Authors' perspective: what is the optimum intake of vitamin C in humans?

The recommended dietary allowance (RDA) of vitamin C has traditionally been based on the prevention of the vitamin C deficiency disease, scurvy. While higher intakes of vitamin C may exert additional health benefits, the limited Phase III randomized placebo-controlled trials (RCTs) of vitamin C supplementation have not found consistent benefit with respect to chronic disease prevention. To date, this has precluded upward adjustments of the current RDA. Here we argue that Phase III RCTs-designed principally to test the safety and efficacy of pharmaceutical drugs-are ill suited to assess the health benefits of essential nutrients; and the currently available scientific evidence is sufficient to determine the optimum intake of vitamin C in humans. This evidence establishes biological plausibility and mechanisms of action for vitamin C in the primary prevention of coronary heart disease, stroke, and cancer; and is buttressed by consistent data from prospective cohort studies based on blood analysis or dietary intake and well-designed Phase II RCTs. These RCTs show that vitamin C supplementation lowers hypertension, endothelial dysfunction, chronic inflammation, and Helicobacter pylori infection, which are independent risk factors of cardiovascular diseases and certain cancers. Furthermore, vitamin C acts as a biological antioxidant that can lower elevated levels of oxidative stress, which also may contribute to chronic disease prevention. Based on the combined evidence from human metabolic, pharmacokinetic, and observational studies and Phase II RCTs, we conclude that 200 mg per day is the optimum dietary intake of vitamin C for the majority of the adult population to maximize the vitamin's potential health benefits with the least risk of inadequacy or adverse health effects.     

Long-chain n-3 PUFA against breast and prostate cancer: Which are the appropriate doses for intervention studies in animals and humans?

The potential antineoplastic effect of the long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) remains a highly controversial issue. Numerous animal studies have supported the anticancer role of these dietary fatty acids, whereas conflicting results have been obtained in population studies, and only a few intervention human trials have been so far performed. In view of the possibility that the anticancer effects may be maximally observed within a defined range of EPA and DHA doses, herein we critically review the results and doses used in both animal studies and human clinical trials focusing on the possible n-3 PUFA protective effects against breast and prostate cancer. Our main aim is to identify the EPA and/or DHA ranges of doses needed to obtain clear anticancer effects. This may be of great help in designing future animal studies, and also in understanding the most appropriate dose for further human intervention studies. Moreover, since the healthy effects of these fatty acids have been strictly related to their increased incorporation in plasma and tissue lipids, we also examine and discuss the incorporation changes following the administration of the effective anticancer EPA and/or DHA doses in animals and humans.     

Pyrrolizidine alkaloid toxicity in livestock: a paradigm for human poisoning?

Livestock poisoning, primarily liver damage, caused by consumption of plants containing 1,2-dehydropyrrolizidine ester alkaloids (dehydroPAs), and the corresponding N-oxides, is a relatively common occurrence worldwide. Because of the economic impact, extensive investigations of such episodes have been performed, particularly in Australia, South Africa the United States and, more recently, South America. Plant species most commonly involved are members of the families Boraginaceae, Asteraceae and Leguminosae. These may be native species that periodically flourish under particular climatic conditions or introduced species that thrive in the absence of natural control factors such as herbivory and competition. Contamination of grain crops with dehydroPA-producing plants has resulted in large-scale incidents of food poisoning in humans, with high morbidity and mortality, especially in Africa and in central and south Asia, with recent episodes in Afghanistan and possibly Ethiopia. Attention has recently focused on the potential for low levels of dehydroPAs to contaminate many food products in developed countries, possibly leading to progressive, chronic diseases that may not include overt hepatotoxicity. This overview examines the potential for better control of exposure and means of monitoring dehydroPA intake by extrapolation of knowledge gained from animal studies to the human situation.     

