Maternal Dietary Fat Affects Milk Fatty Acid Profile and Impacts on Weight Gain and Thermogenic Capacity of Suckling Rats

We aimed to assess the effects of maternal supplementation with the main fat sources used in the human Western diet (olive oil, butter, margarine) on milk FA composition and on plasma FA profile of offspring, and to determine whether it may influence body-weight-gain (BWG) and adiposity of offspring during the suckling period. Wistar rats were supplemented with the different fat sources from day 14 of gestation and throughout lactation. Olive oil-supplemented dams showed the highest proportion of oleic-acid in milk, with no changes in plasma. Their offspring also showed the highest proportion of this FA in plasma, lower BWG during the suckling period, and higher levels of UCP1 in brown adipose tissue (BAT) at weaning. Margarine-supplemented dams showed the highest percentage of PUFA in milk, and a similar tendency was found in plasma of their offspring. Butter-supplemented dams displayed higher proportion of saturated FA (SFA) in milk compared to other fat-supplemented dams, but lower than controls. Control offspring also showed higher proportion of SFA in plasma and greater BWG during the suckling period than fat-supplemented groups. Significant correlations were found between the relative content of some milk FA and BWG of offspring, in particular, oleic-acid levels correlated negatively with BWG and positively with UCP1 levels. These results show that maternal dietary source of fat affects milk FA composition and circulating FA profile, as could be expected, but also BWG and thermogenic capacity of offspring during the suckling period. An effect of oleic-acid stimulating BAT thermogenic capacity of suckling pups is proposed.     

Divergent incorporation of dietary trans fatty acids in different serum lipid fractions

Trans fatty acids may be involved in atherosclerotic vascular diseases. We investigated the incorporation of dietary trans fatty acids and oleic acid into the serum triglycerides (TG), cholesterol esters (CE), and phospholipids (PL). Fourteen healthy female volunteers, aged 23.2±3.1 yr (mean±SD), body mass index 20.8±2.1 kg/m² participated in this study. All subjects consumed both a trans fatty acid-enriched diet (TRANS diet) and an oleic acid-enriched diet (OLEIC diet) for 4 wk according to a randomized crossover design. Both experimental diet periods were preceded by consumption of a baseline diet for 2 wk which supplied 37% of total energy (E%) as fat: 18 E% from saturated fatty acids (SFA), 12 E% from monounsaturated fatty acids, and 6 E% from polyunsaturated fatty acids. Five E% of the SFA in the baseline diet was replaced by trans fatty acids (18∶1 t and 18∶2 c,t+18∶2t,t, where c is cis and t is trans) in the TRANS diet and by oleic acid (18∶1n-9) in the OLEIC diet. After the TRANS diet, the proportions of 18∶1t and 18∶2t increased (P <0.001) in all serum lipid fractions analyzed. The increase of 18∶1 t in TG and PL (1.80±0.28 vs. 5.26±1.40; 1.07±0.34 vs. 3.39±0.76 mol% of total fatty acids, respectively) was markedly higher than that in CE (0.44±0.07 vs. 0.92±0.26), whereas that of 18∶2t was nearly the same in all three fractions. The proportions of palmitic, stearic, arachidonic, and eicosapentaenoic acids in TG, CE, and PL and that of oleic acid in TG and CE were decreased when compared with the baseline value. In contrast, the proportion of palmitoleic acid in TG and PL and that of linoleic acid in PL increased on the TRANS diet. After consumption of the OLEIC diet, the proportion of oleic acid increased in all three lipid fractions analyzed, and the percentage increase was nearly the same in all fractions. In contrast, the proportions of 18∶1 t in TG and PL and 18∶2 t in TG and CE decreased when compared with the baseline value. In conclusion, a moderate increase in dietary trans fatty acids resulted in a marked incorporation into serum lipids and decreased the conversion of linoleic acid to its more unsaturated long-chain metabolites. Analysis of 18∶1 t from serum TG and PL seems to reflect reliably the dietary intake of this fatty acid.     

