Saturated fat and cardiovascular disease: The discrepancy between the scientific literature and dietary advice

Saturated fat: villain and bogeyman in the development of cardiovascular disease?

AIMS

Cardiovascular disease (CVD) is the leading global cause of death. For decades, the conventional wisdom has been that the consumption of saturated fat (SFA) undermines cardiovascular health, clogs the arteries, increases risk of CVD, and leads to heart attacks. It is timely to investigate whether this claim holds up to scientific scrutiny. The purpose of this paper is to review and discuss recent scientific evidence on the association between dietary SFA and CVD.

METHODS AND RESULTS

PubMed, Google scholar, and Scopus were searched for articles published between 2010 and 2021 on the association between SFA consumption and CVD risk and outcomes. A review was conducted examining observational studies and prospective epidemiologic cohort studies, randomized controlled trials (RCTs), systematic reviews and meta-analyses of observational studies and prospective epidemiologic cohort studies, and long-term RCTs. Collectively, neither observational studies, prospective epidemiologic cohort studies, RCTs, systematic reviews, and meta-analyses have conclusively established a significant association between SFA in the diet and subsequent cardiovascular risk and coronary artery disease, myocardial infarction, or mortality nor a benefit of reducing dietary SFAs on CVD rick, events, and mortality. Beneficial effects of replacement of SFA by polyunsaturated or monounsaturated fat or carbohydrates remain elusive.

CONCLUSION

Findings from the studies reviewed in this paper indicate that the consumption of SFA is not significantly associated with CVD risk, events, or mortality. Based on the scientific evidence, there is no scientific ground to demonize SFA as a cause of CVD. SFA naturally occurring in nutrient-dense foods can be safely included in the diet.

Trans-Fatty Acids in Fast-Food and Intake Assessment for Yerevan’s Population, Armenia

There are stringent regulations applicable for trans-fatty acid (TFA) limitations from food supply across the world. However, in Armenia, there is a scarcity of data on TFA content in food products and their consumption levels. Considering that fast-food is among the major contributors to TFA intake, this study aims to assess the dietary exposure of TFAs through the consumption of fast-food in Yerevan, Armenia. Eleven types of fast-food were included in the study. The Food Frequency Questionnaire (FFQ) was used to evaluate daily fast-food consumption. TFA contents in samples were determined using gas chromatography-mass spectrometry. Mean daily fast-food consumption values ranged from 14.68 g/day to 76.09 g/day, with popcorn as the lowest and pastry as the highest consumed food. The study results indicate that the aggregate average daily intake (DI) of TFA is 0.303 g/day. Even though TFA DI values do not exceed the WHO limit of 1%, they substantially contribute to daily TFA intake and may exceed the limit when combined with other foods. Hence, it is recommended to carry out continuous monitoring of TFA content in the food supply to ensure consumer health protection.

Schemes for enhanced antioxidant stability in frying meat: a review of frying process using single oil and blended oils

Deep-fried meat products are widely popular. However, harmful compounds produced by various chemical reactions during frying have been shown to be detrimental to human health. It is of great necessity to raise practical suggestions for improving the oxidation problem of frying oils and frying conditions in some aspects. Vegetable oils are not as thermally stable as saturated fats, and blended oils have higher thermal stability than single oil. In this review, we discussed the oxidation problems frying oils and meats are subject to during frying, starting from the oil oxidation mechanism, the effects of different oils and fats on the quality of different fried meats under different conditions were concluded to alleviate the oxidation problem, to highlight the necessity of applying blended oils for frying, and effective antioxidants added to frying oils are also introduced, that would provide more convenient and practical options for obtaining higher quality of fried meat products and offer better understanding of the potential of blended frying oils for frying meat products.

[Saturated fatty acids and cardiovascular risk : Is a revision of the recommendations on nutrition indicated?]

Die „Fetthypothese der koronaren Herzkrankheit“, derzufolge „gesättigte Fettsäuren“ („saturated fatty acids“, SFA) die LDL(„low-density lipoprotein“)-Cholesterin-Konzentration (LDL-C) steigern und folglich das Risiko für kardiovaskuläre Erkrankungen erhöhen, prägte die Ernährungsempfehlungen der letzten 60 Jahre, zunächst in den USA und später auch in Europa. Über die Jahre mehrte sich Evidenz aus Epidemiologie und kontrollierten klinischen Studien, dass der Konsum von SFA per se nicht mit einem erhöhten kardiovaskulären Risiko einhergeht bzw. die Einschränkung des Konsums von SFA keine präventive Wirkung zeigt. Die Fokussierung auf den SFA-Gehalt negiert die biologisch heterogenen und zum Teil biologisch günstigen Wirkungen unterschiedlicher SFA. Zudem wird hierbei außer Acht gelassen, dass SFA in intakten Lebensmitteln in unterschiedliche komplexe Matrizes eingebunden sind, die aus Dutzenden Nährstoffen mit unterschiedlicher Struktur und Begleitstoffen bestehen und damit jeweils unterschiedliche biologische Antworten und metabolische Effekte auslösen. Entsprechend sind solche nährstoffbasierten Empfehlungen prinzipiell wenig zielführend und zudem schlecht umsetzbar. Hinzu kommt, dass LDL‑C kein geeigneter Marker ist, um den Effekt von Lebensstilintervention wie der Ernährung oder aber der körperlichen Aktivität auf das globale kardiovaskuläre Risiko zu beurteilen.

Empirico-inductive and/or hypothetico-deductive methods in food science and nutrition research: which one to favor for a better global health?

