THESIS: Recent discoveries of potentially psychoactive
substances in certain agricultural products - cereals and milk - suggest an
additional perspective on the adoption of agriculture and the behavioural
changes ('civilisation') that followed it. In this paper we review the evidence
for the drug-like properties of these foods, and then show how they can help to
solve the biological puzzle just described .
EXCERPT:
Pharmacological properties of cereals and milk
Recent research into the pharmacology of food presents a new perspective on these problems.
Exorphins: opioid substances in food
Prompted by a possible link between diet and mental illness, several researchers in the late 1970s began investigating the occurrence of drug-like substances in some common foodstuffs.
Dohan (1966, 1984) and Dohan et al. (1973, 1983) found that symptoms of schizophrenia were relieved somewhat when patients were fed a diet free of cereals and milk. He also found that people with coeliac disease - those who are unable to eat wheat gluten because of higher than normal permeability of the gut - were statistically likely to suffer also from schizophrenia. Research in some Pacific communities showed that schizophrenia became prevalent in these populations only after they became 'partially westernised and consumed wheat, barley beer, and rice' (Dohan 1984).
Groups led by Zioudrou (1979) and Brantl (1979) found opioid activity in wheat, maize and barley (exorphins), and bovine and human milk (casomorphin), as well as stimulatory activity in these proteins, and in oats, rye and soy. Cereal exorphin is much stronger than bovine casomorphin, which in turn is stronger than human casomorphin. Mycroft et al. (1982, 1987) found an analogue of MIF-1, a naturally occurring dopaminergic peptide, in wheat and milk. It occurs in no other exogenous protein. (In subsequent sections we use the term exorphin to cover exorphins, casomorphin, and the MIF-1 analogue. Though opioid and dopaminergic substances work in different ways, they are both 'rewarding', and thus more or less equivalent for our purposes.)
Since then, researchers have measured the potency of exorphins, showing them to be comparable to morphine and enkephalin (Heubner et al. 1984), determined their amino acid sequences (Fukudome &Yoshikawa 1992), and shown that they are absorbed from the intestine (Svedburg et al.1985) and can produce effects such as analgesia and reduction of anxiety which are usually associated with poppy-derived opioids (Greksch et al.1981, Panksepp et al.1984). Mycroft et al. estimated that 150 mg of the MIF-1 analogue could be produced by normal daily intake of cereals and milk, noting that such quantities are orally active, and half this amount 'has induced mood alterations in clinically depressed subjects' (Mycroft et al. 1982:895). (For detailed reviews see Gardner 1985 and Paroli 1988.)
Most common drugs of addiction are either opioid (e.g heroin and morphine) or dopaminergic (e.g. cocaine and amphetamine), and work by activating reward centres in the brain. Hence we may ask, do these findings mean that cereals and milk are chemically rewarding? Are humans somehow 'addicted' to these foods?
Problems in interpreting these findings
Discussion of the possible behavioural effects of exorphins, in normal dietary amounts, has been cautious. Interpretations of their significance have been of two types:
- where a pathological effect is proposed (usually by cereal researchers, and related to Dohan's findings, though see also Ramabadran & Bansinath 1988), and
- where a natural function is proposed (by milk researchers, who suggest that casomorphin may help in mother-infant bonding or otherwise regulate infant development).
We believe that there can be no natural function for ingestion of exorphins by adult humans. It may be that a desire to find a natural function has impeded interpretation (as well as causing attention to focus on milk, where a natural function is more plausible) . It is unlikely that humans are adapted to a large intake of cereal exorphin, because the modern dominance of cereals in the diet is simply too new. If exorphin is found in cow's milk, then it may have a natural function for cows; similarly, exorphins in human milk may have a function for infants. But whether this is so or not, adult humans do not naturally drink milk of any kind, so any natural function could not apply to them.
Our sympathies therefore lie with the pathological interpretation of exorphins, whereby substances found in cereals and milk are seen as modern dietary abnormalities which may cause schizophrenia, coeliac disease or whatever. But these are serious diseases found in a minority. Can exorphins be having an effect on humankind at large?
Other evidence for 'drug-like' effects of these foods
Research into food allergy has shown that normal quantities of some foods can have pharmacological, including behavioural, effects. Many people develop intolerances to particular foods. Various foods are implicated, and a variety of symptoms is produced. (The term 'intolerance' rather than allergy is often used, as in many cases the immune system may not be involved (Egger 1988:159). Some intolerance symptoms, such as anxiety, depression, epilepsy, hyperactivity, and schizophrenic episodes involve brain function (Egger 1988, Scadding & Brostoff 1988).
Radcliffe (1982, quoted in 1987:808) listed the foods at fault, in descending order of frequency, in a trial involving 50 people: wheat (more than 70 per cent of subjects reacted in some way to it), milk (60 per cent), egg (35 per cent), corn, cheese, potato, coffee, rice, yeast, chocolate, tea, citrus, oats, pork, plaice, cane, and beef (10 per cent). This is virtually a list of foods that have become common in the diet following the adoption of agriculture, in order of prevalence. The symptoms most commonly alleviated by treatment were mood change (>50 per cent) followed by headache, musculoskeletal and respiratory ailments.
