Intake of milk fat, reflected in adipose tissue fatty acids and risk of myocardial infarction: a case–control study

Exhaustive Search of Dietary Intake Biomarkers as Objective Tools for Personalized Nutrimetabolomics and Precision Nutrition Implementation

OBJECTIVE

To conduct an exhaustive scoping search of existing literature, incorporating diverse bibliographic sources to elucidate the relationships between metabolite biomarkers in human fluids and dietary intake.

BACKGROUND

The search for biomarkers linked to specific dietary food intake holds immense significance for precision health and nutrition research. Using objective methods to track food consumption through metabolites offers a more accurate way to provide dietary advice and prescriptions on healthy dietary patterns by healthcare professionals. An extensive investigation was conducted on biomarkers associated with the consumption of several food groups and consumption patterns. Evidence is integrated from observational studies, systematic reviews, and meta-analyses to achieve precision nutrition and metabolism personalization.

METHODS

Tailored search strategies were applied across databases and gray literature, yielding 158 primary research articles that met strict inclusion criteria. The collected data underwent rigorous analysis using STATA and Python tools. Biomarker-food associations were categorized into 5 groups: cereals and grains, dairy products, protein-rich foods, plant-based foods, and a miscellaneous group. Specific cutoff points (≥3 or ≥4 bibliographic appearances) were established to identify reliable biomarkers indicative of dietary consumption.

RESULTS

Key metabolites in plasma, serum, and urine revealed intake from different food groups. For cereals and grains, 3-(3,5-dihydroxyphenyl) propanoic acid glucuronide and 3,5-dihydroxybenzoic acid were significant. Omega-3 fatty acids and specific amino acids showcased dairy and protein foods consumption. Nuts and seafood were linked to hypaphorine and trimethylamine N-oxide. The miscellaneous group featured compounds like theobromine, 7-methylxanthine, caffeine, quinic acid, paraxanthine, and theophylline associated with coffee intake.

CONCLUSIONS

Data collected from this research demonstrate potential for incorporating precision nutrition into clinical settings and nutritional advice based on accurate estimation of food intake. By customizing dietary recommendations based on individualized metabolic profiles, this approach could significantly improve personalized food consumption health prescriptions and support integrating multiple nutritional data.This article is part of a Nutrition Reviews special collection on Precision Nutrition.

Metabolic effects of milk fatty acids: A literature review

Milk and dairy products are known to have a significant role in human development and tissue maintenance due to their high nutritional value. With the higher incidence of obesity and metabolic diseases, nutrition and public health authorities have recommended the intake of fat-free or low-fat dairy due to the saturated fatty acid content of whole-fat products and their effect on serum cholesterol levels. However, recent studies have questioned the association between milk fat consumption and cardiometabolic risk. This literature review aims to compile the scientific evidence of the metabolic effects of milk fatty acids in clinical and basic research studies, as well as their relationship with metabolic disorders and gut microbiota composition. Research shows that various milk fatty acids exert effects on metabolic alterations (obesity, type 2 diabetes and cardiovascular diseases) by modifying glucose homeostasis, inflammation and lipid profile-related factors. Additionally, recent studies have associated the consumption of milk fatty acids with the production of metabolites and the promotion of healthy gut microbiota. From mainly observational studies, evidence suggests that milk and dairy fatty acids are not directly linked to cardiometabolic risk, but further controlled research is necessary to clarify such findings and to assess whether dietary recommendations to choose low-fat dairy foods are necessary for the population for the prevention of obesity and cardiometabolic disease.

Novel lipid biomarkers and ratios as risk predictors for premature coronary artery disease: A retrospective analysis of 2952 patients

This study examined the associations between emerging lipid biomarkers (small dense low-density lipoprotein cholesterol [sdLDL-C), lipoprotein(a) [Lp(a)], and free fatty acids [FFA]), two ratios (sdLDL-C/LDL-C and the triglyceride-glucose [TyG) index), and the Gensini score (GS) in patients with premature coronary artery disease (PCAD) in relation to the extent of coronary stenosis. The authors evaluated a cohort of 2952 individuals undergoing coronary angiography (CAG), encompassing those with PCAD (n = 1749), late-onset coronary artery disease (LCAD; n = 328), and non-coronary artery disease (non-CAD; n = 575). Noteworthy differences were observed in the levels of the novel lipid biomarkers and ratio indexes among the PCAD, LCAD, and non-CAD groups (p < .05). Multiple logistic regression analyses pinpointed Lp(a) (OR = 2.62, 95% CI 1.22-5.63, p = .014) and the TyG index (OR = 2.53, 95% CI 1.08-5.93, p = .033) as independent risk factors for PCAD. Furthermore, these biomarkers and ratio indexes discerned substantial distinctions among PCAD patients with varying GS (p < .05). Consequently, these markers can proficiently anticipate the gravity of coronary artery stenosis (GS > 40) in PCAD patients, as evidenced by the ROC analysis. In conclusion, sdLDL-C, Lp(a), FFA, and the sdLDL-C/LDL-C and TyG indexes have considerable potential as risk and diagnostic markers for coronary artery stenosis in individuals afflicted with PCAD.

