Protein efficiency in intensive dairy production: a Swedish example.

BACKGROUND: Animal agriculture has been criticised in terms of its sustainability from several perspectives. Ruminants such as dairy cows can transform inedible, low-quality protein in roughage and by-products from the food industry into the high-quality protein found in milk and meat. Evaluation of the protein conversion efficiency of dairy production from a sustainability and resource perspective must be based on the proportion of the animal feed edible to humans. A relevant metric is thus edible feed protein conversion ratio (eFPCR), i.e. human-edible protein output in cow's milk per unit human-edible protein input in feed. In this study, eFPCR was calculated for five regionally adapted and realistic feed rations fed to Swedish dairy cows producing different annual milk yields typical for high-yielding, intensive dairy production. RESULTS: All scenarios except one showed a protein efficiency ratio of >1 for human-edible protein. Thus, depending on the composition of their diet, most Swedish dairy cows can convert human-inedible protein into edible, high-value protein. However, higher milk yield led to a decrease in eFPCR, regardless of diet. CONCLUSION: Dairy cows in high-yielding, intensive production systems such as those used in Sweden have the capacity to convert low-value inedible protein into high-value edible protein. However, a minor part of the dairy cow diet is edible for humans and this fraction must be minimised to justify dairy production. These results are in line with previous findings on protein conversion efficiency and add scientific input to the debate on sustainable food systems and sustainable diets. © 2017 Society of Chemical Industry.

Potential role of milk fat globule membrane in modulating plasma lipoproteins, gene expression, and cholesterol metabolism in humans: a randomized study.

BACKGROUND: Butter is rich in saturated fat [saturated fatty acids (SFAs)] and can increase plasma low density lipoprotein (LDL) cholesterol, which is a major risk factor for cardiovascular disease. However, compared with other dairy foods, butter is low in milk fat globule membrane (MFGM) content, which encloses the fat. We hypothesized that different dairy foods may have distinct effects on plasma lipids because of a varying content of MFGM. OBJECTIVE: We aimed to investigate whether the effects of milk fat on plasma lipids and cardiometabolic risk markers are modulated by the MFGM content. DESIGN: The study was an 8-wk, single-blind, randomized, controlled isocaloric trial with 2 parallel groups including overweight men and women (n = 57 randomly assigned). For the intervention, subjects consumed 40 g milk fat/d as either whipping cream (MFGM diet) or butter oil (control diet). Intervention foods were matched for total fat, protein, carbohydrates, and calcium. Subjects were discouraged from consuming any other dairy products during the study. Plasma markers of cholesterol absorption and hepatic cholesterol metabolism were assessed together with global gene-expression analyses in peripheral blood mononuclear cells. RESULTS: As expected, the control diet increased plasma lipids, whereas the MFGM diet did not [total cholesterol (±SD): +0.30 ± 0.49 compared with -0.04 ± 0.49 mmol/L, respectively (P = 0.024); LDL cholesterol: +0.36 ± 0.50 compared with +0.04 ± 0.36 mmol/L, respectively (P = 0.024); apolipoprotein B:apolipoprotein A-I ratio: +0.03 ± 0.09 compared with -0.05 ± 0.10 mmol/L, respectively (P = 0.007); and non-HDL cholesterol: +0.24 ± 0.49 compared with -0.14 ± 0.51 mmol/L, respectively (P = 0.013)]. HDL-cholesterol, triglyceride, sitosterol, lathosterol, campesterol, and proprotein convertase subtilisin/kexin type 9 plasma concentrations and fatty acid compositions did not differ between groups. Nineteen genes were differentially regulated between groups, and these genes were mostly correlated with lipid changes. CONCLUSIONS: In contrast to milk fat without MFGM, milk fat enclosed by MFGM does not impair the lipoprotein profile. The mechanism is not clear although suppressed gene expression by MFGM correlated inversely with plasma lipids. The food matrix should be considered when evaluating cardiovascular aspects of different dairy foods. This trial was registered at clinicaltrials.gov as NCT01767077.

Nutrient density of beverages in relation to climate impact.

