Fatty acid composition of adipose tissue and serum lipids are valid biological markers of dairy fat intake in men

The fatty acid intake is in part reflected by the fatty acid composition of adipose tissue and serum lipids. We evaluated whether the proportions of myristic (14:0), pentadecanoic (15:0) and heptadecanoic (17:0) fatty acids in the adipose tissue triacylglycerols and serum cholesterol esters and phospholipids reflect long-term dairy fat consumption in free-living men. In 114 healthy men aged 40-76 y, we compared the relative content of 14:0, 15:0 and 17:0 in subcutaneous adipose tissue and in serum lipids with relative intake (g/100 g of total fat) assessed by two 1-wk weighed food records made 6 mo apart and assessed by fourteen 24-h dietary recall interviews equally distributed during 1 y. According to food records, the mean +/- SD dairy fat intake was 24.9 +/- 13.1 g/d (29.6 +/- 10.5 g/100 g total fat); intake of 14:0, 15:0 and 17:0 was 4.6, 0.23 and 0.16 g/100 g total fat, and the content in adipose tissue was 3.6, 0.36 and 0.25 g/100 g fatty acids, respectively. Pearson correlation coefficients between intake of dairy fat (based on 24-h recalls) and fatty acid composition of adipose tissue were 0.64 (P: < 0.001) for 14:0, 0.74 (P: < 0.001) for 15:0 and 0.60 (P: < 0.001) for 15:0 + 17:0. Corresponding correlations with serum cholesterol esters were 0.34 (P: < 0.001) (14:0), 0.45 (P: < 0.001) (15:0) and 0.56 (P: < 0.001) (15:0 + 17:0), and with serum phospholipids the values were 0.30 (P: < 0.01) (14:0), 0.50 (P: < 0.001) (15:0) and 0.50 (P: < 0.001) (15:0 plus 17:0). In our study population, the relative content of 15:0 or 14:0 in adipose tissue is a valid biomarker for long-term dairy fat intake in free-living individuals. When adipose tissue is not available, 15:0 content in serum cholesterol esters or phospholipids might be used. Intake data based on repeated 24-h recalls are equally informative and may be an equivalent choice in nutritional studies.     

Associations between estimated fatty acid desaturase activities in serum lipids and adipose tissue in humans: links to obesity and insulin resistance

Fatty acid composition of serum lipids and adipose tissue triacylglycerols (AT-TAG) partly reflect dietary fatty acid intake. The fatty acid composition is, besides the diet, also influenced by desaturating enzymes that can be estimated using product-to-precursor fatty acid ratios. The interrelationships between desaturase indices derived from different serum lipid fractions and adipose tissue are unclear, as well as their associations with obesity and insulin resistance. We aimed to investigate cross-sectional correlations between desaturase indices as measured in serum lipid fractions (phospholipids; PL and free fatty acids; FFA) and in adipose tissue (AT-TAG). In a population-based sample of 301 healthy 60-year-old men various desaturase indices were assessed: stearoyl-CoA-desaturase (16:1n-7/16:0; SCD-16 and 18:1n-9/18:0; SCD-18, respectively), delta-6-desaturase (20:3n-6/18:2n-6; D6D) and delta-5-desaturase (20:4n-6/20:3n-6; D5D). Correlations with BMI and insulin resistance (HOMA-IR) were also examined. SCD-16 and D5D were significantly correlated between fractions and tissues (all r > 0.30), whereas SCD-18 and D6D were not. Desaturase indices in serum FFA and AT-TAG were significantly correlated; SCD-16 (r = 0.63), SCD-18 (r = 0.37), and D5D (r = 0.43). In phospholipids, SCD-16 was positively correlated to BMI (r = 0.15), while D5D negatively to both BMI (r = -0.30) and HOMA-IR (r = -0.31), all p < 0.01. D6D in both phospholipids and AT-TAG was positively correlated to HOMA-IR and BMI (all p < 0.01). In conclusion, SCD-1 and D5D activity indices showed overall strong correlations between lipid pools. SCD-1 activity index in adipose tissue is best reflected by 16:1/16:0-ratio in serum FFA, but associations with obesity and insulin resistance differ between these pools. D5D in PL was inversely related to obesity and insulin resistance, whereas D6D index showed positive associations.     

