Saturday, April 21, 2007

Autism Diva’s Curing Vegetables®

Autism Diva has written a very nice blog on her home manufacture of lactic acid bacteria fermented vegetables, a traditional food of Koreans, known as kimchi. While Autism Diva spoke of selling her Curing Vegetables® as a treatment for ASDs in jest (I presume), I think there is at least a plausible mechanism that could suggest that consuming Autism Diva’s Curing Vegetables® might be beneficial. Something that is completely lacking with every other so called “treatment” sold at a DAN!® conference (that I am aware of). At least it won't be harmful (as many of the DAN!® treatments are).

As is mentioned elsewhere on my blog, I subscribe to the “low NO hypothesis” of ASDs. NO is a pleiotropic signaling molecule that is involved in thousands of different physiological pathways, including many (if not all) known to be disrupted in ASDs. Because NO is used as a signaling molecule, and all “NO detectors” only detect the sum of all NO from all sources, the background level of NO will affect all NO pathways with no threshold.

There are a number of ways of increasing basal NO/NOx levels. As far as I know, there are no "pharmacological" ways. That is, there are no "drugs" per se, that will increase NO/NOx levels. Part of why is simple physiology. NO/NOx physiology is so well regulated that it is very difficult to perturb artificially. It is so coupled, and so complex, that it is virtually impossible to perturb artificially without adverse side effects. There is intense research in these areas, and compounds that are NO/NOx active are in use, but they don't strictly increase the basal NO/NOx level. Nitroglycerine, other organic nitrates have been used to treat angina for over a century, and they work, but precisely why remains unknown. They are not simple NO donors. Sodium nitroprusside is an NO donor, which is used to control refractory blood pressure, but it must be administered continuously. It has a very short lifetime in the blood, and the effect stops within a few minutes. Inhaled NO only has effects in the lung (pretty much). High doses of inhaled NO can have systemic effects, but that is likely do to the metabolite of inhaled NO, nitrite. Nitrite can be infused, and is as a treatment for cyanide poisoning. It works by oxidizing hemoglobin to methemoglobin, which binds cyanide, disinhibiting cytochrome oxidase while sulfuration pathways get rid of it. NO also reversed the inhibition of cytochrome oxidase by cyanide.

As Autism Diva mentioned, kimchi is produced by fermentation of various foods by lactic acid bacteria. Her favorite vegetables include cabbage. Green leafy vegetables are well known to have high nitrate content. A list of tables with nitrate contents of various vegetables. There is considerable thought that the nitrate in green leafy vegetables is part of what makes them so healthy to eat, and contributes to antimicrobial effects in the stomach. Lactic acid bacteria are responsible for the fermentation that turns milk into yogurt, and vegetables into kimchi. It is also responsible for turning chopped up maize stalks into silage.

Quite a number of different strains of lactobacilli are used and can be used to ferment vegetables, where they produce diverse metabolic products including lactic acid, acetic acid, and alcohol.
The reason that Daedalus considers that Autism Diva's Curing Vegetables® would be beneficial to individuals with ASDs is due to what lactic acid bacteria do to the nitrate that is abundantly present in most vegetables. Lactobacilli produce NO and nitrite from nitrate. This is a normal part of the curing process, which generates NO and nitrite and is what makes sausage such as salami bright red. The red color is from nitrosylmyoglobin (NOMb). That is myoglobin with NO attached to the heme where O2 is usually attached. Hemoglobin is red because O2Hb is red. Hb without O2 is blue. NOMb is red, but a slightly different shade (like bacon). COMb is a slightly different shade too. If you have a gas stove, sometimes you can see slightly different shades of red in meat as it is cooked due to the different myoglobin species.

Nitrite is unstable at low pH, and is also fairly easily reduced to NO. When nitrate is consumed, as in green leafy vegetables, the nitrate is well absorbed, concentrated in the saliva from the blood stream, then bacteria on the tongue reduce that nitrate to nitrite. When the nitrite is swallowed, it forms NO in the stomach, and adds considerable anti-microbial effects to the low pH of the stomach, killing the nasty bacteria that would like to live there.

Ingestion of nitrate has a "bad rap" because of the perception that it can cause methemoglobinemia in infants, otherwise known as blue baby. This is the reason that there are limits on nitrate in drinking water. However, the epidemiology of nitrate in drinking water causing methemoglobinemia is quite poor, essentially non-existent. Ingestion of nitrate can lead to methemoglobinemia, but the main dietary source is vegetables (which have ~1000-3000 ppm nitrate) not drinking water. Methemoglobinemia occurs when a large fraction of the blood's hemoglobin becomes oxidized to methemoglobin and so cannot carry O2. Usually this only presents problems if more than 50% of the blood is so converted. Usually this makes people look quite cyanotic, because metHb is dark colored.

With out analyzing Autism Diva's Curing Vegetables®, it would be difficult to predict what NOx species would be present. Nitrite is not stable at low pH, so the nitrite level would be low. But there are a great many other NOx species that might be important as I discuss in an earlier blog. I looked at some sauerkraut, and as expected, there was no nitrite, but there was substantial nitrate.

