Nutrient gene interactions in lipid metabolism

EPA and DHA Enhance CACT Promoter Activity by GABP/NRF2

Carnitine-acylcarnitine translocase (CACT) is a nuclear-encoded mitochondrial carrier that catalyzes the transfer of long-chain fatty acids across the inner mitochondrial membrane for β-oxidation. In this study, we conducted a structural and functional characterization of the CACT promoter to investigate the molecular mechanism underlying the transcriptional regulation of the CACT gene by n-3 PUFA, EPA and DHA. In hepatic BRL3A cells, EPA and DHA stimulate CACT mRNA and protein expression. Deletion promoter analysis using a luciferase reporter gene assay identified a n-3 PUFA response region extending from -202 to -29 bp. This region did not contain a response element for PPARα, a well-known PUFA-responsive nuclear receptor. Instead, bioinformatic analysis revealed two highly conserved GABP responsive elements within this region. Overexpression of GABPα and GABPβ subunits, but not PPARα, increased CACT promoter activity, more remarkably upon treatment with EPA and DHA. ChIP assays showed that n3-PUFA enhanced the binding of GABPα to the -202/-29 bp sequence. Furthermore, both EPA and DHA induced nuclear accumulation of GABPα. In conclusion, our findings indicate that the upregulation of CACT by n3-PUFA in hepatic cells is independent from PPARα and could be mediated by GABP activation.

High Maternal Body Mass Index Is Associated with an Early-Onset of Overweight/Obesity in Pre-School-Aged Children in Malawi. A Multilevel Analysis of the 2015-16 Malawi Demographic and Health Survey

BACKGROUND

Overweight/obesity in young children is one of the most serious public health issues globally. We examined whether individual- and community-level maternal nutritional status is associated with an early onset of overweight/obesity in pre-school-aged children in Malawi.

DESIGN

Data were obtained from the 2015-16 Malawi Demographic and Health Survey (MDHS). The maternal nutritional status as body mass index and childhood overweight/obesity status was assessed by using the World Health Organization (WHO) recommendations. To examine whether the maternal nutritional status is associated with overweight/obesity in pre-school-aged children, two-level multilevel logistic regression models were constructed on 4023 children of age less than five years dwelling in 850 different communities.

RESULTS

The multilevel regression analysis showed that children born to overweight/obese mothers had increased odds of being overweight/obese [adjusted odds ratio (aOR) = 3.11; 95% confidence interval (CI): 1.13-8.54]. At the community level, children born to mothers from the middle (aOR: 1.68; 95% CI: 1.02-2.78) and high (aOR: 1.69; 95% CI: 1.00-2.90) percentage of overweight/obese women had increased odds of being overweight/obese. In addition, there were significant variations in the odds of childhood overweight/obesity in the communities.

CONCLUSIONS

Strategies aimed at reducing childhood overweight/obesity in Malawi should address not only women and their children but also their communities. Appropriate choices of nutrition, diet and physical activity patterns should be emphasized upon in overweight/obese women of childbearing age throughout pregnancy and beyond.

New criteria for supplementation of selected micronutrients in the era of nutrigenetics and nutrigenomics

Advances in molecular biology, emergence of novel techniques and huge amount of information generated in the post-Human Genome Project era have fostered the emergence of new disciplines in the field of nutritional research: Nutrigenomics deals with the effect of diet on gene expression whereas nutrigenetics refers to the impact of inherited traits on the response to a specific dietary pattern, functional food or supplement. Understanding the role of micronutrient supplementation with specific genetic backgrounds may provide an important contribution to a new optimum health strategy based on individualized nutritional treatment and may provide the strategies for the development of safer and more effective dietary interventions. This overview of the various aspects of supplementation of micronutrients in the era of nutrigenetics and nutrigenomics may provide a better understanding of novel nutritional research approach and provide an additional insight that can be applied to the daily dietary practice.