Fatty acid composition of subcutaneous adipose tissue and diet in postmenopausal US women

The distributions of fatty acids in subcutaneous-adipose-tissue aspirates and their relation to intake as assessed by a semiquantitative food-frequency questionnaire were investigated in 115 postmenopausal US women free from cancer. Percentages of fatty acids in adipose tissue were significantly correlated with the percentage of total fat intake for polyunsaturated fatty acids (Spearman correlation = 0.37), n-3 fatty acids of marine origin (Spearman correlation = 0.48), and trans fatty acids (Spearman correlation = 0.51) but not for saturated and monounsaturated fatty acids. Correlations were somewhat stronger in 78 women with stable weight over the 6 mo before fat aspiration. These data suggest that intakes of polyunsaturated fatty acids, including n-3 fatty acids, and trans fatty acids are reflected in the adipose tissue but that intakes of saturated and monounsaturated fatty acids are not. The data also provide further support for the validity of the food-frequency questionnaire in the assessment of fat intake.     

Fatty acid composition of skeletal muscle and adipose tissue in Spanish infants and children

There is a relationship between the fatty acid profile in skeletal muscle phospholipids and peripheral resistance to insulin in adults, but similar data have not been reported in infancy and childhood. The objective of this study was to investigate the fatty acid composition of skeletal muscle and adipose tissue across the paediatric age range. The fatty acid profile of skeletal muscle phospholipids and adipose tissue triacylglycerols was analysed in ninety-three healthy Spanish infants and children distributed into four groups: group 1 (0 to <2 years, n 10); group 2 (2 to <5 years, n 41); group 3 (5 to <10 years, n 24); group 4 (10 to 15 years, n 18). In skeletal muscle phospholipids, oleic acid (18: 1n-9cis) content decreased significantly whereas that of linoleic (18: 2n-6) acid increased significantly with age (P for trend <0.01). In adipose tissue, the contents of triacylglycerol and linoleic acid increased significantly across the paediatric age range (P for trend <0.01), whereas dihomo-gamma-linolenic (20: 3n-6) and arachidonic (20: 4n-6) showed significant differences between groups. The variations in fatty acid composition observed with age indicated an imbalance in dietary n-3/n-6 long-chain PUFA.     

Manipulating the fatty acid composition of muscle and adipose tissue in beef cattle

Enhancing the n-3 polyunsaturated fatty acid (PUFA) content of beef is important in view of the generally saturated nature of fatty acids in ruminant meats and the negative effect this can have on human health. This study examined the effects of different sources of dietary n-3 PUFA on the performance of steers and the fatty acid composition of m. longissimus thoracis muscle and associated subcutaneous adipose tissue. Animals were fed ad libitum on grass silage plus one of four concentrates (60:40 forage:concentrate on a DM basis) containing differing sources of lipid: Megalac (16:0), lightly bruised whole linseed (18:3n-3), fish oil (20:5n-3 and 22:6n-3) and a mixture of linseed and fish oil (1:1, on an oil basis). Diets were formulated so that total dietary oil intake was 6 %, approximately half of which was from the experimental test oil. Linseed feeding not only increased the levels of 18:3n-3 in muscle phospholipid from 9.5 to 19 mg/100 g muscle but also enhanced the synthesis of 20:5n-3, the level of which increased from 10 to 15 mg/100 g muscle. Linseed also increased the proportion of 18:3n-3 in muscle neutral lipid and in adipose tissue lipids by a factor of 1.64 and 1.75 respectively. Fish oil feeding doubled the proportion of 20:5n-3 and 22:6n-3 in muscle phospholipids. The proportion of 18:1 trans in muscle neutral lipid was higher on the n-3 PUFA diets than the control diet, 0.04 and 0.02 respectively. Despite the implied modification to rumen metabolism, lipid source did not affect feed intake, growth rate, cold carcass weight or carcass fatness, but carcass conformation score was higher on fish oil treatments (P < 0.05). However, total muscle fatty acid content was not different between treatments and ranged from 3.5-4.3 % of tissue weight. The increase in n-3 PUFA in the meat produced by feeding linseed or fish oil lowered the n-6:n-3 ratio but had little effect on the P:S ratio.     