Scientific research generally follows two main methods: empirico-inductive (EI), gathering scattered, real-world qualitative/quantitative data to elaborate holistic theories, and the hypothetico-deductive (HD) approach, testing the validity of hypothesized theory in specific conditions, generally according to reductionist methodologies or designs, with the risk of over simplifying the initial complexity empirically perceived in its holistic view. However, in current food and nutrition research, new hypotheses are often elaborated from reductionist data obtained with the HD approach, and aggregated to form (ultra)reductionist theories, with no application of EI observations, limiting the applicability of these hypotheses in real life. This trend and the application of the EI method are illustrated as regards with the global health issue through the examples of food classifications/scoring, clinical studies, the definition of a sustainable diet, the "matrix effect"-related hypothesis, the concept of healthy core metabolism, and obesity prevention within the perspective of social sciences. To be efficient for producing food and nutritional data appropriable by the society, it finally appears that not only both approaches are necessary, starting with the EI method then the HD one, but also a back and forth between the two, this being not always realized, potentially leading to confusion and misunderstanding in society.

Avocado oil: Production and market demand, bioactive components, implications in health, and tendencies and potential uses

Avocado is a subtropical/tropical fruit with creamy texture, peculiar flavor, and high nutritional value. Due to its high oil content, a significant quantity of avocado fruit is used for the production of oil using different methods. Avocado oil is rich in lipid-soluble bioactive compounds, but their content depends on different factors. Several phytochemicals in the oil have been linked to prevention of cancer, age-related macular degeneration, and cardiovascular diseases and therefore have generated an increase in consumer demand for avocado oil. The aim of this review is to critically and systematically analyze the worldwide production and commercialization of avocado oil, its extraction methods, changes in its fat-soluble phytochemical content, health benefits, and new trends and applications. There is a lack of information on the production and commercialization of the different types of avocado oil, but there are abundant data on extraction methods using solvents, centrifugation-assisted aqueous extraction, mechanical extraction by cold pressing (varying concentration and type of enzymes, temperature and time of reaction, and dilution ratio), ultrasound-assisted extraction, and supercritical fluid to enhance the yield and quality of oil. Extensive information is available on the content of fatty acids, although it is limited on carotenoids and chlorophylls. The effect of avocado oil on cancer, diabetes, and cardiovascular diseases has been demonstrated through in vitro and animal studies, but not in humans. Avocado oil continues to be of interest to the food, pharmaceutical, and cosmetic industries and is also generating increased attention in other areas including structured lipids, nanotechnology, and environmental care.

Effect of Rearing Season on Meat and Intramuscular Fat Quality of Beni-Guil Sheep

Twenty Beni-Guil-PGI female lambs were used to study the effects of rearing season on meat quality characteristics, fatty acids profile, and lipid content. The animals were reared according to the pastoral-transhumant system in the eastern region of Morocco. The treatments consisted of 10 female lambs reared in summer-autumn (SA) and slaughtered at winter season and 10 female lambs reared in winter-spring (WS) and slaughtered at spring season. After the slaughter, the longissimus lumborum was collected for each animal for meat quality analysis. Compared to lambs reared in SA, the meat from the WS group showed higher ( $p<0.01$ ) pH, chroma, and lightness values (5.79 vs. 5.72, 23.97 vs. 18.46, and 47.03 vs. 41.04, respectively). On the other hand, the meat from WS presented higher ( $p<0.05$ ) intramuscular fat content (5.14 % vs. 3.82%, respectively). However, the intramuscular fat of the lambs reared in SA was characterized by greater ( $p<0.01$ ) PUFA percentage (16.82% vs. 12.40%, respectively), thrombogenic ( $p<0.001$ ) and atherogenic index ( $p<0.001$ ), and PUFA/SFA ratio ( $p<0.01$ ; 0.42 vs. 0.25, respectively). Nevertheless, those reared in WS season have a higher ( $p<0.001$ ) PUFA n − 3 (2.58% vs. 1.14%, respectively) content, and therefore favorable ( $p<0.001$ ) n − 6/n − 3 ratio (3.78 vs. 12.98, respectively).

"Real-World" Evaluation of Lipid Oxidation Products and Trace Metals in French Fries From Two Chain Fast-Food Restaurants

Differences in lipid oxidation products (LOPs) and trace metal concentrations of French fry samples found between two global chain fast-food restaurants in the UK were investigated using high-resolution proton nuclear magnetic resonance (1H NMR) and inductively coupled plasma-optical emission spectrometry (ICP-OES) analyses, respectively, of extracts derived therefrom. Over the course of 3 days and 3 different diurnal time periods, samples of French fries (FFs) were analyzed, and comparisons of two different oil extraction methods were undertaken for the two restaurants involved. The magnitude of concentrations of LOPs extracted from FFs is discussed. Significant differences between 6/7 aldehyde classifications, and aluminum, manganese, vanadium, lead, iron, copper and nickel levels between samples from the two restaurants are also reported. Redox-active transition and further trace metal concentrations inversely correlated with FF oil sample LOP contents; this suggested an antioxidant rather than a pro-oxidant role for them.

Association of dietary fatty acids and the incidence risk of cardiovascular disease in adults: the Tehran Lipid and Glucose Prospective Study

Background

Considering the inconsistent available findings regarding the cardioprotective effect of dietary fatty acid composition, we prospectively examined the feasible association between the dietary fatty acids and the cardiovascular disease (CVD) incidence in framework of the population-based Tehran Lipid and Glucose Study.

