Saturated fats, dairy foods and health: a curious paradox?

Cardiovascular diseases (CVD) remain a major cause of death and morbidity worldwide. Dietary guidelines aim to restrict the intake of saturated fatty acids (SFA) as they are regarded as an important risk factor for CVD due to their association with increased blood cholesterol. As dairy foods are major contributors of dietary SFA, there have been guidelines to reduce consumption of these foods. However, it is now generally accepted that the effects of reducing intake of SFA are dependent on what replaces them in the diet. Reduced CVD risk has been associated with replacement of SFA with cis-polyunsaturated fatty acids (cis-PUFA) and/or cis-monounsaturated fatty acids (cis-MUFA), with replacement by carbohydrate leading to no reduction or even increased CVD risk. Most studies on the effect of diet/food on CVD risk have used total cholesterol (TC) and/or low-density lipoprotein cholesterol (LDL-C) in blood as the marker(s) of risk. However, because of potentially attenuating effects of dairy foods (e.g. effect of protein on blood lipids and blood pressure; food matrix effects on fat bioavailability), a wider range of markers is needed to more fully evaluate disease risk. Nevertheless, whilst prospective evidence shows no increase in CVD risk from high dairy consumption, it is still unclear whether replacing a proportion of SFA in dairy fat with cis-MUFA will lead to reduced CVD risk. The relatively few randomised controlled trials that have examined this using TC/LDL-C as risk markers give some indications of reduced CVD risk from consumption of milk and dairy products with modified fatty acid composition, compared with those of normal milk fat composition. The results of ongoing studies will add valuable new evidence on this issue

Dairy foods and body mass index over 10-year: evidence from the Caerphilly Prospective Cohort Study

The association between dairy product consumption and body mass index (BMI) remains controversial. The aim of the present study was to investigate the association between total dairy, milk, cheese, cream and butter consumption and BMI change over a 10-year follow-up by using long-term follow-up cohort data from the Caerphilly Prospective Cohort Study (CAPS). The CAPS included 2512 men aged 45⁻59 years at baseline, who were followed up at 5-year intervals for over 20-year. A semi-quantitative food frequency questionnaire estimated the intake of dairy consumption, including milk, cheese, cream and butter at baseline, 5-year and 10-year follow-up. In total, men free of cardiovascular disease, diabetes and cancer ( = 1690) were included in current analysis. General linear regression and logistic regression were used for data analysis. The results showed higher cheese consumption was associated with lower BMI at the 5-year follow-up ( = 0.013). There was no evidence that higher consumption of total dairy, milk, cream and butter were significantly associated with BMI during the over the 10-year following-up. This study suggest that cheese consumption have beneficial effects on lowering BMI, which needs further investigation

Reformulation initiative for partial replacement of saturated with unsaturated fats in dairy foods attenuates the increase in LDL cholesterol and improves flow-mediated dilatation compared with conventional dairy: the randomized, controlled REplacement of SaturatEd fat in dairy on Total cholesterol (RESET) study

Background Modifying dairy fat composition by increasing the MUFA content is a potential strategy to reduce dietary SFA intake for cardiovascular disease (CVD) prevention in the population. Objectives To determine the effects of consuming SFA-reduced, MUFA-enriched (modified) dairy products, compared with conventional dairy products (control), on the fasting cholesterol profile (primary outcome), endothelial function assessed by flow-mediated dilatation (FMD; key secondary outcome), and other cardiometabolic risk markers. Methods A double-blind, randomized, controlled crossover 12-wk intervention was conducted. Participants with a 1.5-fold higher (moderate) CVD risk than the population mean replaced habitual dairy products with study products (milk, cheese, and butter) to achieve a high-fat, high-dairy isoenergetic daily dietary exchange [38% of total energy intake (%TE) from fat: control (dietary target: 19%TE SFA; 11%TE MUFA) and modified (16%TE SFA; 14%TE MUFA) diet]. Results Fifty-four participants (57.4% men; mean ± SEM age: 52 ± 3 y; BMI: 25.8 ± 0.5 kg/m2) completed the study. The modified diet attenuated the rise in fasting LDL cholesterol observed with the control diet (0.03 ± 0.06 mmol/L and 0.19 ± 0.05 mmol/L, respectively; P = 0.03). Relative to baseline, the %FMD response increased after the modified diet (0.35% ± 0.15%), whereas a decrease was observed after the control diet (−0.51% ± 0.15%; P< 0.0001). In addition, fasting plasma nitrite concentrations increased after the modified diet, yet decreased after the control diet (0.02 ± 0.01 μmol/L and −0.03 ± 0.02 μmol/L, respectively; P = 0.01). Conclusions In adults at moderate CVD risk, consumption of a high-fat diet containing SFA-reduced, MUFA-enriched dairy products for 12 wk showed beneficial effects on fasting LDL cholesterol and endothelial function compared with conventional dairy products. Our findings indicate that fatty acid modification of dairy products may have potential as a public health strategy aimed at CVD risk reduction. This trial was registered at clinicaltrials.gov as NCT02089035