Fatty acid composition of adipose tissue in humans: differences between subcutaneous sites

We compared the fatty acid composition of adipose tissue from three different sites, one deep-seated site (perirenal) and two subcutaneous sites (abdominal and buttock), in 143 autopsied adult humans aged 24-61 y. The proportion of saturated fatty acids was highest in the perirenal adipose tissue and lowest in buttock adipose tissue. The proportions of monounsaturated fatty acids in the three sites were in the reverse order. Linoleic and linolenic acids were similar in the three adipose-tissue sites, an important finding for those concerned about the essential fatty acids, which are solely derived from the diet. The results clearly show that the fatty acid composition of the two subcutaneous fat depots differ significantly. We conclude that abdominal fat is more saturated than buttock fat.     

Visceral adipose tissue and markers of the insulin resistance syndrome in obese black and white teenagers

OBJECTIVE: To determine the relationships between visceral and general adiposity, cardiovascular fitness, and markers of the insulin resistance syndrome in obese black and white teenagers. RESEARCH METHODS AND PROCEDURES: Cross-sectional survey of 81 obese 13- to 16-year-old youths. Visceral adipose tissue was measured with magnetic resonance imaging, and percentage body fat was measured with dual-energy X-ray absorptiometry. Cardiovascular fitness was assessed with a submaximal treadmill test. Fasting blood samples were analyzed for lipids/lipoproteins and insulin. Resting blood pressure was obtained using an automated cuff. RESULTS: Visceral adipose tissue was significantly correlated with unfavorable levels of: triacylglycerol (r = 0.27, p < 0.05), total cholesterol (r = 0.27, p < 0.05), high-density lipoprotein cholesterol (r = -0.26, p < 0.05), the ratio of total cholesterol/high-density lipoprotein cholesterol (r = 0.42, p < 0.01), low-density lipoprotein cholesterol (r = 0.27, p < 0.05), apolipoprotein B (r = 0.38, p < 0.01), and systolic blood pressure (r = 0.30, p < 0.01). Multiple regression analyses revealed that visceral adipose tissue was more powerful than percentage body fat for explaining variance in lipoproteins (e.g., for the ratio of total cholesterol/high-density lipoprotein cholesterol, r2 = 0.13, p < 0.01, and for systolic blood pressure, r2 = 0.07, p < 0.05). Ethnicity was the most powerful of the demographic predictors for blood lipids (r2 = 0.15 for triacylglycerol with lower levels in blacks; r2 = 0.10 for high-density lipoprotein cholesterol with higher levels in blacks; r2 = 0.06 for the ratio of total cholesterol/high-density lipoprotein cholesterol with lower levels in blacks). Cardiovascular fitness was not retained as a significant predictor of markers of the insulin resistance syndrome. DISCUSSION: Some of the deleterious relationships between visceral adiposity and markers for the insulin resistance syndrome seen in adults were already present in these obese young people.     

Breast milk and adipose tissue fatty acid composition in relation to maternal dietary intake

The fatty acid (FA) relative concentration (g/100g) of human milk triglyceride (TG) was compared to that of adipose tissue (AT). A high concentration of linoleic acid (C-18:2) was present in AT, probably reflecting long term high linoleic acid dietary intake. Linoleic acid was slightly lower in colostrum and transitional milk. No difference in C-18:2 relative concentration was seen between AT and human milk obtained 6 weeks post-partum. Marked short-term dietary modification in linoleic acid intake of the mother, 6 weeks post-partum, did not result in changes in C-18:2 relative concentration of human milk. In spite of measured marked intradiurnal variability in C-18:2 intake, human milk TG FA relative concentration remained remarkably constant. It is suggested that human milk TG FA composition reflects, mainly, the composition of AT. With the increased dietary intake of polyunsaturated fat in many populations, high levels of linoleic acid in human milk are to be expected. The intake of this fatty acid may exceed the suggested daily allowance and thus cause harmful effects, particularly in preterm infants.     

