Dietary Acrylamide and Cancer Risk in Humans: A Review

In April 2002, researchers from the Swedish National Food Administration reported that they had detected elevated levels of acrylamide in commonly consumed baked and fried foods. Acrylamide is known as a neurotoxin in humans and as a carcinogen in experimental animals, and it is classified as a probable human carcinogen by the International Agency for Research on Cancer (IARC, 1994). Therefore, the discovery that the compound forms naturally during high-heat cooking of starchy foods caused substantial alarm in Sweden and worldwide. Within months of the initial Swedish report, national governments and food companies began their own investigations on acrylamide in foods and discussed the potential impact of dietary acrylamide on the public’s health. The discovery also provoked public debate among scientists about the importance of the finding because of the relative lack of data in humans on the one hand and the knowledge that acrylamide in high doses is genotoxic in cell and animal studies on the other. Since 2002, researchers have engaged in a wide range of studies spanning across disciplines. In this review, we summarize the current state of knowledge on acrylamide in foods. We discuss the formation and intake of acrylamide in foods, present evidence for carcinogenicity in cell and animal studies, and examine the findings from epidemiological studies of occupational and dietary exposures. We conclude with a discussion of future directions in the field.

---

Zusammenfassung (Redaktion). Im April des Jahres 2002 berichteten Forscher der nationalen, schwedischen Lebensmittelbeh?rde über den erh?hten Gehalt an Acrylamid in gebackenen oder frittierten, üblicherweise verzehrten Lebensmitteln. Acrylamid gilt in Bezug auf den Menschen als Neurotoxin und hat sich in Tierversuchen als karzinogen erwiesen; die International Agency for Research on Cancer (IARC) hat Acrylamid als potenziell karzinogen für den Menschen eingestuft. Daher hat die Entdeckung, dass sich diese Substanz natürlicherweise beim starken Erhitzen von st?rkereichen Lebensmitteln bildet, erhebliche Beunruhigung in Schweden und weltweit ausgel?st. Schon wenige Monate, nachdem der schwedische Report über Acrylamid in Lebensmitteln erschienen war, wurden von den Regierungen verschiedener Staaten und auch von der Lebensmittelindustrie eigene, diesbezügliche Forschungsprogramme veranlasst. Der potenzielle Einfluss des Acrylamids in Lebensmitteln auf die Gesundheit der Bev?lkerung wurde ebenso diskutiert wie die Bedeutung dieser Entdeckung angesichts der Tatsache, dass für Menschen zwar kaum Daten vorliegen, dass aber Acrylamid in hohen Dosen auf Zellkulturen und Versuchstiere genotoxisch wirkt. Seit dem Jahr 2002 ist diesen offenen Fragen im Rahmen mehrerer Disziplin-übergreifender Forschungsvorhaben nachgegangen worden. Im vorliegenden Review wird der derzeitige Wissensstand über Acrylamid in Lebensmitteln vorgestellt. Die Autoren diskutieren die Bildung von Acrylamid in und seine Aufnahme mit Lebensmitteln, besprechen seine karzinogenen Eigenschaften in Versuchen mit Zellkulturen oder Tieren und analysieren die Ergebnisse epidemiologischer Studien. Zukünftige Entwicklungen werden er?rtert.

     

Dietary Acrylamide and Cancer Risk in Humans: A Review

In April 2002, researchers from the Swedish National Food Administration reported that they had detected elevated levels of acrylamide in commonly consumed baked and fried foods. Acrylamide is known as a neurotoxin in humans and as a carcinogen in experimental animals, and it is classified as a probable human carcinogen by the International Agency for Research on Cancer (IARC, 1994). Therefore, the discovery that the compound forms naturally during high-heat cooking of starchy foods caused substantial alarm in Sweden and worldwide. Within months of the initial Swedish report, national governments and food companies began their own investigations on acrylamide in foods and discussed the potential impact of dietary acrylamide on the public’s health. The discovery also provoked public debate among scientists about the importance of the finding because of the relative lack of data in humans on the one hand and the knowledge that acrylamide in high doses is genotoxic in cell and animal studies on the other. Since 2002, researchers have engaged in a wide range of studies spanning across disciplines. In this review, we summarize the current state of knowledge on acrylamide in foods. We discuss the formation and intake of acrylamide in foods, present evidence for carcinogenicity in cell and animal studies, and examine the findings from epidemiological studies of occupational and dietary exposures. We conclude with a discussion of future directions in the field.     

