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Is potliquor bane or blessing? A question of arsenic in brown rice and Oxalic acid in greens...  RSS feed

 
Jason Padvorac
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Location: Northeast of Seattle, zone 8: temperate with rainy winters and dry summers.
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For a while now I've been cooking my rice using the pasta method - boil in a lot of water and then drain the potliquor - because that reduces the arsenic levels. Awesome.

Also, I have heard that when cooking things like collard greens, you should discard the water it was boiled in as a convenient way to reduce intake of oxalic acid. Cool.

I just (belatedly) had a light bulb moment. The reason boiling and discarding the water leaches out undesirables is that it leaches out *everything*. Duh. That is why for a long time potliquor was prized, was because it had all the nutrition. I'm not removing the arsenic from the brown rice -- I'm removing everything that could be water soluble. So yes, I'm reducing arsenic exposure, but at the same time I'm sliding the rice on the scale from brown towards white. Identical thought with the collards.

So, what do you all think? Is arsenic a big enough problem in brown rice to discard the goodies along with it? And oxalic acid in greens?
 
r ranson
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Location: Left Coast Canada
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I didn't know about arsenic in brown rice. I'm off to google this. Neat. It looks like rice grown in different parts of the world have different concentrations of this toxin.

When I make rice, I wash the rice very well, like they do in Asia. Swish the grains around in the water with my hands, rinse, swish again, massage rice, swish, rinse, repeat until the water is completely clear. This takes a couple of minutes, but I feel it's worth it. Not only does the rice not boil over, it also drastically improves the taste and texture. I wonder if this reduces contaminants. Some people soak their rice overnight then rinse it. Maybe this is enough to leach out some of the water soluble toxins.

Because I'm on a low fibre diet, I like to mix the brown and white rice together. I found this slightly polished brown rice that cooks the same rate as white. I mix 1 part brown, 3 parts white. I'm still getting the nutritional information from the brown rice, but with less fibre. Maybe something like this would help if there is concern about where the rice comes from.
 
Mira Morse
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Location: Mariposa, California, USDA zone 7b
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In her "Nourishing Traditions" cookbook, sally fallon talks about how various ancient cultural groups skim the foam off the top of boiling food because the foam contains the poisons. I never really noticed the foam that is produced when I am making things like soup until after reading that. It is pretty easy to skim the foam off.
 
Joseph Lofthouse
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I worked as a analytical chemist for 20 years... I extracted a lot of plant tissues for testing. It's not all or nothing. Boiling in water may extract some of the more soluble and accessible chemicals from a plant, but it doesn't extract them all. It doesn't even completely extract the highly water soluble ones. Our protocols in the lab generally required 3 changes of water to get as much as we could out of the plant.

In my own case, I find the taste of oxalic acid to be very distasteful. So I'm more than willing to sacrifice some water soluble vitamins in order to get that taste out of my food. There are plenty of nutrients in every plant that I eat which are not water soluble. I let my taste be my guide... I love pot-liquor from boiled corn. I really dislike it from chard.
 
Dan Boone
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I come from a part of the world (interior Alaska) where the natural background levels of arsenic in groundwater (well water) and surface water (streams and rivers) are higher than the EPA standards for drinking water -- sometimes much higher. This gives municipal water treatment utilities absolute fits in Alaska's few towns large enough to provide public water; it also means it can be technically illegal to fill a bucket from your kitchen sink tap and then dump that bucket into the stream at the bottom of your yard -- because your drinking water is technically a pollutant, even though there might be less arsenic in it than there is in the natural background of the stream you're dumping it into.

So, basically everybody I ever knew spent their entire lives drinking arsenic-laced drinking water, and yet there's little notion (based on epidemiological studies or any other medical observation) of actual health problems ever having been suffered from Alaskan drinking water. Like most potential toxins, with arsenic the dose matters. And the regulatory standards are conservative. EPA acknowledges no safe level of the stuff, which basically means they are using a homeopathic standard: they believe, or at least they fear, that even a single atom (or molecule of an arsenical compound) can have a toxic (or more likely carcinogenic) effect. How likely you think that is to be true is a personal risk-management decision; science cannot currently answer it for you.

How do arsenic levels in rice compare with the natural-background levels of arsenic in interior Alaska? There's probably no rigorous scientific way to even phrase that question, much less answer it. However, Consumer Reports says they found rice with enough arsenic in it that one serving of rice contained as much arsenic as the water you would drink in a day and a half at EPA's drinking water standard. So eating rice once every day and a half is roughly comparable to using tap water as your sole drinking water source -- or at least that's how I parse the risks.