Dietary fat intake, body composition and blood lipids of university men and women

BACKGROUND

Cardiovascular disease rates are high in the U.K., particular in men, and are related to dietary fat intake. We conducted a pilot study to investigate relationships between saturated and unsaturated dietary fat intakes, body composition and blood lipid parameters in Caucasian men and women at university.

METHODS

Volunteers (52 men and 52 women; age range 20-50 years) were recruited from staff and students of London Metropolitan University. Dietary intake, body composition, blood pressure and fasting blood glucose and lipids were assessed. Gender differences between the measured variables and their relationships were assessed by Mann-Whitney U-test, and by multi-linear (stepwise) regression, respectively.

RESULTS

Men consumed more saturated fat (29.5 vs. 20.5 g/day, p < 0.001), and had elevated levels of glucose (5.34 + 0.74 vs. 4.85 + 0.49 mmol/l, p < 0.001), low-density lipoprotein (LDL) cholesterol (2.99 + 1.5 vs. 2.62+ 0.74 mmol/l, p < 0.05), systolic blood pressure (126.4 + 11.0 vs. 112.6 + 17.2 mm/Hg, p < 0.001), and lower high-density lipoprotein (HDL) cholesterol (1.41 ± 0.34 vs. 1.83 ± 0.43, p < 0.001). Saturated fat was positively associated with total body fat ( p < 0.05), trunk fat ( p < 0.001), HDL cholesterol ( p < 0.05) and systolic blood pressure ( p < 0.001) in women, while in men docosahexaenoic acid and total cholesterol ( p < 0.05), total omega-3 fatty acids and LDL cholesterol ( p < 0.001), total omega-3 fatty acids and triglycerides ( p < 0.01) were positively related. Similar n-3 fatty acid intakes were reported in nutritionally aware students and other university subjects.

CONCLUSIONS

The data of this study indicate gender-related differences in response to dietary fat, and widespread low compliance with n-3 fatty acid recommendations. Although the men are highly health conscious and physically active, their blood lipid levels are indicative of a risk of cardiovascular disease. In addition to enhanced nutritional education to increase seafood intakes in this age group of men and women, customised dietary and lifestyle advice may be required in the men.

Dietary fat types differently modulate the activity and expression of mitochondrial carnitine/acylcarnitine translocase in rat liver

The carnitine/acylcarnitine translocase (CACT), an integral protein of the mitochondrial inner membrane, belongs to the carnitine-dependent system of fatty acid transport into mitochondria, where beta-oxidation occurs. CACT exchanges cytosolic acylcarnitine or free carnitine for carnitine in the mitochondrial matrix. The object of this study was to investigate in rat liver the effect, if any, of diets enriched with saturated fatty acids (beef tallow, BT, the control), n-3 polyunsaturated fatty acids (PUFA) (fish oil, FO), n-6 PUFA (safflower oil, SO), and mono-unsaturated fatty acids (MUFA) (olive oil, OO) on the activity and expression of CACT. Translocase exchange rates increased, in parallel with CACT mRNA abundance, upon FO-feeding, whereas OO-dietary treatment induced a decrease in both CACT activity and expression. No changes were observed upon SO-feeding. Nuclear run-on assay revealed that FO-treatment increased the transcriptional rate of CACT mRNA. On the other hand, only in the nuclei of hepatocytes from OO-fed rats splicing of the last intron of CACT pre-mRNA and the rate of formation of the 3'-end were affected. Overall, these findings suggest that compared to the BT-enriched diet, the SO-enriched diet did not influence CACT activity and expression, whereas FO- and OO-feeding alters CACT activity in an opposite fashion, i.e. modulating its expression at transcriptional and post-transcriptional levels, respectively.