Fatty Acid Profile of Sunshine Bass: II. Profile Change Differs Among Fillet Lipid Classes

Fatty acid (FA) profile of fish tissue mirrors dietary FA profile and changes in a time-dependent manner following a change in dietary FA composition. To determine whether FA profile change varies among lipid classes, we evaluated the FA composition of fillet cholesteryl esters (CE), phospholipids (PL), and triacylglycerols (TAG) of sunshine bass (SB, Morone chrysops x M. saxatilis) raised on feeds containing fish oil or 50:50 blend of fish oil and coconut, grapeseed, linseed, or poultry oil, with or without implementation of a finishing period (100% FO feed) prior to harvest. Each lipid class was associated with a generalized FA signature, irrespective of nutritional history: fillet PL was comprised largely of saturated FA (SFA), long-chain polyunsaturated FA (LC-PUFA), and total n-3 FA; fillet TAG was higher in MC-PUFA and total n-6 FA; and fillet CE was highest in monounsaturated FA (MUFA). Neutral lipids reflected dietary composition in a near-direct fashion; conversely, PL showed evidence of selectivity for MC- and LC-PUFA. Shorter-chain SFA were not strongly reflected within any lipid fraction, even when dietary availability was high, suggesting catabolism of these FA. FA metabolism in SB is apparently characterized by a division between saturated and unsaturated FA, whereby LC-PUFA are preferentially incorporated into tissues and SFA are preferentially oxidized for energy production. We demonstrated provision of SFA in grow-out feeds for SB, instead MC-PUFA which compete for tissue deposition, meets energy demands and allows for maximum inclusion of LC-PUFA within fillet lipids.     

Dietary Lipid Intake only Partially Influences Variance in Serum Phospholipid Fatty Acid Composition in Adolescents: Impact of Other Dietary Factors

The present study aimed to assess the correlation between food and fatty acid (FA) intake and the serum phospholipid (PL) FA status in European adolescents and explored the percentage of variation in serum PL FA that could be attributed to dietary habits. Participants included 528 adolescents recruited in the HELENA Study. Dietary intake was assessed by two, self-administered, non-consecutive 24-h recalls. PL FA concentrations were measured in fasting venous serum samples. Reduced rank regressions were applied to examine the combined effect of food intakes. Results indicated that the variance in serum PL FA in adolescents, that could be explained by diet varied from 7.0 % for MUFA to 14.2 % for n-3FA. The variance in the long-chain n-3FA was mainly explained by fish intake but also by coffee and tea consumption. In conclusion this study indicated that dietary intake influences the serum PL FA status to a limited amount but that also other factors interfere. However, dietary intake is important as it is among those factors that could be modified. Furthermore, the results suggest that the overall dietary habits should be considered instead of only the consumption of single foods or nutrients, as the medium of the food or concomitant intake of foods and nutrients might interact and as such influence absorption or metabolism.     

FA composition of cholesteryl esters and phospholipids in maternal plasma during pregnancy and at delivery and in cord plasma at birth

The purpose of this study was to assess the FA composition of both cholesteryl esters (CE) and phospholipids (PL) in maternal plasma during pregnancy and at delivery and in umbilical plasma at birth. A longitudinal study of 32 normal pregnant women was carried out with three cutoff points during pregnancy (first, second, and third trimester) and at delivery. Few significant differences occurred in the FA profile of maternal CE: 18∶1n−9 increased, 18∶2n−6 dropped slightly, and 18∶3n−3 decreased with progressing gestation. In maternal PL, long-chain highly unsaturated FA concentrations dropped and were replaced by saturated FA as gestation progressed. Additionally, changes in saturated FA in PL occurred: Shorter-chain 16∶0 was higher whereas longer-chain 18∶0 was lower at delivery compared to early pregnancy. The FA profile of umbilical venous plasma was strikingly different from that of maternal plasma at delivery. Cord plasma CE contained more saturated and monounsaturated FA than maternal CE. The polyunsaturates 18∶2n−6 and 18∶3n−3 are lower in umbilical CE than in maternal CE whereas 20∶4n−6 and 22∶6n−3 are twice as high in umbilical CE. Cord plasma PL have a higher content of long-chain highly unsaturated FA than maternal plasma PL at delivery. In contrast to maternal plasma PL, 16∶0 was lower and longer-chain saturated FA were higher in cord plasma PL. The FA profile of umbilical plasma at birth shows preferential accumulation of 20∶4n−6 and 22∶6n−3, with low concentrations of 18∶2n−6 and 18∶3n−3 in CE and PL, indicating a preferential supply of the fetus with long-chain highly unsaturated FA needed for fetal development.     