Essential fatty acid composition of human colostrum triglycerides: its relationship with adipose tissue composition

The relationships between essential fatty acid (EFA) composition of colostrum and white adipose tissue (WAT) were examined on day 5 after delivery in 69 healthy women. Fatty acid composition was assessed by capillary gas chromatography, and 33 fatty acids were detected in colostrum and in WAT. Total polyunsaturated fatty acid (PUFA) content was similar in colostrum and in WAT (15.7 +/- 3.1% and 16.1 +/- 3.8%, respectively), but long-chain PUFA content was higher in colostrum than in WAT (2.9 +/- 0.6% and 1 +/- 0.2%, respectively; P less than 0.001). The concentrations of linoleic acid were significantly correlated between colostrum and WAT (r = 0.77, P less than 0.0001). No correlation was found for alpha-linolenic acid. The relationships between long-chain PUFA composition of colostrum and WAT suggested that individual factors along with tissue specificity of the mammary gland are involved in either the capacity of desaturating and chain-elongating pathways and/or incorporation of long-chain PUFAs into colostrum.     

Resistant starch improves insulin resistance and reduces adipose tissue weight and CD11c expression in rat OLETF adipose tissue

ObjectiveCD11s/CD18 dimers induce monocyte/macrophage infiltration into many tissues, including adipose tissues. In particular, it was reported that β2-integrin CD11c-positive macrophages in adipose tissues are closely associated with the development of insulin resistance. The aim of this study was to determine whether intake of resistant starch (RS) reduces macrophage accumulation in adipose tissues and inhibits the development of insulin resistance at an early stage in Otsuka Long-Evans Tokushima Fatty (OLETF) rats.MethodsTwenty-two-wk-old male OLETF rats were fed a control diet (55% α-corn starch) or an RS diet (55% RS) for 5 wk. An oral glucose tolerance test was performed after 4 wk of feeding; tissues (mesenteric and epididymal adipose tissues, and liver) and tail vein blood were collected after 5 wk of feeding the test diets.ResultsFeeding the RS diet to OLETF rats for 5 wk improved insulin resistance, reduced the mesenteric adipose tissue weight, and enhanced the number of small adipocytes. CD68 expression, a macrophage infiltration marker, was not changed by the RS diet, whereas the gene expression levels of integrins such as CD11c, CD11d, and CD18, but not CD11a, and CD11b, were significantly reduced. CD11c protein expression was reduced by the RS diet.ConclusionThese findings suggest that part of the mechanism for the improved insulin resistance by the RS diet involves a reduction of CD11c expression in adipose tissues.     

Association between serum fatty acid composition and innate immune markers in healthy adults

BACKGROUND/OBJECTIVES

Supplementation with n-3 polyunsaturated fatty acids (PUFAs) has been shown to generally decrease levels of innate immune markers and inflammatory cytokines, but the specific associations between blood levels of PUFAs and those of innate immune markers have not been investigated. Thus, the present study was conducted to test the hypothesis that innate immune markers as well as cytokines are negatively associated with n-3 PUFAs but positively associated with n-6 PUFAs in healthy adults.

MATERIALS/METHODS

One hundred sixty-five healthy Korean adults aged 25-70 years old were included in this cross-sectional study.

RESULTS

Serum levels of n-3 PUFAs, such as 18:3n3, 20:5n3, 22:5n3, and 22:6n3 were negatively correlated with eosinophil and basophil counts and TNF-α, IFN-γ, IL-4, and IL-10 levels. Multivariate analysis also showed that serum levels of n-3 PUFAs were negatively associated with monocyte, eosinophil, and basophil counts and TNF-α, IFN-γ, IL-4, and IL-12 levels. Additionally, the ratio of 20:4n6 to 20:5n3 was positively correlated with eosinophil counts and associated with TNF-α, IFN-γ, and IL-4 levels. However, NK cell activity was not associated with serum fatty acid composition.

CONCLUSIONS

Innate immune markers such as eosinophil, monocyte, and basophil counts were inversely associated with serum levels of n-3 PUFAs, but were positively associated with the 20:4n6/20:5n3 ratio in this population.     

