The fatty acid composition of subcutaneous fat in German adults

Statement on additional scientific evidence in relation to the essential composition of total diet replacement for weight control

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to revise the Opinion on the essential composition of total diet replacements for weight control (TDRs) regarding the minimum content of linoleic acid (LA) and alpha-linolenic acid (ALA) and the maximum content of magnesium (Mg). Through a comprehensive literature search, human studies were retrieved reporting on LA and ALA concentrations in adipose tissue (AT), on weight loss and gallstone formation following TDR consumption and on diarrhoea after supplemental Mg intake. The distribution of the amount of LA and ALA release from AT during weight loss when consuming TDRs was estimated using statistical simulations. Using the fifth percentile, the coverage of the adequate intake (AI) for both FA was estimated. For the risk of developing diarrhoea when consuming TDRs with an Mg content of 350 mg/day, four cross-over studies using 360-368 mg Mg/day were reviewed. The Panel concludes that (1) there is no need to add LA to TDRs, as the amount released from AT during weight loss when consuming TDRs is sufficient to cover the AI for LA; (2) a minimum of 0.8 g/day ALA is needed in TDRs in order to meet the AI for ALA; (3) the minimum fat content of TDRs of 20 g/day as derived in the Panel's previous opinion is proposed to be maintained until the availability of further evidence, given the considerable uncertainty as to the amount of fat required for reducing the risk of gallstone formation; and (4) the likelihood that Mg-induced diarrhoea occurs at a severity that may be considered of concern for overweight and obese individuals consuming TDRs is low when the total maximum Mg content in TDRs is 350 mg/day.

Seven Countries Study cohort in Crete, Greece: gluteal adipose-tissue fatty-acid profiles of survivors, at 2010

Objective

To analyse the gluteal adipose-tissue fatty-acid profiles from Cretan cohort survivors of the Seven Countries Study (SCS) at 2010 and to compare them with those of survivors assessed in 2000, as well as with literature data on male Cretans at 1965.

Design

We analysed data concerning the gluteal adipose-tissue fatty acids (analysed by GC) from three studies.

Setting

The island of Crete (rural areas and the city of Heraklion).

Subjects

Twenty-two of the 2010 SCS survivors aged 90 years and over; seventy-eight men aged 80 years of the 2000 SCS survivors; and 280 men assessed in 1965.

Results

In comparison to 1965 and 2000, the SCS survivors in 2010 had a higher amount of 18:1n-9 (P<0·05) in their gluteal adipose tissue and a lower amount of PUFA (P<0·05). On the other hand, a constant decrease in adipose-tissue 14:1n-5 and 16:1n-7 was recorded between 1965 and 2010 (P<0·001), and between 2000 and 2010 (P<0·05), while 18:2n-6 appeared to decrease between the 1965 and 2010 assessments (P<0·001).

Conclusions

Comparison with a 1965 representative Cretan sample and 2000 SCS survivors indicated an increased concentration of oleic acid (known for its protective role against mortality) and a decreased concentration of PUFA (known for their susceptibility to oxidation) in our surviving sample at 2010. These changes may reflect internal physiological processes due to diet change within these years and/or ageing.

Methods of assessment of n-3 long-chain polyunsaturated fatty acid status in humans: a systematic review

BACKGROUND

The availability of reliable biomarkers of n-3 (omega-3) long-chain polyunsaturated fatty acid (LCPUFA) status is a prerequisite for linking dietary n-3 LCPUFA status to clinical outcomes.

OBJECTIVE

The objective of this meta-analysis was to assess the usefulness of different biomarkers of n-3 LCPUFA status in healthy humans.

DESIGN

We searched Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases from inception to September 2007 for human intervention studies in which n-3 LCPUFA status changed after > or =2 wk of n-3 LCPUFA supplementation. We used formal inclusion/exclusion criteria and applied standard procedures for data extraction, validity assessment, and meta-analysis.