Quantum chemical investigation on the mechanism and kinetics of PBDE photooxidation by ·OH: a case study for BDE-15

Computational approaches are crucial to risk assessment and pollution prevention of newly synthesized compounds prior to large-scale production and commercialization. Understanding the kinetics and mechanism of the tropospheric reaction of semivolatile organic compounds with ·OH is an indispensable component of risk assessment. In this study, we show that the density functional theory (DFT) can be successfully employed to probe the kinetics and mechanism of atmospheric photooxidation of polybrominated diphenyl ethers (PBDEs) by ·OH, taking 4,4'-dibromodiphenyl ether (BDE-15) as a case. The predicted products (HO-PBDEs, brominated phenols and Br(2)) and overall rate constant (k(OH)) at 298 K are consistent with the experimental results. Two pathways leading to formation of HO-PBDEs are identified: Br substitution by ·OH, and abstraction of H gem to ·OH in BDE-OH adducts by O(2). This study offers a cost-effective way for probing the atmospheric indirect photooxidation kinetics and mechanism of PBDEs.     

Vitamins in wine: Which,what for,and how much?

Vitamins are essential compounds to yeasts, and notably in winemaking contexts. Vitamins are involved in numerous yeast metabolic pathways, including those of amino acids, fatty acids, and alcohols, which suggests their notable implication in fermentation courses, as well as in the development of aromatic compounds in wines. Although they are major components in the course of those microbial processes, their significance and impact have not been extensively studied in the context of winemaking and wine products, as most of the studies focusing on the subject in the past decades have relied on relatively insensitive and imprecise analytical methods. Therefore, this review provides an extensive overview of the current knowledge regarding the impacts of vitamins on grape must fermentations, wine-related yeast metabolisms, and requirements, as well as on the profile of wine sensory characteristics. We also highlight the methodologies and techniques developed over time to perform vitamin analysis in wines, and assess the importance of precisely defining the role played by vitamins in winemaking processes, to ensure finer control of the fermentation courses and product characteristics in a highly complex matrix.     

Reduced Cd accumulation in Zea mays: a protective role for phytosiderophores?

Cadmium is a nonessential trace metal and a frequent soil contaminant. Because plants vary in their accumulation of Cd, an understanding of the specific processes that control uptake could reveal methods for reducing Cd levels in edible plant tissues and conversely increasing Cd accumulation in plants used for phytoremediation. Phytosiderophores are iron chelators excreted by graminaceous plants under conditions of iron limitation, but they also complex other metals including cadmium. Here we examine the influence of Cd exposure on phytosiderophore production by hydroponically grown maize. Cd increased the rate of the phytosiderophore 2'-deoxymugineic acid (DMA) release under both Fe-sufficient and Fe-limiting conditions (+/-Fe). In addition, the -Fe plants released more DMA while taking up less Cd than the +Fe plants. In other short-term Cd uptake experiments, plants exposed to Cd in the presence of root exudates in which the DMA-Cd complex was likely the dominant Cd species displayed reduced Cd accumulation in root tissue, and plants similarly exposed to strongly chelated Cd in the presence of EDTA (employed as a positive control) contained the least Cd. Collectively, these results indicate that Cd stress causes Fe deficiency symptoms that result in greater DMA production by maize roots, and then the DMA appears to reduce Cd accumulation.     

Safety assessment of β-nitropropionic acid: a monograph in support of an acceptable daily intake in humans

