Isomeric fatty acids in the US diet: levels and health perspectives.

Objective: Alcohol drinkers are generally considered to underreport their alcohol intake, but little is known about whether they correctly report their energy intake (EI). We assessed the validity of the reported energy intake of alcohol drinkers using the 24-hour urinary (U) excretion of potassium (K) and sodium (Na) as biomarkers.

Methods: A total of 2,124 men and 1,998 women 25 to 74 years of age with a 24-hour urine collection, a random sample of the Belgian Interuniversity Research on Nutrition and Health (BIRNH), were studied. Dietary intake (D), including alcohol consumption, was assessed by a one-day food record. Basal metabolic rate (BMR) was predicted from age, gender and weight. As a measure for the degree of reporting error, D-K/U-K, D-Na/U-Na, EI/U-K, Non-alcohol EI/U-Na (NAEI/U-Na), EI/U-Na, EI/U-creatinine and EI/BMR ratios were calculated and compared among non-, moderate and heavy drinkers in both genders.

Results: EI, NAEI and all seven ratios examined generally increased with the level of alcohol intake in both genders. After adjustment for age, body mass index, smoking and educational level, most ratios were significantly higher in moderate drinkers (p < 0.02 to p < 0.0001) and in heavy drinkers (all p < 0.0001) than in non-drinkers. These differences were most significant in male heavy drinkers. The exceptions were D-K/U-K, D-Na/U-Na and NAEI/U-Na in moderate and female heavy drinkers and EI/U-K in male moderate drinkers. The estimated amount of the overreporting of EI by heavy drinkers was 27.8% in men and 13.7% in women.

Conclusions: This study provides evidence that EI and NAEI obtained from the BIRNH study was overreported among alcohol drinkers, especially among male heavy drinkers. It also indicates that EI from alcohol replaced EI from food.     

Isomeric trans fatty acids in the U.S. diet

Since actual consumption data for trans fatty acid (FA) intakes for the U.S. population do not exist, estimates of trans fatty acids (FAs) available in the U.S. food supply have been calculated from U.S. Department of Agriculture-Economic Research Service (USDA-ERS) fats and oils production figures and food disappearance data for fats and oils. Based on weighted averages for the trans levels in each fats and oils category, these estimates of trans FAs available in the U.S. food supply range from 12.5 to 15.2 g/person/day (average 13.3 +/- 1.1 g/person/day). Estimates of trans FA consumption have been calculated; these estimates predict a wide range from 1.6 to 38.7 g/person/day. These calculations are based on published estimates of trans FAs available in the total fat of 5-15%, and the total fat intake (range 31-258 g/person/day) of a representative sample of adults (ages 20-59) as determined by the Lipid Research Clinics (LRC). Using an equation based on a relationship between trans FAs in adipose tissue and dietary fat, an intake range of 0.7-28.7 g/person/day trans FAs for the same LRC fat consumption data can be predicted. Adipose tissue isomer profiles that indicate 90-95% of the trans FAs in the tissues comes from partially hydrogenated vegetable fats and oils allow us to predict a dietary intake range from 11.1 to 27.6 g/person/day trans FAs. The significance of these estimates to nutrition policy is discussed.     

Isomeric trans fatty acids in the U.S. diet.

Since actual consumption data for trans fatty acid (FA) intakes for the U.S. population do not exist, estimates of trans fatty acids (FAs) available in the U.S. food supply have been calculated from U.S. Department of Agriculture-Economic Research Service (USDA-ERS) fats and oils production figures and food disappearance data for fats and oils. Based on weighted averages for the trans levels in each fats and oils category, these estimates of trans FAs available in the U.S. food supply range from 12.5 to 15.2 g/person/day (average 13.3 +/- 1.1 g/person/day). Estimates of trans FA consumption have been calculated; these estimates predict a wide range from 1.6 to 38.7 g/person/day. These calculations are based on published estimates of trans FAs available in the total fat of 5-15%, and the total fat intake (range 31-258 g/person/day) of a representative sample of adults (ages 20-59) as determined by the Lipid Research Clinics (LRC). Using an equation based on a relationship between trans FAs in adipose tissue and dietary fat, an intake range of 0.7-28.7 g/person/day trans FAs for the same LRC fat consumption data can be predicted. Adipose tissue isomer profiles that indicate 90-95% of the trans FAs in the tissues comes from partially hydrogenated vegetable fats and oils allow us to predict a dietary intake range from 11.1 to 27.6 g/person/day trans FAs. The significance of these estimates to nutrition policy is discussed.     