One of the most striking phenomena in these studies is that patients often exhibit cravings, addiction and withdrawal symptoms with regard to these foods (Egger 1988:170, citing Randolph 1978; see also Radcliffe 1987:808-10, 814, Kroker 1987:856, 864, Sprague & Milam 1987:949, 953, Wraith 1987:489, 491). Brostoff and Gamlin (1989:103) estimated that 50 per cent of intolerance patients crave the foods that cause them problems, and experience withdrawal symptoms when excluding those foods from their diet. Withdrawal symptoms are similar to those associated with drug addictions (Radcliffe 1987:808). The possibility that exorphins are involved has been noted (Bell 1987:715), and Brostoff and Gamlin conclude (1989:230):
'... the results so far suggest that they might influence our mood. There is certainly no question of anyone getting 'high' on a glass of milk or a slice of bread - the amounts involved are too small for that - but these foods might induce a sense of comfort and wellbeing, as food-intolerant patients often say they do. There are also other hormone-like peptides in partial digests of food, which might have other effects on the body.'
There is no possibility that craving these foods has anything to do with the popular notion of the body telling the brain what it needs for nutritional purposes. These foods were not significant in the human diet before agriculture, and large quantities of them cannot be necessary for nutrition. In fact, the standard way to treat food intolerance is to remove the offending items from the patient's diet.
A suggested interpretation of exorphin research
But what are the effects of these foods on normal people? Though exorphins cannot have a naturally selected physiological function in humans, this does not mean that they have no effect. Food intolerance research suggests that cereals and milk, in normal dietary quantities, are capable of affecting behaviour in many people. And if severe behavioural effects in schizophrenics and coeliacs can be caused by higher than normal absorption of peptides, then more subtle effects, which may not even be regarded as abnormal, could be produced in people generally.
The evidence presented so far suggests the following interpretation.
The ingestion of cereals and milk, in normal modern dietary amounts by normal humans, activates reward centres in the brain. Foods that were common in the diet before agriculture (fruits and so on) do not have this pharmacological property. The effects of exorphins are qualitatively the same as those produced by other opioid and / or dopaminergic drugs, that is, reward, motivation, reduction of anxiety, a sense of wellbeing, and perhaps even addiction. Though the effects of a typical meal are quantitatively less than those of doses of those drugs, most modern humans experience them several times a day, every day of their adult lives.
http://membres.lycos.fr/xbeluga/orig...riculture.html
EXCERPT:
Pharmacological properties of cereals and milk
Recent research into the pharmacology of food presents a new perspective on these problems.
Exorphins: opioid substances in food
Prompted by a possible link between diet and mental illness, several researchers in the late 1970s began investigating the occurrence of drug-like substances in some common foodstuffs.
Dohan (1966, 1984) and Dohan et al. (1973, 1983) found that symptoms of schizophrenia were relieved somewhat when patients were fed a diet free of cereals and milk. He also found that people with coeliac disease - those who are unable to eat wheat gluten because of higher than normal permeability of the gut - were statistically likely to suffer also from schizophrenia. Research in some Pacific communities showed that schizophrenia became prevalent in these populations only after they became 'partially westernised and consumed wheat, barley beer, and rice' (Dohan 1984).
Groups led by Zioudrou (1979) and Brantl (1979) found opioid activity in wheat, maize and barley (exorphins), and bovine and human milk (casomorphin), as well as stimulatory activity in these proteins, and in oats, rye and soy. Cereal exorphin is much stronger than bovine casomorphin, which in turn is stronger than human casomorphin. Mycroft et al. (1982, 1987) found an analogue of MIF-1, a naturally occurring dopaminergic peptide, in wheat and milk. It occurs in no other exogenous protein. (In subsequent sections we use the term exorphin to cover exorphins, casomorphin, and the MIF-1 analogue. Though opioid and dopaminergic substances work in different ways, they are both 'rewarding', and thus more or less equivalent for our purposes.)
Since then, researchers have measured the potency of exorphins, showing them to be comparable to morphine and enkephalin (Heubner et al. 1984), determined their amino acid sequences (Fukudome &Yoshikawa 1992), and shown that they are absorbed from the intestine (Svedburg et al.1985) and can produce effects such as analgesia and reduction of anxiety which are usually associated with poppy-derived opioids (Greksch et al.1981, Panksepp et al.1984). Mycroft et al. estimated that 150 mg of the MIF-1 analogue could be produced by normal daily intake of cereals and milk, noting that such quantities are orally active, and half this amount 'has induced mood alterations in clinically depressed subjects' (Mycroft et al. 1982:895). (For detailed reviews see Gardner 1985 and Paroli 1988.)