The food chain contributes to a substantial part of greenhouse gas (GHG) emissions and growing evidence points to the urgent need to reduce GHGs emissions worldwide. Among suggestions were proposals to alter food consumption patterns by replacing animal foods with more plant-based foods. However, the nutritional dimensions of changing consumption patterns to lower GHG emissions still remains relatively unexplored. This study is the first to estimate the composite nutrient density, expressed as percentage of Nordic Nutrition Recommendations (NNR) for 21 essential nutrients, in relation to cost in GHG emissions of the production from a life cycle perspective, expressed in grams of CO(2)-equivalents, using an index called the Nutrient Density to Climate Impact (NDCI) index. The NDCI index was calculated for milk, soft drink, orange juice, beer, wine, bottled carbonated water, soy drink, and oat drink. Due to low-nutrient density, the NDCI index was 0 for carbonated water, soft drink, and beer and below 0.1 for red wine and oat drink. The NDCI index was similar for orange juice (0.28) and soy drink (0.25). Due to a very high-nutrient density, the NDCI index for milk was substantially higher (0.54) than for the other beverages. Future discussion on how changes in food consumption patterns might help avert climate change need to take both GHG emission and nutrient density of foods and beverages into account.

Dairy products and metabolic effects in overweight men and women: results from a 6-mo intervention study.

BACKGROUND: Some epidemiologic studies have suggested inverse relations between intake of dairy products and components of the metabolic syndrome. OBJECTIVE: The objective was to investigate the effects of an increased intake of dairy products in persons with a habitually low intake on body composition and factors related to the metabolic syndrome. DESIGN: Middle-aged overweight subjects (n = 121) with traits of the metabolic syndrome were recruited in Finland, Norway, and Sweden and randomly assigned into milk or control groups. The milk group was instructed to consume 3-5 portions of dairy products daily. The control group maintained their habitual diet. Clinical investigations were conducted on admission and after 6 mo. RESULTS: There were no significant differences between changes in body weight or body composition, blood pressure, markers of inflammation, endothelial function, adiponectin, or oxidative stress in the milk and the control groups. There was a modest unfavorable increase in serum cholesterol concentrations in the milk group (P = 0.043). Among participants with a low calcium intake at baseline (<700 mg/d), there was a significant treatment effect for waist circumference (P = 0.003) and sagittal abdominal diameter (P = 0.034). When the sexes were analyzed separately, leptin increased (P = 0.045) and vascular cell adhesion molecule-1 decreased (P = 0.001) in women in the milk group. CONCLUSIONS: This study gives no clear support to the hypothesis that a moderately increased intake of dairy products beneficially affects aspects of the metabolic syndrome. The apparently positive effects on waist circumference and sagittal abdominal diameter in subjects with a low calcium intake suggest a possible threshold in relation to effects on body composition.

Stroke and plasma markers of milk fat intake--a prospective nested case-control study.

BACKGROUND: Dairy products are high in saturated fat and are traditionally a risk factor for vascular diseases. The fatty acids 15:0 and 17:0 of plasma lipids are biomarkers of milk fat intake. The aim of the present study was to evaluate the risk of a first-ever stroke in relation to the plasma milk fat biomarkers. METHODS: A prospective case-control study was nested within two population based health surveys in Northern Sweden. Among 129 stroke cases and 257 matched controls, plasma samples for fatty acid analyses were available in 108 cases and 216 control subjects. Proportions of 15:0 and 17:0 of plasma lipids, weight, height, blood lipids, blood pressures, and lifestyle data were employed in conditional logistic regression modelling. RESULTS: The proportions of fatty acids 17:0 and 15:0+17:0 of total plasma phospholipids were significantly higher in female controls than cases, but not in men. 17:0 and 15:0+17:0 were significantly and inversely related to stroke in the whole study sample as well as in women. The standardised odds ratio (95% CI) in women to have a stroke was 0.41 (0.24-0.69) for 17:0 in plasma phospholipids. Adjustment for traditional cardiovascular risk factors, physical activity and diet had marginal effects on the odds ratios. A similar, but non-significant, trend was seen in men. CONCLUSION: It is hypothesised that dairy or milk fat intake may be inversely related to the risk of a first event of stroke. The intriguing results of this study should be interpreted with caution. Follow up studies with greater power, and where intakes are monitored both by dietary recordings and fatty acid markers are needed.

Conjugated linoleic acid increased C-reactive protein in human subjects.

We previously showed that conjugated linoleic acid (CLA) increases 15-keto-dihydro-prostaglandin F2alpha, a marker for cyclooxygenase-mediated lipid peroxidation and thus an indicator of cyclooxygenase-mediated inflammation. The aim of the present study was to investigate the effects of CLA on other indicators of inflammation in human subjects, including C-reactive protein, TNF-alpha, TNF-alpha receptors 1 and 2, and vascular cell adhesion molecule-1. In a double-blind, placebo-controlled study, fifty-three human subjects were supplemented with a mixture (4.2 g/d) of the isomers cis-9,trans-11 CLA and trans-10,cis-12 CLA or control oil for 3 months. CLA supplementation increased levels of C-reactive protein (P=0.003) compared with the control group. However, no changes in TNF-alpha, TNF-alpha receptors 1 and 2, and vascular cell adhesion molecule-1 were detected.