Pentadecanoic Acid (C15:0), an Essential Fatty Acid, Shares Clinically Relevant Cell-Based Activities with Leading Longevity-Enhancing Compounds

Pentadecanoic acid (C15:0) is an essential odd-chain saturated fatty acid with broad activities relevant to protecting cardiometabolic, immune, and liver health. C15:0 activates AMPK and inhibits mTOR, both of which are core components of the human longevity pathway. To assess the potential for C15:0 to enhance processes associated with longevity and healthspan, we used human cell-based molecular phenotyping assays to compare C15:0 with three longevity-enhancing candidates: acarbose, metformin, and rapamycin. C15:0 (n = 36 activities in 10 of 12 cell systems) and rapamycin (n = 32 activities in 12 of 12 systems) had the most clinically relevant, dose-dependent activities. At their optimal doses, C15:0 (17 µM) and rapamycin (9 µM) shared 24 activities across 10 cell systems, including anti-inflammatory (e.g., lowered MCP-1, TNFα, IL-10, IL-17A/F), antifibrotic, and anticancer activities, which are further supported by previously published in vitro and in vivo studies. Paired with prior demonstrated abilities for C15:0 to target longevity pathways, hallmarks of aging, aging rate biomarkers, and core components of type 2 diabetes, heart disease, cancer, and nonalcoholic fatty liver disease, our results support C15:0 as an essential nutrient with activities equivalent to, or surpassing, leading longevity-enhancing candidate compounds.

Biomarkers of dairy fat intake, incident cardiovascular disease, and all-cause mortality: A cohort study, systematic review, and meta-analysis

BACKGROUND

We aimed to investigate the association of serum pentadecanoic acid (15:0), a biomarker of dairy fat intake, with incident cardiovascular disease (CVD) and all-cause mortality in a Swedish cohort study. We also systematically reviewed studies of the association of dairy fat biomarkers (circulating or adipose tissue levels of 15:0, heptadecanoic acid [17:0], and trans-palmitoleic acid [t16:1n-7]) with CVD outcomes or all-cause mortality.

METHODS AND FINDINGS

We measured 15:0 in serum cholesterol esters at baseline in 4,150 Swedish adults (51% female, median age 60.5 years). During a median follow-up of 16.6 years, 578 incident CVD events and 676 deaths were identified using Swedish registers. In multivariable-adjusted models, higher 15:0 was associated with lower incident CVD risk in a linear dose-response manner (hazard ratio 0.75 per interquintile range; 95% confidence interval 0.61, 0.93, P = 0.009) and nonlinearly with all-cause mortality (P for nonlinearity = 0.03), with a nadir of mortality risk around median 15:0. In meta-analyses including our Swedish cohort and 17 cohort, case-cohort, or nested case-control studies, higher 15:0 and 17:0 but not t16:1n-7 were inversely associated with total CVD, with the relative risk of highest versus lowest tertile being 0.88 (0.78, 0.99), 0.86 (0.79, 0.93), and 1.01 (0.91, 1.12), respectively. Dairy fat biomarkers were not associated with all-cause mortality in meta-analyses, although there were ≤3 studies for each biomarker. Study limitations include the inability of the biomarkers to distinguish different types of dairy foods and that most studies in the meta-analyses (including our novel cohort study) only assessed biomarkers at baseline, which may increase the risk of misclassification of exposure levels.

CONCLUSIONS

In a meta-analysis of 18 observational studies including our new cohort study, higher levels of 15:0 and 17:0 were associated with lower CVD risk. Our findings support the need for clinical and experimental studies to elucidate the causality of these relationships and relevant biological mechanisms.

Plasma Free Fatty Acid Concentration as a Modifiable Risk Factor for Metabolic Disease

Plasma free fatty acid (FFA) concentration is elevated in obesity, insulin resistance (IR), non-alcoholic fatty liver disease (NAFLD), type 2 diabetes (T2D), and related comorbidities such as cardiovascular disease (CVD). Furthermore, experimentally manipulating plasma FFA in the laboratory setting modulates metabolic markers of these disease processes. In this article, evidence is presented indicating that plasma FFA is a disease risk factor. Elevations of plasma FFA can promote ectopic lipid deposition, IR, as well as vascular and cardiac dysfunction. Typically, elevated plasma FFA results from accelerated adipose tissue lipolysis, caused by a high adipose tissue mass, adrenal hormones, or other physiological stressors. Reducing an individual’s postabsorptive and postprandial plasma FFA concentration is expected to improve health. Lifestyle change could provide a significant opportunity for plasma FFA reduction. Various factors can impact plasma FFA concentration, such as chronic restriction of dietary energy intake and weight loss, as well as exercise, sleep quality and quantity, and cigarette smoking. In this review, consideration is given to multiple factors which lead to plasma FFA elevation and subsequent disruption of metabolic health. From considering a variety of medical conditions and lifestyle factors, it becomes clear that plasma FFA concentration is a modifiable risk factor for metabolic disease.

Fatty acids: facts vs. fiction

During the last 100 years official dietary guidelines have recommended an increased consumption of fats derived from seeds while decreasing the consumption of traditional fats, especially saturated fats. These recommendations are being challenged by recent studies. Furthermore, the increased use of refining processes in fat production had deleterious health effects. Today, the number of high-quality studies on fatty acids is large enough to make useful recommendations on clinical application and everyday practice. Saturated fats have many beneficial functions and palmitic acid appears to be problematic only when it is synthesized due to excess fructose consumption. Trans fatty acids were shown to be harmful when they are manmade but beneficial when of natural origin. Conjugated linoleic acid has many benefits but the isomer mix that is available in supplement form differs from its natural origin and may better be avoided. The ω3 fatty acid linolenic acid has rather limited use as an anti-inflammatory agent - a fact that is frequently overlooked. On the other hand, the targeted use of long chain ω3 fatty acids based on blood analysis has great potential to supplement or even be an alternative to various pharmacological therapies. At the same time ω6 fatty acids like linoleic acid and arachidonic acid have important physiological functions and should not be avoided but their consumption needs to be balanced with long chain ω3 fatty acids. The quality and quantity of these fats together with appropriate antioxidative protection are critical for their positive health effects.

Plasma fatty acids and kidney function decline in post-myocardial infarction patients of the Alpha Omega Cohort

BACKGROUND AND AIMS

Age-related kidney function decline is accelerated in patients with coronary heart disease (CHD). CHD and chronic kidney disease may share common etiologies. We examined plasma fatty acids (FAs) as novel biomarkers of kidney function decline after myocardial infarction (MI).

