From: jack@dcs.glasgow.ac.uk (Jack Campin)
Newsgroups: rec.food.historic
Subject: Re: toxins in food
Date: 31 Aug 92 19:28:20 GMT
Reply-To: jack@dcs.glasgow.ac.uk (Jack Campin)
Organization: COMANDOS Project, Glesga Yoonie

dcryberg@magnus.acs.ohio-state.edu (David J Cryberg) wrote:
> A friend is preparing to do a seminar on toxins that are naturally occuring
> in common foods that we eat.  It is hard to find sources for this kind of
> information. [...]  For example, eating too many raw green beans is
> dangerous because of an enzyme present in the bean pod...or peanut butter
> has carcinogenic properties....etc....  Any good ideas on places to begin
> researching this topic? [...]  It would be good to compare historic sources
> with current articles.

A random scratch through the medical journals section of the library should
find quite a bit.  Start with a general one like the Lancet or NEJM.  Here
are a few things to look for:

- phytates in wheat: these are not toxic but bind iron and calcium so you
  can't take them in.  They are destroyed by fermentation, which is one
  reason why no culture eats wheat in the same way as rice.
  
- oxalates, which occur in many plant foods including rhubarb and spinach.
  They have both a chelating action like phytate and also bind to haemoglobin;
  large doses can kill you.

- ketharism: this is a peripheral neuropathy caused by regular consumption
  of a legume called kethari dal, which is used by the poor in northern
  India.  There was an article about it in New Scientist a few years ago.

- Guam dementia: eating a cycad that used to be used as a food in Guam will
  eventually produce a condition like Alzheimer's disease.

- karaka poisoning: the karaka berry grows in New Zealand.  The Maori used
  to use part of it (either the flesh or the seed, I forget which) as food;
  the other part is a violent strychnine-like poison, with the even nastier
  property that if  you recover your limbs will be frozen for good in whatever
  position you last convulsed into.  The Maori treatment was to bury the victim
  in a narrow pit up to the neck in a standing-at-attention posture, so that
  if they recovered they'd at least be capable of lying down rather than stuck
  in a caltrop-like posture.  I read about part of this in some book on the
  early history of New Zealand and picked the rest up orally.

- fugu: Japanese puffer fish, part of which contains a deadly neurotoxin.  Lots
  of stuff in print on this.

- Szechwan pickled cabbage: there is a cabbage-fermenting technique used in
  central China where the microorganisms produce a carcinogenic toxin that
  causes cancer of the oesophagus in a very large proportion of the people
  who eat it.

- smoked foods: the classic case here is of a village in Iceland whose
  people used to eat almost nothing but smoked salmon all winter.  About
  half of them would die of stomach cancer.  Presumably all smoked foods
  are carcinogenic; anyone seen an estimate of what proportion of stomach
  cancers are due to them?

- bracken: some Japanese eat bracken shoots, which contain one of the most
  powerful carcinogens known.  They get stomach cancer from it.

- salt: another Japanese specialty is giving yourself a stroke from excessive
  sodium intake.  Salty pickles don't help.

- cassava: this has lethal quantities of cyanide-releasing compounds.  The
  usual treatments wash *most* of it out but the residue may cause peripheral
  neuropathy if eaten over a long period.

- methylene chloride: used to dissolve the caffeine out of decaffeinated
  coffee.  *Most* of it is evaporated away.  Look it up in "Dangerous
  Properties of Industrial Materials" for what it can do to you.

- nitrate: found in drinking water contaminated by runoff from modern farms
  (artificial fertilizers are only part of the story; seems like cultivation
  cycles are more responsible).  Binds to infantile forms of haemoglobin
  and can cause permanently damaging anaemia in small children.

- fruit pips: many fruits have pips that contain cyanide-releasing compounds
  (apples, peaches, apricots,...).  They don't have any obvious effect when
  you eat these fruit normally but a few hundred crushed fresh apple pips can
  kill you.  The ancient Greeks used to use peach pips as a poison for
  executions.

- salicylates: these are ubiquitous in fruit (kiwifruit has the most: I
  think strawberries are the only common fruit that doesn't contain them).
  Dangerous for people with sensitivity to chemicals in the aspirin/azo-dye
  group, and kiwifruit probably has enough (about the equivalent of one
  aspirin tablet per fruit) to be dangerous for people with ulcers or
  bleeding disorders.

- microscopic stone splinters: these get into flour milled with stone wheels.
  Usually harmless, but in some areas millstones contain fibrous minerals
  which have the same violently carcinogenic effect as asbestos.

- mercury: this is concentrated by some fish, notably tuna.  If you ate tuna
  as a staple food you'd be risking brain damage.

- solanine: this is an atropine-like poison found in the green bits of
  potatoes.  People vary a lot in their sensitivity to it.  May be a cause
  of neural tube defects (much commoner in Celtic peoples, who eat a lot of
  potatoes).

- buttercup: another convulsant poison, used by the people of ancient
  Sardinia to kill off surplus old people.  Present in small amounts in
  most dairy products.  I doubt if this is very significant but don't know
  for sure.

- nitrite: added to preserved meat products.  Probably contributes to stomach
  cancer by forming nitrosamines.

- lots and lots of other additives used in modern food technology - there
  are several books about this.  Try "E for Additives" for a start, though
  it's not very well-referenced.  Textbooks on food technology might be
  handy as well, though most don't cover anything like the full range of
  chemical glop used today.

A wonderful book on the unspeakable garbage our ancestors had to eat is Piero
Camporesi's "Bread of Dreams: food and fantasy in early modern Europe".

Pre-government-regulation books about factory-produced foods often describe
horrific kinds of adulteration; if all you got was ground-up chalk in your
flour to make it heavier you were damn lucky.

-- 
--  Jack Campin    room G092, Computing Science Department, Glasgow University,
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