Plasma concentrations of dihydro-vitamin K1 following dietary intake of a hydrogenated vitamin K1-rich vegetable oil

Dihydro-vitamin K₁ is a dietary form of vitamin K₁ (phylloquinone) produced during the hydrogenation of vegetable oils. To determine if dihydro-vitamin K₁ is present in plasma following dietary intake of a hydrogenated fat, eight healthy adults consumed each of two diets containing 30% of calories from fat, of which 20% was either soybean oil or a partially hydrogenated soybean oil-based stick margarine. Of the fats and oils analyzed, dihydro-vitamin K₁ was only found in the hydrogenated products. The soybean oil diet contained 180 ±12 μg (mean±SD) of vitamin K₁/day and nondetectable levels of dihydro-vitamin K₁, whereas the stick margarine diet contained 199±7 μg of vitamin K₁/day and 23±2 μg of dihydrovitamin K₁/day. After consuming each diet for five weeks, plasma dihydro-vitamin K₁ concentrations were higher (P=0.002) in all eight subjects when consuming the stick margarine diet (0.56 ±0.33 nmol/L) compared to the soybean oil diet (0.12±0.11 nmol/L). There was no significant change in plasma vitamin K₁ concentrations when the two diets were compared. In conclusion, dihydro-vitamin K₁ is detectable in plasma following dietary intake of a hydrogenated vitamin K₁-rich vegetable oil.     

Fat in today’s food supply—Level of use and sources

Nutrient fat—food fats and oils, as well as fat from meat, milk, and other fat containing foods—in the U.S. food supply has increased ca. one-fourth over the past 60 years or so on a per person/day basis. Ca. two-fifths of the fat currently comes from fats and oils, including butter; over a third comes from meat (including fat pork cuts), poultry, and fish; and ca. one-eight comes from dairy products. This large increase in nutrient fat is due mainly to the use of more vegetable fats—margarine, shortening, and salad and cooking oils. The per capita amount provided by animal fats actually has decreased, because the large decreases in consumption of butter and lard are only partly offset by increases in fat associated with greater consumption of meats. Despite the decrease in consumption of animal fats, they continue to provide ca. one-fourth of the total calories. Although the proportion of calories from vegetable fats has increased, animal products still account for the largest share of the calories provided by fat. Shifts in sources of fat and the increased amount of fat have changed the fatty acid content of the food supply. One of five papers presented at the symposium, “Status of Fat in Food and Nutrition,” AOCS Fall Meeting, Chicago, September 1973. ARS, USDA.     

Fatty Acid Profile of Cardiac Muscle Phospholipid and Triacylglycerol in MDX Mice and C57BL/10ScSnJ Controls

The mdx mouse is a model for Duchenne muscular dystrophy (DMD), a debilitating disease affecting striated muscle. It is established that the fatty acid (FA) composition of skeletal muscle phospholipid (PL) is altered in mdx mice, but it is not known if cardiac muscle is similarly affected by dystrophin-deficiency. We tested FA profiles in PL and triacylglycerol (TAG) in cardiac muscle of 12-week old mdx and control (con) mice. Of 22 different FA, similar to our previous finding for skeletal muscle, the most abundant FA in heart PL were palmitic, stearic, cis-vaccenic, linoleic, and docosahexaenoic acid, while for TAG the most abundant FA were palmitic, oleic, cis-vaccenic, and linoleic acid. In comparing mdx and con, no significant group differences were detected for any FA in PL or TAG. Thus, unlike skeletal muscle, FA composition in cardiac muscle PL is not different between mdx and con at the age studied. The results can be understood in the context of tissue-specific disease severity in mdx mice, as pathology is quite modest in cardiac compared with skeletal muscle.     