METHODS AND RESULTS

The analysis included 2329 Dutch post-MI patients aged 60-80y (Alpha Omega Cohort) most receiving state-of-the-art medications. Plasma FAs (% total FAs) in cholesteryl esters were assessed at baseline (2002-2006), and ∼40 months change in creatinine-cystatin C based glomerular filtration rate was estimated (eGFR, in ml/min per 1.73 m²). Beta coefficients for annual eGFR change in relation to plasma linoleic acid (LA; 50.1% of total FAs in CE), omega-3 FAs (EPA + DHA; 1.7%), odd-chain FAs (C15:0 and C17:0; 0.2%), and C14:0 (0.7%) were obtained from linear regression analyses adjusted for age, sex, smoking, and alcohol intake. Mean baseline eGFR ±SD was 78.5 ± 18.7, which declined by 4.7 ± 13.1 during follow-up, or 1.4 ± 3.9 per year. The annual decline in eGFR was less in patients with higher plasma LA (adjusted beta: 0.40 for LA >47 vs ≤ 47%, 95% CI: 0.01; 0.78; p = 0.046). Associations of plasma LA with annual eGFR decline were stronger in 437 patients with diabetes (1.21, 0.24; 2.19) and in 402 patients with CKD (eGFR<60; 0.90, -0.09; 1.89). Weaker, non-significant associations with kidney function decline were observed for the other plasma FAs.

CONCLUSION

Higher plasma LA may be a good predictor of less kidney function decline after MI, particularly in patients with diabetes. The Alpha Omega Cohort is registered with clinicaltrials.gov, NCT03192410.

EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Castenmiller J, de Henauw S, Hirsch‐Ernst K, Kearney J, Knutsen HK, Mangelsdorf I, McArdle HJ, Naska A, Pelaez C, Pentieva K, Siani A, Thies F, Tsabouri S, Vinceti M, Titz A, Turck D. Statement on additional scientific evidence in relation to the essential composition of total diet replacement for weight control

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to revise the Opinion on the essential composition of total diet replacements for weight control (TDRs) regarding the minimum content of linoleic acid (LA) and alpha-linolenic acid (ALA) and the maximum content of magnesium (Mg). Through a comprehensive literature search, human studies were retrieved reporting on LA and ALA concentrations in adipose tissue (AT), on weight loss and gallstone formation following TDR consumption and on diarrhoea after supplemental Mg intake. The distribution of the amount of LA and ALA release from AT during weight loss when consuming TDRs was estimated using statistical simulations. Using the fifth percentile, the coverage of the adequate intake (AI) for both FA was estimated. For the risk of developing diarrhoea when consuming TDRs with an Mg content of 350 mg/day, four cross-over studies using 360-368 mg Mg/day were reviewed. The Panel concludes that (1) there is no need to add LA to TDRs, as the amount released from AT during weight loss when consuming TDRs is sufficient to cover the AI for LA; (2) a minimum of 0.8 g/day ALA is needed in TDRs in order to meet the AI for ALA; (3) the minimum fat content of TDRs of 20 g/day as derived in the Panel's previous opinion is proposed to be maintained until the availability of further evidence, given the considerable uncertainty as to the amount of fat required for reducing the risk of gallstone formation; and (4) the likelihood that Mg-induced diarrhoea occurs at a severity that may be considered of concern for overweight and obese individuals consuming TDRs is low when the total maximum Mg content in TDRs is 350 mg/day.

The memory of the fatty acid system

Mental memory system has sensory memory, short-term memory, working memory, and long-term memory. Working memory "keeps things in mind in parallel" when performing complex tasks. Similar aspects can be found for immunological memory. However, there exists another one, the memory of the fatty acid system. This article shows sensory memory of the fatty acid system, which is the perception apparatus of small intestine enterocytes (CD36, SR-B1, FATP4, FABP1, FABP2) and hepatocytes. In these cells, the fatty acid short-term memory is located, consisting of a cytoplasmic lipid droplet cycle. Similar like a working memory in the brain, the short-term memory of enterocytes and hepatocytes use parallel processing and recourse to long-term fatty acid memory. The fatty acid long-term memory is far away from these primary points of uptake. It is located in the adipocyte and in cellular membranes. The process of building a fatty acid memory is described with constructs like sensing environmental material, encoding, consolidation, long-term storage, retrieval, re-encoding, re-consolidation, and renewed long-term storage. The article illustrates the dynamics of building a fatty acid memory, the information content of fatty acids including the code, the roles of fatty acids in the body, and a new understanding of the expression "you are what you eat". The memory of the fatty acid system, plays a decisive role in integrating environmental signals over time (diet and microbiome).

Dietary intake of fatty acids and its relationship with FEV1/FVC in patients with chronic obstructive pulmonary disease

BACKGROUND & AIMS

The deterioration of pulmonary function has been associated with increased levels of systemic inflammation that can be stimulated by consumption of saturated fatty acids and trans fats. We hypothesized that fatty acids intake impact on pulmonary function. However, evidence about the impact of different types of fatty acids on pulmonary function in patients with chronic obstructive pulmonary disease (COPD) is limited and heterogeneous. The aim of this study was to evaluate the association between intake of fatty acids and pulmonary function in patients with COPD.

METHODS

Cross sectional study of patients diagnosed with COPD. The relationship between consumption of fatty acids and the FEV₁/FVC ratio obtained by spirometry was assessed. Patients with exacerbations during the prior 2 months, diagnosis of asthma or administration of a dietary supplement were excluded.