RESULTS

We included 41 studies (34 randomized controlled trials and 7 before-after studies) reporting on 18 different biomarkers. The data allowed specific evaluation of biomarkers of docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) status in response to supplementation. There were sufficient data to determine that plasma DHA, plasma phospholipid DHA, plasma triacylglycerol DHA, plasma cholesteryl ester DHA, plasma nonesterified DHA, erythrocyte DHA, erythrocyte phospholipid DHA, and platelet DHA were all effective biomarkers of DHA status and that plasma phospholipid EPA was an effective marker of EPA status. Plasma phospholipid DHA appears to be a good marker of DHA status in adult men and women irrespective of DHA baseline status or supplementation dose, but its usefulness in other population subgroups is unclear.

CONCLUSION

There appears to be a range of useful biomarkers of DHA status in humans, but further research is needed to characterize which work best in particular population subgroups.

Trans fatty acids: implications for health, analytical methods, incidence in edible fats and intake (a review)

Trans fatty acids (TFA) are supposed to be related to a variety of physiological effects. Numerous studies in this field are gathered and compared, which mainly deal with the influences on lipoprotein levels in plasma and their effects with regard to coronary heart diseases. Furthermore, the analytical accessibility of trans fatty acids by different methods is presented. Thus, the most reliable method for an exact quantitation of trans fatty acids in edible fats is the combination of Ag-TLC with GC. The contents of TFA, in particular trans-octadecenoic acids, in bovine and human milk fat, in partially hydrogenated vegetable fats and oils as well as in processed food from different countries, determined in numerous studies, are summarized. Especially results on the isomeric distribution of positional isomers of trans-octadecenoic acid may be of future interest, since negative metabolic activities might only originate from certain isomers. Finally, intake rates of TFA in several countries are presented. It can be concluded that there still is need for further nutritional studies and that the discussion about TFA should not neglect the comparison with the saturated fatty acids C12, C14 and C16.

Fatty acid composition of adipose tissue in humans. Implications for the dietary fat-serum cholesterol-CHD issue

Interest in studies of the fatty acid composition of adipose tissue has arised from the dietary fat-serum cholesterol-CHD issue. The fatty acid composition of depot fat reflects that of the diet. Gas chromatography analysis of subcutaneous adipose tissue yield objective and reliable information of the fatty acid composition of the habitual diet of individuals. A relative linoleic acid deficiency, as depicted by low adipose tissue linoleate levels, has not convincingly been demonstrated to be of importance in the aetiology of atherosclerosis or related disorders. Inverse correlation between n-3 fatty acids and coronary artery disease has been reported. Dietary supplementation of n-3 fatty acids may be of relevance, however the risk of hazardous side-effects do exist. In conclusion, a simple reduction of the total fat content of the diet still seems to be the most important strategy for prevention of atherosclerosis.

Trans monounsaturated fatty acids in nutrition and their impact on serum lipoprotein levels in man

Trans-C18:1 in the diet originate predominantly from partially hydrogenated oils, with beef, mutton and dairy products being an additional source. These fatty acids are absorbed and incorporated into lipids. Their estimated consumption is about 5-7% of total fatty acids, although reliable data are lacking. In addition, large variations between individuals exist. There is no evidence that trans fatty acids accumulate in human tissues. Elaidic acid and its positional isomers do, however, raise LDL cholesterol and apoprotein B and Lp(a) and probably depress HDL cholesterol and apoprotein A-I, compared with the cis isomer, oleic acid. In view of these adverse effects, patients at high risk for atherosclerosis, in addition to reducing their intake of saturated fatty acids and of cholesterol might also do well to avoid excessive intakes of trans fatty acids. Still, trans fatty acids form only a minor component of the diets of most patients and therefore even marked relative reductions in intake will probably have less of an impact on LDL cholesterol than a sizeable reduction in saturated fatty acids and cholesterol will produce.