Health-Related Aspects of Beer: A Review

Abstract

Beer is consumed worldwide and is a universally popular beverage. This is due to its sensory, nutritional, and medicinal properties. Surveys have shown that light to moderate consumption of alcoholic beverages (including beer) with relatively low alcohol contents can provide various favorable impacts on humans' health, including nutritional benefits, anti-mutagenic and anti-carcinogenic effects, reduction of cardiovascular disease (cardioprotective effect), hypolipidemic effect, immune system stimulation, anti-osteoporosis effect, and reducing risk of dementia. On the contrary, consumption of these beverages in excessive amounts results in some heath disorders, such as allergy induction, increase in the plasma concentration of uric acid, mutation and cancer induction, increase in the risk of dementia, obesity, and some social misbehaviors. Health-related aspects of beer (both positive and negative impacts) have been comprehensively reviewed in this article.

Keywords:

• Allergy
• Beer
• Cancer
• Coronary heart disease
• Health
• Nutrition

INTRODUCTION

Beer, the complex brewed beverage made from malt (germinated barely), hops, water, and yeast, is widely consumed all over the world. In 2002, the estimated average beer consumption per capita was 72.9 L. In some countries, this figure was higher than 130 L.[1] According to the FAO, in 2002, beer with the annual consumption of 1.3 hectoliter ranked as the fifth world-consumed beverage, after tea, fizzy drinks, milk and coffee.[2] The consumption of beer is of special interest because of its organoleptic and health-related characteristics and also due to its low cost as compared with other types of Western and European alcoholic beverages, such as wine. For instance, research examinations have shown that overall positive expectancies for beer were much higher than that for wine. Hard liquor is linked to the largest number of negative consequences expected by the participants.[3–6 Hittner[7] reported that, among female college students classified as female “high-frequency” drinkers, 48.1% preferred mixed drinks and 43.5% preferred beer, while “low-frequency” drinkers preferred mixed drinks to other alcoholic beverages. According to the above study, the majority of male students preferred beer, whether they were “high-frequency” or “low-frequency” drinkers. It seems that male college students may choose beer because of its cheaper price, its acceptance as a normal drink in the Western societies, and also due to its association with perceived masculinity.[8,9] According to Innes,[10] effectiveness and lower cost of beer are among the reasons for replacing red wine as the cardioprotective beverage. Statistics indicate that those engaged in team sports consume more beer than wine.[11]

Beer has traditionally been a popular drink among many cultures. For example, in ancient Egypt, and subsequently in many other cultures, beer was the beverage of choice for all members of the family at different ages.[12] The oldest historical evidence show that formal brewing dates back to about 6000 B.C. in ancient Babylonia. About 160 types of beers were produced at that time. In ancient Egypt, Rome, China, India, and Iran, numerous types of beers and beer-like beverages from different grains were industrially manufactured and regulations were set for their production, sale, and export. Beer was consumed not only as a regular social drink, but also as an important component of religious ceremonies.[13]

The basic ingredient of classic/normal beer is malted barley. Other cereals can also be added as adjuncts. Hops add a characteristic bitter flavor and yeast is essential for the fermentation.[14] Various brewing parameters, such as the variety of barely and the malting process, temperature, and pH of mashing, sparging, boiling, the variety of hops added during wort boiling and fermentation conditions, including yeast strains, pitching rate, temperature, pressure, aeration, agitation, and stirring as well as storage and aging conditions, influence the type and quality of beer.[13,15] Normal beer contains 2.5–13% (v/v) ethanol. Most beers worldwide have alcohol contents in the range 3 to 6% (v/v).[5,12] Considering their alcohol contents, beers are usually classified as low-strength (having about 2–3% alcohol), medium/average strength (having about 5% alcohol), and high-strength/strong (>5–6% alcohol) beers.[12] Lager, ale, pilsener, and stout are several of the most consumed types of beers.[1] Low-alcohol beers with <2.5% alcohol and non-alcoholic beers with <0.5% alcohol have been developed in recent years.[13]

Studies have shown that light-to-moderate consumption of alcoholic beverages, including beer, can provide various advantages to human health due to the presence of protein, B vitamins, certain minerals, phenolics (antioxidants), ethanol, dietary fibers, and even prebiotic compounds.[16,17] However, an excessive amount of alcohol consumption leads to adverse effects on the individuals and also to the society. In the present study, the health-related aspects of beer (both positive and negative) have been comprehensively reviewed.

STAGES OF BEER MANUFACTURE

The process for brewing normal beer consists essentially of malting barley that includes steeping, germinating and kilning stages, crushing the malted barley and adding water to create the mash, separating the resultant aqueous extract known as “wort,” boiling the wort with hops, cooling and clarifying the wort, fermenting the wort (in two stages), filtering, adding other additives, pasteurizing, and finally packaging the beer. Beer characteristics can be influenced by the variety of barley used for the brewing and the conditions applied in each of the above steps.[14] Figure 1 shows generic stages of beer manufacture.