The method for preserving foliage for use as feed for ruminants by making silage is the same method as Autism Diva uses to make Autism Diva's Curing Vegetables®; that is fermentation with lactic acid bacteria. When silage is made, the bacteria reduce the nitrate that plants accumulate into nitrite, and that nitrite decomposes in the low pH forming NO which is then easily oxidized by the O2 in air to form NO2, nitrogen dioxide. NO2 is a brown gas, extremely toxic. When you look at the exhaust gases from a large power plant, if the exhaust stream is brown, that is NO2. NO2 can accumulate during silage production, and people have been killed by formation of "silo gas", which can kill with a single breath. NO2 is toxic like that, the threshold is a few ppm. NO isn't toxic at all, people can routinely breath hundreds of ppm, but only if provision is made to ensure there is no NO2 which can very rapidly form. Your nasal passages produce a few hundred ppb NO in the air you breathe to regulate the perfusion of the lung, and match it to air inhalation.

So what form are the NOx species in Autism Diva’s Curing Vegetables®? They could be S-nitrosothiols. When a thiol containing protein (which includes most every protein) is exposed to nitrosative conditions, (that is nitrite, low pH, and something oxidizing), then NO can attach to the thiol and form the S-nitrosothiol. S-nitrosoglutathione, S-nitrosoalbumin, S-nitrosocysteine are all well known S-nitrosothiols. Human blood has about 7 micromolar S-nitrosothiol, the most abundant S-nitrosothiol in the blood is S-nitrosoalbumin, which is present at variable levels, but in humans is about 5 micromolar in plasma. S-nitrosothiols are likely generated in the stomach from salivary nitrite, low stomach pH. Ingestion of nitrate does reportedly does have physiological effects most likely mediated through S-nitrosothiol formation in the stomach.

There is a higher incidence of stomach cancer among Koreans. Whether this is due to consumption of kimchi or to particular kinds of kimchi is unknown. Nitrosamines can be carcinogenic. This is the concern over nitrite in bacon and other cured meats, that under nitrosative conditions (low pH and nitrite and air), that nitrosamines can form. The reason they are carcinogenic is that they can attach to DNA and modify it. The risk associated with bacon and other nitrite-cured meats is purely theoretical. That is, there hasn't been good epidemiology to show that there is a connection to induction of cancer. Most studies have shown that when ascorbate is consumed with the nitrite containing food, that no nitrosamines can be detected.

If I had to guess, I would suppose that vegetable based kimchi was completely safe (due to the ascorbate), and that only meat-based kimchi was potentially problematic. Red meat is associated with increased gut cancers, and that is due to the heme content. Nitrosylating that heme might render it non-cancer forming. Heme is a reasonably good catalyst for oxidation reactions (most every oxidation enzyme contains heme for that reason). Nitrosylating heme does block its catalytic activity toward O2. Would nitrosylating heme prevent heme from being cancer forming? That isn't something that has been tested yet that I am aware of. Fish does have amines in it, that is what makes it smell "fishy". Amines plus nitrosating conditions does make nitrosamines. So I would consider it poor practice to put fish into kimchi while it is fermenting. If you do, you want to make sure that the container is completely anaerobic. That is, that the CO2 the lactobacilli are making has displaced all the air. Then you would want to consume the kimchi fairly soon, or keep it anaerobic until you do consume it. Putting it up in sealed jars is probably ok, but not in open containers. This mimics the action of the stomach, which is also anaerobic. The head space in the stomach can reach ~100 ppm NO due to the action of low pH on salivary nitrite. That level would probably kill you if you breathed it long term due to formation of NO2 from mixing with air. But in the stomach away from air, it is a natural and healthful source of NOx species. Mimicking those conditions while fermenting kimchi would probably be similarly healthful.


Executive Crackhead said...

Hi Daedeulus2u -

I'm curious about your thoughts on NO in autism and / or bacterial imbalances as the mechanism of action.

Executive Crackhead said...

Oops. Double posed on accident. Anyways, with the understanding that NO chemistry is very complicated, can you spend a few minutes explaining to the scientificly minded, but untrained parent, the differences in NO concentrations in different areas as it applies to your theory?

I've found several articles that seem to indicate that NO levels in autistics are higher than the normal population,

In these cases, it seems that plasma concentrations of NO were significantly higher in the autistic population than others.

However, it seems likely that plasma concentrations are not the thrust of your theory. Could you explain why high plasma concentrations might mean low concentrations in other areas that might account symtpoms seen in autism?


- ec

daedalus2u said...

As posted elsewhere on my blog, yes, I do think that many of the symptoms associated with ASDs are due to low NO, and are due (in part) to loss of commensal ammonia oxidizing bacteria living on the external skin.

daedalus2u said...

I have a good discussion of basal NO here.

The papers that have "reported" high NO, didn't acutally measure NO, what they measured was the sum of nitrite plus nitrate. Those are the terminal metabolites of NO. They only indicate that NO was produced, they say absolutely nothing about what the NO concentration actually was. It is sort of like trying to use CO2, the terminal metabolite of O2 to infer O2 concentrations. It is simply the wrong way to do it.

The NO concentrations that are important in this context are in the 10 nanomoles per liter range. Nitrate and nitrite are typically in the micromolar range.

What actually matters is the NO concentration at the actual site of the "NO detector". There simply are no techniques for measuring NO on the length, concentration and tiem scales that we know are important.

Nancy said...

Hi Daedalus
Enjoyed your article on nitrates and nitrites. A huge thank you. I am a devoted home kraut/fermented foods maker and eater. I consume about 2 to 3 cups of my stuff daily. Mainly they consist of cabbage, ginger, curry, apples, carrots and onions. Do you think that by taking extra vitamin C with each of these meals I can offset the possible stomach cancer risk? My mother died of adenocarcinoma--bile duct pancreatic type. She had been treated for H Pylori. I am healing from rheumatoid arthritis and lyme diseae. I would welcome any thoughts from you.

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Eleanora said...

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