Isomeric fatty acids and tumorigenesis: A commentary on recent work

This article critically reviews the existing, although limited, literature concerning trans fatty acids and tumorigenesis. Neither epidemiological nor experimental studies published to date have demonstrated any valid association between trans fatty acid ingestion and tumorigenesis. A recent study showed that under controlled conditions, a fat with a high content of ‘trans fatty acids did not promote the development of mammary tumors induced in rats by 7,12‐dimethylbenz[a]anthracene to any greater extent than did a comparable fat with a high content of as fatty acids. In addition, in this study a high trans fat was less tumor promoting than was a blend of fats that simulated the dietary fat composition of the United States and had a lower level of trans fatty acids. Another study using comparable cis and trans fats demonstrated that the high trans fat did not affect the growth and metastasis of implanted mammary tumors in mice relative to the high cis fat. Also, two recent studies reported no significant difference in the development of induced colon tumors in ratsfed diets high in cis or trans fatty acids. The results of these and other studies are consistent with the conclusion that trans fatty acids are not uniquely related to tumor development.     

Isomeric fatty acids and tumorigenesis: a commentary on recent work

This article critically reviews the existing, although limited, literature concerning trans fatty acids and tumorigenesis. Neither epidemiological nor experimental studies published to date have demonstrated any valid association between trans fatty acid ingestion and tumorigenesis. A recent study showed that under controlled conditions, a fat with a high content of trans fatty acids did not promote the development of mammary tumors induced in rats by 7,12-dimethylbenz[a]anthracene to any greater extent than did a comparable fat with a high content of cis fatty acids. In addition, in this study a high trans fat was less tumor promoting than was a blend of fats that simulated the dietary fat composition of the United States and had a lower level of trans fatty acids. Another study using comparable cis and trans fats demonstrated that the high trans fat did not affect the growth and metastasis of implanted mammary tumors in mice relative to the high cis fat. Also, two recent studies reported no significant difference in the development of induced colon tumors in rats fed diets high in cis or trans fatty acids. The results of these and other studies are consistent with the conclusion that trans fatty acids are not uniquely related to tumor development.     

Reassessment of trans fatty acid availability in the US diet

This report updates our 1984 estimate of the amount of trans fatty acids available for consumption in the US diet, namely 7.6 g.person-1.d-1, for 1989. Compared with 1984 data, we found essentially no change in 1989 for the per capita availability of trans fatty acids from total food service fats and oils. The 1989 value we obtained for industrial fats and oils is somewhat higher than the value we reported for 1984, in part because more complete data were available for 1989. In contrast, however, since 1984 the per capita availability of trans fatty acids from household salad and cooking oils, household shortenings, and all margarines and spreads (retail, food service, and industrial) has decreased. Overall, our reassessed (1989) value for total trans fatty acid availability is 8.1 g.person-1.d-1, which is similar to our original estimate. This total may increase slightly (approximately 0.3 g.person-1.d-1) as a result of the recent switch by many establishments from the use of tallow to partially hydrogenated vegetable oils for frying.     

n-3 fatty acids and periodontitis in US adults

Background

Periodontitis is a common, chronic inflammatory disease. Although n-3 fatty acids have anti-inflammatory properties, it is unclear whether n-3 fatty acids can treat or prevent periodontitis.

Method

We studied 9,182 adults aged 20 years and older who participated in the National Health and Nutrition Examination Survey between 1999 and 2004. Periodontitis was assessed by dental exam and was defined as >4 mm pocket depth and >3 mm attachment loss in any one tooth. Intake of n-3 fatty acids was assessed by 24-hour dietary recall. We used multivariable logistic regression to estimate the associations between periodontitis and intakes of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and linolenic acid (LNA).

Results

The weighted prevalence and 95% confidence interval (CI) of periodontitis was 8.2% (95% CI 7.0 to 9.4). Compared with the lowest tertiles, the adjusted odds ratios for periodontitis associated with the highest tertiles of dietary n-3 intake were 0.78 (95% CI 0.61 to 1.00; P=0.009) for DHA, 0.85 (95% CI 0.67 to 1.08; P=0.10) for EPA, and 0.86 (95% CI 0.60 to 1.23; P=0.28) for LNA. The associations were little changed by multivariable adjustment or exclusion of individuals reporting use of dietary supplements containing DHA, EPA, or LNA.

Conclusions

In this nationally representative sample, higher dietary intakes of DHA and, to a lesser degree, EPA, were associated with lower prevalence of periodontitis. Interventional studies are needed to confirm the potential protective effects of n-3 fatty acids on periodontitis.     

Polyunsaturated fatty acids and cardiovascular health

Epidemiologic studies have shown a beneficial association between polyunsaturated fatty acid (PUFA), specifically linoleic acid (C18:2, n-6), intake and cardiovascular disease morbidity and mortality. Clinical studies have shown that n-6 PUFAs have the most potent cholesterol-lowering effects of the individual fatty acid classes, and emerging evidence suggests that PUFAs have favorable effects on postprandial lipemia. However, some studies suggest that high intakes of linoleic acid may have adverse effects on proinflammatory cytokines and adhesion molecules. Research is needed to establish the optimal level of dietary PUFAs that maximally affects the greatest number of health risk factors.     