Figure 1 Generic stages of beer manufacture.

HEALTH BENEFITS OF BEER

Beer contains components that bring some nutritional and medicinal health advantages for consumers. From a nutritional point of view, beer contains protein, B vitamins, and some minerals. Beer contains more protein and B vitamins than wine does. However, the antioxidant content of beer is equivalent to that of wine, but the specific antioxidants are different in these sources.[18] From a medicinal standpoint, components, such as phenolic compounds, ethanol, and dietary fibers, are also important and are discussed below along with their nutritional properties.

Nutritional Highlights

Beer can offer significant contributions to the dietary intake. Table 1 shows this daily contribution to the men and women from a nutrients intake point of view, in average. The nutritional highlights of beer are discussed below:

Table 1 The approximate percentages of nutrients after the ingestion of 1 L of normal beer, as compared with recommended daily intake (modified from Bamforth[12,17])

	The minimum and maximum approximate percentage of nutrient supply for adults (age 25–50)
	Male		Female
Nutrients	Min.	Max.	Min.	Max.
Energy (Kcal)	6	43	8	57
Protein (g)	5	8	6	10
Carbohydrate (g)	A	A	a	a
Fat (g)	A	A	a	a
Vitamin A (μg)	Neg.*			Neg.
Vitamin D (μg)	Neg.			Neg.
Vitamin E (mg)	Neg.			Neg.
Vitamin K (μg)	Neg.			Neg.
Vitamin C (mg)	nS**	50	nS**	50
Thiamine (mg)	0.2	5	0.3	7
Riboflavin (mg)	1	47	1.5	61.5
Niacin (mg)	16	42	20	53
Vitamin B6 (mg)	3.5	85	4.5	106
Folate (μg)	20	300	22	333
Vitamin B12 (μg)	150	1500	150	1500
Biotin (μg)	2 or 7***	15 or 50	2 or 10	15 or 75
Calcium (mg)	5	17.5	5	17.5
Phosphorus (mg)	11	50	11	50
Magnesium (mg)	17	57	22	71
Potassium (mg)^b	nS	nS	nS	nS
Sodium (mg)^b	nS	nS	nS	nS
Iron (mg)	1	5	0.6	3
Zinc (mg)	0.07	10	0.08	12
Selenium (μg)	<0.6	10	<0.7	13
^aFor a diet containing alcohol, the recommendation is that the population average should have 15% of total dietary energy in the form of protein, 47% as carbohydrate, and 33% as fat.
^bBeer contains potassium and sodium in the range of 330–1100 and 40–230, respectively.
*Negligible. **nS = not specified. ***Dependent on the individuals and conditions.

Vitamins

As shown in Table 1, significant levels of several B vitamins are supplied through the moderate consumption of beer. The quantity of the present vitamins depends upon the raw materials as well as the process practices. However, among B vitamins, thiamine is notably deficient in beer. It has been proven that thiamine deficiency stimulates alcohol consumption, because thiamine shortage interferes with glucose metabolism.[19] Ethanol shows antagonism with the bio-utilization of vitamins. Therefore, non-alcoholic beer would be a wiser choice than high-alcoholic beverages. There is also a negative correlation between the intake of alcohol and that of carbohydrates.[12]

Minerals

Cereals, water, hops, yeast, processing conditions, and type of containers can contribute to the mineral contents of the beer.[20] Minerals in beer have nutritional importance and may also influence the brewing process.[21] In addition, the type and concentration of minerals have been used to differentiate among different types of drinks, such as wines,[22,23] vinegars,[24] coffees, teas, and beers.[1] Beer is an important dietary source of selenium. The relatively high potassium to sodium ratio (typically 4:1) in beer is consistent with a low sodium diet. This ratio gives beer a significantly greater diuretic effect than water.[25] It was reported that beer is a good source of silicon compared with seafood and cereal products.[26]

Medicinal Values

Despite the healthy aspects achieved by regular/moderate consumption of beer, its excessive daily intake can lead to different health disorders as described in its own section subsequently. Recently, a renewal interest has been focused on beer, a common beverage with a moderate antioxidant activity/capacity coupled with low ethanol content, without the negative effects produced by high doses of ethanol.[27]