Several molds, Aspergillus, Penicillium and to a lesser extent, Arthrinium can produce β-nitropropionic acid (NPA). The presence of NPA has been detected in at least four families of higher plants. Use of Aspergillus as an economic mould in the production of foods and the accidental contamination of foods provides for an historically lengthy and widespread exposure of humans to NPA. Despite widespread consumption of foods containing NPA, human poisoning by NPA is rare and confined to circumstances involving gross mishandling of the food products. NPA is absorbed in the gastrointestinal tract, enters the circulation and is metabolized to nitrite, although some may bind succinate dehydrogenase upon oxidation. The primary mechanism of toxicity of NPA is as a “suicide” substrate (non-competitive inhibitor) of succinate dehydrogenase, an enzyme of the mitochondrial membrane (part of Complex II) that catalyzes the oxidation of succinate to fumarate, which is manifested as pathological change in striatal areas of the brain. The physiological damage caused by NPA metabolic compromise resembles the genetic disorder, Huntington's disease. This resemblance has been extensively exploited in recent years to understand the mechanisms of neurodegeneration. There are no irreversible effects resulting from ingestion of subthreshold doses of NPA, nor is there any accumulation of NPA in the body. The LD₅₀ dose of NPA for mice and rats is between 60 and 120 mg/kg. In long-term studies, NPA did not exhibit carcinogenicity or chronic toxicity. The reported no observed adverse effect level (NOAEL) for NPA is 2.5 and 3.75 mg/kg/day for male and female rats, respectively. Results of mutagenicity tests are mixed, but positive assays can be traced back to the use of a single impure sample of NPA. Based on the NOAEL of the chronic rodent bioassay, an ADI of 25 μg/kg/day or 1.750 mg/day for a 70 kg human is appropriate.     

Meat,eggs, full-fat dairy,and nutritional boogeymen: Does the way in which animals are raised affect health differently in humans?

ABSTRACT

Background: Food recommendations to improve cancer prevention are generally based on epidemiologic data and remain inconsistent. These epidemiologic studies, while controversial, have generally produced results that caution against the consumption of high-fat foods, including eggs, red meat, and full-fat dairy, such as butter and cheese. Yet, limited data exist assessing the quality of individual sources of these foods and the effect each has after its consumption. This study set out to assess the impact sources of food within the same groups from animals raised differently on variables associated with health in human studies. Methods and Materials: A search was conducted through MEDLINE, Embase, and PubMed. In total, twenty-nine studies met inclusion criteria, measuring physiologic changes in humans after consuming animal products following animal diet manipulation. A meta-analysis was attempted to assess the differences between the cohorts in these studies, but was aborted due to poor study quality, vast differences in study design, and a limited number of studies. Results: Studies varied by animal, animal diet manipulation, food product, and overall design. Significant differences were present between groups eating the same food (cheese, beef, eggs, and butter) from animals raised differently, including levels of: conjugated linoleic acid, omega-3 fatty acids (alpha linoleic acid [ALA], docosahexaenoic acid [DHA], and eicosapentaenoic acid [EPA]), and inflammatory factors (triacyl glycerol [TAG], interleukin-6 [IL-6], interleukin-8 [IL-8], tumor necrosis factor [TNF], and C-reactive protein [CRP]). Lipid levels were minimally affected. Conclusions: This work highlights differences in human health markers after consumption of the same foods from animals raised differently. Overall, lipid levels remained relatively neutral, but significant changes in inflammatory and other serum markers and phospholipids were present. Future studies and dietary recommendations should consider how animals are raised, as this can produce different effects on health markers.     

Brominated and fluorinated organic pollutants in the breast milk of first-time Irish mothers: is there a relationship to levels in food?