RESULTS

A simple linear regression showed that for each gram of carbohydrates and total l fatty acids intake, the FEV₁/FVC ratio decreased -0.03 ml (β: -0.03, 95% CI -0.06 to -0.01, p = 0.008) and -0.009 ml (β: -0.00, 95% CI -0.02 to 0.00, p = 0.031) respectively. Pentadecanoic acid (C15:0) was associated with an increase of 0.47 ml in the FEV₁/FVC ratio for each milligram intake (β: 0.47, 95% CI 0.04 to 0.91, p = 0.031). Subsequently, when adjusted for calories intake, an increase of 0.53 ml was observed in the FEV₁/FVC for each milligram of C15:0 fatty acid intake (β:0.53, 95% CI 0.09 to 0.97, p = 0.018).

CONCLUSION

A positive association was observed between pentadecanoic acid and the FEV₁/FVC ratio with a beneficial effect on patients with COPD.

Physicochemical and nutritional characteristics of Béni Guil lamb meat raised in eastern Morocco

BACKGROUND: The Béni Guil sheep is the main ovine breed that dominates livestock farming in the semi-arid region of eastern Morocco. No previous data is available on the quality of Béni Guil PGI (Protected Geographical Indication) lamb meat raised on the natural pasture of this area. OBJECTIVE: This study aims to provide the physicochemical and nutritional characteristics of Béni Guil PGI lamb meat. METHODS: Béni Guil PGI lamb meat was analysed for its quality parameters, fatty acid composition and amino acid profile. RESULTS: Results show that the Béni Guil PGI lamb meat has a significant juiciness (high water holding capacity), a marked tenderness (low collagen content) and a bright red colour. Longissimus lumborum muscle from Béni Guil PGI lambs contains 25.72% dry matter, including 19.43% protein, 5.14% fat, and 0.94% minerals. Gas chromatography-flame ionisation detection, for fatty acid analysis, revealed 49.45% saturated fatty acids (SFA), 38.48% monounsaturated fatty acids (MUFA) and 12.4% polyunsaturated fatty acids (PUFA). The UFA:SFA and n-6:n-3 PUFA ratios were 1.04 and 3.78, respectively, and were comparable to those recommended for a balanced diet. The amino acid analysis, allowed the identification of eight essential amino acids. The chemical index and the protein digestibility-corrected amino acid score values were 132 and 124, respectively. CONCLUSION: The results of this study indicate that the Beni Guil PGI meat has nutritional values in accordance with the nutritional recommendations and specific to the feeding system based mainly on grazing.

Dairy Products, Dairy Fatty Acids, and the Prevention of Cardiometabolic Disease: a Review of Recent Evidence

PURPOSE OF REVIEW

To examine recent literature on dairy products, dairy fatty acids, and cardiometabolic disease. Primary questions of interest include what unique challenges researchers face when investigating dairy products/biomarkers, whether one should consume dairy to reduce disease risk, whether dairy fatty acids may be beneficial for health, and whether one should prefer low- or high-fat dairy products.

RECENT FINDINGS

Dairy composes about 10% of the calories in a typical American diet, about half of that coming from fluid milk, half coming from cheese, and small amounts from yogurt. Most meta-analyses report no or weak inverse association between dairy intake with cardiovascular disease and related intermediate outcomes. There is some suggestion that dairy consumption was inversely associated with stroke incidence and yogurt consumption was associated with lower risk of type 2 diabetes. Odd chain fatty acids (OCFAs) found primarily in dairy (15:0 and 17:0) appear to be inversely associated with cardiometabolic risk, but causation is uncertain. Substitution analyses based on prospective cohorts suggested that replacing dairy fat with vegetable fat or polyunsaturated fat was associated with significantly lower risk of cardiovascular disease. Current evidence suggests null or weak inverse association between consumption of dairy products and risk of cardiovascular disease. However, replacing dairy fat with polyunsaturated fat, especially from plant-based foods, may confer health benefits. More research is needed to examine health effects of different types of dairy products in diverse populations.

Milk fat biomarkers and cardiometabolic disease

PURPOSE OF REVIEW

Dairy is a major food group with potential impact on cardiometabolic health. Self-reported dairy intake has limitations that can partly be avoided by using biomarkers. This review aims to summarize the evidence of odd-chain saturated fatty acids (OCFAs), that is, pentadecanoic acid (C15 : 0) and heptadecanoic acid (17 : 0), as biomarkers of dairy fat intake. In addition, the associations of OCFA biomarkers with cardiometabolic disease will be overviewed.

RECENT FINDINGS

Adipose tissue 15 : 0 is the preferred biomarker but also circulating 15 : 0, and to a weaker extent 17 : 0, reflects both habitual and changes in dairy intake. Whereas results from studies assessing cardiovascular outcomes are inconsistent, OCFA biomarkers are overall associated with lower diabetes risk. Residual confounding should however be considered until interventional data and mechanisms are available. Although OCFA biomarkers mainly reflect dairy fat intake, recently proposed endogenous synthesis and metabolism do motivate further research.

SUMMARY

Taking into account the study population diet and limitations of OCFA biomarkers, both adipose and circulating levels of 15 : 0, in particular, are useful for estimating total dairy fat intake. OCFA biomarkers are overall not linked to cardiovascular disease risk, but a possible beneficial role of dairy foods in diabetes prevention warrant further study.

Saturated fatty acids are not off the hook

A recent meta-analysis by Chowdhury et al. (2014) has disclaimed the association between coronary artery diseases and either circulating blood levels or the intake of total saturated fatty acids (SFA). Scrutiny revealed that two of the eight studies included in the meta-analysis focused on the proportion of pentadecanoic acid (C15:0) and heptadecanoic acid (C17:0) and their impact on cardiovascular disease (CVD) risk. These odd-chain fatty acids are markers for milk or ruminant fat intake. Both studies indicated inverse associations between milk-fat intake and first-ever myocardial infarction. Neither of the two studies described the association between total circulating blood SFA on coronary outcomes. In contrast to the cardioprotective effects of dairy consumption, we expected that an elevated intake of palmitic acid (C16:0) and stearic acid (C18:0) de novo may raise CVD risk. Thus, it is of particular importance to differentiate the effects of individual circulating SFA on cardiovascular outcomes. Excluding the studies that evaluated the association of fatty acids from milk fat and cardiovascular outcomes revealed a positive association of total SFA blood levels and coronary outcome (RR 1.21, CI 1.04-1.40). Therefore, results obtained from studies of C15:0 and C17:0 cannot be mixed with results from studies of other SFA because of the opposite physiological effects of regular consumption of foods rich in C16:0 and C18:0 compared to high intake of milk or ruminant fat. In our opinion, it is vital to analyze the impact of individual SFA on CVD incidence in order to draw prudent conclusions.