Mechanisms Linking Colorectal Cancer to the Consumption of (Processed) Red Meat: A Review

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the world. The vast majority of CRC cases have been linked to environmental causes rather than to heritable genetic changes. Over the last decades, epidemiological evidence linking the consumption of red and, more convincingly, of processed red meat to CRC has accumulated. In parallel, hypotheses on carcinogenic mechanisms underlying an association between CRC and the intake of red and processed red meat have been proposed and investigated in biological studies. The hypotheses that have received most attention until now include (1) the presence of polycyclic aromatic hydrocarbons and heterocyclic aromatic amines, two groups of compounds recognized as carcinogenic, (2) the enhancing effect of (nitrosyl)heme on the formation of carcinogenic N-nitroso compounds and lipid peroxidation. However, none of these hypotheses completely explains the link between red and processed red meat intake and the CRC risk. Consequently, scientists have proposed additional mechanisms or refined their hypotheses. This review first briefly summarizes the development of CRC followed by an in-depth overview and critical discussion of the different potential carcinogenic mechanisms underlying the increased CRC risk associated with the consumption of red and processed red meat.     

Impact of Diet on Breast Cancer Risk: A Review of Experimental and Observational Studies

Breast cancer, which presents the highest global incidence of all female cancers, is caused by the interaction of genetic and environmental factors. Among the latter, diet has attracted considerable attention, as it is a modifiable risk factor and thus offers an opportunity to design preventive strategies. Nevertheless, only alcohol consumption has been unequivocally related to increased breast cancer risk. Despite the failure of observational studies in human populations to clearly define the nature of the relationship between specific nutrient exposures and breast cancer risk, in vivo and in vitro studies strongly suggest its existence. Moreover, studies at the molecular level have identified the putative action mechanism by which the nutritional constituents of specific foodstuffs may exert protective or enhancing effects with respect to breast cancer risk. The inadequate experimental design of some observational studies, or the occurrence of measurement errors and/or recall bias during data collection, or insufficient follow-up and subject characterization, may underlie these controversies. By improving the methods used to study the relationship between diet and breast cancer risk, and by applying new technologies linked to novel approaches such as “nutrigenomics,” it might be possible to derive effective recommendations for breast cancer prevention and thus improve anti-cancer treatment.     

The Relationship Between Iron Status and Adiposity in Women from Developing Countries: A Review

Scientific reports have shown that iron deficiency is positively associated with adiposity. With the high prevalence of iron deficiency and obesity in developing countries and women being particularly affected, this review was carried out with the aim of elucidating the link between iron status and adiposity in women from developing countries and to examine factors influencing this relationship. An extensive literature search was conducted using several search engines. A systematic approach with prespecified inclusion criteria was used in selecting relevant literature. Eight studies that met the inclusion criteria were selected for review. The relationship between iron status indices and adiposity in women in developing countries varied widely. While some studies observed negative relationships, some reported positive relationships, and others no significant relationships. Furthermore, other factors such as infection, alcohol consumption, type of diet, and genes were shown to affect the relationship between iron status and adiposity in women in developing countries. In conclusion, the possibility of iron status playing a role in adiposity in women from developing countries is likely, and it may be influenced by several other factors as described in the results. Thus, it is recommended that a special research effort should be directed toward this area.     

Ochratoxin A and Human Health Risk: A Review of the Evidence

Ochratoxin A (OTA) is a mycotoxin produced by several fungal species including Aspergillus ochraceus, A. carbonarius, A. niger, and Penicillium verrucosum. OTA causes nephrotoxicity and renal tumors in a variety of animal species; however, human health effects are less well-characterized. Various studies have linked OTA exposure with the human diseases Balkan endemic nephropathy (BEN) and chronic interstitial nephropathy (CIN), as well as other renal diseases. This study reviews the epidemiological literature on OTA exposure and adverse health effects in different populations worldwide, and assesses the potential human health risks of OTA exposure. Epidemiological studies identified in a systematic review were used to calculate unadjusted odds ratios for OTA associated with various health endpoints. With one exception, there appears to be no statistically significant evidence for human health risks associated with OTA exposure. One Egyptian study showed a significantly higher risk of nephritic syndrome in those with very high urinary OTA levels compared with relatively unexposed individuals; however, other potential risk factors were not controlled for in the study. Larger cohort or case–control studies are needed in the future to better establish potential OTA-related human health effects, and further duplicate-diet studies are needed to validate biomarkers of OTA exposure in humans.     

