weight, respectively.
However, parboiled and non-parboiled polished rice grain of BRRI dhan28 contained 0.4±0.0 and 0.3±0.1 mg kg-1 dry weight of arsenic, respectively while those of BRRI hybrid dhan1 contained 0.43±0.01 and 0.5±0.0 mg kg-1 dry weight, respectively
However, parboiled and non-parboiled polished rice grain of BRRI dhan28 contained 0.4±0.0 and 0.3±0.1 mg kg-1 dry weight of arsenic, respectively while those of BRRI hybrid dhan1 contained 0.43±0.01 and 0.5±0.0 mg kg-1 dry weight, respectively
ie: white rice has half the arsenic content of brown rice.
Suboptimal cooking methods and contaminated drinking water are the culprits in the areas most affected by Arsenic poisoning.
Methods like soaking the rice in arsenic-free water prior to cooking will probably cut out some Arsenic. Some claims are on the order of 20-30%. The mechanism will probably be the same as this research, though less extreme (those researchers cooked the rice in a coffee percolater
) -- Rethinking Rice Preparation for Highly Efficient Removal of Inorganic Arsenic Using Percolating Cooking WaterIn any case, rinsing / soaking rice in the traditional Asian method is probably preferable.
----
Populations where Arsenic toxicity is a real threat
Regarding the very high arsenic consuming populations -- : http://dspace.lib.kanazawa-u.ac.jp/dspace/bitstream/2297/2866/1/TE-PR-HASEGAWA-H-01.pdf
Note the concentration of arsenic, which is at least 3x higher than averages elsewhere in the world (values cited after this section). This is an environment issue that will vary in severity from location to location
The average daily consumption of rice by an adult Bangladeshi male/female is between 400 and 650 g raw rice (Duxbury et al., 2003) and the average concentration of arsenic in raw rice was found to be 0.57±0.04 - 0.69±0.21 mg/kg in the present experiment. Thus, the expected daily intake of arsenic from raw rice has been estimated to be 0.25 - 0.36 mg
However, the actual intake would be much higher than the expected value because of the use of arsenic contaminated water in rice cooking and also because of traditional cooking method.
From this experiment, it was found that the cooked rice contained higher concentrations of arsenic than that of raw rice and the actual daily intake of arsenic from cooked rice was found to be 0.16 - 0.26 mg when the rice is cooked with excess arsenic contaminated water and the gruel is discarded after cooking (0.13 mg/l was the arsenic concentration in drinking and cooking water of the experimental area) though the value was be 0.36 - 0.56 mg when the rice is cooked with limited water and gruel is not discarded.
Watanabe et al. (2004) estimated that rice grain containing 173 ng of As/g may exposed 90 and 52 µg of arsenic/day to an adult male and female, respectively if they intake 523 and 300 g raw rice, respectively.
In the present report, the mean arsenic concentration in Shallow Tube Well’s (STW) water of arsenic contaminated area, which has been used as drinking as well as cooking purposes, is recorded as 0.13 mg/l (n=6). The concentration is much higher than the acceptable limit for arsenic in drinking water according to WHO standard (0.01 mg/l) and Bangladesh standard (0.05 mg/l). Thus, when the arsenic concentration in drinking water is 0.13 mg/l, as we found in the present study, a Bangladeshi adult is expected to intake 0.50 to 0.78 mg of arsenic/day only from drinking water
However, the actual intake would be much higher than the expected value because of the use of arsenic contaminated water in rice cooking and also because of traditional cooking method.
From this experiment, it was found that the cooked rice contained higher concentrations of arsenic than that of raw rice and the actual daily intake of arsenic from cooked rice was found to be 0.16 - 0.26 mg when the rice is cooked with excess arsenic contaminated water and the gruel is discarded after cooking (0.13 mg/l was the arsenic concentration in drinking and cooking water of the experimental area) though the value was be 0.36 - 0.56 mg when the rice is cooked with limited water and gruel is not discarded.
Watanabe et al. (2004) estimated that rice grain containing 173 ng of As/g may exposed 90 and 52 µg of arsenic/day to an adult male and female, respectively if they intake 523 and 300 g raw rice, respectively.
