A recent feature in the Guardian rehearsed many reservations over soya foods and derivatives. Much of it was old and questionable information and ignored the results of relevant research...
A recent feature in the Guardian rehearsed many reservations over soya foods and derivatives. Much of it was old and questionable information and ignored the results of relevant research in the UK, Finland, and USA, as well as manufacturing practices in the preparation of various soya meats and milks. Subsequent correspondence focused on animal milks and possible physiological effects on sucklings who are human consumers (the probable benefits to the intended species were overlooked). As with blood, the composition of freshly secreted milk may vary during the day or night, seasonally, or at the stage of the lactation or during the period of sucking and from which breast or teat. Bulking samples, as is normal commercial practice and may also occur, as in donations of blood, in supplies of donated human milk reduces such variation. Hormone fluxes may include prolactin, oxytocin, and thyroid and growth factors varying from species to species, and with specific activities. In this respect we may count the importance also of precursors of hormones such as vitamin D, iodine, and tyrosine.
VEGA has been in consultation with the Food Standards Agency on this issue and long before that with other physiologists. The ancient Doctrine of Signatures led to deductions that virility in men was beefed up by Britain’s John Bulls (who were probably cowboys, consuming much beef from spent dairy cows and most of the other meat was from killed castrates, anyway), and it was milksops who were thus disparaged for a feminine streak. However, the butcher could easily see differences in the meat on the slab: it might vary in color and be classified DFD (dark, firm, dry) or PSE (pale, soft, exudative). These were signs of injury just before slaughter, as might arise during transport and auctioning, loading and unloading, and fighting, beating and goading during the animal’s last hours. Fighting was fiercest among young and randy animals, so consumers in North America and Europe preferred meat from steers (castration itself was a stressful experience). Pre-slaughter fright, flight, fight response set off floods of stressor hormones (the catecholamines) that are responsible for changes in the meat.
Do daily intakes of residues of these hormones arouse human consumers to the fighting spirit? Or is it consumers with aggressive tendencies who consume more of the meats that intensify their fierceness and virility? Milk is baby food and unnatural for adult animals of any species, so are milksops the callow boys while strong men eat bull-beef? And how do these factors affect girls and women? And one can continue the debate to domestic pets and what they are given to eat or catch (and which organs the hunters eat first).
There are many factors to pursue here. We merely offer now the following summary of reactions prompted by the feature and correspondence on soya in the Guardian.
Soya, Cows, Milk and Hormones
Debate over the merits and demerits of soya dairy-products and comparable animal milks has overlooked some aspects of the physiologically active constituents of the white stuff which reflect those circulating in the red stuff. These fluctuate with endocrinological changes imposed on the cows, who are freaks of breeding tricks and artificial insemination and forced into feats of production that entail simultaneous lactation and gestation for 6 months of each of the few years before they succumb to production and reproduction diseases, among them metabolic syndromes such as milk fever.
Although Europe is trying to resist pressure for reasons of free trade to resort – as is done in the USA and many other cattle-rearing countries – to boost production and outputs by means of injections of hormones such as somatotrophins, notably BST, other physiological interferences are used in Europe.
Injections of hormones such as prostaglandins, and gonadotrophins, some (premarins) derived from pregnant mares “milked” for their urine, are used by farmers and vets to synchronize estrus and thus lower the requirements for high levels of care and stockmanship during parturition in herds and flocks in a more nearly natural system. The hormone melatonin is used in sheep to override the natural seasonal control of reproduction, so that the butcher can sell “spring lamb” into the very early and profitable market. Melatonin has been applied as a drug or supplement, eg in the relief of jet-lag, but over-the-counter sales are not permitted in the UK, owing to possible adverse effects. However, milk from morning milkings of cows is sold commercially on the assumption that increased content of the “nocturnal hormone” will have benefits not easily available from supplements nor milkings later in the day.
Milk from cows, sheep, and goats – like human breast milk – contain other hormones. The occasional human baby expresses “witches milk”, prompted by mother’s lactational stimuli, and the whole subject of dairy milks and soya alternatives needs review of the physiology of gender, agonists, receptors, and metabolism and the various responses and distributions of these factors, for which experience with the drug tamoxifen and the epidemiology of breast cancer is informative. Imported soya being used extensively in feeds for “British” livestock, we look for evidence of reproduction problems attributable to specific hormonal effects. There is quite a lot of anecdotal evidence now that fecundity is declining in British herds, and reproductive failures account for appreciable losses of cows who are prematurely culled; however, other factors of intensification, now extending to zero-grazing systems, may be responsible. Soya is only one of many crops reported to have estrogenic activity. There has been speculation that brewer’s droop reflects the effects, again objectively unconfirmed.
Production of cow’s milk may expose stockpersons to bacterial diseases such as leptospirosis (“flabby bag” in the cows) and an insidious threat lingers of transmission of BSE, not so much from cow’s milk, but – if BSE jumps and manifests as a form of scrapie – with a higher risk from the lactations, as well as the meat, from goats and sheep.