There's an interesting document here that may help you parse the risks. It's from the water department in Anchorage, Alaska, and it's talking about an area where local residents have drinking water wells averaging 89 ppb (parts per billion) of arsenic. It tries to answer the question of whether that level (which is nine times the 10 ppb level that EPA allows in drinking water) is harmful to human health. And it's clear that they don't know the answer. Instead what they do is reference the only documented long-term medical effects of arsenical drinking water that they have (from Taiwan and South America) where drinking water levels are said to be "higher" than the 89 ppb in question. But they do not say how much higher. (I think I remember seeing that research back when I was working on this stuff professionally, and I am remembering hundreds or thousands of ppb. But I could so easily be wrong.) Thus, if we sort of round things to single significant digits and summarize things implied but not stated, the bottom line is that eating rice every day is in the same order of magnitude of risk as drinking tap water. And we've got populations in Anchorage whose water is roughly ten times worse than the EPA standard (which would make it in the same order of magnitude as eating ten services of rice a day) and no evidence that they came to any harm. But we know that if we go up another order of magnitude in drinking water, then they can document a bunch of cancers from it. So it's pretty clearly a bad idea to eat fifty or a hundred servings of rice a day.

Further complicating all of this is the number of different chemical compounds that arsenic forms. Each one of them has a different bioavailability, and probably thus a different degree of uptake in plants. What's more, toxicity and carcinogenicity is not well-documented for each distinct arsenical compound. So there's no real way to know if the arsenic in your rice (or your drinking water) is one of the bad ones or one of the less-bad ones. I tend to have a bias toward the notion that the compounds that get cycled through plant systems are less likely to be harmful than the ones plants won't touch, but I freely admit this is most likely a superstitious notion on my part.

Very long winded way of saying: "No, I don't worry about arsenic in my rice." I don't wash my rice. I also don't throw out any pot liquors. I don't much enjoy greens, but the ones I do eat go into soups and stews, so nothing gets washed or leached away in the cooking process.


 
Dave de Basque
Posts: 129
Location: Basque Country, Spain-42N lat-Köppen Cfb-Zone8b-1035mm/41" rain: 118mm/5" Dec., 48mm/2" July
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I would love to see links to folks that really know their stuff about both of these issues, especially if they're on the permie wavelength at all.

I also had never heard of the arsenic in brown rice issue before. Is the concentration high enough to worry about? Maybe it can be, I found an article over at Dr. Mercola's that says high levels have been found in well water, apple juice, rice, chicken and processed baby food. Maybe most of us permies can be relied on to avoid the last one, but the rest will catch a lot of us. Apparently there is "inorganic arsenic" in a lot of commercial (non-organic) animal feed, contributing to the chicken problem, so maybe free-range permies are safe? He has loads of articles on his site related to arsenic and I'm just scratching the surface.

I may need to educate myself about oxalic acid too. It seems the main danger is kidney stones (though this seems like it's not really the main factor). Is that right? However, at least according to Dr. Merc, if you drink a lot of (non-fluoridated) water and follow a few more pretty basic health guidelines I bet a lot of permies follow (avoid sugar and soda, exercise, eat modestly, etc. -- you know the drill), then we can still have our raw leafy greens! And avoid the Catch-22 of having to cut out the healthiest foods in order to avoid health problems.

I wonder if drinking (uncontaminated!) water also helps with the arsenic thing?

I like to think that by generally eating an uncontaminated (as much as possible), varied and healthy diet, generally sticking to the lowish end of the food chain, and making the obvious lifestyle choices, I will stay on the right track the great majority of the time. But of course, it's important to have a glance at the details occasionally to avoid stupid mistakes. We can always improve our well-being in one way or another.

Edits 1 and 2: Of course, seconds later, I find a very informative thread in Permies that's been down the oxalic acid path before, with excellent posts such as this one. Very informative. For my own purposes at least, I hearby remove oxalic acid concerns from my radar screen.
 
Dave de Basque
Posts: 129
Location: Basque Country, Spain-42N lat-Köppen Cfb-Zone8b-1035mm/41" rain: 118mm/5" Dec., 48mm/2" July
23
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Dan Boone wrote:
<snip lots of interesting & informative stuff>
Very long winded way of saying: "No, I don't worry about arsenic in my rice." I don't wash my rice. I also don't throw out any pot liquors. I don't much enjoy greens, but the ones I do eat go into soups and stews, so nothing gets washed or leached away in the cooking process.


Thanks Dan, for your informative post too. You must have posted it while I was working on mine. I think we are in rough agreement except in the not liking greens part -- yumm! So maybe I will not worry too much about arsenic at the moment (as always, YMMD) and go back to looking for other well-being improvements to focus on. Open to more info on the subject though!
 
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