Association between dairy consumption and cardiovascular disease events, bone fracture and all-cause mortality

Dairy products are important constituents of a healthy and balanced diet, but their association with health outcomes remains to be established. We investigated the association of total dairy, total fermented dairy, and different dairy subtypes (including total/high-fat/low-fat milk, yogurt, cheese, butter, and cream) and the risk of cardiovascular disease (CVD), coronary heart disease (CHD), bone fracture and all-cause mortality among 1746 Danish healthy men and women (30–60 years, 52%female). Hazard ratios (HRs) and 95% CIs were estimated using the multivariable Cox proportional hazard models. During a mean follow-up of 30 years, incident cases of CVD (n = 904), CHD (n = 332), fracture (n = 447) and all-cause mortality (n = 680) were reported. High intake of total fermented dairy was associated with lower fracture risk (HR 0.67, 95% CI: 0.51–0.90, P = 0.02) than observed in the lowest tertile of the fermented dairy group. Furthermore, high intake of low-fat milk was associated with lower risks of CVD (HR 0.84, 95% CI: 0.68–1.03, P = 0.03), CHD (HR 0.82, 95% CI: 0.59–1.16, P = 0.04), and all-cause mortality (HR 0.77, 95% CI: 0.61–0.97, P = 0.004) compared with the lowest tertile of low-fat milk group. No associations were found with other dairy subtypes. The findings from this prospective cohort study suggest an inverse association between total fermented dairy and fracture risk, and also inverse associations were found between low-fat milk consumption and risk of CVD, CHD and all-cause mortality

A 25-hydroxycholecalciferol–fortified dairy drink is more effective at raising a marker of postprandial vitamin D status than cholecalciferol in men with suboptimal vitamin D status

Background: One strategy for improving population vitamin D status is consumption of fortified foods. However, the effects of dairy products fortified with different vitamin D isoforms on postprandial vitamin D status and metabolic outcomes have not been addressed. Objective: We investigated whether consumption of dairy drinks fortified with either 25-hydroxycholecalciferol [25(OH)D3] or cholecalciferol (vitamin D3) had differential effects on 24-h circulating plasma 25(OH)D3 concentration (a marker of vitamin D status) and cardiometabolic risk markers. Methods: A randomized, controlled, 3-way crossover, double-blind, postprandial study was conducted in 17 men with suboptimal vitamin D status [mean 6 SEM age: 49 6 3 y; body mass index (in kg/m2): 26.4 6 0.6; and plasma 25(OH)D3 concentration: 31.7 6 3.4 nmol/L]. They were randomly assigned to consume 3 different test meals (4.54 MJ, 51 g fat, 125 g carbohydrate, and 23 g protein),which contained either a nonfortified dairy drink (control), 20 mg 25(OH)D3-fortified (+HyD3) dairy drink, or 20 mg vitamin D3–fortified (+D3) dairy drink with toasted bread and jam on different occasions, separated by a 2-wk washout. Plasma 25(OH)D3 concentrations and cardiometabolic risk markers, including vascular stiffness, serum lipids, and inflammatory markers, were measured frequently within 8 h postprandially and 24 h after the dairy drink was consumed. Results: Plasma 25(OH)D3 concentrations (the primary outcome) were significantly higher after the +HyD3 dairy drink was consumed compared with +D3 and control (P = 0.019), which was reflected in the 1.5-fold and 1.8-fold greater incremental area under the curve for the 0–8 h response, respectively. The change in plasma 25(OH)D3 concentrations from baseline to 24 h for the +HyD3 dairy drink was also 0.9-fold higher than the +D3 dairy drink and 4.4-fold higher than the control (P < 0.0001), which were not significantly different from each other. Conclusion: The dairy drink fortified with 25(OH)D3 was more effective at raising plasma 25(OH)D3 concentrations postprandially than was the dairy drink fortified with vitamin D3 in men with suboptimal vitamin D status

