Saturated fatty acids are not off the hook

Dairy foods and cardiometabolic diseases: an update and a reassessment of the impact of SFA

Type 2 diabetes (T2D) and CVD are major causes of mortality and chronic morbidity. Whilst mortality from CVD has decreased they remain the largest cause of death in Europe and the prevalence of T2D is increasing rapidly. A consistent component of public health advice is to reduce intake of SFA to reduce CVD in particular, which implies limiting dairy food consumption. The prospective studies and randomised controlled trials included in this review show that for dairy foods at least, SFA are not consistently associated with CVD or T2D risk. For CVD the association with dairy foods is generally neutral despite dairy foods being the major source of SFA in many diets. This creates considerable doubt, at least for dairy foods, concerning the validity of the traditional diet-heart hypothesis which positively relates SFA intake to increased serum LDL-cholesterol and subsequent increased CVD. There is now emerging evidence to explain this which is highly relevant to dairy foods. These include the potentially counterbalancing effect of SFA-stimulated HDL-cholesterol and specific food matrix factors. In addition, SFA are associated with the less atherogenic large buoyant LDL particles and possible counterbalancing hypotensive effects of dairy proteins. Overall, dairy foods have either a neutral or beneficial association with CVD and T2D. Beneficial associations are seen for blood pressure and the reduced T2D risk linked to yoghurt consumption, a subject that needs urgent attention given the sharp rise in T2D prevalence in many countries.

Saturated fats, dairy foods and cardiovascular health: No longer a curious paradox?

Cardiovascular diseases (CVDs) are a major cause of death and morbidity in many parts of the world, and many dietary guidelines limit the intake of saturated fatty acids (SFA) as they are regarded as an important risk factor for CVDs due to their association with increased blood cholesterol. Dairy foods are often a major contributor to dietary intake of SFA, and since many dietary guidelines contain restrictions on SFA intake, this can lead to a moderation of dairy food intake despite meta-analyses generally showing dairy to have a neutral or negative association with CVDs. Many prospective studies and randomised controlled trials do not support a simple positive association between SFA intake and the risk of atherosclerotic CVD and its components although some early studies had a number of methodological weakness. Studies that included blood cholesterol data do broadly support the positive relationship between SFA and blood low-density lipoprotein cholesterol (LDL-C) but without increased CVD risk resulting, despite LDL being a causal factor in atherosclerotic CVD. These data suggest that LDL-C alone is not a consistently good predictor or cause of CVD risk, perhaps particularly in relation to dairy food consumption although some non-dairy food studies have also shown LDL-C reduction was not reflected in reduced CVD risk. This narrative review examines some reasons for these findings. Overall, restrictions on dairy food intake do not seem warranted, although there remains a need to further understand the association of different dairy food types with chronic diseases, perhaps particularly for type 2 diabetes.

Association between diet quality and obesity indicators among the working-age adults in Inner Mongolia, Northern China: a cross-sectional study

Background

Obesity is a major risk factor for the global burden of disease in countries that are economically developed or not. This study aimed to investigate the association between diet quality and obesity indicators applying DASH and aMed.

Methods

This cross-sectional study on adult nutrition and chronic disease in Inner Mongolia (n = 1320). Dietary data were collected using 24-h diet recall for 3 consecutive days and weighing method. DASH and aMed were used to assess the dietary quality. WC, BMI and WC-BMI were used as obesity indicators. Logistic regression models were used to examine the associations between diet quality and obesity indicators.

Results

Higher diet quality, assessed by DASH, was only associated with WC. The odds ratio (OR) for abdominal obesity in the highest tertile of DASH scores compared with the lowest was 0.71 (95% confidence interval (CI) 0.53, 0.96; P_trend = 0.03). Furthermore, aMed was inversely associated with obesity indicators. OR for abdominal obesity in the highest tertile of aMed score compared with the lowest were 0.63 (95% CI 0.47, 0.87; P_trend = 0.005) and 0.57 (95% CI 0.41, 0.77; P_trend = 0.02) for overweight and obesity, respectively, and 0.60 (95% CI 0.44, 0.81; P_trend = 0.02) for high obesity risk.

Conclusions

Our findings suggest that dietary quality assessed using aMed is more closely associated with obesity than assessment using DASH in working-age adults in Inner Mongolia. The Mediterranean diet can be recommended as a healthy diet to control weight.

Association Between Fatty Acids of Blood Cell Membranes and Incidence of Coronary Heart Disease

Objective—

To examine the associations between baseline levels of fatty acids in blood cell membranes and their 1-year changes with the incidence of coronary heart disease (CHD) in older adults at high cardiovascular disease risk.

