Berthold Koletzko, Frauke Lehner
Div. Metabolic Diseases and Nutrition, Dr. von Haunersches Kinderspital, University of Munich, Germany
Key words: Beer, lactogenesis, prolactin
Abstract: Traditional wisdom claims that moderate beer consumption may be beneficial for initiation of breastfeeding and enhancement of breastfeeding success. Here we review the question whether or not there-is any scientific basis for this popular belief. There are clear indications that beer can stimulate prolactin secretion which may enhance lactogenesis both in non-lactating humans and in experimental animals. The component in beer responsible for the effect on prolactin secretion is not the alcohol content but apparently a polysaccharide from barley, which explains that the effect on prolactin can also be induced by non-alcoholic beer. No systematic studies are available to evaluate the clinical effects of beer on induction of lactogenesis, and short term studies have shown a reduced breast milk intake by infants after moderate alcohol consumption of their mothers. It is conceivable that relaxing effects of both alcohol and components of hop might also have beneficial effects on lactogenesis is some women, but there is no hard evidence for causal effects. It appears prudent not to generally advocate the regular use of alcoholic drinks during lactation but to rather refer mothers to non-alcoholic beer, even though no adverse effects of an occasional alcoholic drink during lactation have been documented.
Traditional wisdom not only in Bavaria, but also in many other areas of the world claims that moderate consumption ofbeer may be beneficial for initiation of breastfeeding and enhancement of breastfeeding success '. During the early part of the 20th century, beer companies marketed low alcoholic beers or "tonics" as a means for women to stimulate appetite,
Short and Long Term Effects ofBreast Feeding on Child Health
Edited by Berthold Koletzko et al., Kluwer Academic/Plenum Publishers, 2000
increase their strength and enhance milk production2. Also in more recent years, beer has been discussed as a beverage withpossible special effects on lactation 3-5. At a conference discussing breastfeeding in a Baroque monastery with an active monastery brewery (Irseer Klosterbräu), located close to the world's beer capital Munich, it seems appropriate to briefly review the question whether or not there is any scientific basis for the popular belief that beer consumption has effect on the initiation of breastfeeding.
Some have proposed that beer drinking may facilitate the initiation of breastfeeding by a soothing effect 4-6 Several authors have discussed effects on the secretion ofthe hormone prolactin by the adenohypophysis. Prolactin, in concert with the gradual fall in progesterone levels during the postpartum period, effectively stimulates lactogenesis during the first days after child birth 5,7 The effects of alcohol consumption on the secretion of prolactin is controversial 8 , but beer indeed seems to have a stimulating effect9. De Rosa and coworkers 10 studied 1 1 female volunteers aged 18-36 years during the early follicular phase of the menstrual cycle. At three times with an interval of 48 hours, the subjects were given 1 litre of one of three fluids under standard conditions. After 12 hours of fasting and fluid deprivation, and at least 1 hour ofbed rest, the subjects consumed within 15 minutes 1 litre either ofbeer (6 % ethanol), sparkling water or sparkling water with 6 % alcohol. Prolactin was measured from blood samples obtained at 0, 30,60, 90 and 120 minutes. Peak values were obtained at 30 minutes in all three groups, but the prolactin increase was significantly larger after beer (27.1±13.7 ng/ml) than after water (12.6±4.1 ng/ml) or water with alcohol (12.0±2.2 ng/ml) (p<0.05). An induction of prolactin secretion by beer consumption was also reported by Carlson et al. u. Five healthy men aged 3 1-47 years and seven healthy, non-lactating women aged 22-46 years were studied in the late morning after their usual breakfast. After collection of 3 baseline samples, the subjects consumed 800 ml ofbeer with 4.5 % alcohol in 30-45 minutes, and blood samples were collected at 15 minute intervals for 2.5 hours. In the male subjects, serum prolactin levels increased after beer consumption from 7. 0±1.5 ng/ml(M±SE) to 12.0±2.1 ng/ml (p<0.025). In females there was an increase from 9.6±1.8 ng/ml to a peak of 22.6±2.6 ng/ml (p<0.005). A similar response was observed in one woman who drank nonalcoholic beer. Pretreatment of the women in the study with naloxone had no effect on prolactin secretion. In contrast to beer, there was no prolactin response in female volunteers after oral ingestion of a hot cacoa drink or a an aqueous solution of D,L-salisonol, a tetrathydoisoquinolone component of beer and some other alcoholic beverages which had been proposed as a potential responsible agent 12 .These two studies as well as other data 13-16 demonstrate that neither ethanol alone nor a simple volume stimulus induce a rise of serum prolactin, whereas beer drinking can induce an acute increase of prolactin secretion in non-lactating humans.