Brominated flame retardants – polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), hexabromocyclododecane (HBCD) and others – have been measured in 11 pooled breast milk samples from 109 first-time mothers in Ireland. Additionally, the study has measured levels of polybrominated dibenzo-p-dioxins and furans (PBDD/Fs), mixed halogenated dioxins (PXCC/Fs) and biphenyls (PXBs), polychlorinated naphthalenes (PCNs) and perfluoroalkylated substances (PFAS) in these samples. The mean sum of 19 PBDEs including BDE-209 was 4.85 ng g^?1 fat, which is comparable with that found in other European countries. BDE-47, BDE-153, BDE-209, BDE-99 and BDE-100 were found at the highest concentrations. The only PBBs detected consistently were BB-77, BB-126 and BB-153, with highest concentrations being found for BB-153 (mean = 0.13 ng g^?1 fat). The mean sum of HBCD enantiomers was 3.52 ng g^?1 fat, with α-HBCD representing over 70% of the total. Of the other brominated flame retardants – tetrabromobisphenol-A (TBBP-A), hexabromobenzene (HBB), decabromodiphenylethane (DBDPE) and bis(2,4,6-tribromophenoxyethane) (BTBPE) – examined, only TBBP-A was detected above the limit of detection (LOD), in two of the 11 pools analysed. All measured PBDF congeners were observed (at 0.02–0.91 pg g^?1 fat), but 2,3,7,8-tetrabromo-dibenzodioxin (TeBDD) was the only PBDD detected, with a mean concentration of 0.09 pg g^?1 fat. The occurrence of the mixed chlorinated/brominated dibenzodioxins, dibenzofurans and biphenyls, 2-B-3,7,8-CDD, 2,3-B-7,8-CDF, 4-B-2,3,7,8-CDF, PXB 105, PXB 118, PXB 126 and PCB 156 in breast milk in the current study may indicate that levels of these contaminants are increasing in the environment. Polychlorinated naphthalenes were detected in all samples, but not perfluorooctane sulfonate (PFOS) and other PFAS. The pattern of occurrence of these brominated and fluorinated persistent organic pollutants (POPs) in Irish breast milk shows a general relationship to their occurrence in food, as reported in a number of surveillance studies carried out by the Food Safety Authority of Ireland.     

Is indirect exposure a significant contributor to the burden of perfluorinated acids observed in humans?

In comparison to other persistent organic pollutants, human fluorochemical contamination is relatively complicated. This complication arises at least in part from a disparity between the chemicals used commercially and those measured in the environment and humans. Commercial fluorochemical products are dominated by fluorinated polymers used in textile or carpet applications, or fluorosurfactants used in applications ranging from personal care products, leveling and wetting agents, to greaseproofing food-contact materials. Investigations into environmental and human fluorochemical contamination have focused on perfluorinated acids (PFAs), either the perfluorinated carboxylates (PFCAs) or sulfonates (PFSAs). In this review we will present an overview of data related to human fluorochemical exposure including a discussion of fluorochemical production, concentrations in exposure media, biotransformation processes producing PFAs, and trends in human sera. These data will be presented in the context of how they can inform sources of human PFA contamination, specifically whether the contamination results from direct PFA exposure or indirect exposure via the biotransformation of commercial fluorochemicals or their residuals. Concentrations of both perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) began to decrease in human sera around the year 2000, a change that mirrored the 2000-2002 phase-out of perfluorooctane sulfonyl fluoride (POSF) production. These temporal trends suggest exposure to current-use POSF-based materials was a significant source of PFOA and PFOS exposure prior to 2000. Relatively slow PFOA elimination and increasing concentrations of the C9 and C10 PFCAs in human sera suggest continued PFCA exposure, without similar exposure to PFOS, which is consistent with indirect exposure via the biotransformation of fluorotelomer-based materials. Conversely, human exposure models have suggested direct exposure to PFAs present in food items is the major source of human contamination. The data set presented here cannot unequivocally delineate between direct and indirect human exposure, however temporal trends in human sera and exposure media are consistent with indirect exposure representing a significant portion of observed human PFA contamination.     

Is there a future for antioxidants in atherogenesis?

Antioxidants, preferentially those of dietary origin, have for a long time been considered to help against diseases that are presumably aggravated by oxidative stress, such as cardiovascular diseases, cancer, and neurodegenerative disorders. The outcome of clinical trials undertaken to corroborate this hypothesis, however, remained largely inconclusive. Evidence is now emerging that some dietary "antioxidants" influence signaling pathways and the expression of genes relevant in atherosclerosis by mechanisms other than antioxidative ones. By concrete examples we show that (1) vitamin E has gene regulatory functions which might be more important than acting as an antioxidant in vivo, (2) selenium itself is not an antioxidant at all, and even not in general when incorporated into glutathione peroxidases, and (3) a moderate oxidative stress is beneficial rather than detrimental since it can induce defense mechanisms counteracting xenobiotic and oxidative stress. Thus, there is only a future for antioxidants in the prevention of any disease if their real mechanism of action is considered and suitable read-outs and biomarkers are established.     