Methods

A total of 2369 participants (19–70 years, 43.5% men) without CVD at baseline (2006–2008) were included and followed-up for 6.7 years. Fatty acids’ dietary intake was estimated using a 168-item semi-quantitative food frequency questionnaire. The CVD incidence risk across tertiles of dietary fatty acids was predicted via Cox proportional hazards regression models.

Results

The average age and body mass index of the included population were 38.5 ± 13.3 years and 26.6 ± 4.8 kg/m² at baseline. Over 6.7 years of follow-up, 79 cases of CVD were detected. The risk of CVD was lower in upper tertile of monounsaturated fatty acids, oleic acid, and docosahexaenoic acid + eicosapentaenoic acid among the tertiles. No significant associations were found between total fat, saturated and polyunsaturated fatty acids’ intake, and CVD.

Conclusions

Our results suggest that the dietary fatty acid composition might affect the incidence risk of CVD within the Iranian population.

Milk fat: opportunities, challenges and innovation

Milk fat is a high-value milk component that is processed mainly as butter, cheese, cream and whole milk powder. It is projected that approximately 35 million tonnes of milk fat will be produced globally by 2025. This surplus, enhances the need for diversification of milk fat products and the milk pool in general. Infant milk formula producers, for instance, have incorporated enzyme modified ("humanised") milk fat and fat globule phospholipids to better mimic human milk fat structures. Minor components like mono- and di-glycerides from milk fat are increasingly utilized as emulsifiers, replacing palm esters in premium-priced food products. This review examines the chemistry of milk fat and the technologies employed for its modification, fractionation and enrichment. Emerging processing technologies such as ultrasound, high pressure processing, supercritical fluid extraction and fractionation, can be employed to improve the nutritional and functional attributes of milk fat. The potential of recent developments in biological intervention, through dietary manipulation of milk fatty acid profiles in cattle also offers significant promise. Finally, this review provides evidence to help redress the imbalance in reported associations between milk fat consumption and human health, and elucidates the health benefits associated with consumption of milk fat and dairy products.

Lipid findings from the Diabetes Education to Lower Insulin, Sugars, and Hunger (DELISH) Study

Background

A carbohydrate-restricted (CR) diet can improve glycemic control in people with type 2 diabetes mellitus (T2DM). There are concerns, however, that the high dietary fat content of CR diets can increase low-density lipoprotein cholesterol (LDL-C), thus increasing cardiovascular disease (CVD) risk. Quantifying CVD risk associated with changes in LDL-C in the context of CR diets is complicated by the fact that LDL-C reflects heterogeneous lipids. For example, small LDL particle number (sLDL-P) is more closely associated with CVD risk than is total LDL-C, and CR diets tend to decrease the proportion of sLDL-C in LDL-C, which standard lipid measures do not indicate. Advanced lipoprotein assays, such as nuclear magnetic resonance (NMR) testing, can subfractionate lipoproteins by size and density and may better depict the effects of CR diets on CVD risk.

Methods

Adults (N = 58) with T2DM (n = 37 women; baseline HbA1c ≥ 6.5%) completed a 6-month group-based CR diet intervention. We obtained a standard lipid panel, advanced lipoprotein assays (NMR testing), and two 24-h diet recalls at baseline and post-intervention (6 months). Participants also completed home-based blood ketone testing (a biological index of dietary adherence) during the final five weeks of the intervention.

Results

From baseline to post-intervention, participants had increased mean HDL-C, decreased triglycerides and triglyceride/HDL ratio, decreased mean sLDL-P, and increased LDL size, which reflect reductions in CVD risk (ps < 0.05). Participants did not have statistically significant changes in total cholesterol, non-HDL-C cholesterol, LDL-P, or HDL-P. Twelve participants (23.1%) had a ≥ 5% increase in sLDL-P. Exploratory analyses revealed that participants with sLDL-P increases of ≥ 5% reported larger increases in servings of red meat than participants without sLDL-P increases of ≥ 5% (+ 0.69 vs − 0.29 servings; p = 0.033). Changes in saturated fat intake were not associated with changes in sLDL-P.

Conclusions

Among most participants, we observed changes in several lipid measures consistent with decreased CVD risk. Approximately one in four participants evidenced increases in sLDL-P. Further research should clarify whether individuals with increased sLDL-P after implementing a CR diet can reverse observed increases by limiting red meat consumption.

Trial registration

ClinicalTrials.gov, NCT03207711, Registered 6/11/2017. Retrospectively registered.

Saturated Fat: Part of a Healthy Diet

PURPOSE OF REVIEW

Despite the American public following recommendations to decrease absolute dietary fat intake and specifically decrease saturated fat intake, we have seen a dramatic rise over the past 40 years in the rates of non-communicable diseases associated with obesity and overweight, namely cardiovascular disease. The development of the diet-heart hypothesis in the mid twentieth century led to faulty but long-held beliefs that dietary intake of saturated fat led to heart disease. Saturated fat can lead to increased LDL cholesterol levels, and elevated plasma cholesterol levels have been shown to be a risk factor for cardiovascular disease; however, the correlative nature of their association does not assign causation.

RECENT FINDINGS

Advances in understanding the role of various lipoprotein particles and their atherogenic risk have been helpful for understanding how different dietary components may impact CVD risk. Numerous meta-analyses and systematic reviews of both the historical and current literature reveals that the diet-heart hypothesis was not, and still is not, supported by the evidence. There appears to be no consistent benefit to all-cause or CVD mortality from the reduction of dietary saturated fat. Further, saturated fat has been shown in some cases to have an inverse relationship with obesity-related type 2 diabetes. Rather than focus on a single nutrient, the overall diet quality and elimination of processed foods, including simple carbohydrates, would likely do more to improve CVD and overall health. It is in the best interest of the American public to clarify dietary guidelines to recognize that dietary saturated fat is not the villain we once thought it was.