Epidemiological, experimental, and clinical investigations have revealed that light-to-moderate consumption of alcoholic beverages, such as beer, provides various health benefits to humans. According to studies reported,[28–30 a U-shaped model describes the connection between alcohol consumption and most of the diseases. This means higher death rates among those who abstain as well as those who drink an excess of six drinks a day. Statistics indicates that low alcohol consumption (10–15 g alcohol/day, equivalent to about one glass of normal beer per day) reduces annual mortality when compared with non-drinking and heavy drinking rabbits.[15] The therapeutic effects of beer have been partly attributed to its alcohol content as well as to its phenolic and protein profiles. Ethanol, regardless of its direct impact on platelet aggregation, HDL metabolism, and fibrinolysis (all involved in the pathogenesis of cardiovascular diseases), could play an important role in the absorption of phenolic compounds in vivo.[27]

Epidemiological studies have suggested associations between the consumption of phenolic compounds and the prevention of many human diseases associated with oxidative stresses, such as atherosclerosis, cancer and tumor development, diabetes, neurodegenerative diseases, and aging. It has been reported that flavonoids have an anti-inflammatory effect.[31,32] Phenolics, which are more efficient than other types of antioxidants (e.g., vitamin E, Vitamin C, and β-carotene), may significantly contribute in maintaining the endogenous redox balance in humans.[27,33–37 A large number of phenolics may act as antioxidants, with mechanisms involving both free radical scavenging and metal chelating.[27,38–42 Free radicals can initiate reactions that modify unsaturated lipids (especially polyunsaturated ones), proteins, and nucleic acids, which are associated with the early stages of atherosclerosis and carcinogenesis and also with the development of neurodegenerative diseases.[43] Coffee has been recognized as the main source of phenolic compounds followed by other phenolic-rich foods, such as red wine, fruits and fruit juices, vegetables, beer, tea, olive oil, and milk.[35,44,45] More than 35 phenolic compounds have been identified in beer (about 80–90% from malt and 10–20% from hops).[15,46] However, the in-vivo antioxidant potential and efficiency of these compounds substantially are affected by their bioavailabilities.[35] It has been shown that phenolic acids from beer are assimilated and extensively metabolized in humans.[35] From the structural point of view, phenolic compounds in beer belong to simple phenols; benzoic and cinnamic acid derivatives; coumarins; catechins; di-, tri-, and oligomeric proanthocyanidins; prenylated chalcones; and flavonoids as well as alpha- and iso-alpha acids.[15] Besides antioxidant compounds, trace elements, such as zinc, copper, and selenium, also play an important role in antioxidant protection in vivo. These elements are part of the active site of intercellular antioxidant enzyme superoxide dismutase and glutathione peroxidase.[38] The most important medicinal properties of beer are described in the following sections. The principal medicinal values of beer after regular drinking in light-to-moderate amounts and relevant selected publications are summarized in Table 2.

Table 2 The principal medicinal values of beer after regular drinking in light-to-moderate amounts

Medical impacts	Main involved component(s)	Some suggested mechanism(s)	Sources
Anti-mutagenic and anti-carcinogenic effects	Phenolics, Pseudouridine, Spongouridine, Glycine betaine, Melanoidins	-Antioxidant effect -Modulation of carcinogens metabolism -Anti-inflammatory effect	31, 32, 43, 47–50, 60, 62, 65, 66, 101
	Dietary fibres	-Facilitating intestinal excretion
Cardioprotective effect
	Ethanol	-Increasing serum HDL-C	10, 29, 49, 51, 52, 77, 80, 83, 87, 92, 93, 101, 103
		-Stress alleviation
		-Decrease of cholesterol and triglycerides
		-Protection against oxidative stresses
	Phenolics	-Avoiding hyperhomocysteinemia
	Folic acid	-Immunomodulation
	Different compounds	-Sedative and hypnotic impacts
	Hop-derived bittering agents	-Stress alleviation
Immune system stimulation		-Hypolipidemic effect
	Proteins and amino acids
Anti-osteoporosis effect
		-Stimulating non-specific immunity and secretion of cytokines	87
Reducing risk of dementia, retardation of aging	Different components
		-Inhibiting bone resorption	43, 49, 50, 104
	Phenolics
Reducing risk of dementia, retardation of aging	Ethanol, Phenolics	-Stress alleviation	31, 32, 35, 49, 60, 101, 109, 110
-Protection against oxidative stresses
-Antibacterial activity
Prevention of diabetes	Phenolics	-Bacterial intracellular modifications	31
Anti-microbial activity (gram positive bacteria)	Isohumulones		113–116
Treating stomach ulcer	Ethanol	-Anti-infective effect on Helicobacter pylori	131
Radio-protective effect	β-pseudouridine		120
Enhancing sociability, sexuality, and tension reduction (relaxation)	Ethanol		135, 136
Mouthwash, enema, and vaginal douche, and application on wounds	Ethanol, low pH/high acidity, other components		12, 121
Appetite stimulation and promotion of bowel movement in the elderly	Ethanol, low pH/high acidity		122
Better cognitive function at old ages	Ethanol, probably phenolics		123, 124
Facilitating renal excretion of aluminium	Salicylic acid		126
Estrogenic properties (treatment of pre-menopausal problems (hot flashes) as well as prevention of osteoporosis in post-menopausal women	Phenolics (especially prenylnaringenin)		43, 61
Anti-viral and anti-HIV activities	Prenylated chalcone xanthohumol, further hop constituents	- Inhibiting HIV-1 induced cytopathic effects and HIV-1 replication in peripheral blood mononuclear cells	134