Recommended dairy product intake modulates circulating fatty acid profile in healthy adults: a multi-centre cross-over study

Dairy products are rich sources of an array of fatty acids (FA) that have been shown individually and in certain clusters to exert varying effects on cardiovascular health, for which the circulating lipid profile is a powerful biomarker. Whether the profile of these FA is reflected in blood upon short terms of intake, possibly contributing to the lipid-related health impacts of dairy products, remains to be fully established. The objectives of the present study were to assess a recommended dairy product consumption in relation to circulating FA and lipid profiles, and to evaluate certain FA in dairy fat as potential biomarkers of intake. In a free-living, multi-centre, cross-over design, 124 healthy individuals consumed 3 servings/d of commercial dairy (DAIRY; 1% fat milk, 1·5% fat yogurt and 34% fat cheese) or energy-equivalent control (CONTROL; fruit and vegetable juice, cashews and a cookie) products for 4 weeks each, separated by a 4-week washout period. Plasma FA and serum lipid profiles were assessed by standard methods at the end of each dietary phase. After 4 weeks of intake, plasma levels of FA pentadecanoic acid (15 : 0) and heptadecanoic acid (17 : 0) were higher (0·26 v. 0·22% and 0·42 v. 0·39% of the total identified FA, respectively) after the DAIRY phase than after the CONTROL phase (P< 0·0001). This was accompanied by a small but significant increase in serum LDL-cholesterol levels after the DAIRY phase compared with the CONTROL phase (+0·08 mmol/l; P= 0·04). In conclusion, intake of 3 servings/d of conventional dairy products may modify certain circulating FA and lipid profiles within 4 weeks, where 15 : 0 and 17 : 0 may be potential short-term biomarkers of intake.

Adipose tissue trans-fatty acids and changes in body weight and waist circumference

Previous studies have suggested that the intake of trans-fatty acids (TFA) plays a role in the development of obesity. The proportions of adipose tissue fatty acids not synthesised endogenously in humans, such as TFA, usually correlate well with the dietary intake. Hence, the use of these biomarkers may provide a more accurate measure of habitual TFA intake than that obtained with dietary questionnaires. The objective of the present study was to investigate the associations between the proportions of specific TFA in adipose tissue and subsequent changes in weight and waist circumference (WC). The relative content of fatty acids in adipose tissue biopsies from a random sample of 996 men and women aged 50-64 years drawn from a Danish cohort study was determined by GC. Baseline data on weight, WC and potential confounders were available together with information on weight and WC 5 years after enrolment. The exposure measures were total trans-octadecenoic acids (18:1t), 18:1 Δ6-10t, vaccenic acid (18:1 Δ11t) and rumenic acid (18:2 Δ9c, 11t). Data were analysed using multiple regression with cubic spline modelling. The median proportion of total adipose tissue 18:1t was 1.52% (90% central range 0.98, 2.19) in men and 1.47% (1.01, 2.19) in women. No significant associations were observed between the proportions of total 18:1t, 18:1 Δ6-10t, vaccenic acid or rumenic acid and changes in weight or WC. The present study suggests that the proportions of specific TFA in adipose tissue are not associated with subsequent changes in weight or WC within the exposure range observed in this population.

Biomarkers of dairy intake and the risk of heart disease

BACKGROUND AND AIMS

Despite their relatively high content of saturated fat, studies of dairy product intake and the risk of cardiovascular disease have often yielded null or inverse results. The use of fatty acid biomarkers to reflect dairy intake could elucidate this association. This study aims to evaluate the association between dairy intake, assessed by adipose pentadecanoic (15:0) and heptadecanoic (17:0) fatty acids and food frequency questionnaire (FFQ), and the risk of nonfatal myocardial infarction (MI), in a matched case-control study of Costa Rican adults (n=3630).

METHODS AND RESULTS

The association was examined using conditional logistic regression, adjusted for potential confounders. The associations of adipose tissue 15:0 and 17:0 with the risk of MI were not statistically significant (for 15:0: multivariate-adjusted OR for 5th quintile vs. 1st=1.14 (95% CI=0.85, 1.53), p-value for linear trend=0.77; for 17:0: multivariate-adjusted OR for 5th quintile vs. 1st=1.15 (95% CI=0.88, 1.51), p-value for linear trend=0.18). The association between the FFQ measure of dairy intake and MI showed evidence of a possible threshold effect, with a protective association observed for all but the top quintile of the exposure distribution.

CONCLUSION

Dairy product intake as assessed by adipose tissue 15:0, 17:0, and by FFQ is not associated with a linear increase in the risk of MI in the study population. It is possible that the adverse effect of saturated fat in dairy products on cardiovascular health is offset by presence of beneficial nutrients.

Is dairy product consumption associated with the incidence of CHD?

OBJECTIVE

Studies examining the association of dairy consumption with incident CHD have yielded inconsistent results. The current prospective study examined the association between dairy consumption and CHD in a population-based sample of older community-dwelling adults.

DESIGN

Baseline CHD risk factors were assessed and an FFQ was self-administered. Participants were followed for morbidity and mortality with periodic clinic visits and annual mailed questionnaires for an average of 16?2 years, with a 96% follow-up rate for fatal and non-fatal CHD.