Coconut oil consumption improves fat-free mass, plasma HDL-cholesterol and insulin sensitivity in healthy men with normal BMI compared to peanut oil

BACKGROUND & AIMS

The existing scientific evidence on coconut oil consumption and its health effects remains inconclusive due to varied reasons. In this context, we conducted a well-controlled metabolic study, eliminating some of the confounding factors and assessed the effects of the consumption of coconut oil-based diet on various anthropometric, biochemical and inflammatory markers and compared with peanut oil-diet.

METHODS

Nine healthy male volunteers with BMI ≤25 kg/m² were enrolled for this study and given balanced diets prepared with coconut oil (CO; ~35 g) for a period of eight weeks. After a wash-out period of six weeks, the same subjects were provided with diets prepared with peanut oil (~35 g) for eight weeks. Except fat source, the composition of the diets was identical in all aspects.

RESULTS

Compared to basal values, there were significant increases in fat-free mass (p ≤ 0.022), plasma HDL-cholesterol (HDL-C) (p ≤ 0.047) and insulin sensitivity of the subjects at the end of CO-consumption. Further, compared to peanut oil, increase in plasma HDL-C was significant (p = 0.004) in CO treatment. On the other hand, plasma inflammatory markers-associated with cardiovascular diseases (CVD), namely soluble vascular cell adhesion molecule 1 (sVCAM1) and matrix metalloproteinase levels were reduced significantly by CO-intake. Further, these subjects displayed elevated levels of myristic acid (14:0) in plasma phospholipids at the end of CO-consumption, which correlated positively with HDL-C and negatively with sVCAM1. However, no such changes were observed after peanut oil diet consumption.

CONCLUSIONS

In conclusion, compared to peanut oil, the consumption of coconut oil in a balanced diet resulted in increased fat-free mass, plasma HDL-C, elicited favourable changes on insulin sensitivity and CVD risk-associated parameters in healthy men with normal BMI.

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.

Were policies in Brazil effective to reducing trans fat from industrial origin in foods?

OBJECTIVE

To determine the trans fatty acids content of processed foods frequently consumed by adults living in a Rio de Janeiro, Brazil, after the enactment of a mandatory trans fatty acids labelling policy.

METHODS

Between February 2014 and January 2015, a specifically dietary questionnaire was completed by 107 adults to assess the frequency of processed foods consumption. The most commonly consumed products from the survey, including vegetable oils, margarine, biscuits, snacks, cheese bread (pão de queijo), french fries, cheeseburger and ice cream, were then analyzed for their trans fatty acids content using gas chromatography with a flame ionization detector.

RESULTS

Differences in the levels of trans fatty acids were observed among 22 products analyzed, considering that trans fatty acids content ranged between 0.0 g/100 g in samples of cream cracker biscuit 1 and olive oil to 0.83 g/100 g in samples of cheeseburger (fast food), 0.51 g/100 g in samples of frozen pão de queijo and 12.92 g/100 g in samples of chocolate sandwich cookies with cream filling 2. The overall trans fatty acids content of the different samples of margarine brands was 0.20 g/100 g for brand 1 and 0.0 g/100 g for brand 2. These data are significantly lower than those observed in a survey conducted in 2003, when the regulation had been enacted.

CONCLUSIONS

Our data indicate that Brazilian regulation is very likely implicated in the observed drop in trans fatty acids of the most processed foods but has yet to eliminate them, which reinforces the urgent need to revise the legislation, since a minimum amount of trans fat does not mean that the food product does not contain this type of fat.

Nutrients and Oxidative Stress: Friend or Foe?

There are different types of nutritionally mediated oxidative stress sources that trigger inflammation. Much information indicates that high intakes of macronutrients can promote oxidative stress and subsequently contribute to inflammation via nuclear factor-kappa B- (NF-κB-) mediated cell signaling pathways. Dietary carbohydrates, animal-based proteins, and fats are important to highlight here because they may contribute to the long-term consequences of nutritionally mediated inflammation. Oxidative stress is a central player of metabolic ailments associated with high-carbohydrate and animal-based protein diets and excessive fat consumption. Obesity has become an epidemic and represents the major risk factor for several chronic diseases, including diabetes, cardiovascular disease (CVD), and cancer. However, the molecular mechanisms of nutritionally mediated oxidative stress are complex and poorly understood. Therefore, this review aimed to explore how dietary choices exacerbate or dampen the oxidative stress and inflammation. We also discussed the implications of oxidative stress in the adipocyte and glucose metabolism and obesity-associated noncommunicable diseases (NCDs). Taken together, a better understanding of the role of oxidative stress in obesity and the development of obesity-related NCDs would provide a useful approach. This is because oxidative stress can be mediated by both extrinsic and intrinsic factors, hence providing a plausible means for the prevention of metabolic disorders.