N-3 fatty acids reduced trans fatty acids retention and increased docosahexaenoic acid levels in the brain

Introduction: The levels of docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6) are critical for the normal structure and function of the brain. Trans fatty acids (TFA) and the source of the dietary fatty acids (FA) interfere with long-chain polyunsaturated fatty acids (LC-PUFA) biosynthesis.

Objectives: The aim of this study was to investigate the effect of TFA supplementation in diets containing different proportions of n-9, n-6, and n-3 FA on the brain FA profile, including the retention of TFA, LC-PUFA levels, and n-6/n-3 PUFA ratios. These parameters were also investigated in the liver, considering that LC-PUFA are mainly bioconverted from their dietary precursors in this tissue and transported by serum to the brain. Also, stearoyl-CoA desaturase-1 (SCD1) and sterol regulatory element-binding protein-1c (SREBP-1c) gene expressions were evaluated.

Methods: Male CF1 mice were fed (16 weeks) diets containing different oils (olive, corn, and rapeseed) with distinct proportions of n-9, n-6, and n-3 FA (55.2/17.2/0.7, 32.0/51.3/0.9, and 61.1/18.4/8.6), respectively, substituted or not with 0.75% of TFA. FA composition of the brain, liver, and serum was assessed by gas chromatography.

Results: TFA were incorporated into, and therefore retained in the brain, liver, and serum. However, the magnitude of retention was dependent on the tissue and type of isomer. In the brain, total TFA retention was lower than 1% in all diets.

Discussion: Dietary n-3 PUFA decreased TFA retention and increased DHA accretion in the brain. The results underscore the importance of the type of dietary FA on the retention of TFA in the brain and also on the changes of the FA profile.     

Polyunsaturated fatty acids and endocannabinoids in health and disease

Polyunsaturated fatty acids (PUFAs) are lipid derivatives of omega-3 (docosahexaenoic acid, DHA, and eicosapentaenoic acid, EPA) or of omega-6 (arachidonic acid, ARA) synthesized from membrane phospholipids and used as a precursor for endocannabinoids (ECs). They mediate significant effects in the fine-tune adjustment of body homeostasis. Phyto- and synthetic cannabinoids also rule the daily life of billions worldwide, as they are involved in obesity, depression and drug addiction. Consequently, there is growing interest to reveal novel active compounds in this field. Cloning of cannabinoid receptors in the 90s and the identification of the endogenous mediators arachidonylethanolamide (anandamide, AEA) and 2-arachidonyglycerol (2-AG), led to the characterization of the endocannabinoid system (ECS), together with their metabolizing enzymes and membrane transporters. Today, the ECS is known to be involved in diverse functions such as appetite control, food intake, energy balance, neuroprotection, neurodegenerative diseases, stroke, mood disorders, emesis, modulation of pain, inflammatory responses, as well as in cancer therapy. Western diet as well as restriction of micronutrients and fatty acids, such as DHA, could be related to altered production of pro-inflammatory mediators (e.g. eicosanoids) and ECs, contributing to the progression of cardiovascular diseases, diabetes, obesity, depression or impairing conditions, such as Alzheimer’ s disease. Here we review how diets based in PUFAs might be linked to ECS and to the maintenance of central and peripheral metabolism, brain plasticity, memory and learning, blood flow, and genesis of neural cells.     

高脂饮食对非酒精性脂肪肝病模型大鼠肠道短链脂肪酸的影响

目的　观察高脂饮食诱导的非酒精性脂肪肝病（NAFLD）大鼠模型血脂及肠道短链脂肪酸的变化,探讨肠道短链脂肪酸改变在NAFLD发病过程中作用。方法　雄性SD大鼠12只采用随机数字表法分为对照组和高脂组,对照组以普通饮食饲养,高脂组给予高脂饲料喂养,于喂养8周末处死大鼠,HE染色观察两组大鼠肝脏病理改变,并检测血清脂质的变化,气相色谱分析法测定两组大鼠粪便短链脂肪酸含量的变化。结果　高脂组大鼠血清谷丙转氨酶［（139.6±17.29）U/L比（37.67±5.28）U/L］、谷草转氨酶［（367±49.36）U/L比（97.67±13.92）U/L］、三酰甘油［（0.83±0.08）mmol/L比（0.60±0.04）mmol/L］、总胆固醇［（6.34±0.53）mmol/L比（1.77±0.29）mmol/L］、极低密度脂蛋白［（0.31±0.03）mmol/L比（0.22±0.01）mmol/L］水平较对照组明显升高,差异均有统计学意义（P＜0.05）;与对照组相比,高脂组粪便乙酸、丙酸和总短链脂肪酸（SCFA）水平明显降低［（0.16±0.03）ng/μl比（0.21±0.04）ng/μl;（0.05±0.01）ng/μl比（0.08±0.01）ng/μl; (0.25±0.05)ng/μl比（0.33±0.05）ng/μl］,差异均有统计学意义（P＜0.05）。结论　高脂饮食诱导的NAFLD模型大鼠肠道SCFA含量明显减少,粪便SCFA的监测对NAFLD的诊治有重要的指导意义。