Novel methodologies for assessing omega-3 fatty acid status - a systematic review

A health technology assessment of personalized nutrition interventions using the EUnetHTA HTA Core Model

OBJECTIVES

Poor nutrition links to chronic diseases, emphasizing the need for optimized diets. The EU-funded project PREVENTOMICS, introduced personalized nutrition to address this. This study aims to perform a health technology assessment (HTA) comparing personalized nutrition interventions developed through this project, with non-personalized nutrition interventions (control) for people with normal weight, overweight, or obesity. The goal is to support decisions about further development and implementation of personalized nutrition.

METHODS

The PREVENTOMICS interventions were evaluated using the European Network for HTA Core Model, which includes a methodological framework that encompasses different domains for value assessment. Information was gathered via [1] different statistical analyses and modeling studies, [2] questions asked of project partners and, [3] other (un)published materials.

RESULTS

Clinical trials of PREVENTOMICS interventions demonstrated different body mass index changes compared to control; differences ranged from -0.80 to 0.20 kg/m2. Long-term outcome predictions showed generally improved health outcomes for the interventions; some appeared cost-effective (e.g., interventions in UK). Ethical concerns around health inequality and the lack of specific legal regulations for personalized nutrition interventions were identified. Choice modeling studies indicated openness to personalized nutrition interventions; decisions were primarily affected by intervention's price.

CONCLUSIONS

PREVENTOMICS clinical trials have shown promising effectiveness with no major safety concerns, although uncertainties about effectiveness exist due to small samples (n=60-264) and short follow-ups (10-16 weeks). Larger, longer trials are needed for robust evidence before implementation could be considered. Among other considerations, developers should explore financing options and collaborate with policymakers to prevent exclusion of specific groups due to information shortages.

Main nutritional deficiencies

Nutrition is the source of energy that is required to carry out all the processes of human body. A balanced diet is a combination of both macro- and micronutrients. "Nutritional inadequacy" involves an intake of nutrients that is lower than the estimated average requirement, whereas "nutritional deficiency" consists of severely reduced levels of one or more nutrients, making the body unable to normally perform its functions and thus leading to an increased risk of several diseases like cancer, diabetes, and heart disease. Malnutrition could be caused by environmental factors, like food scarcity, as well as disease conditions, like anorexia nervosa, fasting, swallowing inability, persistent vomiting, impaired digestion, intestinal malabsorption, or other chronic diseases. Nutritional biomarkers - like serum or plasma levels of nutrients such as folate, vitamin C, B vitamins, vitamin D, selenium, copper, zinc - could be used for the evaluation of nutrient intake and dietary exposure. Macronutrients deficiencies could cause kwashiorkor, marasmus, ketosis, growth retardation, wound healing, and increased infection susceptibility, whereas micronutrient - like iron, folate, zinc, iodine, and vitamin A - deficiencies lead to intellectual impairment, poor growth, perinatal complications, degenerative diseases associated with aging and higher morbidity and mortality. Preventing macro- and micronutrient deficiency is crucial and this could be achieved through supplementation and food-based approaches.

Ultralong TE In Vivo 1 H MR Spectroscopy of Omega-3 Fatty Acids in Subcutaneous Adipose Tissue at 7 T

BACKGROUND

Omega-3 (n-3) fatty acids (FA) play and important role in neural development and other metabolic diseases such as obesity and diabetes. The knowledge about the in vivo content and distribution of n-3 FA in human body tissues is not well established and the standard quantification of FA is invasive and costly.

PURPOSE

To detect omega-3 (n-3 CH3 ) and non-omega-3 (CH3 ) methyl group resonance lines with echo times up to 1200 msec, in oils, for the assessment of n-3 FA content, and the n-3 FA fraction in adipose tissue in vivo.

STUDY TYPE

Prospective technical development.

POPULATION

Three oils with different n-3 FA content and 24 healthy subjects.

FIELD STRENGTH/SEQUENCE

Single-voxel MR spectroscopy (SVS) with a point-resolved spectroscopy (PRESS) sequence with an echo time (TE) of 1000 msec at 7 T.

ASSESSMENT

Knowledge about the J-coupling evolution of both CH3 resonances was used for the optimal detection of the n-3 CH3 resonance line at a TE of 1000 msec. The accuracy of the method in oils and in vivo was validated from a biopsy sample with gas chromatography analysis.

STATISTICAL TESTS

SVS data were compared to gas chromatography with the Pearson correlation coefficient.