Anti-mutagenic and anti-carcinogenic effects

Cancer has been a serious cause of human mortality.[47] It has been shown that the consumption of phenolic compounds, as proper antioxidants, through beer or other phenolic-rich foods is associated with the protection against oxidative-related diseases including various types of cancers.[42] These compounds are able to block free radicals.[43] There are some reports showing that beer may counteract the carcinogenesis.[48–50 Investigations on the laboratory animals and humans indicated an increase in the plasma antioxidant activity after the ingestion of beer.[51,52] Angiogenesis, the formation of new capillary blood vessels for supplying oxygen and nutrients, play a key role in the development of malignant tumors.[53] The inhibition of angiogenesis by beer consumption prevents tumor growth and metastasis.[54,55] It has been indicated that humulone (a bitter acid from beer), which was isolated from hop extract, is a strong inhibitor of angiogenesis, in vivo and in vitro.[56,57] There are several reports indicating that phenolic compounds in beer can inhibit the development of prostate, breast, intestine, ovarian, and blood cancers.[58,59] Xanthohumol (a principal prenylated flavonoid) and other hop prenylflavonoids have been found to be a cancer chemoprotective/chemopreventive agent. These components can inhibit the metabolic activation of procarcinogens, induce carcinogen-detoxifying enzymes, and also prevent tumor growth via inhibiting inflammatory signals of angiogenesis at early stages.[43,60] However, it was concluded in a study that dietary intake of prenylflavonoids through normal beer consumption would not be sufficient, unfortunately, to achieve plasma concentration that could inhibit IQ (2-amino-3-methylimidazo[4,5-f]quinoline) activation in vivo. IQ is a procarcinogen found in cooked meats, in the Ames Salmonella mutagenicity test, and in an assay for binding of IQ metabolites to DNA at micro-molar concentrations.[61] Xanthohumol, iso-xanthohumol, 8-prenylnaringenin, and other prenyflavonoids from hops inhibited the cDNA-expressed human cytochrome P450 enzyme, Cyp1A1, Cyp1B1, and Cyp1A2, but not Cyp2E1 and Cyp3A4 at micro-molar concentrations.[61] These cytochrome P450s mediate the metabolic activation of many chemical carcinogens.[48] Phenolics have shown a positive effect on phase 2 enzymes activity. Phase 2 enzymes mediate the conjugation of carcinogens to endogenous ligands (such as glutathione, glucuronic acid, acetate, and sulfate) and, therefore, facilitate their excretion.[43] Several phenolic compounds derived from hops have reportedly shown antimutagenic properties against heterocyclic amines and similar carcinogenic compounds.[47–49,61] Ethanol alone did not show any antimutagenic activity against these heterocyclic amines and such effect has mainly been attributed to the pseudouridine and its analogs, such as spongouridine[47] as well as glycine betaine (betaine glycine)[62] present in the beer rather than phenolics. Kimuar et al.[62] and Arimoto-Kobayashi[63] reported that the mutagenic action of some heterocyclic amines generated in cooked proteinaceous foods (such as meat and fish) could be modified by the presence of glycine betaine in beer. Melanoidins (the polymeric and coloured final products of the Maillard reaction), which are formed non-enzymatically during the roasting of malt, indicate peroxyl radical scavenging potential.[64,65] Melanoidin fractions with relatively high molecular weight (>200 kDa) also weakly induced NADPH-cytochrome c reductase and size-dependently modulated GST activities in the Caco-2 colon cancer cell line.[66] The in-vivo action of melanoidins on the cancer requires further investigation.

Beer has been shown to contain 0.4–6.2 g L⁻¹ of dietary fibers.[67] The British Nutrition Foundation recommended 18 g of dietary fiber per day as a desirable level for adults.[12] Therefore, beer might be able to prevent colon cancer in individuals drinking beer on a regular basis. Consumed beer does not support the growth/activity of harmful and pathogenic intestinal microorganisms.[12] Stimulating the growth and/or activity of faecal bacteria increases the risk of cancer because of converting pro-carcinogen compounds to carcinogenic compounds.[68]

Reduction of cardiovascular disease (cardioprotective effect)