SETTING

Community.

SUBJECTS

Participants were 751 men and 1008 women aged 50–93 years who attended a clinic visit in 1984–1987.

RESULTS

At baseline the mean age was 70.6 (SD 9.8) years for men and 70.1 (SD 9.3) years for women. Participants who developed CHD during follow-up were significantly older (P < 0.001), had higher BMI (P = 0.035) and higher total cholesterol (P = 0.050), and were more likely to be male (P < 0.001), diabetic (P = 0.011) and hypertensive (P < 0.001), than those who did not develop CHD. Multivariate regression analyses adjusting for age, BMI, diabetes, hypertension, LDL-cholesterol and oestrogen use (in women) indicated that women who consumed low-fat cheese ‘sometimes/often’ and women who consumed non-fat milk ‘sometimes/often’ had an increased risk of incident CHD (hazard ratio 52.32; 95% CI 1.57, 3.41) and CHD (hazard ratio 51.48; 95% CI 1.02, 2.16) compared with women who ‘never/rarely’ ate these dairy products.

CONCLUSIONS

Woman with higher intake of low-fat cheese and non-fat milk seem to have a higher risk of incident CHD. This needs further investigation considering recent evidence of cardiovascular benefits from certain dairy fat.

The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease

PURPOSE

To comprehensively review the data on the relationship between the consumption of dairy fat and high-fat dairy foods, obesity, and cardiometabolic disease.

METHODS

We have conducted a systematic literature review of observational studies on the relationship between dairy fat and high-fat dairy foods, obesity, and cardiometabolic disease. We have integrated these findings with data from controlled studies showing effects of several minor dairy fatty acids on adiposity and cardiometabolic risk factors, and data on how bovine feeding practices influence the composition of dairy fat.

RESULTS

In 11 of 16 studies, high-fat dairy intake was inversely associated with measures of adiposity. Studies examining the relationship between high-fat dairy consumption and metabolic health reported either an inverse or no association. Studies investigating the connection between high-fat dairy intake and diabetes or cardiovascular disease incidence were inconsistent. We discuss factors that may have contributed to the variability between studies, including differences in (1) the potential for residual confounding; (2) the types of high-fat dairy foods consumed; and (3) bovine feeding practices (pasture- vs. grain-based) known to influence the composition of dairy fat.

CONCLUSIONS

The observational evidence does not support the hypothesis that dairy fat or high-fat dairy foods contribute to obesity or cardiometabolic risk, and suggests that high-fat dairy consumption within typical dietary patterns is inversely associated with obesity risk. Although not conclusive, these findings may provide a rationale for future research into the bioactive properties of dairy fat and the impact of bovine feeding practices on the health effects of dairy fat.

Dietary shifts and human health: cancer and cardiovascular disease in a sustainable world

INTRODUCTION

Increasing evidence suggests that optimal food choice is critical for sizable prevention of western diseases such as cardiovascular disease and cancer. The Mediterranean diet is an important step in this direction. Moreover, substantially lower rates of Western disease, even compared to Mediterranean countries, have been observed among hunter-gatherers and other non-western populations (Lindeberg 2010). Observational studies and controlled trials support the notion that an evolutionary perspective is helpful when designing food models for optimal human health.

DISCUSSION

However, sustainable health for the individual patient is not enough: environmental sustainability must also be considered. Are fish and fruit sustainable for everyone? Are starchy root vegetables a better option than cereal grains? Is locally produced meat an underestimated wholesome food? These and other questions need to be addressed in order to cut greenhouse gases and the consumption of (blue) water and nonrenewable energy.

Whole grain products, fish and bilberries alter glucose and lipid metabolism in a randomized, controlled trial: the Sysdimet study

Background

Due to the growing prevalence of type 2 diabetes, new dietary solutions are needed to help improve glucose and lipid metabolism in persons at high risk of developing the disease. Herein we investigated the effects of low-insulin-response grain products, fatty fish, and berries on glucose metabolism and plasma lipidomic profiles in persons with impaired glucose metabolism.

Methodology/Principal Findings

Altogether 106 men and women with impaired glucose metabolism and with at least two other features of the metabolic syndrome were included in a 12-week parallel dietary intervention. The participants were randomized into three diet intervention groups: (1) whole grain and low postprandial insulin response grain products, fatty fish three times a week, and bilberries three portions per day (HealthyDiet group), (2) Whole grain enriched diet (WGED) group, which includes principally the same grain products as group (1), but with no change in fish or berry consumption, and (3) refined wheat breads (Control). Oral glucose tolerance, plasma fatty acids and lipidomic profiles were measured before and after the intervention. Self-reported compliance with the diets was good and the body weight remained constant. Within the HealthyDiet group two hour glucose concentration and area-under-the-curve for glucose decreased and plasma proportion of (n-3) long-chain PUFAs increased (False Discovery Rate p-values <0.05). Increases in eicosapentaenoic acid and docosahexaenoic acid associated curvilinearly with the improved insulin secretion and glucose disposal. Among the 364 characterized lipids, 25 changed significantly in the HealthyDiet group, including multiple triglycerides incorporating the long chain (n-3) PUFA.

Conclusions/Significance

The results suggest that the diet rich in whole grain and low insulin response grain products, bilberries, and fatty fish improve glucose metabolism and alter the lipidomic profile. Therefore, such a diet may have a beneficial effect in the efforts to prevent type 2 diabetes in high risk persons.

Trial Registration

ClinicalTrials.gov NCT00573781

Conjugated linoleic acid in adipose tissue and risk of myocardial infarction

BACKGROUND

Despite the high saturated fat content of dairy products, no clear association between dairy product intake and risk of myocardial infarction (MI) has been observed. Dairy products are the main source of conjugated linoleic acid (CLA; 18:2n-7t), which is produced by the ruminal biohydrogenation of grasses eaten by cows. Pasture-grazing dairy cows have more CLA in their milk than do grain-fed cows. Some animal models have reported beneficial effects of CLA on atherosclerosis.