Approach and Results—

This is a case-control study nested in the PREDIMED trial (Prevención con Dieta Mediterránea), with 136 CHD cases and 272 controls (matched on age, sex, body mass index, intervention group, and time of permanence in the study to the time event). We used gas chromatography to measure the proportion of 22 fatty acids in blood cell membranes at baseline and after 1 year. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% CIs. After adjustment for classical CHD risk factors and multiple testing, 1 SD increase in baseline levels of C22:0, C24:0 and the sum of individual very long chain saturated fatty acids was associated with 56% (OR, 0.44 [95% CI, 0.28–0.69]), 59% (OR, 0.41 [95% CI, 0.25–0.65]), and 55% (OR, 0.45 [95% CI, 0.29–0.70]) a decreased odds of developing CHD, respectively. Baseline C20:1n9 was associated with higher odds of CHD (OR, 1.58 [95% CI, 1.25–2.00]).

Conclusions—

Higher levels of C22:0 and C24:0 were associated with a lower CHD incidence, whereas higher levels of C20:1n9 were associated with a higher risk. This study adds to the growing body of evidence suggesting potential differences in the cardiovascular disease effects of different types of circulating saturated fatty acids.

The elongation of very long-chain fatty acid 6 gene product catalyses elongation of n-13 : 0 and n-15 : 0 odd-chain SFA in human cells

Normal odd-chain SFA (OCSFA), particularly tridecanoic acid (n-13 : 0), pentadecanoic acid (n-15 : 0) and heptadecanoic acid (n-17 : 0), are normal components of dairy products, beef and seafood. The ratio of n-15 : 0:n-17 : 0 in ruminant foods (dairy products and beef) is 2:1, while in seafood and human tissues it is 1:2, and their appearance in plasma is often used as a marker for ruminant fat intake. Human elongases encoded by elongation of very long-chain fatty acid (ELOVL)1, ELOVL3, ELOVL6 and ELOVL7 catalyse biosynthesis of the dominant even-chain SFA; however, there are no reports of elongase function on OCSFA. ELOVL transfected MCF7 cells were treated with n-13 : 0, n-15 : 0 or n-17 : 0 (80 µm) and products analysed. ELOVL6 catalysed elongation of n-13 : 0→n-15 : 0 and n-15 : 0→n-17 : 0; and ELOVL7 had modest activity toward n-15 : 0 (n-15 : 0→n-17 : 0). No elongation activity was detected for n-17 : 0→n-19 : 0. Our data expand ELOVL specificity to OCSFA, providing the first molecular evidence demonstrating ELOVL6 as the major elongase acting on OCSFA n-13 : 0 and n-15 : 0 fatty acids. Studies of food intake relying on OCSFA as a biomarker should consider endogenous human metabolism when relying on OCSFA ratios to indicate specific food intake.

Cardiovascular mortality attributable to dietary risk factors in 51 countries in the WHO European Region from 1990 to 2016: a systematic analysis of the Global Burden of Disease Study

This study was performed to highlight the relationship between single dietary risk factors and cardiovascular diseases (CVDs) in the WHO European Region. We used the comparative risk assessment framework of the Global Burden of Disease Study to estimate CVD mortality attributable to diet; comprising eleven forms of CVDs, twelve food and nutrient groups and 27 risk-outcome pairs in four GBD regions including 51 countries by age and sex between 1990 and 2016. In 2016, dietary risks were associated with 2.1 million cardiovascular deaths (95% uncertainty interval (UI), 1.7-2.5 million) in the WHO European Region, accounting for 22.4% of all deaths and 49.2% of CVD deaths. In terms of single dietary risks, a diet low in whole grains accounted for approximately 429,000 deaths, followed by a diet low in nuts and seeds (341,000 deaths), a diet low in fruits (262,000 deaths), a diet high in sodium (251,000 deaths), and a diet low in omega-3 fatty acids (227,000 deaths). Thus, with an optimized, i.e. balanced diet, roughly one in every five premature deaths could be prevented. Although age-standardized death rates decreased over the last 26 years, the absolute number of diet-related cardiovascular deaths increased between 2010 and 2016 by 25,600 deaths in Western Europe and by 4300 deaths in Central Asia. In 2016, approximately 601,000 deaths (28.6% of all diet-related CVD deaths) occurred among adults younger than 70 years. Compared to other behavioural risk factors, a balanced diet is a potential key lever to avoid premature deaths.

Saturated Fatty Acid Intake Is Associated with Total Mortality in a Nationwide Cohort Study

Background

Dietary intakes of total and specific types of saturated fatty acids (SFAs) in relation to total mortality remain largely unknown in China.

Objective

We assessed the associations of total and individual SFA intakes with total mortality in a Chinese nationwide population.

Methods

This prospective analysis included 7888 women and 6495 men, aged >20 y, from the China Health and Nutrition Survey (1989-2011). Cumulative mean of SFA intake was calculated based on 3 d of 24-h records in each round of the survey. Multivariable Cox proportional hazard models were used to estimate HR and 95% CI.