In the present report, the mean arsenic concentration in Shallow Tube Well’s (STW) water of arsenic contaminated area, which has been used as drinking as well as cooking purposes, is recorded as 0.13 mg/l (n=6). The concentration is much higher than the acceptable limit for arsenic in drinking water according to WHO standard (0.01 mg/l) and Bangladesh standard (0.05 mg/l). Thus, when the arsenic concentration in drinking water is 0.13 mg/l, as we found in the present study, a Bangladeshi adult is expected to intake 0.50 to 0.78 mg of arsenic/day only from drinking water
These particular populations are at more Arsenic risk from their drinking water. The high arsenic-concentrating ability of rice makes this even worst.
In most high-rice-consuming populations though (eg: China), the Rice is the bigger factor -- BMC Public Health
Sidenote: Commercial Apple and Grape Juice is claimed to contain some inorganic arsenic -- Arsenic in Juice | Apple and Grape Juice Arsenic Levels - Consumer Reports
That report claims a wide range of 1ppb to 25ppb in some grape juices. "ppb" means "parts per billion", ie: nano-grams / kg. So lets say you drink one liter of a 10 ppb apple juice --> that's 10 nanograms of arsenic. ie: Not a big risk if you ask me.
That report claims a wide range of 1ppb to 25ppb in some grape juices. "ppb" means "parts per billion", ie: nano-grams / kg. So lets say you drink one liter of a 10 ppb apple juice --> that's 10 nanograms of arsenic. ie: Not a big risk if you ask me.
----
"Normal" Population Exposure
If you want to compare these values to other populations:
+ European Adult 0.14 to 0.64 μg/kg b.w. per day => if you are 70kg, that is 0.009mg to 0.045mg per day -- http://www.efsa.europa.eu/sites/default/files/scientific_output/files/main_documents/3597.pdf
+ Japanese Adults "total daily InAs intake of adults (21 μg/person/day on a bioaccessible-fraction basis and 24 μg/person/day on a content basis)". That's 0.021 mg per day -- Inorganic arsenic in the Japanese diet: daily intake and source. - PubMed - NCBI
ie: We're talking about huge variations in Arsenic consumption in the most vulnerable regions.
If we're talking about what is a realistic upper limit, say you eat 500g (raw) of Rice (which is a large amount of rice => something like 380g carbs and 1800kcal)
Say that rice is grown in Thailand -- Total and inorganic arsenic in rice and rice bran purchased in Thailand. - PubMed - NCBI . That's an average of 76 nano-gram of Inorganic Arsenic per gram of rice, and therefore 76 * 500 = 38,000 ng = 0.038 mg. We are actually within the realm of "normal European consumption".
Say that rice is grown in Australia -- Assessment of arsenic in Australian grown and imported rice varieties on sale in Australia and potential links with irrigation practises and soil g... - PubMed - NCBI . The average is 0.22mg of Inorganic Arsenic per Kilogram in the short rain varieties. 500g of rice means 0.11mg of inorganic Arsenic. That's more than double the high value we see in European populations.
Clearly we see a different depending on source. This research shows a 7-fold difference in Arsenic levels around the world -- http://pubs.acs.org/doi/abs/10.1021/es802612a
IMO, a 7-fold difference is the difference between "no issue at all", and "toxic in the long run".
-----
Detox
None of the above even takes into account how efficiently Arsenic is removed via the methylation system in a particular individual.
There will be too many factors to consider here, like genetic propensity toward under- or over-methylation. existing state of liver stress, how much fat and protein are in the diet (both of which compete for methylation), etc .....
We also have no clue as to how well the body can get off already stored Arsenic.
Note that these concerns apply generically to all toxins, and not just arsenic
----
But against these unknowns, we can definitely say that at least in the case of Arsenic, less is probably better.
If you're really concerned about levels of Arsenic, and/or get rice from an area that is arsenic contaminated (do your own research here), then you may choose to avoid rice.
Me personally, I don't really bother
. I get varying quantities of Thai sticky rice (and not Aussie rice), buy local root tubers whenever I can (they are available year round), avoid all the other offending arsenic containing items (eg: seaweeds and other grains), and work toward growing my own sweet potatoes one day . My consumption range would probably still be in the "normal" range......
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