Determinação de tetraciclinas em leite por cromatografia de camada fina

As tetraciclinas são compostos antibacterianos utilizados em bovinos de leite para tratamento de doenças infecciosas, como a mastite, mas também como aditivos em ração animal. O uso das tetraciclinas pode conduzir à presença de resíduos destes fármacos no leite, principalmente se não forem utilizados de acordo com as indicações, nem respeitado o período mínimo de eliminação dos antibióticos pelo leite. A presença de resíduos de antibióticos no leite interfere no processo industrial dos seus derivados, podendo inviabilizar a produção destes e, consequentemente, causar igualmente prejuízos económicos, como por exemplo, pela inibição de fermentos lácticos que são culturas de microorganismos utilizados na produção de iogurtes, queijos e outros produtos lácteos. Os resíduos de antibióticos no leite de consumo podem representar riscos à saúde humana, podendo causar reacções alérgicas em indivíduos sensíveis ou ter um efeito adverso na flora intestinal humana, prejudicando a sua acção protectora local, além de propiciar a selecção de populações bacterianas resistentes.(Denobile & Nascimento, 2004)

Impact on CVD risk of modifying milk fat to decrease intake of SFA and increase intake of cis-MUFA

Despite the acknowledged benefits of reducing SFA intake few countries within the EU meet recognised targets. Milk and dairy products represent the single largest source of dietary SFA in most countries, yet epidemiological evidence indicates that milk has cardioprotective properties such that simply reducing consumption of dairy foods to meet SFA targets may not be a sound public health approach. The present paper explores the options for replacing some of the SFA in milk fat with cis-MUFA through alteration of the diet of the dairy cow, and the evidence that such changes can improve the indicators for CHD and CVD in general for the consumer. In addition, the outcome of such changes on risk factors for CHD and CVD at the population level is examined in the light of a modelling exercise involving data for eleven EU member states. Given the current and projected costs of health care, the results indicate that urgent consideration should be given to such a strategy.

Impact on CVD risk of modifying milk fat to decrease intake of SFA and increase intake of cis-MUFA

Despite the acknowledged benefits of reducing SFA intake few countries within the EU meet recognised targets. Milk and dairy products represent the single largest source of dietary SFA in most countries, yet epidemiological evidence indicates that milk has cardioprotective properties such that simply reducing consumption of dairy foods to meet SFA targets may not be a sound public health approach. The present paper explores the options for replacing some of the SFA in milk fat with cis-MUFA through alteration of the diet of the dairy cow, and the evidence that such changes can improve the indicators for CHD and CVD in general for the consumer. In addition, the outcome of such changes on risk factors for CHD and CVD at the population level is examined in the light of a modelling exercise involving data for eleven EU member states. Given the current and projected costs of health care, the results indicate that urgent consideration should be given to such a strategy.

Relationship between milk consumption and prostate cancer: a short review

Epidemiological evidence based on both case–control and prospective cohort studies points to an overall positive relationship between consumption of milk/dairy products and the risk of developing prostate cancer. There are inconsistencies in the data, but taken together, the increased relative risk does not seem to be high. A number of mechanisms have been proposed to account for the relationship, with most attention being focused on the involvement of calcium/vitamin D, insulin-like growth factor-1 and oestrogens, although it is unlikely that a single factor in milk is implicated. In any event, any added risk of prostate cancer from increased milk consumption has to be set alongside other evidence, which shows that increased milk consumption can provide substantially reduced risk of coronary heart disease, stroke and colorectal cancer, particularly because cardiovascular disease accounts for vastly more deaths than prostate cancer (although the latter is of course restricted to men).

An assessment of the potential consumption impacts of WHO dietary norms in OECD countries

The member countries of the World Health Organization (WHO) have recently endorsed its global strategy on diet, physical activity and health. The strategy emphasises the need to limit the consumption of saturated fats and trans-fatty acids, salt and sugars, and to increase consumption of fruits and vegetables in order to combat the growing burden of non-communicable diseases. This paper attempts a broad quantitative assessment of the consumption impacts of these norms in OECD countries using a mathematical programming approach. We find that adherence to the WHO norms would involve a significant decrease in the consumption of vegetable oils (30%), dairy products (28%), sugar (24%), animal fats (30%) and meat (pig meat, 13.5%, mutton and goat 14.5%) and a significant increase in the human consumption of cereals (31%), fruits (25%) and vegetables (21%). (c) 2005 Elsevier Ltd. All rights reserved.