Diets rich in lean beef increase arachidonic acid and long-chain ω3 polyunsaturated fatty acid levels in plasma phospholipids

Diets rich in meat are claimed to contribute to the high tissue arachidonic acid (20∶4ω6) content in people in Westernized societies, but there are very few direct data to substantiate this assertion. Because meat contains a variety of long-chain polyunsaturated fatty acids (PUFA) that are susceptible to oxidation, we initially examined the effect of cooking on the long-chain PUFA content of beef, and then determined the effect of ingestion of lean beef on the concentration of long-chain PUFA in plasma phospholipids (PL). First, we examined the effect of grilling (5–15 min) and frying (10 min) different cuts of fat-trimmed lean beef on the long-chain PUFA content. Second, we investigated the effect of including 500 g lean beef daily (raw weight) for 4 wk on the fatty acid content and composition of plasma PL in 33 healthy volunteers. This study was part of a larger trial investigating the effect of lean beef on plasma cholesterol levels. In the first two weeks, the subjects ate a very low-fat diet (10% energy) followed by an increase in the dietary fat by 10% each week for the next 2 wk. The added fat consisted of beef fat, or olive oil (as the oil or a margarine) or safflower oil (as the oil or a margarine). This quantity of beef provided 60, 230, 125, 140 and 20 mg/d, respectively, of eicosatrienoic acid (20∶3ω6), 20∶4ω6, eicosapentaenoic acid (20∶5ω3), docosapentaenoic acid (22∶5ω3) and docosahexaenoic acid (22∶6ω3). Grilling for 10–15 min, but not frying, of the fat-trimmed lean beef resulted in 20–30% losses of the 20 and 22 carbon PUFA. The consumption of the lean beef during the first two-week period, when there was a very low level of dietary fat, was associated with significant increases in the proportion and concentration of 20∶3ω6, 20∶4ω6, 20∶5ω3 and 22∶5ω3 in the plasma PL and a significant decrease in the proportion and content of 18∶2ω6. The addition of beef fat or olive oil to the diets containing lean beef did not alter the plasma PL fatty acid profile compared with the very low-fat diet, whereas the addition of safflower oil maintained the significant increases in 20∶4ω6 and 22∶5ω3 but led to decreases in 18∶3ω3 and 20∶5ω3 compared with the very lowfat diet. The results showed that diets rich in lean beef increased the 20∶3ω6, 20∶4ω6 and the long-chain ω3 PUFA levels in the plasma PL. A high level of linoleic acid in diets rich in lean beef prevented the rise in the plasma level of 20∶3ω6 and 20∶5ω3, two fatty acids known to antagonize the effects of 20∶4ω6 on platelet aggregation.     

Higher Lipophilic Index Indicates Higher Risk of Coronary Heart Disease in Postmenopausal Women

Fatty acids (FAs) are essential components of cell membranes and play an integral role in membrane fluidity. The lipophilic index [LI, defined as the sum of the products between FA levels and melting points (°C), divided by the total amount of FA: \({\text{LI}} = \frac{{\mathop \sum \nolimits_{k} [{\text{fatty acid}} \times {\text{melting point}}]}}{{\mathop \sum \nolimits_{k} {\text{fatty acid}} }}\)] is thought to reflect membrane and lipoprotein fluidity and may be associated with the risk of coronary heart disease (CHD). Therefore, we examined the associations of dietary and plasma phospholipid (PL) LI with CHD risk among postmenopausal women. We determined dietary LI for the cohort with completed baseline food frequency questionnaires and free of prevalent cardiovascular diseases in the Women’s Health Initiative (WHI) observational study (N = 85,563). We additionally determined plasma PL LI in a matched case-control study (N = 2428) nested within the WHI observational cohort study. Cox proportional hazard regression and multivariable conditional logistic regression were used to calculate HRs/ORs for CHD risk between quartiles of LI after adjusting for potential sources of confounding and selection bias. Higher dietary LI in the cohort study and plasma PL LI in the case-control study were significantly associated with increased risk of CHD: HR = 1.18 (95% CI 1.07–1.31, P for trend <0.01) and OR = 1.76 (95% CI 1.33–2.33, P for trend <0.01) comparing extreme quartiles and adjusting for potential confounders. These associations still persisted after adjusting for the polyunsaturated to saturated fat ratio. Our study indicated that higher LI based on either dietary or plasma measurements, representing higher FA lipophilicity, was associated with elevated risk of CHD among postmenopausal women.     