Detailed fatty acid profile of milk, cheese, ricotta and by products, from cows grazing summer highland pastures

In this research two-dimensional GC was used to analyse, for the first time, the detailed fatty acid (FA) profiles of 11 dairy matrices: raw milk (evening whole, evening partially skimmed, morning whole, and vat milk), cream, fresh cheese, whey, ricotta, scotta, 6- and 12-month-ripened cheeses, obtained across artisanal cheese- and ricotta-making trials carried out during the summer period while cows were on highland pastures. Samples were collected during 7 cheese- and ricotta-making procedures carried out at 2-week intervals from bulk milk to study possible differences in the transfer and modification of FA. Compared with morning milk, evening milk had fewer de novo synthetised FA. The detailed FA profile of partially skimmed milk differed little from that of evening whole milk before skimming, but the cream obtained differed from partially skimmed milk and from fresh cheese in about half the FA, due mainly to higher contents of all de novo FA, and lower contents of n-3 and n-6 FA. Fresh cheese and whey had similar FA profiles. The ricotta manufacturing process affected the partition of FA between ricotta and scotta, the FA profile of the latter differing in terms of groups and individual FA from the former, whereas ricotta and fresh cheese had similar composition of FA. In general, there was an increase in medium-chain saturated FA, and a decrease in many polyunsaturated FA during the first 6 months of ripening, but not during the second 6 months. Two-dimensional GC yielded a very detailed and informative FA profile on all the 11 dairy products and by-products analysed.

Evaluation of the informatician perspective: determining types of research papers preferred by clinicians

Background

To deliver evidence-based medicine, clinicians often reference resources that are useful to their respective medical practices. Owing to their busy schedules, however, clinicians typically find it challenging to locate these relevant resources out of the rapidly growing number of journals and articles currently being published. The literature-recommender system may provide a possible solution to this issue if the individual needs of clinicians can be identified and applied.

Methods

We thus collected from the CiteULike website a sample of 96 clinicians and 6,221 scientific articles that they read. We examined the journal distributions, publication types, reading times, and geographic locations. We then compared the distributions of MeSH terms associated with these articles with those of randomly sampled MEDLINE articles using two-sample Z-test and multiple comparison correction, in order to identify the important topics relevant to clinicians.

Results

We determined that the sampled clinicians followed the latest literature in a timely manner and read papers that are considered landmarks in medical research history. They preferred to read scientific discoveries from human experiments instead of molecular-, cellular- or animal-model-based experiments. Furthermore, the country of publication may impact reading preferences, particularly for clinicians from Egypt, India, Norway, Senegal, and South Africa.

Conclusion

These findings provide useful guidance for developing personalized literature-recommender systems for clinicians.

Electronic supplementary material

The online version of this article (doi:10.1186/s12911-017-0463-z) contains supplementary material, which is available to authorized users.

The effect of replacing saturated fat with mostly n-6 polyunsaturated fat on coronary heart disease: a meta-analysis of randomised controlled trials

BACKGROUND

A cornerstone of conventional dietary advice is the recommendation to replace saturated fatty acids (SFA) with mostly n-6 polyunsaturated fatty acids (PUFA) to reduce the risk of coronary heart disease (CHD). Many clinical trials aimed to test this advice and have had their results pooled in several meta-analyses. However, earlier meta-analyses did not sufficiently account for major confounding variables that were present in some of those trials. Therefore, the aim of the study was to account for the major confounding variables in the diet heart trials, and emphasise the results from those trials that most accurately test the effect of replacing SFA with mostly n-6 PUFA.

DESIGN

Clinical trials were identified from earlier meta-analyses. Relevant trials were categorised as 'adequately controlled' or 'inadequately controlled' depending on whether there were substantial dietary or non-dietary differences between the experimental and control groups that were not related to SFA or mostly n-6 PUFA intake, then were subject to different subgroup analyses.

RESULTS

When pooling results from only the adequately controlled trials there was no effect for major CHD events (RR = 1.06, CI = 0.86-1.31), total CHD events (RR = 1.02, CI = 0.84-1.23), CHD mortality (RR = 1.13, CI = 0.91-1.40) and total mortality (RR = 1.07, CI = 0.90-1.26). Whereas, the pooled results from all trials, including the inadequately controlled trials, suggested that replacing SFA with mostly n-6 PUFA would significantly reduce the risk of total CHD events (RR = 0.80, CI = 0.65-0.98, P = 0.03), but not major CHD events (RR = 0.87, CI = 0.70-1.07), CHD mortality (RR = 0.90, CI = 0.70-1.17) and total mortality (RR = 1.00, CI = 0.90-1.10).

CONCLUSION

Available evidence from adequately controlled randomised controlled trials suggest replacing SFA with mostly n-6 PUFA is unlikely to reduce CHD events, CHD mortality or total mortality. The suggestion of benefits reported in earlier meta-analyses is due to the inclusion of inadequately controlled trials. These findings have implications for current dietary recommendations.

Saturated Fat Consumption and Risk of Coronary Heart Disease and Ischemic Stroke: A Science Update

At a workshop to update the science linking saturated fatty acid (SAFA) consumption with the risk of coronary heart disease (CHD) and ischemic stroke, invited participants presented data on the consumption and bioavailability of SAFA and their functions in the body and food technology. Epidemiological methods and outcomes were related to the association between SAFA consumption and disease events and mortality. Participants reviewed the effects of SAFA on CHD, causal risk factors, and surrogate risk markers. Higher intakes of SAFA were not associated with higher risks of CHD or stroke apparently, but studies did not take macronutrient replacement into account. Replacing SAFA by cis-polyunsaturated fatty acids was associated with significant CHD risk reduction, which was confirmed by randomized controlled trials. SAFA reduction had little direct effect on stroke risk. Cohort studies suggest that the food matrix and source of SAFA have important health effects.