Do temporal and geographical patterns of HBCD and PBDE flame retardants in U.S. fish reflect evolving industrial usage?

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) are common flame retardants in polymers and textiles. Recognition of the persistent, bioaccumulative, and toxic properties of PBDEs has prompted reductions in their use. In contrast, HBCD has received less scrutiny. The U.S has historically been a dominant BFR consumer. However, the few publications on HBCD in wildlife here suggest modest levels compared to Asian and European studies. In contrast, the HBCD concentrations we detected in U.S. fish are among the highest reported in the world. The temporal trends observed suggest that HBCD use may have risen, and that of Penta-BDE declined, following the 2004 termination of its U.S. manufacture. For example, Hyco River carp collected in 1999-2002 exhibited a mean ∑HBCD (sum of α-, β- and γ-HBCD) concentration of only 13 ng/g (lipid weight basis), but was 4640 ng/g in fish collected in 2006-2007. In contrast, the mean ∑PBDE level in these same fish decreased from 40,700 ng/g in 1999-2002 to 9140 ng/g in 2006-2007. Concentrations of HBCD and PBDEs in several Hyco River fish species exceeded those from rivers less influenced by manufacturing outfalls. Results support the contention that textile-related production, relative to its BFR market share, may release disproportionately large amounts of HBCD to the environment.     

Mitigating Nutrition and Health Deficiencies in Older Adults: A Role for Food Innovation?

The aim of this review is to describe the factors contributing to diminished food intake, resulting in nutritional deficiencies and associated health conditions in older adults and proposes food innovation strategies to mitigate these. Research has provided convincing evidence of a link between healthy eating patterns and healthy aging. There is a need to target new food product development (NPD) with functional health benefits specifically designed to address the particular food‐related needs of older consumers. When developing foods for older adults, consideration should be given to the increased requirements for specific macro‐ and micronutrients, especially protein, calcium, vitamin D, and vitamin B. Changes in chemosensory acuity, chewing difficulties, and reduced or poor swallowing ability should also be considered. To compensate for the diminished appetite and reduced intake, foods should be energy dense, nutritionally adequate, and, most importantly, palatable, when targeting this cohort. This paper describes the potential of new food product development to facilitate dietary modification and address health deficiencies in older adults.     

Parvalbumin in fish skin-derived gelatin: is there a risk for fish allergic consumers?

The major allergen parvalbumin was purified from cod muscle tissues, and polyclonal antibodies were raised towards it. The antibodies were tested for specificity and an enzyme-linked immunosorbent assay (ELISA) was developed using these antibodies. The ELISA was applied to measure parvalbumin in cod skin, the starting material for fish gelatin made from deep sea, wild fish. The ELISA was sufficiently sensitive (LLOQ?=?0.8?ng?ml(-1) in extracts, corresponding to 0.02?μg of parvalbumin per g of tissue), and did not cross-react with common food constituents. Fish gelatin, wine and beer, matrices for the potential use of this ELISA, did not cause disturbance of the assay performance. The data show that the parvalbumin content in cod muscle tissue is 6.25?mg?g(-1), while the skins contained considerably less, 0.4?mg?g(-1). Washing of the skins, a common industrial procedure during the manufacturing of fish gelatin, reduced the level of parvalbumin about 1000-fold to 0.5?μg?g(-1), or 0.5?ppm. From 95 commercial lots of fish gelatin it is shown that 73 are below 0.02?μg?g(-1) parvalbumin. From the other 22 lots, the one with the highest concentration contained 0.15?μg?g(-1) of parvalbumin. These levels are generally assumed to be safe for fish-allergic individuals.     