Coronary artery disease (CAD)/cardiovascular disease (CVD) are the main cause of mortality in Western industrial countries[69] and are one of the most dangerous diseases of our time.[70,71] The main reason for the high mortality from CAD is myocardial infarction due to the thrombosis of coronary arteries.[72] The regular light-to-moderate consumption of alcoholic beverages is associated with significant reductions in the mortality related to coronary heart disease (CHD). This is known as the cardioprotective effect of beer.[10,29,30,36,49,51,52,73–87 Ethanol is able to increase high density lipoprotein (HDL)-cholesterol plasma level, to decrease platelet aggregation, and to enhance blood fibrinogenesis, all associated with a low risk of CHD.[88,89] The same results have been reported for beer.[82,87] Vinson et al.[86] found that consumption of lager significantly decreased cholesterol and triglycerides. Moderate consumption of beer has been reported to improve lipid metabolism and to increase antioxidant and anticoagulant activity of the host resulting in higher cardioprotective effects.[36,51,52] Beer may protect the organisms from oxidative stresses and prevent atherosclerosis.[49,50] The antioxidant capacity of beer, as mentioned before, is related to its polyphenolic compounds.[90,91] These compounds block free radicals, which are potent oxidizing agents of fats in the body. The lowest risk of myocardial infection was observed among men who drank beer almost on a daily basis (4–9 L a week).[82] According to recent large population-based studies, moderate drinking of beer in the range of 1–3 daily drinks is associated with a 30–40% decrease in the coronary diseases compared to not drinking it at all.[29] Hypolipidemic effect of beer is also associated with a decrease in the risk of cardiovascular diseases. Several studies on laboratory animals and human subjects have shown that the level of plasma lipids decreases after the ingestion of beer.[51,52,92,93] It has been reported that the beer proteins and amino acids might have much wider biological functions than their basic biosynthetic roles as building blocks of the human body.[51] Controlling plasma cholesterol and reducing lipid level in the blood are among those functions. In other words, proteins and essential amino acids are bio-active components of beer.[51,52] Gorinstein et al.[94] found that beer with high protein and essential amino acid concentrations effectively reduced total cholesterol and LDL-cholesterols in rats. However, it did not affect total radical-trapping antioxidative potential. It has been reported that the contents of total proteins, albumin, and most studied amino acids in beer were significantly higher than those in wine.[95] In some sources, the improved lipid metabolism induced by moderate beer consumption has mainly been attributed to its polyphenolic compounds.[51,93,96,97] According to Gasowski et al.,[98] to receive the best results in terms of plasma lipid improvement, beer with the highest antioxidant potential must be consumed. The immune activation property of beer (discussed in the next section) is also deeply involved in atherogenesis.[99] Ingestion of folic acid from beer leads to a decrease in the homocysteine content of the blood.[100] Hyperhomocysteinemia is a significant risk factor for vascular diseases.[12]

The fact that moderate consumption of alcohol leads to stress alleviation may also take part in reducing heart problems.[101] Morrell[102] suggested that beneficial effects of alcohol consumption are consequences of drinking impacts on relaxation. Beer may be particularly valuable as compared to other alcoholic beverages, as the hop-derived bittering agents are said to have sedative and hypnotic impacts.[101]

Immune system stimulation (immunomodulation)

It was observed that beer stimulated non-specific immunity in rats.[103] It appears reasonable that ingredients of beer could play some roles in modulating immune system functions, e.g., influencing the production and secretion of cytokines.[87] More studies are needed to find out other aspects of immunomodulation associated with each component of beer, i.e., bioactive proteins, phenolics, and alcohol.

Anti-osteoporosis effect

Beer may counteract osteoporosis.[49,50] It has been found that humulone (the bitter acid from beer) isolated from beer hop extract strongly inhibits bone resorption.[104] Stevens and Page[43] reported that beer flavonoids have an inhibitory effect on osteoporosis. Beer is a good source of silicon, which can reduce the risk of osteoporosis.[17,105]

Reducing risk of dementia

Due to the enormous burden on our health care system, dementia is becoming one of the major challenges of the current century in our societies.[106] For instance, Alzheimer's disease causes more than 360,000 new cases in the United States annually, with a national annual cost of caring for such patients more than US$50 billion.[107,108] Light-to-moderate alcohol consumption has been recognized to be associated with a reduced risk of dementia in individuals aged 55 or older.[109] It has been pointed out that the consumption of 1–6 drinks per week was correlated with a lower risk of dementia incidents among older adults when compared with abstention.[110] By doing a 2-yr follow-up study of alcohol consumption, Deng et al.[111] found that light-to-moderate drinking was associated with a significantly lower risk of dementia compared with no drinking at all. Phenolic acids of beer with relatively high antioxidant capacity may afford protection against oxidative-stress-related diseases including neurodegenerative diseases.[35] Moderate consumption of beer reduces the odds of age-induced macular degeneration,[112] which is an eye disease related to the lack of certain antioxidants, such as luetin, in the diet.