Results

There were 1011 deaths during a median of 14 y of follow-up. In isocaloric nutrient density models that replace total carbohydrates, intakes of total SFAs and even-chain SFAs were associated with higher total mortality in women but not in men. Compared with the lowest quartiles, the HRs (95% CIs) in the highest quartiles were 1.65 (1.03, 2.62) for total SFAs (P-trend = 0.042) and 1.83 (1.13, 2.94) for even-chain SFAs (P-trend = 0.016) in women. Intake of odd-chain SFAs was associated with lower total mortality both in men [HR (95% CI): 0.64 (0.47, 0.87); P-trend = 0.01] and in women [HR (95% CI): 0.59 (0.42, 0.84); P-trend = 0.0013]. Moreover, intake of medium-chain SFAs was linked with lower total mortality in men [HR (95% CI): 0.64 (0.44, 0.93); P-trend = 0.013]. However, isocalorically replacing 1% of energy from unsaturated fatty acids with even-chain SFAs was associated with higher total mortality in men [HRs (95% CIs): 1.08 (0.97, 1.20) and 1.39 (1.20, 1.60) for replacing PUFAs and MUFAs, respectively].

Conclusions

Total SFA and even-chain SFA intake was associated with higher total mortality in women, whereas intake of odd-chain SFAs was related to lower total mortality in both sexes. This analysis of cohort was registered at clinicaltrials.gov as NCT03281512.

Analysis of fatty acid profiles of free fatty acids generated in deep-frying process

During the deep fat food frying process, the frying media, oil, continuously degenerates when exposed to high temperature, oxygen and moisture. This leads to physical and chemical changes including the formation of hydrolysis products such as free fatty acids (FFAs) which are associated with undesirable darkening in colour, off-flavouring and a lowering of the smoke point. This study was aiming to develop a method capable of identifying and quantifying individual free fatty acids within oil using a small sample size (100 mg of oil). We used liquid/liquid extraction technique to separate FFAs from the rest of the oil followed by esterification using boron trifluoride (BF3) and then gas chromatography analysis. Various extraction conditions were tested. A mixture of 0.02 M phosphate buffer at pH 12 and acetonitrile at solvent: buffer ratio larger than 2:1 showed the highest efficiency in extraction of FFAs. The method was capable of producing accurate fatty acid profiles of FFAs and showed good precision on medium rancidity oil samples. It also captured the differences induced by adding free fatty acids to samples. An interesting discrepancy was found between the new method and the traditional titration method in terms of overall FFA content, which suggests further optimisation and investigation are required.

Recent Science and Clinical Application of Nutrition to Coronary Heart Disease

One of the greatest threats to mortality in industrialized societies continues to be coronary heart disease (CHD). Moreover, the ability to decrease the incidence of CHD has reached a limit utilizing traditional diagnostic evaluations and prevention and treatment strategies for the top five cardiovascular risk factors (hypertension, diabetes mellitus, dyslipidemia, obesity, and smoking). It is well known that about 80% of CHD can be prevented with optimal nutrition, coupled with exercise, weight management, mild alcohol intake, and smoking cessation. Among all of these factors, optimal nutrition provides the basic foundation for prevention and treatment of CHD. Numerous prospective nutrition clinical trials have shown dramatic reductions in the incidence of CHD. As nutritional science and nutrigenomics research continues, our ability to adjust the best nutrition with an individualized approach is emerging. This article reviews the role of nutrition in the prevention and treatment of CHD and myocardial infarction (MI).

Association between dairy intake, lipids and vascular structure and function in diabetes

AIM

To determine lipid species that change in response to a change in dairy consumption. In addition, to investigate whether dairy associated lipid species are correlated with changes in measures of vascular structure and function.

METHODS

A 12-mo randomised controlled trial was conducted to determine the effect of increased consumption of fruit, vegetables and dairy, compared to usual diet, on measures of vascular structure and function in adults with type 1 and type 2 diabetes (n = 108). This paper comprises post-hoc analyses investigating the relationship between dairy intake, serum lipid species and vascular health. Central and peripheral blood pressure, carotid femoral pulse wave velocity, augmentation index, serum lipid species and dietary intake were measured at baseline and 3-mo. Common carotid artery intima media thickness was measured at baseline and 12-mo.

RESULTS

Serum lipid species [lysophosphatidylcholine (LPC) 14:0, LPC 15:0, LPC 16:1, phosphatidylcholine (PC) 29:0 PC 30:0, PC 31:0 and cholesterol ester (CE) 14:0] were associated with the change in full fat dairy consumption (rho 0.19-0.25; P < 0.05). The 3-mo change in some lipids was positively associated with the 3-mo change in central systolic [LPC 14:0 (rho 0.30; P = 0.007), PC 30:0 (rho 0.28; P = 0.010)] and diastolic blood pressure [LPC 14:0 (rho 0.32; P = 0.004), LPC 15:0 (rho 0.23; P = 0.04), LPC 16:1 (rho 0.23; P = 0.035), PC 29:0 (rho 0.28; P = 0.01), PC 30:0 (rho 0.36; P = 0.001), PC 31:0 (rho 0.30; P = 0.007)] and 12-mo change in common carotid artery intimal medial thickness [CE 14:0 (rho 0.22; P = 0.02)]. Pulse wave velocity and augmentation index were unrelated to dairy and lipid species.

CONCLUSION

An increase in dairy associated lipids appears to be associated with an increase in blood pressure and common carotid intimal medial thickness.