Influence of dietary saturated fatty acids on the regulation of plasma cholesterol concentration

The specific effects of individual fatty acids (FA) on plasma cholesterol levels, in the range habitually consumed by humans, is not usually presented by the literature. Conclusions have been made regarding the cholesterolemic effect of individual FA, even though these FA cannot be tested individually. It appears that FA balance of the diet may be more important than individual FA intakes. Variation in plasma cholesterol response to diet is influenced by many factors, such as gene-nutrient interactions. The effect on human health of current processes used in the food industry that are certain to change dietary fat composition and TG structure is yet to be fully explored. Some of the relevant research regarding dietary fat and plasma cholesterol levels is reviewed.     

The prevention of alcoholic fatty liver using dietary supplements: Dihydroxyacetone,pyruvate and riboflavin compared to arachidonic acid in pair-fed rats

Male Sprague-Dawley rats were fed for 30 days a high-fat liquid ethanol diet with dihydroxyacetone, pyruvate and riboflavin added as supplements (AMA-). Plasma triglyceride (TG) levels were 6-fold greater in these rats than in those fed and alcohol with without the supplements (AA-). The liver TG content in rats fed the AMA-diet was similar to that of rats fed a control diet (CA-) in which alcohol was replaced with isocaloric amounts of dextrose. Livers of rats fed the AA- diet had 3 times more TG than controls. Alcohol ingestion also enhanced the hepatic content of cholesteryl esters (CE) and phospholipids (PL). These lipids were reduced to levels found in livers of rats fed the control diet (CA-) when dihydroxyacetone, pyruvate and riboflavin were included in the alcohol diet. The fatty acid compositions of TG, CE and PL from livers of rats fed the AMA-diet were similar to those of corresponding lipids from rats fed the control diet (CA-) but differed from compositions when fed the alcohol diet (AA-). Regardless of the diet fed, TG had the same fatty acid composition in plasma and liver. The same was true of PL fatty acid composition. However, the fatty acid composition of CE differed between liver and plasma. The major fatty acid in liver CE was 18∶1 whereas in plasma it was arachidonic acid (20∶4). Reduced fatty liver was observed in an earlier study when rats were fed ad libitum an ethanol diet containing 20∶4. In the present study, we pair-fed the same diet and fatty liver was not reduced. Dihydroxyacetone, pyruvate and riboflavin did not prevent alcohol-induced fatty liver when 20∶4 was included in the AMA-diet. Our results confirm that dietary dihydroxyacetone, pyruvate and riboflavin prevent alcohol-induced fatty liver, and show that this effect may result from increased mobilization of fat from liver.     

Kidney lipids: Changes caused by dietary 9-Trans, 12-Trans-octadecadienoate

Trans, trans-linoleate at 50 and 100% of dietary fat decreased kidney size and altered its composition.Trans, trans-linoleate as the sole source of dietary fat imparied growth and caused more severe symptoms of essential fatty acid deficiency than was observed with hydrogenated coconut oil (HCO). The concentration of renal cholesterol, phospholipids (PL), triglycerides (TG) and cholesteryl esters (CE) were also decreased. Linoleic (18∶2), homo-γ-linolenic acid (20∶3n6) and arachidonic acid (20∶4n6) were significantly depressed in lipid classes, especially in PL and CE, by dietarytrans, trans-linoleate. The increase in eicosatrienoate (20∶3n9), especially in PL and CE of kidneys of rats fed HCO (essential fatty acid deficient), was slight in rats fed 100%trans, trans-linoleate, indicating that thetrans, trans acid probably inhibited acyl elongation and desaturation.     

