Lessons from the war on dietary fat

Macronutrient-differential dietary pattern impacts on body weight, hepatic inflammation, and metabolism

Introduction

Obesity is a multi-factorial disease frequently associated with poor nutritional habits and linked to many detrimental health outcomes. Individuals with obesity are more likely to have increased levels of persistent inflammatory and metabolic dysregulation. The goal of this study was to compare four dietary patterns differentiated by macronutrient content in a postmenopausal model. Dietary patterns were high carbohydrate (HC), high fat (HF), high carbohydrate plus high fat (HCHF), and high protein (HP) with higher fiber.

Methods

Changes in body weight and glucose levels were measured in female, ovariectomized C57BL/6 mice after 15 weeks of feeding. One group of five mice fed the HCHF diet was crossed over to the HP diet on day 84, modeling a 21-day intervention. In a follow-up study comparing the HCHF versus HP dietary patterns, systemic changes in inflammation, using an 80-cytokine array and metabolism, by untargeted liquid chromatography-mass spectrometry (LCMS)-based metabolomics were evaluated.

Results

Only the HF and HCHF diets resulted in obesity, shown by significant differences in body weights compared to the HP diet. Body weight gains during the two-diet follow-up study were consistent with the four-diet study. On Day 105 of the 4-diet study, glucose levels were significantly lower for mice fed the HP diet than for those fed the HC and HF diets. Mice switched from the HCHF to the HP diet lost an average of 3.7 grams by the end of the 21-day intervention, but this corresponded with decreased food consumption. The HCHF pattern resulted in dramatic inflammatory dysregulation, as all 80 cytokines were elevated significantly in the livers of these mice after 15 weeks of HCHF diet exposure. Comparatively, only 32 markers changed significantly on the HP diet (24 up, 8 down). Metabolic perturbations in several endogenous biological pathways were also observed based on macronutrient differences and revealed dysfunction in several nutritionally relevant biosynthetic pathways.

Conclusion

Overall, the HCHF diet promoted detrimental impacts and changes linked to several diseases, including arthritis or breast neoplasms. Identification of dietary pattern-specific impacts in this model provides a means to monitor the effects of disease risk and test interventions to prevent poor health outcomes through nutritional modification.

The Origins of the Obesity Epidemic in the USA–Lessons for Today

The obesity epidemic appeared in the USA in 1976–1980 and then spread across Westernized countries. This paper examines the most likely causes of the epidemic in the USA. An explanation must be consistent with the emergence of the epidemic in both genders and in all age groups and ethnicities at about the same time, and with a steady rise in the prevalence of obesity until at least 2016. The cause is closely related to changes in the American diet. There is little association with changes in the intake of fat and carbohydrate. This paper presents the opinion that the factor most closely linked to the epidemic is ultra-processed foods (UPFs) (i.e., foods with a high content of calories, salt, sugar, and fat but with very little whole foods). Of particular importance is sugar intake, especially sugar-sweetened beverages (SSBs). There is strong evidence that consumption of SSBs leads to higher energy intake and more weight gain. A similar pattern is also seen with other UPFs. Factors that probably contributed to the increased intake of UPFs include their relatively low price and the increased popularity of fast-food restaurants. Other related topics discussed include: (1) the possible importance of Farm Bills implemented by the US Department of Agriculture; (2) areas where further research is needed; (3) health hazards linked to UPFs; and (4) the need for public health measures to reduce intake of UPFs.

The Data Behind Popular Diets for Weight Loss

Both scientific evidence and popular diet trends have sought to identify the ideal diet for weight loss with strategies focused on either restricting carbohydrates or fat. While there is a strong physiologic rationale for either carbohydrate restriction or fat restriction to achieve a calorie deficit needed for weight loss, evidence from randomized controlled trials suggest either type of diet is effective for weight loss. The level of adherence, rather than macronutrient content, is the driver of successful weight loss.

Metabolism and Health Impacts of Dietary Sugars

Consumption of excessive amounts of added sugars and their effects on human health has been a major concern in the last several decades. Epidemiological data suggest that the incidence of metabolic disorders, such as obesity, nonalcoholic fatty liver disease, cardiovascular disease and diabetes, has increased due to chronic surplus consumption of these sugars. While many of these sugars have been isolated and studied for centuries, their health impacts and exact underlying mechanisms are still unclear. In this review, we discuss the pathophysiological role of 6 major simple sugars present in the human diet and the biochemical and molecular pathways related to their metabolism by different organs and gut microbiota, with a focus on the most recent investigations.