Conjugated linoleic acid and human health-related outcomes

There has been increasing interest in health benefits of conjugated linoleic acid (CLA) based on findings with laboratory animals. Some human studies have also suggested health benefits of CLA, but because of the mixes used these could not be readily associated with a particular isomer of CLA. A recent study examined the separate effects of near-pure cis-9,trans-11 CLA (c9,t11 CLA) or trans-10,cis-12 CLA (t10,c12 CLA) on health-related outcomes in healthy young males. The CLA isomers were provided in capsules and at three doses (up to about 2.5 g/day) each for 8 weeks. Both c9,t11 and t10,c12 CLA were incorporated in a dose–response fashion into blood lipids and cells. At the doses and durations used, neither isomer of CLA affected bodyweight, body mass index or body composition, insulin sensitivity, immune function or markers of inflammation. However, at the doses and durations used, c9,t11 and t10,c12 CLA had opposing effects on blood lipid concentrations. Altered dairy cow-feeding practices were used to produce c9,t11 CLA-rich milk and, from this ultra heat-treated milk, cheese and butter were produced. The milk and the dairy products made from it had ninefold higher contents of c9,t11 CLA, higher contents of n-3 fatty acids and lower contents of total fat and of saturated fatty acids. They also contained much higher contents of trans-vaccenic acid (tVA). The modified dairy products were used in a 6-week controlled dietary intervention study in healthy middle-aged males. c9,t11 CLA and tVA were incorporated from dairy products into blood lipids and cells. Consumption of the CLA-rich (and tVA-rich) dairy products did not affect bodyweight or body mass index, insulin sensitivity or inflammatory markers. However, there were some detrimental effects on blood lipids. These effects may be due to tVA rather than to c9,t11 CLA, as they are consistent with the effects of trans fatty acids and not consistent with the effects of c9,t11 CLA identified in the earlier study with c9,t11 CLA in capsules.

The gut microbiota in obesity and metabolic disease - a novel therapeutic target

Obesity is sweeping the westernized world at a rate which far outstrips human genomic evolution, highlighting the importance of the obesogenic environment. Diet is an important component of this obesogenic environment, with certain diets (high fat, high refined carbohydrates and sugar) predisposing to overweight. On the other hand, there are also foods shown to protect against obesity and the diseases of obesity, including whole plant foods, dairy products, dietary fibre and functional foods like probiotics, prebiotics and phytochemicals. Interestingly, many of these foods mediate their health-promoting activities through the gut microbiota. The human gut microbiota itself has recently been identified as a contributory factor in this obesogenic environment, with differences observed between lean and obese. Evidence from human studies indicates that important groups of fermentative bacteria differ in abundance between lean and obese. Recently it has been suggested that anomalous microbiota composition in infancy can predispose to overweight in later life, highlighting the important role of optimal microbiota successional development, and that – as observed in laboratory animals – the gut microbiota may contribute to the aetiology of obesity. In this review we will introduce the gut microbiota, describe its interactions with major dietary components and the host, and then go on to discuss evidence indicating that the gut microbiota may contribute to the obesogenic environment. Finally, we will explore possible strategies for modulating the composition and activity of the human gut microbiota which may impact on obesity or the metabolic diseases associated with obesity. (Nutritional Therapy & Metabolism 2009; 27: 113-33)

Effects of cis-9,trans-11 and trans-1 0,cis-12 conjugated linoleic acid on immune cell function in healthy humans

Background: Animal studies have suggested that conjugated linoleic acid (CLA), a natural component of ruminant meat and dairy products, may confer beneficial effects on health. However, little information on the effects of CLA on immune function is available, especially in humans. Furthermore, the effects of individual isomers of CLA have not been adequately investigated. Objective: This study investigated the effects of supplementing the diet with 3 doses of highly enriched cis-9,trans-11 CLA (0.59, 1.19, and 2.38 g/d) or trans-10,cis-12 CLA (0.63, 1.26, and 2.52 g/d) on immune outcomes in healthy humans. Design: The study had a randomized, double-blind, crossover design. Healthy men consumed 1, 2, and 4 capsules sequentially that contained 80% of either cis-9,trans-11 CLA or trans-10,cis-12 CLA for consecutive 8-wk periods. This regimen was followed by a 6-wk washout and a crossover to the other isomer. Results: Both CLA isomers decreased mitogen-induced T lymphocyte activation in a dose-dependent manner. There was a significant negative correlation between mitogen-induced T lymphocyte activation and the proportions of both cis-9,trans-11 CLA and trans-10,cis-12 CLA in peripheral blood mononuclear cell lipids. However, CLA did not affect lymphocyte subpopulations or serum concentrations of C-reactive protein and did not have any consistent effects on ex vivo cytokine production. Conclusion: CLA supplementation results in a dose-dependent reduction in the mitogen-induced activation of T lymphocytes. The effects of cis-9,trans-l I CLA and trans-10,cis-12 CLA were similar, and there was a negative correlation between mitogen-induced T lymphocyte activation and the cis-9,trans-11 CLA and trans-10,cis-12 CLA contents of mononuclear cells.