Food consumption and the actual statistics of cardiovascular diseases: an epidemiological comparison of 42 European countries

BACKGROUND

The aim of this ecological study was to identify the main nutritional factors related to the prevalence of cardiovascular diseases (CVDs) in Europe, based on a comparison of international statistics.

DESIGN

The mean consumption of 62 food items from the FAOSTAT database (1993-2008) was compared with the actual statistics of five CVD indicators in 42 European countries. Several other exogenous factors (health expenditure, smoking, body mass index) and the historical stability of results were also examined.

RESULTS

We found exceptionally strong relationships between some of the examined factors, the highest being a correlation between raised cholesterol in men and the combined consumption of animal fat and animal protein (r=0.92, p<0.001). The most significant dietary correlate of low CVD risk was high total fat and animal protein consumption. Additional statistical analyses further highlighted citrus fruits, high-fat dairy (cheese) and tree nuts. Among other non-dietary factors, health expenditure showed by far the highest correlation coefficients. The major correlate of high CVD risk was the proportion of energy from carbohydrates and alcohol, or from potato and cereal carbohydrates. Similar patterns were observed between food consumption and CVD statistics from the period 1980-2000, which shows that these relationships are stable over time. However, we found striking discrepancies in men's CVD statistics from 1980 and 1990, which can probably explain the origin of the 'saturated fat hypothesis' that influenced public health policies in the following decades.

CONCLUSION

Our results do not support the association between CVDs and saturated fat, which is still contained in official dietary guidelines. Instead, they agree with data accumulated from recent studies that link CVD risk with the high glycaemic index/load of carbohydrate-based diets. In the absence of any scientific evidence connecting saturated fat with CVDs, these findings show that current dietary recommendations regarding CVDs should be seriously reconsidered.

Meta-analysis of intramuscular fatty acid composition of Mediterranean lambs

Abstract. The aim of this work was to study the intramuscular fatty acid profile of Mediterranean lambs using a meta-analysis. The database was created from five journal articles and one doctoral dissertation, and included lambs of the Talaverana, Comisana, Churra Tensina, Merino Branco and Pramenka breeds. All analyses were performed using Comprehensive Meta-Analysis and R statistical software. According to the overall pooled result, lambs of Mediterranean breeds included in our meta-analysis had 22.85 % of palmitic (C16:0), 14.78 % of stearic (C18:0) and 5.32 % of myristic acid (C14:0). The overall pooled result for oleic acid (C18:1) was 32.53 %, and it was 5.60 % for linoleic acid (C18:2 n-6) and 1.95 % for α-linolenic acid (C18:3 n-3). Regardless of the proportions of the main fatty acids, Mediterranean lambs had 47.85 % of SFA (saturated fatty acid), 37.87 % of MUFA (monounsaturated fatty acid) and 11.50 % of PUFA (polyunsaturated fatty acid). The overall pooled result for the PUFA / SFA ratio was 0.23, and it was 2.22 for the n-6 /n-3 ratio. The results of our meta-analysis enabled us to gain an important scientific insight into the lipid profile of intramuscular fat in Mediterranean lambs. A systematic combination of quantitative data from several carefully selected studies provided estimates of greater statistical power and enabled a more truthful comparison of results originating from different independent studies than any previously published research on this issue.

The relation of saturated fatty acids with low-grade inflammation and cardiovascular disease

The mantra that dietary (saturated) fat must be minimized to reduce cardiovascular disease (CVD) risk has dominated nutritional guidelines for decades. Parallel to decreasing intakes of fat and saturated fatty acids (SFA), there have been increases in carbohydrate and sugar intakes, overweight, obesity and type 2 diabetes mellitus. The "lipid hypothesis" coined the concept that fat, especially SFA, raises blood low-density lipoprotein-cholesterol and thereby CVD risk. In view of current controversies regarding their adequate intakes and effects, this review aims to summarize research regarding this heterogenic group of fatty acids and the mechanisms relating them to (chronic) systemic low-grade inflammation, insulin resistance, metabolic syndrome and notably CVD. The intimate relationship between inflammation and metabolism, including glucose, fat and cholesterol metabolism, revealed that the dyslipidemia in Western societies, notably increased triglycerides, "small dense" low-density lipoprotein and "dysfunctional" high-density lipoprotein, is influenced by many unfavorable lifestyle factors. Dietary SFA is only one of these, not necessarily the most important, in healthy, insulin-sensitive people. The environment provides us not only with many other proinflammatory stimuli than SFA but also with many antiinflammatory counterparts. Resolution of the conflict between our self-designed environment and ancient genome may rather rely on returning to the proinflammatory/antiinflammatory balance of the Paleolithic era in consonance with the 21st century culture. Accordingly, dietary guidelines might reconsider recommendations for SFA replacement and investigate diet in a broader context, together with nondietary lifestyle factors. This should be a clear priority, opposed to the reductionist approach of studying the effects of single nutrients, such as SFA.

Insulin resistance determines a differential response to changes in dietary fat modification on metabolic syndrome risk factors: the LIPGENE study

BACKGROUND

Previous data support the benefits of reducing dietary saturated fatty acids (SFAs) on insulin resistance (IR) and other metabolic risk factors. However, whether the IR status of those suffering from metabolic syndrome (MetS) affects this response is not established.

OBJECTIVE

Our objective was to determine whether the degree of IR influences the effect of substituting high-saturated fatty acid (HSFA) diets by isoenergetic alterations in the quality and quantity of dietary fat on MetS risk factors.