Nutrigenomics, rumen-derived bioactive fatty acids, and the regulation of milk fat synthesis

Mammary synthesis of milk fat continues to be an active research area, with significant advances in the regulation of lipid synthesis by bioactive fatty acids (FAs). The biohydrogenation theory established that diet-induced milk fat depression (MFD) in the dairy cow is caused by an inhibition of mammary synthesis of milk fat by specific FAs produced during ruminal biohydrogenation. The first such FA shown to affect milk fat synthesis was trans-10, cis-12 conjugated linoleic acid, and its effects have been well characterized, including dose-response relationships. During MFD, lipogenic capacity and transcription of key mammary lipogenic genes are coordinately down-regulated. Results provide strong evidence for sterol response element-binding protein-1 (SREBP1) and Spot 14 as biohydrogenation intermediate responsive lipogenic signaling pathway for ruminants and rodents. The study of MFD and its regulation by specific rumen-derived bioactive FAs represents a successful example of nutrigenomics in present-day animal nutrition research and offers several potential applications in animal agriculture.

Fish oil -- how does it reduce plasma triglycerides?

Long chain omega-3 fatty acids (FAs) are effective for reducing plasma triglyceride (TG) levels. At the pharmaceutical dose, 3.4g/day, they reduce plasma TG by about 25-50% after one month of treatment, resulting primarily from the decline in hepatic very low density lipoprotein (VLDL-TG) production, and secondarily from the increase in VLDL clearance. Numerous mechanisms have been shown to contribute to the TG overproduction, but a key component is an increase in the availability of FAs in the liver. The liver derives FAs from three sources: diet (delivered via chylomicron remnants), de novo lipogenesis, and circulating non-esterified FAs (NEFAs). Of these, NEFAs contribute the largest fraction to VLDL-TG production in both normotriglyceridemic subjects and hypertriglyceridemic, insulin resistant patients. Thus reducing NEFA delivery to the liver would be a likely locus of action for fish oils (FO). The key regulator of plasma NEFA is intracellular adipocyte lipolysis via hormone sensitive lipase (HSL), which increases as insulin sensitivity worsens. FO counteracts intracellular lipolysis in adipocytes by suppressing adipose tissue inflammation. In addition, FO increases extracellular lipolysis by lipoprotein lipase (LpL) in adipose, heart and skeletal muscle and enhances hepatic and skeletal muscle β-oxidation which contributes to reduced FA delivery to the liver. FO could activate transcription factors which control metabolic pathways in a tissue specific manner regulating nutrient traffic and reducing plasma TG. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.

The association of sleep duration with adolescents' fat and carbohydrate consumption

STUDY OBJECTIVES

To investigate the relation between sleep duration and energy consumption in an adolescent cohort.

DESIGN

Cross-sectional.

SETTING

Free-living environment.

PARTICIPANTS

Two hundred forty adolescents (mean age 17.7 +/- 0.4 years).

MEASUREMENTS AND RESULTS

Daily 24-hour food-recall questionnaires and wrist-actigraphy measurements of sleep duration were employed to test the hypothesis that shorter weekday sleep duration (< 8 h) is associated with altered nutrient intake. Nutrition parameters included total calories, calories from meals and snacks, and proportions of caloric intake from fat and carbohydrates. Compared with adolescents sleeping 8 or more hours on average on weekdays, those sleeping less than 8 hours consumed a higher proportion of calories from fats (35.9% +/- 6.7% vs 33.2% +/- 6.9%; mean +/- SD; P = 0.004) and a lower proportion of calories from carbohydrates (49.6% +/- 8.2% vs 53.3% +/- 8.3%; P = 0.001). After adjusting for potential confounders, shorter sleep duration was significantly associated with an average daily increase of calories consumed from fat of 2.2 percentage points and an average daily decrease in percentage of calories from carbohydrates of 3.0 percentage points. In unadjusted analyses, shorter sleep duration was also associated with a 2.1-fold increased odds (95% confidence interval: 1.03, 4.44) of daily consuming 475 or more kcal from snacks.

CONCLUSION

Quantitative measures of macronutrient intake in adolescents were associated with objectively measured sleep duration. Short sleep duration may increase obesity risk by causing small changes in eating patterns that cumulatively alter energy balance.