Characterization and in vitro digestibility of bovine beta-lactoglobulin glycated with galactooligosaccharides

Galactooligosaccharides (GOS) are well-known prebiotic ingredients which can form the basis of new functional dairy products. In this work, the production and characterization of glycated beta-lactoglobulin beta-LG) with prebiotic GOS through the Maillard reaction under controlled conditions (a(w) = 0.44, 40 degrees C for 23 days) have been studied. The extent of glycation of beta-LG was evaluated by formation of furosine which progressively increased with storage for up to 16 days, suggesting that the formation of Amadori compounds prevailed over their degradation. RP-HPLC-UV, SIDS-PAGE, and IEF profiles of beta-LG were modified as a consequence of its glycation. MALDI-ToF mass spectra of glycated beta-LG showed an increase of up to similar to 21% in its average molecular mass after storage for 23 days. Moreover, a decrease in unconjugated GOS (one tri-, two tetra-, and one pentasaccharide) was observed by HPAEC-PAD upon glycation. These results were confirmed by ESI MS. The stability of the glycated beta-LG to in vitro simulated gastrointestinal digestion was also described and compared with that of the unglycated protein. The yield of digestion products of glycated beta-LG was lower than that observed for the unglycated protein. The conjugation of prebiotic carbohydrates to stable proteins and peptides could open new routes of research in the study of functional ingredients.

Effects of consumption of probiotics and prebiotics on serum lipid levels in humans

The objective of this article is to review existing studies concerning the effects of probiotics and prebiotics on serum cholesterol concentrations, with particular attention on the possible mechanisms of their action. Although not without exception, results from animal and human studies suggest a moderate cholesterol-lowering action of dairy products fermented with appropriate strain(s) of lactic acid bacteria and bifidobacteria. Mechanistically, probiotic bacteria ferment food-derived indigestible carbohydrates to produce short-chain fatty acids in the gut, which can then cause a decrease in the systemic levels of blood lipids by inhibiting hepatic cholesterol synthesis and/or redistributing cholesterol from plasma to the liver. Furthermore, some bacteria may interfere with cholesterol absorption from the gut by deconjugating bile salts and therefore affecting the metabolism of cholesterol, or by directly assimilating cholesterol. For prebiotic substances, the majority of studies have been done with the fructooligosaccharides inulin and oligofructose, and although convincing lipid-lowering effects have been observed in animals, high dose levels had to be used. Reports in humans are few in number. In studies conducted in normal-lipidemic subjects, two reported no effect of inulin or oligofructose on serum lipids, whereas two others reported a significant reduction in serum triglycerides (19 and 27%, respectively) with more modest changes in serum total and LDL cholesterol. At present, data suggest that in hyperlipidemic subjects, any effects that do occur result primarily in reductions in cholesterol, whereas in normal lipidemic subjects, effects on serum triglycerides are the dominant feature.