Other health-related benefits of beer

Epidemiological studies have suggested a close relation between the consumption of phenolics from phenolic-rich foods and the prevention of diabetes and aging.[35] Iso-humulones from hops have indicated certain levels of antibacterial activity on most gram-positive bacteria.[113–116 However, their positive role in the human body is still questionable. Lactic acid bacteria (gram-positive) are the most abundant microbial contaminants in beer.[117,118] Thus, further investigations are required about the impact of these components on the pathogenic microorganisms regarding gastrointestinal infections in vivo. Drinking beer reduces radiation-induced chromosome aberration in human lymphocytes too.[119] β-Pseudouridine separated from beer was found to be a potent protector against the damage caused by radiation.[120] Beer has also been reported for such applications as mouthwash, enema, and vaginal douche.[12,121] However, regular consumption of beer can prevent vitamin deficiency diseases, such as beriberi, and other neurological diseases.[12] Low doses of alcohol, including that of beer, have been reported to stimulate appetite and facilitate bowel movement in the elderly.[122] There is evidence that moderate alcohol consumption may be associated with better cognitive function at old age.[123,124] Beer drinking, as well as a low fat or weight reduction diet, relates to substantial reduction in the risk of urolithiasis.[125] Silicic acid from beer can promote the renal excretion of aluminum.[126] There are several reports that some extracted phenolic compounds from hops (especially 8-prenylnaringenin) exhibit estrogenic properties.[15,43,127 ^– 129] Therefore, drinking 8-geranylnaringenin-rich beverages may have positive influence on the treatment of pre-menopausal problems (hot flashes) as well as prevention of osteoporosis in post-menopausal women[43]. On the contrary, it has been implied that xanthohumol shows anti-estrogenic properties[60]. This characteristic effect might be beneficial because of the competitive receptor-binding between xanthohumol and mutagenic hormones such as 17β-estradiol. These hormones are considered as endogenous tumor promoters stimulating cell growth via interaction with estrogen receptors leading to an increase in the risk of breast and uterine cancers[130]. Further investigations are required to clarify the overall impact of beer (in-vivo) containing mixed estrogen/anti-estrogen activities. It has been reported that alcohol protects against infection by Helicobacter pylori, which is known as a key factor in producing stomach ulcer[131,132]. Prenylated chalcone xanthohumol (XN) and other hop constituents possess antiviral activities against a series of DNA and RNA viruses.[133] XN inhibited HIV-1-induced cytopathic effects (i.e., the production of viral p24 antigen and reverse transcriptase in C8166 lymphocytes) with EC₅₀ values of 2.3, 3.6, and 1.4 μM, respectively. XN also inhibited HIV-1 replication in peripheral blood mononuclear cells with an EC₅₀ value of 58.5 μM.[134] Wall et al.[135] found that college students endorsed greater “positive” alcohol outcome expectancies, including enhanced sociability, sexuality, tension reduction, and liquid courage in an on-campus bar as compared to a laboratory setting. By surveying female college students, MacLatchy-Gaudet and Stewart[136] found a positive correlation between the five positive alcohol outcome expectancies (arousal, social/sexual enhancement, personality transformation, global positive effect, and relaxation) in three specific contexts (social, sexual, and tension) and moderate alcohol consumption. It has been reported that beer contains some fibers with prebiotic potential.[17]

SPECIAL TYPES OF BEER

Production of novel-type beers (produced from grain with different manufacturing practices compared with normal beer) and beer-like beverages (produced basically from non-grain materials) have recently been developed. Low-alcohol and non-alcoholic beers, beer with high amounts of dietary plant proteins, low-calorie beers, gluten-free beers, beers containing savoury agents (such as fruits), and beers containing functional agents are among novel-type beers. Some of these kinds of beers may exhibit additional health advantages over the regular beers. However, these effects are rather complicated. For example, although it is somewhat reasonable to assume that non-alcoholic beers should possess all of the health-beneficial effects of normal beers (except for those related to the alcohol), the synergistic or probably antagonistic impacts of ethanol on the health potency of some medicinal components should also be considered. It is of course acceptable that low-alcohol and non-alcoholic beers do not display possible harmful impacts of beers containing higher alcohol levels, i.e., those issues related to the alcohol part of the beer. Dietary plant proteins (especially soy) play a positive role in controlling plasma cholesterol.[137] Opaque sorghum beers with low alcohol content (2–3 mL 100 mL⁻¹) are popular alcoholic beverages in Africa. Their low alcohol content makes them suitable beverages for adults and teenagers.[132,138] This beer can improve the macronutrient supply of the diet and the bioavailability of such micronutrients as iron and zinc.[138,139] Sorghum contains various phenolic and antioxidant compounds with health-promotional effects.[26]

POSSIBLE HARMFUL EFFECTS OF BEER

Although the light-to-moderate consumption of beer comprises different health benefits, an excessive consumption might also lead to health disadvantages due to the excessive intake of such compounds as ethanol and allergens. These aspects are discussed further in the following sections and are summarized in Table 3.