Phospholipid class and FA compositions of modified soybeans processed with two extraction methods

Soybean lecithin is used as an emulsifier in food, cosmetic, and pharmaceutical industries. The proportion of individual phospholipids (PL) and their FA composition may affect the functional properties of lecithin. In this research, lecithins recovered from four modified soybeans and one commodity soybean, which were processed by extrusion-expelling and conventional solvent extraction, were analyzed for proportion of PL class and FA composition. HPLC with an ELSD analysis demonstrated that the percentage of PC in extrusion-expelled lecithin was higher than in solvent-extracted lecithin, whereas the PE content was lower. GC analysis showed that FA compositions of the PL varied with soybean type. The oil extraction method did not significantly affect FA composition. Critical micelle concentration tested with a tensiometer showed differences among the lecithins.     

Hyperphagia modifies FA profiles of plasma phospholipids,plasma FFA,and adipose tissue TAG

Hyperphagia was achieved by continuous intracerebroventricular infusion of a melanocortin receptor antagonist (HS024; Neosystem, Strasbourg, France) in rats. The effects of hyperphagia on FA composition and concentration of plasma phospholipids (PL), plasma FFA, and adipose tissue TAG were studied in rats for 8 d [short-term hyperphagia (STH); n=8], or 28 d [longterm hyperphagia (LTH); n=9]. The control rats were treated with artificial cerebrospinal fluid for 8 d (n=8) or 28 d (n=10). The rats were fed the same regular diet. In STH rats the plasma PL and fasting plasma FFA contained higher concentrations of saturated FA (SFA) and monounsaturated FA (MUFA), and plasma FFA contained lower n−6 PUFA than in the control rats. In LTH rats the plasma PL contained higher concentrations of SFA, MUFA, and n−3 PUFA and higher proportions of 16∶1n−7 and 18∶1n−9 at the expense of 18∶2n−6 than in the control rats. In LTH rats the abundant dietary intake of 18∶2n−6 did not enrich 18∶2n−6 of the plasma PL or adipose tissue TAG. In LTH rats the fasting plasma FFA contained more than twofold higher concentrations of SFA and MUFA, and higher proportions of 16∶1n−7 and 18∶1n−9 at the expense of 18∶2n−6 than in the control rats. This animal obesity model shows that LTH affects the FA composition and concentration of plasma PL, plasma FFA, and adipose tissue TAG, a result consistent with changes associated with increased risk of various diseases in humans. These results also demonstrate that LTH alters the FA composition of plasma PL and adipose tissue TAG in a way that does not reflect the FA composition of dietary fat.     

Fatty acid profiles of 80 vegetable oils with regard to their nutritional potential

The current concern for fat intake in western countries has raised the question of the individual fatty acid (FA) impact on health. This important issue has strengthened the awareness of nutritionists and food manufacturers for the control of the FA profile of food products. The aim of this review is to provide a classification of the FA profiles of 80 vegetable oil sources, according to their nutritional potential. The first part of the review focuses on lipoprotein metabolism, and on the impact of each dietary FA on blood lipid composition (LDL‐cholesterol, HDL‐cholesterol and circulating triacylglycerols). In the second part of the review, the oil sources are clustered by similar FA profiles, and the classification is discussed with regard to the individual FA action on blood lipid composition. Apart from the major vegetable seeds, the clustering highlighted some interesting nutritional oil sources containing mainly α‐linolenic acid (camelina, linseed, perilla and stock oils), or interesting amounts of the two essential FA (purslane, chia, raspberry seed, sea buckthorn seed and salicorn oils). Furthermore, this classification provides a useful tool for the formulation of the FA profile of food products.     