Improved arthritic knee health in a pilot RCT of phytotherapy

Although practitioner-prescribed 'western' herbal medicine (phytotherapy) is a popular complementary therapy in the UK, no clinical studies have been reported on patient-orientated outcomes. The objective of this pilot study was to investigate the effects of phytotherapy on symptoms of osteoarthritis of the knee. A previous study of Chinese herbal medicine for the treatment of irritable bowel syndrome, published in the Journal of the American Medical Association,(1) acted as a model in the development of the protocol of this investigation. Twenty adults, previously diagnosed with osteoarthritis of the knee, were recruited from two Inner London GP practices into this randomized, double-blind, placebo-controlled, pilot study carried out in a primary-care setting. All subjects were seen in consultation three times by a herbal practitioner who was blinded to the randomization coding. Each subject was prescribed treatment and given lifestyle advice according to usual practice: continuation of conventional medication where applicable, healthy-eating advice and nutrient supplementation, Individualized herbal medicine was prescribed for each patient, but only dispensed for those randomized to active treatment - the remainder were supplied with a placebo. At baseline and outcome (after ten weeks of treatment), subjects completed a food frequency questionnaire and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) knee health and Measure Yourself Outcome Profile (MYMOP) wellbeing questionnaires. Subjects completing the study per protocol (n = 14) reported an increased intake of wholegrain foods (p = 0.045) and oily fish (p = 0.039) compared to baseline, but no increase in fruit and vegetables and dairy products intakes. There was no difference in the primary outcome measure of knee health assessed as the difference in the mean response (baseline-week 10) in WOMAC score between the two treatment groups. However, there was, compared with baseline, improvement in the active group (n = 9) for the mean WOMAC stiffness sub-score at week 5 (p = 0.035) and week 10 (p = 0.060) but not in the placebo group (n = 5). Furthermore, for the active, but not the placebo group, the mean WOMAC total and sub-scores all showed clinically significant improvement (>= 20%) in knee symptoms at weeks 5 and 10 compared with baseline. Moreover, the mean MYMOP symptom 2 sub-score, mostly relating to osteoarthritis (OA), showed significant improvement at week 5 (p = 0.02) and week 10 (p = 0.008) compared with baseline for the active, but not for the placebo group. This pilot study showed that herbal medicine prescribed for the individual by a herbal practitioner resulted in improvement of symptoms of OA of the knee.

Functional petit-suisse cheese: measure of the prebiotic effect

Prebiotics and probiotics are increasingly being used to produce potentially synbiotic foods, particularly through dairy products as vehicles. It is well known that both ingredients may offer benefits to improve the host health. This research aimed to evaluate the prebiotic potential of novel petit-suisse cheeses using an in vitro fermentation model. Five petit-suisse cheese formulations combining candidate prebiotics (inulin. oligofructose. hone) and probiotics (Lactobacillus acidophilus, Bifidobacterium lactis) were tested in vitro using, sterile. stirred, batch culture fermentations with human faecal slurry. Measurement of prebiotic effect (MPE) values were generated comparing bacterial changes through determination of maximum growth rates of groups, rate of substrate assimilation and production of lactate and short chain fatty acids. Fastest fermentation and high lactic acid production, promoting increased growth rates of bifidobacteria and lactobacilli. were achieved with addition of prebiotics to a probiotic cheese (made using starter + probiotics). Addition of probiotic strains to control cheese (made using just a starter culture) also resulted in high lactic acid production. Highest MPE values were obtained with addition of prebiotics to a probiotic cheese, followed by addition of prebiotics and/or probiotics to a control cheese. Under the in vitro conditions used, cheese made with the combination of different prebiotics and probiotics resulted in the most promising functional petit-suisse cheese. The study allowed comparison of potentially functional petit-suisse cheeses and screening of preferred synbiotic potential for future market use. (c) 2007 Elsevier Ltd. All rights reserved.

Milk and meat in our diet: good or bad for health?

Foods derived from animals are an important source of nutrients in the diet but there is considerable uncertainty about whether or not these foods contribute to increased risk of various chronic diseases. For milk in particular there appears to be an enormous mismatch between both the advice given on milk/dairy foods items by various authorities and public perceptions of harm from the consumption of milk and dairy products, and the evidence from long-term prospective cohort studies. Such studies provide convincing evidence that increased consumption of milk can lead to reductions in the risk of vascular disease and possibly some cancers and of an overall survival advantage from the consumption of milk, although the relative effect of milk products is unclear. Accordingly, simply reducing milk consumption in order to reduce saturated fatty acid (SFA) intake is not likely to produce benefits overall though the production of dairy products with reduced SFA contents is likely to be helpful. For red meat there is no evidence of increased risk of vascular diseases though processed meat appears to increase the risk substantially. There is still conflicting and inconsistent evidence on the relationship between consumption of red meat and the development of colorectal cancer, but this topic should not be ignored. Likewise, the role of poultry meat and its products as sources of dietary fat and fatty acids is not fully clear. There is concern about the likely increase in the prevalence of dementia but there are few data on the possible benefits or risks from milk and meat consumption. The future role of animal nutrition in creating foods closer to the optimum composition for long-term human health will be increasingly important. Overall, the case for increased milk consumption seems convincing, although the case for high-fat dairy products and red meat is not. Processed meat products do seem to have negative effects on long-term health and although more research is required, these effects do need to be put into the context of other risk factors to long-term health such as obesity, smoking and alcohol consumption.