Table 3 The principal health disadvantages of beer after indiscriminate drinking

Medical impacts	Main involved component(s)	Some suggested mechanism(s)	Sources
Vitamin shortage	Ethanol		19
Allergy induction	Biogenic amines generated by lactic acid bacteria contaminants(ethanol exhibits potentiating effect on biogenic amines function)		117, 118, 149, 153, 154–157, 158–162
Hyperuridemia	Ethanol	-Inhibiting urinary excretion of uric acid, increase in plasma concentration of oxypurines	163–168
Mutagenicity and cancer inductio	Ethanol, toxic amines (nitrosamines)		50, 176, 177.
Increasing risk of dementia	Ethanol, aluminium in canned beer		179, 180
Obesity	Ethanol		37
Adverse effects on digestive system: stimulating increase of hepatitis, fatty degradation of liver, cirrhosis, pancreatitis and peptic ulcers	Ethanol		12, 50, 169–172
Negative effects in pregnant women expert athletes as well as hepatic and medicated people	Ethanol		184–186
Increasing blood pressure	Ethanol		187–189
Harmful effects on teeth	Residual sugar, low pH and high acidity		190
Adversely modifying the hormonal status in men	Isoflavanoids		58
Domestic and social violence, traffic accidents, inappropriate work events, falls, and drawing as well as physical and sexual abuse of children and women	Ethanol		12

Allergy Induction

Several cases of contact urticaria induced by beer have been described since 1980.[140,141] Moreover, ingestion of beer has been related to the cases of severe IgE-mediated anaphylaxis.[142,143] Also, hypertensive crises have been reported after beer consumption in patients treated with drugs inhibiting the detoxification enzyme monoamine oxidase.[144–148 The adverse effects were found both in tap and non-alcoholic beers caused by tyramine.[149] Beer was observed to be a cause of headache in migraine-susceptible consumers.[150] Garcia-Casado et al.[151] isolated two allergens associated with contact urticaria and severe IgE-mediated anaphylaxis from beer, namely, barely protein Z₄ (45 Kd) and lipid transfer protein 1 (LTP1; 9 Kd).

One problem with the beer is that due to the abundance of free precursor amino acids the presence of contaminant microorganisms having decarboxylating activities during the fermentation and storage of beer leads to the formation of biogenic amines, such as tyramine, putrescine, cadaverine, and histamine.[117,152–157 The contaminant microorganisms are usually lactic acid bacteria (i.e., Lactobacillus and Pediococcus spp.).[117,118,157,158] Both tyramine and histamine can be formed in bottled beers by lactic acid bacteria, mainly lactobacilli, surviving insufficient pasteurization.[149] Amine levels can be used as an indicator of poor microbial quality of the brewing procedure.[149,155] Brewer's yeast is unable to form biogenic amines.[117,157] Some amines (such as tyramine and agmatine) can also be formed during mashing and wort boiling due to thermal decarboxylation.[158] Malt is a source of agmatine, putriscine, spermidine, and spermine, while tyramine, histamine, and cadaverine have been formed during the main fermentation by the contaminating lactic acid bacteria.[149] Low to moderate amounts of biogenic amines (about 50 mg/kg food) can be ingested without any side effects on the consumer health. Detoxifying enzymes can alter them before they can be harmful. However, upon a higher intake, some cases of food poisoning could occur with such symptoms as headaches, respiratory distress, heart palpitation, hypertension or hypotension, facial flushing, itching, swelling, diarrhea, vomiting, migraine headache, and several allergy-related disorders.[156,159–162 For instance, tyramine intakes exceeding 6 mg within a 4 h period from beers containing over 10 mg tyramine per liter would be dangerous for consumers.[148] It is important to point out that alcohol, and probably some biogenic amines other than tyramine, present in beer can also potentiate tyramine effects.[149]

Increase in the Plasma Concentration of Uric Acid

Beer, as well as other alcoholic beverages, may increase the plasma concentrations of uric acid, oxypurines, and uridine, and their ingestion occasionally induces gouty arthritis in patients with gout.[163–165 Several mechanisms involved in such ethanol-induced issues have been reported: (1) increase of lactic acid level in the blood as a result of ethanol intake inhibits the urinary excretion of uric acid; (2) adenosine triphosphate (ATP) consumption and purine degradation induced by ethanol ingestion accelerates uric acid production; and (3) the plasma concentration of oxypurines (hypoxanthine and xanthine) is increased due to the enhanced ATP consumption and slightly inhibit xanthine dehydrogenate activity derived from ethanol metabolism.[163–166 Yamamoto et al.[166] reported that beer increased the concentration of uric acid in serum carrying significant amounts of purine (e.g., guanosine, hypoxanthine, xanthine, and guanine) compared to other alcoholic beverages. Beer consumption resulted in a greater increase in the concentration of uric acid in the plasma than did the other alcoholic beverages. On the contrary, there are a few reports indicating that organic acids present in the beer might decrease the uric acid level in the plasma.[167,168] Overall, due to the lack of sufficient information on this area, more studies need to be undertaken to reconfirm some of the findings mentioned here.