OBJECTIVE

The objective was to determine the association between the 9c,11t-CLA isomer in adipose tissue and risk of MI.

DESIGN

The studied population consisted of 1813 incident cases of a first nonfatal acute MI and 1813 population-based controls matched for age, sex, and area of residence. All subjects lived in Costa Rica-a country that uses traditional pasture-grazing for dairy cows. Conditional logistic regression was used to estimate multivariate odds ratios and 95% CIs.

RESULTS

Adipose tissue 9c,11t-CLA was associated with a lower risk of MI in basic and multivariate models. Compared with the lowest quintile, odds ratios and 95% CIs were 0.80 (0.61, 1.04) for the second, 0.86 (0.64, 1.14) for the third, 0.62 (0.46, 0.84) for the fourth, and 0.51 (0.36, 0.71) for the fifth quintiles (P for trend <0.0001). Dairy intake was not associated with risk of MI, despite a strong risk associated with saturated fat intake.

CONCLUSION

9c,11t-CLA, which is present in meaningful amounts in the milk of pasture-grazed cows, might offset the adverse effect of the saturated fat content of dairy products.

Biomarkers of milk fat and the risk of myocardial infarction in men and women: a prospective, matched case-control study

BACKGROUND

High intakes of saturated fat have been associated with cardiovascular disease, and milk fat is rich in saturated fat.

OBJECTIVE

The objective of this study was to investigate the association between the serum milk fat biomarkers pentadecanoic acid (15:0), heptadecanoic acid (17:0), and their sum (15:0+17:0) and a first myocardial infarction (MI).

DESIGN

The study design was a prospective case-control study nested within a large population-based cohort in Sweden. Included in the study were 444 cases (307 men) and 556 controls (308 men) matched on sex, age, date of examination, and geographic region. Clinical, anthropometric, biomarker fatty acid, physical activity, and dietary data were collected. The odds of a first MI were investigated by using conditional logistic regression.

RESULTS

In women, proportions of milk fat biomarkers in plasma phospholipids were significantly higher (P < 0.05) in controls than in cases and were, in general, negatively, albeit weakly, correlated with risk factors for metabolic syndrome. The crude standardized odds ratios of becoming an MI case were 0.74 (95% CI: 0.58, 0.94) in women and 0.91 (95% CI: 0.77, 1.1) in men. After multivariable adjustment for confounders, the inverse association remained in both sexes and was significant in women. In agreement with biomarker data, quartiles of reported intake of cheese (men and women) and fermented milk products (men) were inversely related to a first MI (P for trend < 0.05 for all).

CONCLUSIONS

Milk fat biomarkers were associated with a lower risk of developing a first MI, especially in women. This was partly confirmed in analysis of fermented milk and cheese intake. Components of metabolic syndrome were observed as potential intermediates for the risk relations.

Dairy food consumption and obesity-related chronic disease

Dairy food comprises a range of different products with varying nutritional components. In the context of a healthy diet, dairy food may provide protection against and amelioration of chronic diseases related to obesity. These include overweight, insulin resistance/metabolic syndrome/type 2 diabetes, hypertension/stroke, and cardiovascular disease. Eliciting how dairy food may have this impact represents a challenge for modern nutritional science and requires an integration of knowledge from observational studies of population dietary patterns and disease prevalence, and experimental studies testing the effect of dairy food consumption. It also benefits from the recent identification of biomarkers of dairy fat intake and from mechanistic studies that support the plausibility of the observed effects. Future research might discriminate between types of dairy foods and focus on the synergy provided by the food matrix, rather than simply the component parts of the food.

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.

The survival advantage of milk and dairy consumption: an overview of evidence from cohort studies of vascular diseases, diabetes and cancer

OBJECTIVES

To conduct a detailed evaluation, with meta-analyses, of the published evidence on milk and dairy consumption and the incidence of vascular diseases and diabetes. Also to summarise the evidence on milk and dairy consumption and cancer reported by the World Cancer Research Fund and then to consider the relevance of milk and dairy consumption to survival in the UK, a typical Western community. Finally, published evidence on relationships with whole milk and fat-reduced milks was examined.

METHODS

Prospective cohort studies of vascular disease and diabetes with baseline data on milk or dairy consumption and a relevant disease outcome were identified by searching MEDLINE, and reference lists in the relevant published reports. Meta-analyses of relationships in these reports were conducted. The likely effect of milk and dairy consumption on survival was then considered, taking into account the results of published overviews of relationships of these foods with cancer.

RESULTS

From meta-analysis of 15 studies the relative risk of stroke and/or heart disease in subjects with high milk or dairy consumption was 0.84 (95% CI 0.76, 0.93) and 0.79 (0.75, 0.82) respectively, relative to the risk in those with low consumption. Four studies reported incident diabetes as an outcome, and the relative risk in the subjects with the highest intake of milk or diary foods was 0.92 (0.86, 0.97).

CONCLUSIONS

Set against the proportion of total deaths attributable to the life-threatening diseases in the UK, vascular disease, diabetes and cancer, the results of meta-analyses provide evidence of an overall survival advantage from the consumption of milk and dairy foods.

Intake of dairy fat and dairy products, and risk of myocardial infarction: a case-control study

The role of dairy fat in the aetiology of myocardial infarction (MI) is controversial. The aim of this study was to evaluate the association between intake of dairy fat and dairy products, and risk of a first acute MI. A total of 111 MI patients with a first acute MI and 107 population controls (men and women, age 45 75 years) were studied. Diet was assessed using a 180-item food frequency questionnaire. The MI cases had higher intake of total fat, but lower intake of saturated fat and dairy fat than the control persons. No effect of dairy fat or saturated fat on the odds ratio for MI was observed, however. A significant inverse trend in odds of MI for intake of cheese was observed, but the trend was no longer significant after adjustment for smoking. The results suggest that intake of fat from dairy products may not be associated with increased risk of having a first MI. The healthy control persons had a diet that differed from the diet of the MI patients in many aspects, and dairy products were a part of this diet. This may have protected them from having a first MI.