Dairy foods and body mass index over 20-years: evidence from Caerphilly Prospective Study

The prevalence of obesity has reached epidemic proportions with more than 600 million adults worldwide classified as clinically obese (body mass index (BMI) ⩾ 30 kg/m2)(1). Among the various approaches to tackle obesity and its comorbidities, a heathy diet is one of the key determinants for reducing obesity(2). Given that dairy products are naturally rich in protein and essential micronutrients, including calcium, potassium and vitamin A(3), they are recommended as an integral part of a healthy diet by many countries(4). However, dairy is also a major contributor to saturated fatty acids (SFA) and energy intake(5), thus their role in development of obes- ity has been questioned and explored by several studies(6). We investigated the association between total dairy, milk, cheese, cream and butter consumption and BMI change over a 20-year follow-up using the Caerphilly prospective study (CAPS). The CAPS included 2512 men aged 45–59 years, who were followed up at 5-year intervals for over 20-years. The associations of total dairy, milk, cheese, cream and butter consumption with BMI were examined cross-sectionally at baseline and longitudinally at 5, 10, 15 and 20-years follow-ups. General linear regression and logistic regression were used for data analysis. Men free of cardiovascular disease and diabetes (n = 1704) were included in the current analysis. Higher cheese consumption was associated with lower BMI at the 5-year follow-up (P = 0·008) but not at later follow-ups. There was no evidence that higher consumption of dairy products was associated with increased BMI during the over 20-years follow-up, although total dairy (P = 0·002) and milk consumption (P < 0·001) were inversely associated with BMI at baseline. For the future studies, the association between cheese consumption and BMI requires further investigation

Consumer acceptance of dairy products with a saturated fatty acid-reduced, monounsaturated fatty acid-enriched content

Agriculture-based reformulation initiatives, including oleic acid-rich lipid supplementation of the dairy cow diet, provide a novel means for reducing intake of saturated fatty acids (SFA) at a population level. In a blinded manner, this study evaluated the consumer acceptance of SFA-reduced, monounsaturated fatty acid-enriched (modified) milk, Cheddar cheese, and butter when compared with control and commercially available comparative samples. The effect of providing nutritional information about the modified cheese was also evaluated. Consumers (n = 115) rated samples for overall liking (appearance, flavor, and texture) using 9-point hedonic scales. Although no significant differences were found between the milk samples, the modified cheese was liked significantly less than a regular-fat commercial alternative for overall liking and liking of specific modalities and had a lower liking of texture score compared with the control cheese. The provision of health information significantly increased the overall liking of the modified cheese compared with tasting the same sample in a blinded manner. Significant differences were evident between the butter samples for overall liking and modalities of liking; all of the samples were significantly more liked than the commercial butter and sunflower oil spread. In conclusion, this study illustrated that consumer acceptance of SFA-reduced, monounsaturated fatty acid-enriched dairy products was dependent on product type. Future research should consider how optimization of the textural properties of fatty acid-modified (and fat-reduced) cheese might enhance consumer acceptance of this product

Impact of dairy fat manipulation on endothelial function and lipid regulation in human aortic endothelial cells exposed to human plasma samples: an in vitro investigation from the RESET study

Purpose Longer-term intake of fatty acid (FA)-modified dairy products (SFA-reduced, MUFA-enriched) was reported to attenuate postprandial endothelial function in humans, relative to conventional (control) dairy. Thus, we performed an in vitro study in human aortic endothelial cells (HAEC) to investigate mechanisms underlying the effects observed in vivo. Methods This sub-study was conducted within the framework of the RESET study, a 12-week randomised controlled crossover trial with FA-modified and control dairy diets. HAEC were incubated for 24 h with post-intervention plasma samples from eleven adults (age: 57.5±6.0 years; BMI: 25.7±2.7 kg/m2 ) at moderate cardiovascular disease risk following representative sequential mixed meals. Markers of endothelial function and lipid regulation were assessed. Results Relative to control, HAEC incubation with plasma following the FA-modified treatment increased postprandial NOx production (P-interaction=0.019), yet up-regulated relative E-selectin mRNA gene expression (P-interaction=0.011). There was no impact on other genes measured. Conclusion Incubation of HAEC with human plasma collected after longer-term dairy fat manipulation had a beneficial impact on postprandial NOx production. Further ex vivo research is needed to understand the impact of partial replacement of SFA with unsaturated fatty acids in dairy foods on pathways involved in endothelial function