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Formaldehyde in Foods
Hi Grant,
With regard to your post discussing cauliflower and aspartame being potentially problematic due to formaldehyde levels I'd like to raise a couple of points.
Firstly, cauliflower has around 26.9 mg/kg of formaldehyde (https://www.cfs.gov.hk/english/multimedia/multimedia_pub/multimedia_pub_fsf_06_01.html). In comparison, apples supply much more formaldehyde in the diet via pectin:
In human volunteers, consumption of 10-15 g isolated pectin or of 1 kg apples (containing approximately 10 g natural pectin) induced a significant increase in methanol in the breath and, by inference, in the blood. Consumption of 1kg apples was estimated to release 500 mg methanol.
500 mg of methanol produces almost the same amount of formaldehyde.
Is cauliflower causing problems due to its formaldehyde content? I think it's unlikely, there are far worse sources of formaldehyde in the diet. Although plants contain a range of defense chemicals the most problematic aspect of cruciferous vegetables is the thiocyanate content, thiocyanates directly suppress thyroid function. Cauliflower could certainly be problematic in more than small amounts but I think it would be most likely related to thiocyanates if it is. I personally consume almost no cruciferous vegetable matter for this reason.
With regard to methanol we should be very concerned with the consumption of apples and certain other fruits and vegetables though. Because pectin is the primary source of formaldehyde in the diet and because humans (and primates) metabolise formaldehyde poorly, consuming foods high in it will certainly affect liver function and health to a degree.
In species that metabolise formate poorly, such as primates, acute and short term methanol toxicity is characterised by formic acidaemia, metabolic acidosis, ocular toxicity, nervous system depression, blindness, coma and death. In species which metabolise formate readily, fatal acute toxicity is usually through CNS depression. Longer term exposure to lower levels of methanol may cause various ocular effects such as blurred and misty vision.
Methanol occurs naturally in food, notably in fresh fruits and vegetables and
their juices. It occurs as free methanol, methyl esters of fatty acids or methoxy
groups on polysaccharides such as pectin from which it can be released by
digestion. Pectin is broken down during digestion in the colon, from where methanol
can be absorbed, meaning that the potential methanol intake from the diet is higher
than analysis of the free methanol content of individual foodstuffs might suggest.
It has been estimated that humans may be exposed to approximately 1000 mg methanol per day from fruits and vegetables.
When it comes to the aspartame debate, scientists are comparing the formaldehyde levels resulting from aspartame consumption with formaldehyde intake from fruits and vegetables. Making this comparison makes aspartame look relatively safe. However, with the realization that high fruit and vegetable intake is not actually healthy for a range of reasons we can see that both avoidance of aspartame and adopting a low fruit and vegetable diet makes sense.
COT STATEMENT ON THE EFFECTS OF CHRONIC DIETARY EXPOSURE TO
METHANOL
https://cot.food.gov.uk/sites/default/files/cot/cotstatementmethanol201102revjuly.pdf
Fruits and vegetables typically contain 3–60 mg/kg
Compare this with:
For a person smoking 20 cigarettes per day, this would lead to an exposure of 1 mg/day.
http://www.euro.who.int/__data/assets/pdf_file/0014/123062/AQG2ndEd_5_8Formaldehyde.pdf
Thanks for sharing this information and your insight.
I raised the concerned about the formaldehyde contents of some foods and aspartame too only as one of several possible reasons why some people are now hitting the “detox” wall with this diet. Of course, I specifically spotlighted cauliflower as a suspect because it is one of the few foods that did commonly show up on the food lists on our survey. Very interestingly, I think some people mentioned apple pectin too. So, this could be something, or maybe there’s no connection at all to it. But, there must be a real reason why the “detox” setback is happening to some people, and not to others.
My thinking was that for people with underlying NAFLD, or an otherwise compromised liver condition, then they would be more susceptible to any additional retinyl esters back flowing into circulation. Therefore, even small amounts of methanol and / or formaldehyde would compete for their alcohol and aldehyde dehydrogenase enzymes. Ingesting methanol and / or formaldehyde is most certainly not going to be helping anyone.
Then again, on the other hand, maybe by the very limited nature of this diet we are missing out on essential components needed to produce the alcohol and aldehyde dehydrogenase enzymes too. Of course, I don’t know what’s going on with the “detox” setback. That’s why the goal of the survey was to try to spot suspects and start this discussion. Clearly, we are all still very early into this investigation, and mistakes are going to be made. Therefore, we always need to be open to making course corrections as new information becomes available.