Faith in Fat: A Multisite Examination of University Students' Perceptions of Fat in the Diet

Despite recent relaxation of restrictions on dietary fat consumption in dietary guidelines, there remains a collective "fear of fat". This study examined college students' perceptions of health among foods with no fat relative to foods with different types of fats (unsaturated and saturated). Utilizing a multisite approach, this study collected data from college students at six university dining halls throughout the United States. Data were available on 533 students. Participants were 52% male and consisted largely of first-year students (43%). Across three meal types, the no-fat preparation option was chosen 73% of the time, the unsaturated fat option was selected 23% of the time, and the saturated fat option was chosen 4% of the time. Students chose the no-fat option for all meal types 44% of the time. Findings suggest that college students lack knowledge regarding the vital role played by the type and amount of fats within a healthy diet. Nutrition education and food system reforms are needed to help consumers understand that type of fat is more important than total amount of fat. Efforts across various sectors can encourage incorporating, rather than avoiding, fats within healthy dietary patterns.

Race, Gender, Family Structure, Socioeconomic Status, Dietary Patterns, and Cardiovascular Health in Adolescents

BACKGROUND

Dietary patterns represent a broad picture of food and nutrient consumption and may be more predictive of health outcomes than individual foods and nutrients.

OBJECTIVE

We investigated the relations among race, gender, family structure, parental socioeconomic status (SES), dietary patterns, and cardiovascular disease (CVD) profiles among adolescents in the southeastern region of the United States.

METHODS

A total of 743 adolescents from a cross-sectional study were divided into 4 dietary pattern groups by K-means cluster analysis. Multinomial logistic regression was performed to determine the relations among the parental SES, family structures, and dietary patterns of the adolescents. Associations between dietary patterns and CVD profiles were analyzed by multiple linear regression.

RESULTS

Four dietary patterns were derived: "healthy" (17%), "snacks and sweets" (26%), "processed meat" (20%), and "sugar-sweetened beverage (SSB) and fried food" (37%). Whites and females were more likely to have a "healthy" dietary pattern (Ps < 0.001). There were significant race/ethnicity differences in family structures, SES, and dietary patterns (Ps < 0.05). In whites, higher mother's education and father's education and occupation were associated with greater likelihood of a "healthy" dietary pattern (Ps < 0.05). Stay-at-home mother was associated with less likelihood of an "SSB and fried food" pattern (P = 0.023). In blacks, higher mother's occupation, father's education, and living with both parents were associated with more likelihood of a "healthy" dietary pattern (Ps < 0.05). Stay-at-home father was associated with less likelihood of the "snacks and sweets" (P = 0.025) and "SSB and fried food" dietary patterns (P = 0.044). Overall, adolescents with poor dietary patterns exhibited higher percentage body fat, waist circumference, systolic blood pressure, fasting insulin, homeostasis model assessment of insulin resistance, C-reactive protein, and total triglyceride (Ps < 0.05).

CONCLUSIONS

Our data suggest that family structure, parental working status, and SES are associated with the diet quality in adolescents. Moreover, "snacks and sweets," "processed meat," and "SSB and fried food" dietary patterns are all associated with worse CVD risk profiles.

High olive oil diets enhance cervical tumour growth in mice: transcriptome analysis for potential candidate genes and pathways

BACKGROUND

Numerous epidemiologic studies have found a close association between obesity and cancer. Dietary fat is a fundamental contributor to obesity and is a risk factor for cancer. Thus far, the impact of dietary olive oil on cancer development remains inconclusive, and little is known about its underlying mechanisms.

METHODS

Nude mouse xenograft models were used to examine the effects of high olive oil diet feeding on cervical cancer (CC) development and progression. Cell proliferation, migration and invasion were observed by the methods of EdU incorporation, Wound healing and Transwell assay, separately. RNA-sequencing technology and comprehensive bioinformatics analyses were used to elucidate the molecular processes regulated by dietary fat. Differentially expressed genes (DEGs) were identified and were functionally analyzed by Gene Ontology (GO), Kyoto Enrichment of Genes and Genomes (KEGG). Then, protein-protein interaction (PPI) network and sub-PPI network analyses were conducted using the STRING database and Cytoscape software.

RESULTS

A high olive oil diet aggravated tumourigenesis in an experimental xenograft model of CC. Oleic acid, the main ingredient of olive oil, promoted cell growth and migration in vitro. Transcriptome sequencing analysis of xenograft tumour tissues was then performed to elucidate the regulation of molecular events regulated by dietary fat. Dietary olive oil induced 648 DEGs, comprising 155 up-regulated DEGs and 493 down-regulated DEGs. GO and pathway enrichment analysis revealed that some of the DEGs including EGR1 and FOXN2 were involved in the transcription regulation and others, including TGFB2 and COL4A3 in cell proliferation. The 15 most strongly associated DEGs were selected from the PPI network and hub genes including JUN, TIMP3, OAS1, OASL and EGR1 were confirmed by real-time quantitative PCR analysis.