Effect of sampling site on fatty acid composition of human breast adipose tissue

The effect of sampling site and proximity of malignant tumor on the relative fatty acid composition of human breast adipose tissue was studied in 10 cases of breast cancer. The four anatomic quadrants of breast did not statistically significantly differ from each other in relation to any of the 30 fatty acids studied. Proximity of the malignant tumor did not affect the relative fatty acid composition of fat when compared with more distant sampling sites. Representative samples of breast adipose tissue for fatty acid composition analysis can be obtained from tissue adjacent to the tumor.     

Effect of sampling site on fatty acid composition of human breast adipose tissue

The effect of sampling site and proximity of malignant tumor on the relative fatty acid composition of human breast adipose tissue was studied in 10 cases of breast cancer. The four anatomic quadrants of breast did not statistically significantly differ from each other in relation to any of the 30 fatty acids studied. Proximity of the malignant tumor did not affect the relative fatty acid composition of fat when compared with more distant sampling sites. Representative samples of breast adipose tissue for fatty acid composition analysis can be obtained from tissue adjacent to the tumor.     

Differences in adipose tissue fatty acid composition between black and white men in New Orleans

We report fatty acid composition in perirenal and buttock adipose tissue in 714 deceased black and white men aged 25-44 yr in New Orleans. Percent saturated fatty acids were higher (p less than 0.001) whereas percent monounsaturated fatty acids were lower (p less than 0.001) in perirenal than in buttock fat. Percent linoleic acid was similar in both races. We conclude that dietary intake of linoleic acid is similar in both races. The trend of decreasing linoleic acid with advancing age suggests that either intake of linoleic acid progressively decreases or its mobilization rate increasingly exceeds deposition rate or both. Percent palmitoleic acid (16:1) is lower (p less than 0.001) and that of stearic acid (18:0) is higher (p less than 0.001) in blacks than in whites. We believe no explanation can rest solely on differences in habitual dietary fat intake.     

Fatty acid-binding protein activities in bovine muscle, liver and adipose tissue

Subcutaneous adipose tissue, sternomandibularis muscle and liver were obtained from steers immediately postmortem. Muscle strips and adipose tissue snips were incubated with 0.75 mM [1-14C]palmitate and 5 mM glucose. Muscle strips esterified palmitate at the rate of 2.5 nmol/min per gram tissue, which was 30% of the rate observed for adipose tissue. Fatty acid-binding protein activity was measured in 104,000 x g supernatant fractions of liver, muscle and adipose tissue homogenates. Muscle and adipose tissue fractions bound 840 and 140 pmol [1-14C]palmitoyl-CoA per gram tissue, respectively. Fatty acid-binding protein activity was greater in adipose tissue than in muscle when data were expressed per milligram protein (35 vs. 13 pmol palmitoyl-CoA bound per milligram of soluble protein, respectively). Fatty acid binding-protein activity was correlated with the rate of palmitate esterification within each tissue. Liver contained the highest fatty acid-binding protein activity (13,000 pmol palmitoyl-CoA bound per gram tissue and 215 pmol palmitoyl-CoA bound per milligrams soluble protein).     

(n-3) Fatty acids alleviate adipose tissue inflammation and insulin resistance: mechanistic insights

Obesity is associated with the metabolic syndrome, a significant risk factor for developing type 2 diabetes and cardiovascular diseases. Chronic low-grade inflammation occurring in the adipose tissue of obese individuals is causally linked to the pathogenesis of insulin resistance and the metabolic syndrome. Although the exact trigger of this inflammatory process is unknown, adipose tissue hypoxia, endoplasmic reticular stress, and saturated fatty acid-mediated activation of innate immune processes have been identified as important processes in these disorders. Furthermore, macrophages and T lymphocytes have important roles in orchestrating this immune process. Although energy restriction leading to weight loss is the primary dietary intervention to reverse these obesity-associated metabolic disorders, other interventions targeted at alleviating adipose tissue inflammation have not been explored in detail. In this regard, (n-3) PUFA of marine origin both prevent and reverse high-fat-diet-induced adipose tissue inflammation and insulin resistance in rodents. We provide an update on the pathogenesis of adipose tissue inflammation and insulin resistance in obesity and discuss potential mechanisms by which (n-3) PUFA prevent and reverse these changes and the implications in human health.