Do marine algal polyphenols have antidiabetic,antihyperlipidemic or anti-inflammatory effects in humans? A systematic review

Cardiovascular disease and type 2 diabetes are leading causes of morbidity and mortality globally. Marine algal polyphenols have potential to reduce the risk of these conditions, however, little is known about their impact in humans. This systematic review investigates the antidiabetic, antihyperlipidemic and anti-inflammatory effects of marine polyphenols in humans. Scopus, Medline, PsychInfo, Embase and Cochrane Library databases were searched in November 2016. Eligible studies included (1) human adults, (2) marine polyphenol intervention, (3) blood lipid, glucose, insulin or inflammatory marker outcomes, and (4) were a randomized-controlled trial. One postprandial cross-over trial and four parallel design trials were included involving 271 adults. Analysis across studies was performed using Cohen's d effect sizes. Supplementation with polyphenol-rich extracts had small-to-medium positive effects on fasting blood glucose, total cholesterol and LDL-cholesterol; however, there is inadequate evidence as yet to confirm if these are consistent effects. Further randomized-controlled trials should investigate polyphenols from Ecklonia cava and other macroalgal sources, to determine if there is a role for marine polyphenols in reducing the risk factors of chronic disease in humans.

(PROSPERO registration number CRD42015016890)     

Beyond Desperation: Motivations for Dumpster™ Diving for Food in Vancouver

In the global food system, food is considered a disposable commodity and waste is produced at extraordinarily high levels. In a number of affluent nations, including Canada, “dumpster diving” for food has emerged as an approach to food provisioning. This article is based on a research project conducted for an honors thesis that examines dumpster diving for food in Vancouver, British Columbia. While an earlier report (Miewald 2009) identified dumpster diving in Vancouver as a survival strategy for people living in poverty who experience food insecurity, research for this article reveals that motivations also extend beyond economic desperation. The data contest some common assumptions and provide explanations of people's motivations and their means of “dumpstering” in the Vancouver locale. As such, the article reveals divers’ broader political, social, and economic motivations in a specific locale, enabling an exploration of some systemic contradictions of food production, distribution, provisioning, and consumption.     

Bacteriophages: New Tools for Safer Food?

The recent FDA approval of Listeria-specific bacteriophage preparations for food preservation has opened the door to new applications of these natural bacterial killers. Bacteriophages are viruses that only infect and lyse bacterial cells and are harmless to mammalians. There is now a renewed interest to use the ability of these viruses to kill pathogenic bacteria for biotechnological purposes. We will describe the biology of bacteriophages, the concept of ,,phage therapy' and recent applications of phages as biocontrol agents with emphasis on applications for food safety.

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Zusammenfassung: Die amerikanische Zulassungsbeh?rde FDA (Food and Drug Agency) hat kürzlich die Verwendung von Bakteriophagenpr?paraten zur Bek?mpfung von Listeria monocytogenes in Lebensmitteln erlaubt. Bakteriophagen (Phagen) sind Viren, die spezifi sch Bakterien t?ten. Für Zellen h?herer Lebewesen sind diese Viren ungef?hrlich. Die Listeria-Phagenpr?parate zeigen die potentielle biotechnologische Nutzung solcher Viren, die Sicherheit von Lebensmitteln durch eine gezielte Bek?mpfung eines pathogenen Keims zu erh?hen. In dieser übersichtsarbeit werden verschiedene Anwendungsbereiche von Phagen in der Lebensmittelproduktion vorgestellt, die sich zurzeit noch weitgehend im experimentellen Stadium befi nden. Die Applikation von Phagen an lebenden Tieren (,,preharvest"), um die Keimzahl eines pathogenen Bakteriums zu reduzieren, ist als Phagentherapie bekannt. Ihre Anwendung am Lebensmittel (,,postharvest") wird als Biokontrolle bezeichnet. Der sichere Gebrauch von Phagen erfordert Kenntnisse über ihre Biologie; daraus leiten sich spezielle Anforderungen an Pr?parate ab, die in der Lebensmittelproduktion verwendet werden sollen.

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Received: March 19, 2007