CONCLUSIONS

Our study suggests that a high olive oil diet aggravates CC progression in vivo and in vitro. We provide clues to build a potential link between dietary fat and cancerogenesis and identify areas requiring further investigation.

Spermidine and Voluntary Activity Exert Differential Effects on Sucrose- Compared with Fat-Induced Systemic Changes in Male Mice

BACKGROUND

Excess dietary fat and sugar are linked to obesity and metabolic syndrome. Polyamines such as spermidine are implicated in fat accumulation and may support activity-induced weight loss.

OBJECTIVE

This study tested interventional spermidine supplementation and voluntary activity against fat- and sucrose-induced systemic and gut microbiota changes.

METHODS

A 3-factorial study design (3 × 2 × 2) was used to test the factors diet, activity, and spermidine. Male 6-wk-old C57BL/6N mice were fed a control diet (CD; carbohydrate:protein:fat, 70%:20%:10% of energy; 7% sucrose), a high-fat diet (HFD; carbohydrate:protein:fat, 20%:20%:60% of energy; 7% sucrose), or a high-sucrose diet (HSD; carbohydrate:protein:fat, 70%:20%:10% of energy; 35% sucrose). Diet groups were left untreated (+0) or had unlimited access to running wheels (+A) or were supplemented with 3 mM spermidine via drinking water (+S) or a combination of both (+A+S) for 30 wk (n = 7-10).

RESULTS

In comparison to the CD, the HFD enhanced body weights (by 36%, P < 0.001), plasma lipids (cholesterol by 24%, P < 0.001; triglycerides by 27%, P = 0.004), and glucose concentrations (by 18%, P < 0.001), whereas the HSD increased weight by 13% (P < 0.001) and fasting glucose by 17% (P < 0.001) but did not increase plasma lipids. Microbiota taxonomic composition changed upon the HFD and HSD (both P < 0.001); however, only the HSD increased microbial diversity (P < 0.001) compared with the CD. Activity influenced microbiota composition (P < 0.01) and reduced glucose concentrations in HSD-fed (P = 0.021) and HFD-fed (P < 0.001) mice compared with nonactive mice. The combination of activity and spermidine affected energy intake (P-interaction = 0.037) and reduced body weights of HSD+A+S mice compared with HSD+0 mice (P = 0.024).

CONCLUSIONS

In male C57BL/6N mice, dietary sucrose and fat caused diverse metabolic and microbiota changes that were differentially susceptible to physical exercise. Spermidine has the potential to augment activity-induced beneficial effects, particularly for sucrose-induced obesity.

Pathways and mechanisms linking dietary components to cardiometabolic disease: thinking beyond calories

Calories from any food have the potential to increase risk for obesity and cardiometabolic disease because all calories can directly contribute to positive energy balance and fat gain. However, various dietary components or patterns may promote obesity and cardiometabolic disease by additional mechanisms that are not mediated solely by caloric content. Researchers explored this topic at the 2017 CrossFit Foundation Academic Conference 'Diet and Cardiometabolic Health - Beyond Calories', and this paper summarizes the presentations and follow-up discussions. Regarding the health effects of dietary fat, sugar and non-nutritive sweeteners, it is concluded that food-specific saturated fatty acids and sugar-sweetened beverages promote cardiometabolic diseases by mechanisms that are additional to their contribution of calories to positive energy balance and that aspartame does not promote weight gain. The challenges involved in conducting and interpreting clinical nutritional research, which preclude more extensive conclusions, are detailed. Emerging research is presented exploring the possibility that responses to certain dietary components/patterns are influenced by the metabolic status, developmental period or genotype of the individual; by the responsiveness of brain regions associated with reward to food cues; or by the microbiome. More research regarding these potential 'beyond calories' mechanisms may lead to new strategies for attenuating the obesity crisis.

Assessing nutrition and other claims on food labels: a repeated cross-sectional analysis of the Canadian food supply

Background

In 2010, nutrition claims were investigated in Canadian foods; however, many nutrition and other claims have been introduced since then. This study aimed to determine: i) the proportion of foods carrying claims in 2013, ii) the types and prevalence of nutrition claims (nutrient content claims, health claims, general health claims) and other claims displayed on labels in 2013, iii) and trends in use of nutrition claims between 2010 and 2013.