DESIGN

In this single-blind, parallel, controlled, dietary intervention study, MetS subjects (n = 472) from 8 European countries classified by different IR levels according to homeostasis model assessment of insulin resistance (HOMA-IR) were randomly assigned to 4 diets: an HSFA diet; a high-monounsaturated fatty acid (HMUFA) diet; a low-fat, high-complex carbohydrate (LFHCC) diet supplemented with long-chain n-3 polyunsaturated fatty acids (1.2 g/d); or an LFHCC diet supplemented with placebo for 12 wk (control). Anthropometric, lipid, inflammatory, and IR markers were determined.

RESULTS

Insulin-resistant MetS subjects with the highest HOMA-IR improved IR, with reduced insulin and HOMA-IR concentrations after consumption of the HMUFA and LFHCC n-3 diets (P < 0.05). In contrast, subjects with lower HOMA-IR showed reduced body mass index and waist circumference after consumption of the LFHCC control and LFHCC n-3 diets and increased HDL cholesterol concentrations after consumption of the HMUFA and HSFA diets (P < 0.05). MetS subjects with a low to medium HOMA-IR exhibited reduced blood pressure, triglyceride, and LDL cholesterol levels after the LFHCC n-3 diet and increased apolipoprotein A-I concentrations after consumption of the HMUFA and HSFA diets (all P < 0.05).

CONCLUSIONS

Insulin-resistant MetS subjects with more metabolic complications responded differently to dietary fat modification, being more susceptible to a health effect from the substitution of SFAs in the HMUFA and LFHCC n-3 diets. Conversely, MetS subjects without IR may be more sensitive to the detrimental effects of HSFA intake. The metabolic phenotype of subjects clearly determines response to the quantity and quality of dietary fat on MetS risk factors, which suggests that targeted and personalized dietary therapies may be of value for its different metabolic features. This study was registered at clinicaltrials.gov as NCT00429195.

Statistical review of US macronutrient consumption data, 1965-2011: Americans have been following dietary guidelines, coincident with the rise in obesity

BACKGROUND

For almost 50 y, the US National Health and Nutrition Examination Survey (NHANES) has measured the caloric consumption, and body heights and weights of Americans. The aim of this study was to determine, based on that data, how macronutrient consumption patterns and the weight and body mass index in the US adult population have evolved since the 1960s.

METHODS

We conducted the first comprehensive analysis of the NHANES data, documenting how macronutrient consumption patterns and the weight and body mass index in the US adult population have evolved since the 1960s.

RESULTS

Americans in general have been following the nutrition advice that the American Heart Association and the US Departments of Agriculture and Health and Human Services have been issuing for more than 40 y: Consumption of fats has dropped from 45% to 34% with a corresponding increase in carbohydrate consumption from 39% to 51% of total caloric intake. In addition, from 1971 to 2011, average weight and body mass index have increased dramatically, with the percentage of overweight or obese Americans increasing from 42% in 1971 to 66% in 2011.

CONCLUSIONS

Since 1971, the shift in macronutrient share from fat to carbohydrate is primarily due to an increase in absolute consumption of carbohydrate as opposed to a change in total fat consumption. General adherence to recommendations to reduce fat consumption has coincided with a substantial increase in obesity.

Strategic nutrition: a vision for the twenty-first century

It is now widely accepted that poor nutrition plays a major role in the epidemic of various diseases, including obesity, type 2 diabetes and CVD. There has also been much research regarding the role of related factors such as advertising and food prices. Many intervention studies have been carried out where attempts have been made to persuade people to modify their behaviour, such as by making dietary changes, in order to enhance health (health promotion). There has also been much debate on the potential of government policy as a tool for achieving these goals. Various proposals have been made, such as a tax on sugary drinks, the redirection of food subsidies and how the salt content of food can be reduced. However, the great majority of previous papers have considered only single aspects of the topics discussed here. The present paper reviews strategies for improving public health, both health promotion interventions and the use of government policy approaches. Topics discussed include providing advice for the general population and the design of food guides and food labels. This leads to the conclusion that we need an overall strategy that integrates this diverse body of information and formulates a comprehensive action plan. I propose the term ‘strategic nutrition’. The implementation of this plan opens up a path to a major advance in public health.

Impact of dietary protein level and source of polyunsaturated fatty acids on lipid metabolism-related protein expression and fatty acid concentrations in porcine tissues

The study assessed the effects of reduced protein (RPD) vs high protein diet (HPD) in combination with n-3/n-6 PUFA-containing plant oils [linseed oil (LO)/sunflower seed oil (SO)] supplementation on lipid metabolism-related protein expression and fatty acid concentrations in porcine tissues. Forty male Landrace pigs (castrates) were allocated into four groups fed diets different in dietary protein and PUFA level and one control group. SCD-1 protein expression in pig muscle, back fat, and liver was not affected by diet. The protein expression of precursor (pSREBP-1c) and active nuclear form of SREBP-1c (mSREBP-1c) in muscle and back fat was affected by diet, however not in liver of pigs. In contrast, the expression of ACC and FAS expression was significantly affected by diet only in the liver. The fatty acid concentrations in muscle, liver, and back fat resulted in higher n-3 PUFA concentrations of LO groups compared to the SO groups.

It is time to revisit current dietary recommendations for saturated fat

The extent to which a high intake of saturated fat (SFA) increases the risk of cardiovascular disease (CVD) has become a highly controversial topic. Dietary SFA primarily raises low-density lipoprotein cholesterol, while having a relatively neutral impact on other key CVD risk factors. Recent epidemiological data also challenge the concept that SFA increases the risk of CVD. This short review provides arguments for the urgency to re-assess the association between dietary SFA and CVD risk in light of recent data on the subject.