A similar effect of beer on prolactin secretion was also reported in animal experiments. A study aimed primarily at investigating a potential relationship between beer intake and development of mammary adenocarcinoma 17 investigated female C3H/St mice that were infected with a b-type RNA virus (Bittner particle) to induce mammary adenocarcinomas. The animals were either given water or decarbonated light beer (Budweiser) as the sole liquid. While there was no difference in tumor prevalence or tumor growth, beer drinking mice tended to have higher serum prolactin levels at 49 days after weaning (65±35 ng/ml)than controls (53±23 ng/ml; n.s.). Similarly, intravenous injection of an aqueous beer extract induced a marked increase ofprolactin secretion in ewes 18.
Sawagado and Houdebine from the Laboratoire de Physiologie de la Lactation at Jouy-en-Josas, France, attempted to further characterise the lactogenic compound in beer 18. Mature virgin Wistar rats aged 14 weeks were given orally for 4 days lyophilised beer powder produced from Pelfort ordinary stout, or aqueous barley extracts. Measurements of beta-casein contents in rat mammary gland by radioimmunoassay demonstrated a marked beta-casein accumulation with both beer and barley administration, which could be prevented by the simultaneous administration of the dopaminergic drug CB 154. Thus, it appeared that the effect on casein accumulation was mediated by prolactin. Further studies in ewe showed that beer powder, barley extract and a crude malt extract, but not hop extract triggered a prolactin response, which suggested that the lactogenic principle in beer does not derive from hop but from beer barley and malt. The authors also found that maltose, which is abundantly found in barley, was unable to stimulate a prolactin response.
In order to identify the class of molecules to which the lactogenic compound or compounds belong, Sawagado and Houdebine went on and treated beer, barley and malt extracts with various solvents 18. It turned out that the active compound in beer is insolubilized in 50 % ethanol. After resuspension in water and extraction with chloroform, the active compound was detected in the water phase. Thus, the authors concluded that the active molecule is neither a protein not a lipid but rather a polysaccharide. It turned out that more alcohol was required to precipitate the lactogenic activity from beer than from barley and malt suggests that the active polysaccharides might be partly cleaved into smaller molecules during the fermentation process.
In further studies, the authors found that several other plants also contain lactogenic compounds, including cotton seed, Europhorbia hirta and Accacia nilotica. Thus, in addition to beer some other plants or plant extracts might be utilisable for enhancing lactogenesis.
In an electronic literature search, we did not find any controlled studies that investigated the possible clinical effects of beer consumption on lactogenesis and breastfeeding success. Indeed, it seems rather difficult to realise such a controlled study due to both ethical and practical limitations. However, studies are available that investigated the effects of alcoholic drinks on the short-term behaviour ofbreastfed infants.
Menella and Beauchamp studied a group of 12 lactating women in a study with a cross-over design 19.On two consecutive days, they consumed either beer with 4.5 % alcohol providing an alcohol intake of0.3 g/kg, or an equal volume ofnon-alcoholic beer. Following alcoholic beer consumption, the odor of expressed milk was altered and infants drank less milk (149.5±13.1 ml vs. 193.1±18.4 ml, p<0.05) than after maternal consumption of non-alcoholic beer. In contrast to the alteration of drinking behaviour, there was no significant difference in maternal perception of their infant's behaviour or their own lactational performance. A similar effect on infant feeding was observed in another study on 12 mother-infant pairs after maternal consumption of either orange juice or orange juice with a small amount of alcohol (0.3 g/kg) 20.When the mothers had consumed alcohol, their infants sucked more frequently during the minute offeeding (67.0±6.5 vs. 58.4±5.9 sucks/minute, p<0.05),but consumed significantly less breast milk milk (120.4±9.5 ml vs. 156.4±8.2 ml, p<0.001. Both these studies could not provide information on potential longer-term effects of maternal alcohol intake on breastfeeding.
In addition to these short-term observations, concern arises with regard to early alcohol exposure of the breastfed infant in view of the proposed potential long-term effects of early flavour experience on later preferences for foods and drinks 21 . It has been considered that exposure to significant amounts of alcohol during early life might enhance later alcohol consumption. Moreover, the possible pharmacological effects of alcohol in young infants let lead us to consider a regular alcohol intake ofbreastfeeding women undesirable 22,23, ,even though modest consumption has not been associatedwithadverse effects5.
In conclusion, there are clear indications that beer can stimulate prolactin secretion which may enhance lactogenesis. The active principle responsible for the effect ofbeer on prolactin is not the alcohol content but apparently a polysaccharide from barley, which explains that the effect on prolactin can also be induced by non-alcoholic beer. However, no systematic studies are available to evaluate the clinical effects ofbeer on induction oflactogenesis, and short term studies have shown a reduced breast milk intake by infants after moderate alcohol consumption of their mothers. It is conceivable that relaxing effects of both alcohol and components of hop might also have beneficial effects on lactogenesis is some women, but no hard evidence of causal effects is available. It appears prudent not to generally advocate the regular use of alcoholic drinks during lactation but to rather refer mothers to non-alcoholic beer, although no adverse effects ofan occasional drink during lactation have been documented.
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