Dietary Polyphenols and Human Gut Microbiota: a Review

Dietary polyphenols are substrates for colonic microbiota. They and their metabolites contribute to the maintenance of gastrointestinal health by interacting with epithelial cells, and largely by modulating the gut microbial composition. Polyphenols may act as promoting factors of growth, proliferation, or survival for beneficial gut bacteria—mainly Lactobacillus strains—and thus, exerting prebiotic actions and inhibiting the proliferation of some pathogenic bacteria such as Salmonella and Helicobacter pylori species. To date the interactions affecting metabolic pathways and numerous metabolites of dietary polyphenols have been widely documented. However, the effects of dietary polyphenols on the modulation of the intestinal ecology and on the growth of gut microbial species are still poorly understood. This paper summarizes data on the influence of dietary polyphenols on gut microbiota and the main interactions between dietary polyphenols and beneficial and pathogenic intestinal bacteria.     

Colorectal Cancer and Nonfermented Milk,Solid Cheese,and Fermented Milk Consumption: A Systematic Review and Meta-Analysis of Prospective Studies

Colorectal cancer is the second most prevalent cancer worldwide. A systematic review and meta-analysis of prospective studies was conducted to examine the association between intake of different types of dairy foods during adulthood and the development of colorectal cancer, specifically comparing nonfermented milk, solid cheese, and fermented milk. Seven databases were systematically searched and 15 cohort studies selected for inclusion, involving over 900,000 subjects and over 5200 colorectal cancer cases. Meta-analysis resulted in an overall relative risk of colon cancer of 0.74 (95% confidence interval 0.60–0.91) in men consuming nonfermented milk (highest intake category averaging 525 g/day). No association was found between consumption of nonfermented milk and rectal cancer in men or nonfermented milk and colon or rectal cancer in women. No protective association was found between consumption of solid cheese or fermented milk and colorectal cancer. Reasons for the differences in the impact of nonfermented milk, solid cheese, and fermented milk in the colon are discussed. This meta-analysis supports the inverse association between nonfermented milk consumption and risk of colon cancer in men, and provides an evidence base to assist in the formulation of dietary guidelines involving dairy foods.     

微量元素铁的生理功能及对人体健康的影响

铁是人体内含量最高的必需微量元素,它有参与氧的运输和贮存,参与合成细胞色素和多种金属酶,增强机体免疫功能等非常重要的生理作用。人体内缺铁或铁过量都会发生相应病变。     

柑橘属果皮渣制备膳食纤维的研究进展

柑橘属果皮渣作为柑橘加工的副产物,其中含有大量的膳食纤维,具有较好的生理功能。本文重点综述柑橘属果皮渣中膳食纤维的化学组成和制备方法,对其理化特性、生理功能的研究情况展开论述,并讨论柑橘属果皮渣膳食纤维在食品工业中的综合利用情况。     

Tannins and Human Health: A Review

Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods. They have been reported to be responsible for decreases in feed intake, growth rate, feed efficiency, net metabolizable energy, and protein digestibility in experimental animals. Therefore, foods rich in tannins are considered to be of low nutritional value. However, recent findings indicate that the major effect of tannins was not due to their inhibition on food consumption or digestion but rather the decreased efficiency in converting the absorbed nutrients to new body substances. Incidences of certain cancers, such as esophageal cancer, have been reported to be related to consumption of tannins-rich foods such as betel nuts and herbal teas, suggesting that tannins might be carcinogenic. However, other reports indicated that the carcinogenic acitivity of tannins might be related to components associated with tannins rather than tannins themselves. Interestingly, many reports indicated negative association between tea consumption and incidences of cancers. Tea polyphenols and many tannin components were suggested to be anticarcinogenic. Many tannin molecules have also been shown to reduce the mutagenic activity of a number of mutagens. Many carcinogens and/or mutagens produce oxygen-free radicals for interaction with cellular macromolecules. The anticarcinogenic and antimutagenic potentials of tannins may be related to their antioxidative property, which is important in protecting cellular oxidative damage, including lipid peroxidaton. The generation of superoxide radicals was reported to be inhibited by tannins and related compounds. The antimicrobial activities of tannins are well documented. The growth of many fungi, yeasts, bacteria, and viruses was inhibited by tannins. We have also found that tannic acid and propyl gallate, but not gallic acid, were inhibitory to foodborne bacteria, aquatic bacteria, and off-flavor-producing microorganisms. Their antimicrobial properties seemed to be associated with the hydrolysis of ester linkage between gallic acid and polyols hydrolyzed after ripening of many edible fruits. Tannins in these fruits thus serve as a natural defense mechanism against microbial infections. The antimicrobial property of tannic acid can also be used in food processing to increase the shelf-life of certain foods, such as catfish fillets. Tannins have also been reported to exert other physiological effects, such as to accelerate blood clotting, reduce blood pressure, decrease the serum lipid level, produce liver necrosis, and modulate immunoresponses. The dosage and kind of tannins are critical to these effects. The aim of this review is to summarize and analyze the vast and sometimes conflicting literature on tannins and to provide as accurately as possible the needed information for assessment of the overall effects of tannins on human health.     