Plasma and erythrocyte biomarkers of dairy fat intake and risk of ischemic heart disease

BACKGROUND

The relation between dairy product intake and the risk of ischemic heart disease (IHD) remains controversial.

OBJECTIVE

We aimed to explore biomarkers of dairy fat intake in plasma and erythrocytes and to assess the hypothesis that higher concentrations of these biomarkers are associated with a greater risk of IHD in US women.

DESIGN

Among 32,826 participants in the Nurses' Health Study who provided blood samples in 1989-1990, 166 incident cases of IHD were ascertained between baseline and 1996. These cases were matched with 327 controls for age, smoking, fasting status, and date of blood drawing.

RESULTS

Among controls, correlation coefficients between average dairy fat intake in 1986-1990 and 15:0 and trans 16:1n-7 content were 0.36 and 0.30 for plasma and 0.30 and 0.32 for erythrocytes, respectively. In multivariate analyses, with control for age, smoking, and other risk factors of IHD, women with higher plasma concentrations of 15:0 had a significantly higher risk of IHD. The multivariate-adjusted relative risks (95% CI) from the lowest to highest tertile of 15:0 concentrations in plasma were 1.0 (reference), 2.18 (1.20, 3.98), and 2.36 (1.16, 4.78) (P for trend = 0.03). Associations for other biomarkers were not significant.

CONCLUSIONS

Plasma and erythrocyte contents of 15:0 and trans 16:1n-7 can be used as biomarkers of dairy fat intake. These data suggest that a high intake of dairy fat is associated with a greater risk of IHD.

Bovine milk in human nutrition--a review

Milk and milk products are nutritious food items containing numerous essential nutrients, but in the western societies the consumption of milk has decreased partly due to claimed negative health effects. The content of oleic acid, conjugated linoleic acid, omega-3 fatty acids, short- and medium chain fatty acids, vitamins, minerals and bioactive compounds may promote positive health effects. Full-fat milk has been shown to increase the mean gastric emptying time compared to half-skimmed milk, thereby increasing the gastrointestinal transit time. Also the low pH in fermented milk may delay the gastric emptying. Hence, it may be suggested that ingesting full-fat milk or fermented milk might be favourable for glycaemic (and appetite?) regulation. For some persons milk proteins, fat and milk sugar may be of health concern. The interaction between carbohydrates (both natural milk sugar and added sugar) and protein in milk exposed to heat may give products, whose effects on health should be further studied, and the increasing use of sweetened milk products should be questioned. The concentration in milk of several nutrients can be manipulated through feeding regimes. There is no evidence that moderate intake of milk fat gives increased risk of diseases.

Dietary patterns, food groups and myocardial infarction: a case-control study

Certain dietary patterns may be related to the risk of CVD. We hypothesised that a plant-centred dietary pattern would be associated with a reduced risk of first myocardial infarction (MI). A case-control study of Norwegian men and postmenopausal women (age 45-75 years) was performed. A FFQ was administered, generally within 3 d after incident MI (n 106 cases). Controls (n 105) were frequency matched on sex, age and geographic location. On the FFQ, 190 items were categorised into thirty-five food groups and an a priori healthy diet pattern score was created. We estimated OR using logistic regression with adjustment for energy intake, family history of heart disease, marital status, current smoking, education and age. Among food groups, the risk of MI was significantly higher per SD of butter and margarine (OR 1.66 (95 % CI 1.12, 2.46)), and lower per SD of tomatoes (OR 0.53 (95 % CI 0.35, 0.79)), high-fat fish (OR 0.57 (95 % CI 0.38, 0.86)), wine (OR 0.58 (95 % CI 0.41, 0.83)), salad (OR 0.59 (95 % CI 0.40, 0.87)), whole grain breakfast cereals (OR 0.64 (95 % CI 0.45, 0.90)), cruciferous vegetables (OR 0.66 (95 % CI 0.47, 0.93)) and non-hydrogenated vegetable oil (OR 0.68 (95 % CI 0.49, 0.95)). An abundance of cases were found to have a low a priori healthy diet pattern score. A dietary pattern emphasising nutrient-rich plant foods and high-fat fish and low in trans fatty acids was associated with decreased risk of MI among Norwegians.

Milk and the metabolic syndrome

The metabolic syndrome is a cluster of metabolic disorders, namely dyslipidaemia, hypertension, obesity and glucose intolerance. Insulin resistance is the core phenomenon. Co-occurrence is associated with increased cardiovascular disease (CVD) risk. Observational studies found no increased CVD risk with increasing consumption of milk and other dairy products. In several studies dairy consumption was inversely associated with the occurrence of one or several facets of the metabolic syndrome. Many dairy components may contribute to the beneficial effects. Milk and particularly whey appeared insulinotropic when given in a single meal, but not in longer-term intervention. Medium chain fatty acids improve insulin sensitivity. Whey proteins, amino acids, medium chain fatty acids and in particular calcium and other minerals may contribute to the beneficial effect of dairy products on body weight and body fat. Peptides, calcium and other minerals reduce blood pressure. Fermented products and probiotic bacteria decrease absorption of cholesterol, sphingomyelin of cholesterol and fat, calcium of cholesterol, bile acids and fat. Proteins, peptides and bacteria may also reduce plasma cholesterol. Lactose, citrate, proteins and peptides improve weight control, blood pressure and plasma lipids indirectly, by improving calcium bioavailability. Furthermore, dairy consumption improves the bioavailability of folate and other secondary plant components.