The types of circulating fatty acids influence vascular reactivity

The objective of this study was to investigate the relationship between the composition of FA in serum lipids, a marker of dietary fat intake, and vascular reactivity using a combination of cross-sectional and intervention approaches. Fifty-six middle-aged subjects were evaluated in a cross-sectional protocol regarding the relationship between the proportion of FA in serum cholesterol esters and vascular reactivity using measurements of forearm blood flow (FBF) with venous occlusion plethysmography during hyperemia. Another 19 middle-aged subjects were given a rapeseed oil-based diet rich in mono-and polyunsaturated FA or a control diet rich in saturated FA during two consecutive 4-wk periods separated by a 4-wk washout period. In the cross-sectional protocol, the FA 18:0 and 20:3 were positively related to resting FBF, whereas an inverse relationship was seen for the FA 20:5 and 22:6 (P<0.05−0.01). Opposite relationships were seen between these four FA and the relative increase in maximal FBF during hyperemia (P<0.05−0.01). In the intervention protocol, the saturated diet increased resting FBF, as well as the relative increase in maximal FBF during reactive hyperemia, compared to the diet rich in unsaturated FA (P<0.05). Both the cross-sectional and intervention data support the view that the composition of serum FA, which at least partly reflects the quality of dietary fat, plays a role in determinations of vascular reactivity.     

The Distribution of Fatty Acid Biomarkers of Dairy Intake across Serum Lipid Fractions: The Prospective Metabolism and Islet Cell Evaluation (PROMISE) Cohort

Circulating fatty acids (FA) derived largely from dairy consumption have most commonly been measured in total human serum or phospholipid (PL) fractions, and have been used as validated biomarkers of dairy intake in a growing number of epidemiological studies. Nevertheless, measurement and characterization of a wider spectrum of FA biomarkers of dairy across the four major serum lipid fractions is lacking. This study aimed to (1) quantify FA biomarkers of dairy in PL, triacylglycerol (TAG), cholesteryl ester (CE), and unesterified fatty acid (FFA) serum lipid fractions; and (2) identify potential demographic and metabolic factors that may modify the proportions of these FA across serum fractions. Baseline data from 444 adults in the PROMISE cohort were analyzed. FA biomarkers, 15:0, t16:1n-7, 18:2-c9,t11, and t18:1n-7 were quantified from serum. Dairy intake was estimated using the validated Canadian Diet History Questionnaire. Our results show that t18:1n-7 was the most abundant FA biomarker in all fractions except CE, where 18:2-c9,t11 was the most abundant. Positive correlations within fractions, and across FA in the PL, CE, and FFA fractions were found, however, TAG FA were negatively correlated with the other fractions. PL and CE FA were positively associated with dairy intake, and negatively associated with markers of dysmetabolism while, in contrast, these markers were predictors of higher TAG dairy FA. This study is the first to demonstrate distinct proportions of dairy FA in different serum lipid fractions. PL and CE FA marked dairy intake in this cohort, while TAG FA appeared to be markers of dysmetabolism.     

Effect of the nature and amount of dietary energy on lipid composition of rat bone marrow

The effect of the nature and amount of dietary calories on the lipid composition of bone marrow of rats was studied. Male weanling rats were fed 3 isocaloric diets, containing high carbohydrate, normal protein, and high protein, and a fourth high fat diet for 49 days. Feeding of the high carbohydrate, high protein, and high fat diets caused a significant increase in the level of total lipids compared to the normal protein diet. This increase of total lipids was due primarily to the increase in the level of triglycerides. There was no significant difference in fatty acid composition of either nonpolar or polar lipids of bone marrow among rats fed high carbohydrate diet and those fed normal protein diet. A comparison of fatty acid compositions between bone marrow lipids of rats fed high protein diet and the other 2 isocaloric diets revealed that the proportion of palmitic acid was higher and the proportion of oleic acid was lower in animals fed high protein diet than in animals fed the other 2 diets. Compared to the 3 isocaloric low fat diets, dietary feeding of high fat diet caused a decrease in the proportion of palmitic and palmitoleic acids and an increase in the proportion of oleic and linoleic acids in total fatty acids of both nonpolar and polar lipids.