血红素铁的制备及应用研究进展

血红素铁是与血红蛋白或肌红蛋白结合的铁,能以卟啉铁的方式直接被肠黏膜上皮细胞吸收,不受植酸根等抑制因素影响,且生物利用率高,不会产生任何消化道不适症状,是理想的生态补铁剂,被广泛用于食品保健品领域。此外,血红素铁还被作为抗癌药、功能性材料应用于医药、化工等行业。本文就血红素铁的制备纯化及功能、应用等方面做相关阐述。     

营养素补充剂广告宣传现状调查及其健康相关信息分析

目的:了解营养素补充剂广告宣传与传达健康相关信息的现况。方法:在对健康相关信息进行人群调查的基础上,对SFDA网站上2009年营养素补充剂广告的健康相关信息提炼、评分,并对健康相关信息进行人群调查,进行描述性统计分析。结果:营养素补充剂广告得分以3-4分的广告数量最多,占总数的43.86%;广告数量较多的以维生素C、维生素E和钙为活性物质的营养素补充剂广告评分的平均分分别为4.94、4.61和4.61;健康相关信息出现在广告中的频率居前4位的依次是"功效成分"、"剂型"、"适宜人群"和"营养素功能声称或健康声称"。结论:营养素补充剂广告宣传所传达的健康相关信息的整体水平有待进一步提高。     

A Question Mark on Iron Deficiency in 185 Million People of Pakistan: Its Outcomes and Prevention

Micronutrient deficiency especially the iron deficiency is the bane of our lives, affecting all strata of society. Unfortunately, the women during pregnancy, adolescence, and children are under this curse particularly in developing countries like Pakistan. It is one of the biggest reasons of complications during pregnancy and malnourished children under five years of age. Maternal death, still-births, and underweight births are most common consequences of iron deficiency and these outbreaks as iron-deficiency anemia in Pakistan. Disastrous nature of iron deficiency requires an urgent call to eradicate it. Hence, the solution should not be frail comparing with the huge economic loss and other incompatibilities. Flour fortification, supplementation, dietary diversification, and especially maternal education are possible solutions for combating this micronutrient deficiency.     

Dietary Buffering Requirements of the Lactating Dairy Cow: A Review

Requirements for buffering agents in dairy cow diets are a function of salivary buffer secretion, feedstuff buffering capacity, and feed acidity. Decreasing diet ADF by one percentage unit results in a .0564 unit decline in rumen pH. Reduction in rumen pH below 6.3 in dairy cows results in a 3.6 percentage unit decline in ADF digestion per .1 pH unit decrease and may result in depressed feed intake. Effects of decreased rumen pH on whole animal acid-base balance and metabolism are less well-defined. Although salivary buffer flow is not well-defined because of inadequate methodology available for measurement of saliva flow, the estimates of 108 to 308 L/d in beef and dairy cows is equivalent to 390 to 1115 g/d disodium phosphate and 1134 to 3234 g/d NaHCO₃ secretion, making saliva the predominant source of rumen buffering. Where buffer flow from saliva is inadequate, added dietary buffers may be justified. Data from a total of 82 experiments were summarized by buffering material and basal diets. Published experiments documented that the use of NaHCO₃, MgO, KHCO₃, K₂CO₃, and other buffering agents in low forage diets, are effective in increasing rumen pH, rumen acetate:propionate molar ratio, and milk fat percent. In diets containing at least 30% DM from forages, effects of dietary buffers on rumen pH and milk fat percent are less pronounced. In 17 studies where corn silage was the sole forage, addition of dietary NaHCO₃ increased feed intake by .5 kg/d and FCM by 1.1 kg/d. However, when alfalfa haylage or hay crop silage was included as all or part of the forage portion of the diet, responses were less. There is no justification for use of dietary buffers in alfalfa hay-based diets from a summary of eight experiments. Regression analysis of milk fat percent responses to dietary ADF, NaHCO₃, and MgO suggest that in diets containing 14% ADF, 44 g NaHCO₃, or 20 g MgO are equivalent to increasing dietary fiber by one percentage unit with responses to added buffers diminishing as dietary fiber increases.     