Raising the concern about cauliflower etc. was a call out to see if people in the “detox” setback phase can now experimentally tweak their diets and report any responses one way or the other. Surprisingly, a few people have already reported seeing an improvement by dropping the cauliflower. I know the sample set is incredibly small, like n=2, but it’s a start.
As I mentioned in my blog post, there is at least one person who reported that including one egg per day was enough to keep himself out of the “detox” setback cycle. I am still very intrigued by that report. Maybe people are going too low for too long? I don’t know.
That does not imply that I think vitamin A is essential or in some way needed. My personal view is still very much that it is nothing but a toxin. However, very clearly, we’ve not yet found the safe and reliable detox protocol.
Lastly, I think when scientists are testing for the safe levels of formaldehyde and aspartame consumption they are always doing so in the normal healthy population. That is generally not the same for most people on this diet. Therefore, I think we need to be very careful with these compounds.
Thanks
Grant
There are many other sources of aldehydes in foods that require aldehyde dehydrogenase to deal with them.
Heating oil to frying temperatures creates lots of aldehydes.
Vanilla (4-Hydroxy-3-methoxybenzaldehyde) flavour is an aldehyde.
I have no idea if this interferes with retinaldehyde dehydrogenase.
Does eating lots of vanilla while binging on alcohol give you a worse hangover?
We have lots of unknowns to deal with 😉
Thanks for your response Grant, yeah I agree ADH is probably going to be overworked dealing with VA in many of us so it is really wise to try to minimize stress on this pathway.
The fact that cauliflower is listed (along with chargrilled meat) as a cytochrome P450 modulator gives a clue that it does contain some really undesirable substances.
https://en.wikipedia.org/wiki/List_of_cytochrome_P450_modulators
Yeast contains ADH however being heat treated I doubt nutritional yeast has ADH.
While we are talking about enzymes isn't the fact that 11-cis-retinol dehydrogenase is present mainly in the eye evidence that VA is an essential vitamin for eye health?
It is well known cauliflower messes with CYP1A1, I found this:
RA can be further oxidized to 4-hydroxy-retinoic acid by cytochrome P450s (CYP26A1, CYP26B1, and CYP26C1) which is considered the first step of RA degradation as it leads to more easily excreted metabolites.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3161159/
Perhaps thiocyanates also interfere with these P450s?
On the basis of studies conducted in animals, it has been established that isothiocyanates suppress cytochrome P450 activity, leading to impairment of the bioactivation of carcinogens, this being a principal mechanism of their chemopreventive activity.
Quote from tim on October 26, 2019, 3:02 pmWhile we are talking about enzymes isn't the fact that 11-cis-retinol dehydrogenase is present mainly in the eye evidence that VA is an essential vitamin for eye health?
I don’t see it that way. IMO, just because these compounds are accumulating in the eye in no way suggests that they are vitamins. I think it’s similar the argument that since vitamin A accumulates in breast milk, it must have an essential vitamin role. That’s because other toxins such as dioxin, lead, and PCBs now also accumulate in human breast milk, and they are definitely not vitamins.
Maybe the 11-cis-retinol dehydrogenase is specific to this tissue as part of the retinoids photo decomposition processes? I don’t know.
Grat
I’ve just finished reading the book by Dr Woodrow Monte - While science sleeps a sweetener kills (posted on Garrett Smith’s forum). It offers some very interesting insights as to why methanol in food is so dangerous. It converts into formaldehyde within cells. It’s an obvious competitor for the ADH/ALDH enzyme system but probably very nasty in its own right. Methanol food sources are very much worth looking at & avoiding imo. I’ve confiscated my husband’s orange squash as it contained aspartame- he’s not happy!!
I strongly agree with you. Monte did some good work but he isn't perfect, he falls for the naturalistic fallacy to a degree. Pectin is present in most/all fruits and vegetables. Simply eating apples or oranges leads to absorption of high levels of methanol. Apples and oranges aren't even natural foodstuffs as both are not edible in the wild. Wild oranges are only eaten by San bushmen after they have been fermented underground. I won't avoid eating them ever again but I will definitely be avoiding fruit juices.