Fatty acid profile of biscuits and salty snacks consumed by Brazilian college students

High levels of biscuit and salty snack consumption have an effect on human health. This aim of this study was to determine the fatty acid (FA) composition of 19 different biscuits and 10 types of salty snacks by gas chromatography. Palmitic acid was predominant in 79% of biscuits and represented more than 55% of the total saturated fatty acids (SFAs) in salty snacks. Low concentrations of trans fatty acids were observed in biscuits (0.86% of total FAs), and the highest values were observed in salty snacks (7.94% of total FAs). The results indicate a high daily intake of SFAs and trans fatty acids, which may have an unfavourable effect on health. Changes in dietary habits and appropriate food choices by students are strongly recommended to prevent the risk of chronic disease. Furthermore, knowledge of the FA profile of food can help to establish health programs targeted to this population.

Inclusion of red meat in healthful dietary patterns

Dietary patterns are an important concept in dietary recommendations. The Western pattern is most commonly defined as a diet characterized by high intakes of refined grains, sugar and red meat, and has been shown to be associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity. However, isolating the independent effects of individual foods on health outcomes is central to helping individuals choose foods to build healthier dietary patterns to which they can adhere. Red meat is a popular source of high quality protein and provides a variety of essential nutrients that improve overall diet quality. It is also a source of saturated fatty acids, which observational evidence suggests are associated with heart disease, although recent data challenge this. Several studies have shown that lean red meat can be successfully included in recommended heart-healthy dietary patterns without detriment to blood lipids. Furthermore, increased dietary protein has been shown to promote healthy body weight and composition, in part by increasing satiety, and to improve vitality and stamina.

Effect of diet on vascular health

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in the Western world in older people. Diet and lifestyle change can reduce CVD risk in older people, and this evidence base is reviewed. For example, diets low in trans fats can reduce CVD risk, while for saturated fats the CVD-lowering effect depends on what is substituted for the saturated fat. Diets rich in fish reduce CVD risk, although n-3 supplements have not been shown to have a consistent effect on CVD end-points. Antioxidant and B-group vitamin supplementation are unlikely to reduce CVD risk, but diets rich in these micronutrients (e.g. rich in fruits and vegetables and the Mediterranean diet) are associated with lower CVD risk, while, for the Mediterranean diet, this has been supported by randomized controlled trials. Maintaining a healthy weight and being physically active reduce CVD risk factors and CVD incidence and mortality.

Dietary PUFA Intervention Affects Fatty Acid- and Micronutrient Profiles of Beef and Related Beef Products

The study investigated the dietary impact of 18:3n-3 vs. 18:2n-6 on fatty acid- and micronutrient concentration of beef muscle and the extent of diet- and processing-induced changes of lipid- and micronutrient concentrations of beef products made thereof (German Corned beef (GCB), tea sausage spread (TSS), scalded sausage (SS)). Beef and beef products were obtained from German Holstein bulls which either received a control diet consisting of maize silage and concentrate with soybean meal (41%), or an experimental diet of grass silage and concentrate plus rapeseed cake (12%) and linseed oil (3%). The study revealed that upon an 18:3n-3 vs. 18:2n-6 intervention the amounts of 18:3n-3, EPA and Σn-3 LC-PUFA were significantly increased by 2.6, 2.3 and 1.7 fold, respectively. Experimental diet significantly increased β-carotene contents, and the γ-tocopherol contents were decreased. During beef processing, n-3 PUFA from beef were found to be product-specifically transferred into the corresponding beef products. 18:3n-3 and Σn-3 LC-PUFA contents were found to be 1.4 and 1.5 times higher in GCB from grass silage- than maize silage-fed bulls. The trace element contents in GCB (iron, copper, zinc, selenium) were not affected by the diet; however γ-tocopherol contents were decreased by experimental diet. In conclusion, dietary n-3 PUFA were completely transferred into beef products unaffected by beef processing conditions.

Nutritionally mediated oxidative stress and inflammation

There are many sources of nutritionally mediated oxidative stress that trigger inflammatory cascades along short and long time frames. These events are primarily mediated via NF κ B. On the short-term scale postprandial inflammation is characterized by an increase in circulating levels of IL-6 and TNF- α and is mirrored on the long-term by proinflammatory gene expression changes in the adipocytes and peripheral blood mononuclear cells (PBMCs) of obese individuals. Specifically the upregulation of CCL2/MCP-1, CCL3/MIP-1 α , CCL4/MIP-1 β , CXCL2/MIP-2 α , and CXCL3/MIP-2 β is noted because these changes have been observed in both adipocytes and PBMC of obese humans. In comparing numerous human intervention studies it is clear that pro-inflammatory and anti-inflammatory consumption choices mediate gene expression in humans adipocytes and peripheral blood mononuclear cells. Arachidonic acid and saturated fatty acids (SFAs) both demonstrate an ability to increase pro-inflammatory IL-8 along with numerous other inflammatory factors including IL-6, TNF α , IL-1 β , and CXCL1 for arachidonic acid and IGB2 and CTSS for SFA. Antioxidant rich foods including olive oil, fruits, and vegetables all demonstrate an ability to lower levels of IL-6 in PBMCs. Thus, dietary choices play a complex role in the mediation of unavoidable oxidative stress and can serve to exacerbate or dampen the level of inflammation.