Dietary fibre and fibre-rich by-products of food processing: Characterisation,technological functionality and commercial applications: A review

Incidental products derived from the manufacturing or processing of plant based foods: cereals, fruits, vegetables, as well as algae, are sources of abundant dietary fibre. These fibre-rich by-products can fortify foods, increase their dietary fibre content and result in healthy products, low in calories, cholesterol and fat. They may also serve as functional ingredients to improve physical and structural properties of hydration, oil holding capacity, viscosity, texture, sensory characteristics, and shelf-life. Analytic methods and fractionation techniques of dietary fibres are evaluated.     

Lipid Stability of Beef Model Systems with Heating and Iron Fractions

Catalytic effects of different temperatures (55, 70, 85, and 100°C) on lipid oxidation were studied in aqueous- and chloroform/methanol-extracted beef model lipid systems containing iron forms inherent in beef (water-extractable, diffusate, nondiffusate, ferritin, myoglobin, hemoglobin), hematin, FeCl₂, or FeCl₃. Heating increased thiobarbituric acid and peroxide values in both systems. All forms of iron catalyzed lipid oxidation in aqueous systems, with greatest oxidation by heme and low molecular weight iron fractions. Oxidation in lipid extracts was not increased by ferritin, FeCl₂, or FeCl₃, but heme iron was the major oxidation catalyst. Lipid stability decreased with addition of any iron forms inherent in beef or with increased heating, which helps understanding of rapid oxidation of meat during refrigerated storage or after cooking.     

Mediterranean Diet and Cardiovascular Risk Factors: A Systematic Review

The aim of this paper was to systematically review and analyze the epidemiological evidence on the role of Mediterranean diet (MD) in the prevention of cardiovascular diseases (CVD). Fifty-eight studies exploring the relation between MD and lipoprotein concentration, antioxidative capacity and inflammatory markers, hypertension, obesity, diabetes, and metabolic syndrome, were identified and selected. These included 33 cross-sectional, 9 cohort, and 16 intervention studies. Most of the studies showed favorable effects of MD on CVD, although a certain degree of controversy remains in the respect of some issues, as obesity. Important methodological differences and limitations in the studies make difficult to compare results, thus further studies, particularly randomized clinical trials, are needed to finally substantiate the benefits of MD and to shed some lights on mechanisms.     

Brassica Foods as a Dietary Source of Vitamin C: A Review

Brassica genus includes known horticultural vegetables with major economical importance worldwide, and involves vegetables of economical importance being part of the diet and source of oils for industry in many countries. Brassicales own a broad array of health-promoting compounds, emphasized as healthy rich sources of vitamin C. The adequate management of pre- and postharvest factors including crop varieties, growth conditions, harvesting, handling, storage, and final consumer operations would lead to increase or preserve of the vitamin C content or reduced losses by interfering in the catalysis mechanisms that remains largely unknown, and should be reviewed. Likewise, the importance of the food matrix on the absorption and metabolism of vitamin C is closely related to the range of the health benefits attributed to its intake. However, less beneficial effects were derived when purified compounds were administered in comparison to the ingestion of horticultural products such as Brassicas, which entail a closely relation between this food matrix and the bioavailability of its content in vitamin C. This fact should be here also discussed.

 These vegetables of immature flowers or leaves are used as food stuffs all over the world and represent a considerable part of both western and non-Western diets, being inexpensive crops widely spread and reachable to all social levels, constituting an important source of dietary vitamin C, which may work synergistically with the wealth of bioactive compounds present in these foods.