Mutation and Cancer Induction

There are enough evidences showing that excessive consumption of alcohol increases the risk of mouth, pharynx, larynx, esophagus, liver, colon, and breast cancers.[12,169–172 These effects are merely related to the daily intake of alcohol. In the case of beer, there are a few studies suggesting that the intake of beer increases the risk of certain cancers, not because of alcohol, mainly due to the toxic amines present in the beer.[173–175 Some amines at relatively high concentrations can react with nitrate-forming nitrosamines, many of which are known to be carcinogenic, mutagenic, teratogenic, and embriopatic.[154,156,176,177] For individuals consuming red meat more than twice a day and for those having a white-collar job, excessive intake of beer is associated with an increased risk of colon cancer.[173] There is a theory that nitrosamines are produced through the malting process by drying with hot air heated by direct firing techniques. However, some recent studies have reported that the level of nitrosamines in the beer are very low imposing no risk to the consumers, especially due to the fact that nowadays maltsters have altered the process to indirect firing techniques.[15]

Increasing Risk of Dementia

While light-to-moderate alcohol intake can reduce the odds of dementia, excessive alcohol consumption is associated with an increased risk of dementia and depression.[111,178] Cerebral, cerebellar, brain stem degeneration, optic atrophy, polyneuropathy and pellagra are from nerves system disorder symptoms arising from excessive consumption of alcohol.[12] The acidic nature of beer increases the metal migration (including aluminum) from the containers in canned beers, in which aluminum together with tin, steel, or steel foil have a protective effect on the quality of beer. Aluminum (at 10 mg L⁻¹) was found in the canned beer without any adverse impact on the flavor, color, or the clarity of it. If the aluminum alloy of high quality is not used during the production of the containers, migration of aluminum to the product will accelerate.[179] There is a possible direct relation between high aluminum content in the tissues and neurodegenerative disorders (such as Alzheimer's disease) or other encephalopathies or in some cases osteomalacia is present.[180,181]

Enhancing Obesity

Excessive intake of energy as alcohol may predispose consumers to obesity, especially in susceptible individuals. Consumers taking high-alcoholic (strong) beers are more prone to obesity than those consuming light beers.[37]

Other Health Threatening Effects of Beer

It has been reported that high consumption of alcoholic beverages can have a negative influence on the digestive system and incidence of hepatitis, fatty degradation of liver, cirrhosis, pancreatitis, and peptic ulcers.[12] A negative effect of beer on the protein metabolism in the body has also been proven.[182,183] Drinking alcoholic beverages is not recommended for pregnant women and expert athletes as well as hepatic and medicated individuals.[184–186 There are a few reports showing that consumption of alcoholic beverages increases blood pressure.[187,188] This is contrary to the results of Jastrzebski et al.,[189] who reported that beer consumption had no adverse effects on blood pressure in rats. Therefore, complementary investigations are required to further clarify the matter. This point should be taken into special consideration as statistical data show that CHD patients are often suffering also from high blood pressure.[188] High consumption of beer might have harmful effects on teeth due to its significant levels of residual sugar as well as its low pH (especially at pH < 4.0).[190] Lapcik et al.[58] demonstrated that isoflavanoids (phytoestrogens) from beer may adversely modify the hormonal status of men.

CONCLUSIONS

Beer is one of the most commonly consumed alcoholic beverages with beneficial effects on human health. This is mainly true when “medium-strength beer” is ingested in a moderate level (light-to-medium consumption). Health advantages of beer (nutritional and medicinal) are associated with the presence of components, such as antioxidants, certain minerals, certain vitamins, fiber, as well as relatively low levels of ethanol. Health disadvantages of beer are mainly attributed to the excessive intake of alcohol and to a lesser extent to the ingestion of some poisonous and allergen agents. Non-alcoholic beers could possess certain health benefits associated with the components other than the alcohol. On the other hand, consumption of low-alcohol and non-alcoholic beers can avoid possible health threatening issues related to excessive alcohol intake.

ACKNOWLEDGMENT

This article is related to the Ph.D. student thesis (Shahid Beheshti University of Medical Sciences).