Metabolic effects of conjugated linoleic acid in humans: the Swedish experience.

Conjugated linoleic acid (CLA) comprises a group of unsaturated fatty acid isomers with a variety of biological effects. CLA reduces body fat accumulation in animal models and has been ascribed significant effects on lipid and glucose metabolism. It has been suggested that the trans-10,cis-12 isomer is the active isomer with regard to antiobesity and insulin-sensitizing properties. The metabolic effects in humans are not well characterized. We have investigated and published the effects of CLA (given as the commercially available mixture and as the purified trans-10,cis-12 isomer) on anthropometry, lipid and glucose metabolism, and markers of lipid peroxidation. The results from those studies indicate that CLA might slightly decrease body fat in humans, particularly abdominal fat, but there is no effect on body weight or body mass index. There is no simultaneous improvement in lipid or glucose metabolism. Rather, the trans-10,cis-12 CLA isomer unexpectedly caused significant impairment of the peripheral insulin sensitivity as well as of blood glucose and serum lipid concentrations. In addition, CLA markedly elevated lipid peroxidation. Thus, the metabolic effects of CLA in humans seem complex, and further studies, especially of specific isomers and of longer duration, are needed.

Isomer-specific effects of conjugated linoleic acid on lipid peroxidation in humans: regulation by alpha-tocopherol and cyclo-oxygenase-2 inhibitor.

We have found previously that supplementation with conjugated linoleic acid (CLA) induces lipid peroxidation and inflammation in humans as indicated by an increase of 8-iso-prostaglandin F2alpha (PGF2alpha) and 15-keto-dihydro-PGF2alpha respectively. The present study was undertaken firstly to study the regulatory mechanisms behind these effects, and secondly to see if these effects are specific to different isomers of CLA. Sixty healthy men and women, divided into six groups, were given a cyclo-oxygenase (COX)-2 inhibitor (rofecoxib; 12 mg/day), alpha-tocopherol (200 mg/day) or neither treatment (control group) over a period of 6 weeks. During the last 4 weeks, three groups were given a CLA preparation (3.5 g/day) mainly containing the isomers cis-9, trans-11 and trans-10, cis-12 (CLA mix), and the three other groups a CLA preparation mainly containing the isomer trans-10, cis-12 (CLA 1012; 4.0 g/day). Treatment with alpha-tocopherol or COX-2 inhibitor did not alter the basal urinary levels of either 8-iso-PGF2alpha or 15-keto-dihydro-PGF2alpha. Both CLA preparations induced an increase in 8-iso-PGF2alpha and 15-keto-dihydro-PGF2alpha in the urine, with a larger increase being found in the CLA 1012 group. Treatment with the COX-2 inhibitor suppressed the increase in urinary 15-keto-dihydro-PGF2alpha in the CLA 1012 group, but not in the CLA mix group. Neither the COX-2 inhibitor nor alpha-tocopherol had any effect on 8-iso-PGF2alpha levels after supplementation with CLA. The CLA-induced production of PGF2alpha metabolites is probably partially mediated by COX-2. Levels of the induced lipid peroxidation may be dependent on the isomeric property of CLA.

CLA and body weight regulation in humans.

CLA comprises a group of unsaturated FA isomers with a variety of biological effects in experimental animals. CLA reduces body fat accumulation in animal models and has been suggested to have significant effects on lipid and glucose metabolism, e.g., antidiabetic effects in obese Zucker rats. It has been proposed that the trans10-cis12 isomer is the active isomer associated with the antiobesity and insulin-sensitizing properties of CLA. The metabolic effects in humans in general, and isomer-specific effects specifically, are not well characterized. In a series of controlled studies in humans, we investigated the effects of CLA (given as the commercially available mixture of isomers and as the purified trans10-cis12 CLA isomer) on anthropometry, lipid and glucose metabolism, and markers of lipid peroxidation. Preliminary results indicate that CLA may slightly decrease body fat in humans also, particularly abdominal fat, but there is no effect on body weight or body mass index. There is no simultaneous improvement in lipid or glucose metabolism. Rather, the trans10-cis12 CLA isomer unexpectedly caused significant impairment of the peripheral insulin sensitivity as well as of blood glucose and serum lipid levels. In addition, CLA markedly elevated lipid peroxidation. Thus, the metabolic effects of CLA in humans seem complex; further studies, especially of isomer-specific effects and for longer time periods, are warranted.