EPA and DHA are required for normal cell function and can also induce health benefits. Oily fish are the main source of EPA and DHA for human consumption. However, food choices and concerns about the sustainability of marine fish stocks limit the effectiveness of dietary recommendations for EPA + DHA intakes. Seed oils from transgenic plants that contain EPA + DHA are a potential alternative source of EPA and DHA. The present study investigated whether dietary supplementation with transgenic Camelina sativa seed oil (CSO) that contained EPA and DHA was as effective as fish oil (FO) in increasing EPA and DHA concentrations when consumed as a dietary supplement in a blinded crossover study. Healthy men and women (n 31; age 53 (range 20–74) years) were randomised to consume 450 mg/d EPA + DHA provided either as either CSO or FO for 8 weeks, followed by 6 weeks washout and then switched to consuming the other test oil. Fasting venous blood samples were collected at the start and end of each supplementation period. Consuming the test oils significantly (P < 0·05) increased EPA and DHA concentrations in plasma TAG, phosphatidylcholine and cholesteryl esters. There were no significant differences between test oils in the increments of EPA and DHA. There was no significant difference between test oils in the increase in the proportion of erythrocyte EPA + DHA (CSO, 12 %; P < 0·0001 and FO, 8 %; P = 0·02). Together, these findings show that consuming CSO is as effective as FO for increasing EPA and DHA concentrations in humans.

n-3 Fatty acids are associated with better cardiovascular and cognitive health. However, the concentration of EPA, DPA and DHA in different plasma lipid pools differs and factors influencing this heterogeneity are poorly understood. Our aim was to evaluate the association of oily fish intake, sex, age, BMI and APOE genotype with concentrations of EPA, DPA and DHA in plasma phosphatidylcholine (PC), NEFA, cholesteryl esters (CE) and TAG. Healthy adults (148 male, 158 female, age 20–71 years) were recruited according to APOE genotype, sex and age. The fatty acid composition was determined by GC. Oily fish intake was positively associated with EPA in PC, CE and TAG, DPA in TAG, and DHA in all fractions (P≤0·008). There was a positive association between age and EPA in PC, CE and TAG, DPA in NEFA and CE, and DHA in PC and CE (P≤0·034). DPA was higher in TAG in males than females (P<0·001). There was a positive association between BMI and DPA and DHA in TAG (P<0·006 and 0·02, respectively). APOE genotype×sex interactions were observed: the APOE4 allele associated with higher EPA in males (P=0·002), and there was also evidence for higher DPA and DHA (P≤0·032). In conclusion, EPA, DPA and DHA in plasma lipids are associated with oily fish intake, sex, age, BMI and APOE genotype. Such insights may be used to better understand the link between plasma fatty acid profiles and dietary exposure and may influence intake recommendations across population subgroups.

Type 2 diabetes (T2D) is a major risk factor of CVD. The effects of purified sardine proteins (SP) were examined on glycaemia, insulin sensitivity and reverse cholesterol transport in T2D rats. Rats fed a high-fat diet (HFD) for 5 weeks, and injected with a low dose of streptozotocin, were used. The diabetic rats were divided into four groups, and they were fed casein (CAS) or SP combined with 30 or 5 % lipids, for 4 weeks. HFD-induced hyperglycaemia, insulin resistance and hyperlipidaemia in rats fed HFD, regardless of the consumed protein. In contrast, these parameters lowered in rats fed SP combined with 5 or 30 % lipids, and serum insulin values reduced in SP v. CAS. HFD significantly increased total cholesterol and TAG concentrations in the liver and serum, whereas these parameters decreased with SP, regardless of lipid intake. Faecal cholesterol excretion was higher with SP v. CAS, combined with 30 or 5 % lipids. Lecithin:cholesterol acyltransferase (LCAT) activity and HDL3-phospholipids (PL) were higher in CAS-HF than in CAS, whereas HDL2-cholesteryl esters (CE) were lower. Otherwise, LCAT activity and HDL2-CE were higher in the SP group than in the CAS group, whereas HDL3-PL and HDL3-unesterified cholesterol were lower. Moreover, LCAT activity lowered in the SP-HF group than in the CAS-HF group, when HDL2-CE was higher. In conclusion, these results indicate the potential effects of SP to improve glycaemia, insulin sensitivity and reverse cholesterol transport, in T2D rats.

Epidemiological studies fairly convincingly suggest that higher intakes of fatty fish and n-3 fatty acids are associated with reduced risk of Alzheimer's disease (AD). DHA in plasma is normally positively associated with DHA intake. However, despite being associated with lower fish and DHA intake, unexpectedly, plasma (or brain) DHA is frequently not lower in AD. This review will highlight some metabolic and physiological factors such as ageing and apoE polymorphism that influence DHA homeostasis. Compared with young adults, blood DHA is often slightly but significantly higher in older adults without any age-related cognitive decline. Higher plasma DHA in older adults could be a sign that their fish or DHA intake is higher. However, our supplementation and carbon-13 tracer studies also show that DHA metabolism, e.g. transit through the plasma, apparent retroconversion and β-oxidation, is altered in healthy older compared with healthy young adults. ApoE4 increases the risk of AD, possibly in part because it too changes DHA homeostasis. Therefore, independent of differences in fish intake, changing DHA homeostasis may tend to obscure the relationship between DHA intake and plasma DHA which, in turn, may contribute to making older adults more susceptible to cognitive decline despite older adults having similar or sometimes higher plasma DHA than in younger adults. In conclusion, recent development of new tools such as isotopically labelled DHA to study DHA metabolism in human subjects highlights some promising avenues to evaluate how and why DHA metabolism changes during ageing and AD.

The developing fetus requires an adequate supply of fatty acids, in particular PUFA, for optimal growth and development. Little is known about the transfer of fatty acids by the placenta into the fetal circulation. However, the molecular form in which fatty acids are transferred into the fetal circulation may influence their metabolism and hence their availability to specific tissues. The aim of the present study was to determine which lipid pools in the fetal circulation become enriched in fatty acids from the placenta by comparing the fatty acid compositions of individual lipid pools between umbilical venous (UV) and umbilical arterial (UA) plasma. Plasma from the UV and UA was collected after delivery from ten uncomplicated pregnancies, and the fatty acid composition of each lipid class was determined by GC. Total NEFA concentration in the UV was twofold higher than in the UA (P < 0·05) due to enrichment in 16 : 0, 16 : 1n-7, 18 : 1n-9, 18 : 1n-7, 18 : 2n-6, 20 : 3n-6, 20 : 4n-6, 24 : 0 and 22 : 6n-3. Total cholesteryl ester concentration was twofold higher in the UV than in the UA (P < 0·05) due to enrichment in 16 : 0, 16 : 1n-7, 18 : 0, 18 : 1n-9, 18 : 1n-7, 18 : 2n-6 and 20 : 4n-6. There were no significant UV–UA differences in the total concentration or composition of TAG or phosphatidylcholine. The present study demonstrates differential enrichment across the placenta of fatty acids into specific lipid pools in the fetal circulation. Such partitioning may facilitate supply of individual fatty acids to specific fetal tissues.