Methods

Repeated cross-sectional analysis of the University of Toronto Food Label Information Program (FLIP) of Canadian foods (2010/11 n = 10,487; 2013 n = 15,342). Regulated nutrition claims (nutrient content, health claims) were classified according to Canadian regulations. A decision tree was used to classify non-regulated general health claims (e.g., front-of-pack claims). Other claims (e.g., gluten-free) were also collected. Proportions of claims in 2013 were determined and χ² was used to test significant differences for different types of claims between 2010 and 2013.

Results

Overall, 49% of products in 2013 displayed any type of claim and 46% of foods in FLIP 2013 carried a nutrition claim (nutrient content claim, health claim, general health claim). Meal replacements and fruits/fruits juices were the categories with the largest proportion of foods with claims. At least one approved nutrient content claim was carried on 42.9% of products compared to 45.5% in 2010 (p < 0.001). Health claims, specifically disease risk reduction claims, were slightly lower in 2013 (1.5%) compared to 1.7% in 2010 (p = 0.225). General health claims, specifically front-of-pack claims, were carried on 20% of foods compared to 18.9% in 2010 (p = 0.020). Other claims, specifically gluten-free, were present on 7.3% of foods.

Conclusions

Nutrition and other claims were used on half of Canadian prepackaged foods in 2013. Many claims guidelines and regulations have been released since 2010; however, little impact has been seen in the prevalence of such claims in the food supply. Claims related to nutrients of public health priority, such as sugars and sodium, were not commonly used on food labels. Monitoring trends in the use of nutrition and other claims is essential to determine if their use on food labels reflects public health objectives, or instead are being used as marketing tools.

Structural design approaches for creating fat droplet and starch granule mimetics

This article focuses on hydrogel-based strategies for creating reduced calorie foods with desirable physicochemical, sensory, and nutritional properties.

Association of dietary intakes of total and subtypes of fat substituted for carbohydrate with metabolic syndrome in Koreans

Amount of fat consumption has gradually increased among Koreans, which is relatively lower than western countries. In the current study, we examined the association between dietary fat and metabolic syndrome (MetS) prevalence among Korean adults. 3,212 participants who are aged 30-74 years from the Korea National Health and Nutritional Examination Survey (KNHANES) VI (2013) were included for cross-sectional analyses. Dietary intake data was assessed using 24-hour recall method, and MetS was defined using guideline of the National Cholesterol Education Program Adult Treatment panel III (NCEP-ATP III). Multivariate logistic regression analysis was used to estimate MetS odds ratios, using nutrient density model, according to 5% percent unit of dietary fat intake. The prevalence of MetS was significantly associated with dietary intake of total fat and saturated fatty acid (SFA) after adjustment (odds ratio [OR] 0.984 95% confidence interval [CI] 0.972-0.996; OR 0.946 95% CI 0.915-0.979). When dietary intake of total fat and SFA were substituted for carbohydrate (CHO), ORs for MetS were 0.985 (95% CI 0.972-0.998) and 0.948 (95% CI 0.907-0.990), respectively, after adjusting for potential covariates. In summary, MetS was significantly associated with dietary intakes of total fat and SFA, and when substituting dietary fat for carbohydrate among Koreans.

Nutrition Knowledge, Attitudes, and Confidence of Australian General Practice Registrars

Nutrition knowledge, attitudes, and confidence were assessed in General Practice Registrars (GPRs) throughout Australia. Of approximately 6,000 GPRs invited to complete a nutrition survey, 93 respondents (2%) completed the online survey, with 89 (20 males, 69 females) providing demographic and educational information. Fifty-one percent had graduated from medical school within the last two years. From a list of 11 dietary strategies to reduce cardiovascular risk, respondents selected weight loss (84%), reducing saturated fats (90%), a maximum of two alcoholic drinks/day (82%), and increasing vegetables (83%) as “highly appropriate” strategies, with only 51% indicating that salt reduction was “highly appropriate.” Two-thirds of registrars felt “moderately” (51%) or “very” confident (16%) providing nutrition advice. Most of them (84%) recalled receiving information during training, but only 34% recalled having to demonstrate nutritional knowledge. The results indicate that this group of Australian GPRs understood most of the key dietary recommendations for reducing cardiovascular risk but lacked consensus regarding the recommendation to reduce salt intake and expressed mixed levels of confidence in providing nutritional advice. Appropriate nutrition education before and after graduation is recommended for GPRs to ensure the development of skills and confidence to support patients to make healthy dietary choices and help prevent chronic diseases.