Most common drugs of addiction are either opioid (e.g heroin and morphine) or dopaminergic (e.g. cocaine and amphetamine), and work by activating reward centres in the brain. Hence we may ask, do these findings mean that cereals and milk are chemically rewarding? Are humans somehow 'addicted' to these foods?
Problems in interpreting these findings
Discussion of the possible behavioural effects of exorphins, in normal dietary amounts, has been cautious. Interpretations of their significance have been of two types:
- where a pathological effect is proposed (usually by cereal researchers, and related to Dohan's findings, though see also Ramabadran & Bansinath 1988), and
- where a natural function is proposed (by milk researchers, who suggest that casomorphin may help in mother-infant bonding or otherwise regulate infant development).
We believe that there can be no natural function for ingestion of exorphins by adult humans. It may be that a desire to find a natural function has impeded interpretation (as well as causing attention to focus on milk, where a natural function is more plausible) . It is unlikely that humans are adapted to a large intake of cereal exorphin, because the modern dominance of cereals in the diet is simply too new. If exorphin is found in cow's milk, then it may have a natural function for cows; similarly, exorphins in human milk may have a function for infants. But whether this is so or not, adult humans do not naturally drink milk of any kind, so any natural function could not apply to them.
Our sympathies therefore lie with the pathological interpretation of exorphins, whereby substances found in cereals and milk are seen as modern dietary abnormalities which may cause schizophrenia, coeliac disease or whatever. But these are serious diseases found in a minority. Can exorphins be having an effect on humankind at large?
Other evidence for 'drug-like' effects of these foods
Research into food allergy has shown that normal quantities of some foods can have pharmacological, including behavioural, effects. Many people develop intolerances to particular foods. Various foods are implicated, and a variety of symptoms is produced. (The term 'intolerance' rather than allergy is often used, as in many cases the immune system may not be involved (Egger 1988:159). Some intolerance symptoms, such as anxiety, depression, epilepsy, hyperactivity, and schizophrenic episodes involve brain function (Egger 1988, Scadding & Brostoff 1988).
Radcliffe (1982, quoted in 1987:808) listed the foods at fault, in descending order of frequency, in a trial involving 50 people: wheat (more than 70 per cent of subjects reacted in some way to it), milk (60 per cent), egg (35 per cent), corn, cheese, potato, coffee, rice, yeast, chocolate, tea, citrus, oats, pork, plaice, cane, and beef (10 per cent). This is virtually a list of foods that have become common in the diet following the adoption of agriculture, in order of prevalence. The symptoms most commonly alleviated by treatment were mood change (>50 per cent) followed by headache, musculoskeletal and respiratory ailments.
One of the most striking phenomena in these studies is that patients often exhibit cravings, addiction and withdrawal symptoms with regard to these foods (Egger 1988:170, citing Randolph 1978; see also Radcliffe 1987:808-10, 814, Kroker 1987:856, 864, Sprague & Milam 1987:949, 953, Wraith 1987:489, 491). Brostoff and Gamlin (1989:103) estimated that 50 per cent of intolerance patients crave the foods that cause them problems, and experience withdrawal symptoms when excluding those foods from their diet. Withdrawal symptoms are similar to those associated with drug addictions (Radcliffe 1987:808). The possibility that exorphins are involved has been noted (Bell 1987:715), and Brostoff and Gamlin conclude (1989:230):
'... the results so far suggest that they might influence our mood. There is certainly no question of anyone getting 'high' on a glass of milk or a slice of bread - the amounts involved are too small for that - but these foods might induce a sense of comfort and wellbeing, as food-intolerant patients often say they do. There are also other hormone-like peptides in partial digests of food, which might have other effects on the body.'
There is no possibility that craving these foods has anything to do with the popular notion of the body telling the brain what it needs for nutritional purposes. These foods were not significant in the human diet before agriculture, and large quantities of them cannot be necessary for nutrition. In fact, the standard way to treat food intolerance is to remove the offending items from the patient's diet.
A suggested interpretation of exorphin research
But what are the effects of these foods on normal people? Though exorphins cannot have a naturally selected physiological function in humans, this does not mean that they have no effect. Food intolerance research suggests that cereals and milk, in normal dietary quantities, are capable of affecting behaviour in many people. And if severe behavioural effects in schizophrenics and coeliacs can be caused by higher than normal absorption of peptides, then more subtle effects, which may not even be regarded as abnormal, could be produced in people generally.
The evidence presented so far suggests the following interpretation.
The ingestion of cereals and milk, in normal modern dietary amounts by normal humans, activates reward centres in the brain. Foods that were common in the diet before agriculture (fruits and so on) do not have this pharmacological property. The effects of exorphins are qualitatively the same as those produced by other opioid and / or dopaminergic drugs, that is, reward, motivation, reduction of anxiety, a sense of wellbeing, and perhaps even addiction. Though the effects of a typical meal are quantitatively less than those of doses of those drugs, most modern humans experience them several times a day, every day of their adult lives.
http://membres.lycos.fr/xbeluga/orig...riculture.html
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