RESULTS

T2 relaxation times in oils were assessed as follows: CH2 , 65 ± 22 msec; CH3 , 325 ± 7 msec; and n-3 CH3 , 628 ± 34 msec. The n-3 FA fractions from oil phantom experiments (n = 3) were in agreement with chromatography analysis and the comparison of in vivo obtained data with the results of chromatography analysis (n = 5) yielded a significant correlation (P = 0.029).

DATA CONCLUSION

PRESS with ultralong-TE can detect and quantify the n-3 CH3 signal in vivo at 7 T.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:71-82.

Considerations for Secondary Prevention of Nutritional Deficiencies in High-Risk Groups in High-Income Countries

Surveys in high-income countries show that inadequacies and deficiencies can be common for some nutrients, particularly in vulnerable subgroups of the population. Inadequate intakes, high requirements for rapid growth and development, or age- or disease-related impairments in nutrient intake, digestion, absorption, or increased nutrient losses can lead to micronutrient deficiencies. The consequent subclinical conditions are difficult to recognize if not screened for and often go unnoticed. Nutrient deficiencies can be persistent despite primary nutrition interventions that are aimed at improving dietary intakes. Secondary prevention that targets groups at high risk of inadequacy or deficiency, such as in the primary care setting, can be a useful complementary approach to address persistent nutritional gaps. However, this strategy is often underestimated and overlooked as potentially cost-effective means to prevent future health care costs and to improve the health and quality of life of individuals. In this paper, the authors discuss key appraisal criteria to consider when evaluating the benefits and disadvantages of a secondary prevention of nutrient deficiencies through screening.

Whole blood glycerophospholipids in dried blood spots - a reliable marker for the fatty acid status

BACKGROUND

Whole blood total fatty acid analysis in capillary blood has recently been proposed for fatty acid status determination, but the accuracy of this method is affected by the fast turnover of triaclyglyceride (TAG) fatty acids, the individual hematocrit and postprandial state.

METHOD

An established method for the glycerophospholipid (GPL) analysis in plasma was adapted for the analysis of whole blood GPL and tested in a fat challenge test. Blood samples were collected from nine participants after receiving a standardised breakfast containing 42g of sunflower oil. Whole blood GPL fatty acids were compared against whole blood total lipid, plasma TAG and phospholipid fatty acids.

RESULTS

All fatty acid concentrations in dried blood samples showed a coefficient of variation <5.7%. The fat challenge test induced a significant increase of TAG fatty acid concentration (mean Δ=42.3%±35.7) and whole blood total fatty acid concentration (mean Δ=5.2%±3.7) whereas whole blood GPL fatty acids were hardly changed (mean Δ=1.3%±1.6).

CONCLUSION

Whole blood GPL fatty acids are a robust biological marker for the fatty acid status of fasted and non-fasted subjects. The influence of very recent dietary intake on whole blood GPL is smaller than on whole blood total lipids.

Evaluation of less invasive methods to assess fatty acids from phospholipid fraction: cheek cell and capillary blood sampling

Plasma is the most commonly employed matrix for analyzing fatty acids (FAs), but its extraction is not well accepted in the infant population. The objectives of this study were to evaluate cheek cells and capillary blood as alternatives to plasma sampling for FA analysis and to standardize the methodology. Samples were obtained from 20 children who underwent lipid extraction, phospholipid isolation by Solid Phase Extraction (SPE) in a 96-well plate, methylation, and analysis by fast gas chromatography (GC). A positive correlation was found for most of the FAs, especially long-chain polyunsaturated fatty acids (LC-PUFAs), in cheek cells and capillary blood versus plasma samples (r = 0.32-0.99). No differences were found in the levels of n-6: n-3 PUFA and n-6: n-3 LC-PUFA ratios between cheek cells and capillary blood. These two proposed samples can therefore be used as alternatives to plasma sampling for phospholipid FA analysis, especially LC-PUFAs.

Omega-3 fatty acids moderate effects of physical activity on cognitive function

Greater amounts of physical activity (PA) and omega-3 fatty acids have both been independently associated with better cognitive performance. Because of the overlapping biological effects of omega-3 fatty acids and PA, fatty acid intake may modify the effects of PA on neurocognitive function. The present study tested this hypothesis by examining whether the ratio of serum omega-6 to omega-3 fatty acid levels would moderate the association between PA and executive and memory functions in 344 participants (Mean age=44.42 years, SD=6.72). The Paffenbarger Physical Activity Questionnaire (PPAQ), serum fatty acid levels, and performance on a standard neuropsychological battery were acquired on all subjects. A principal component analysis reduced the number of cognitive outcomes to three factors: n-back working memory, Trail Making test, and Logical Memory. We found a significant interaction between PA and the ratio of omega-6 to omega-3 fatty acid serum levels on Trail Making performance and n-back performance, such that higher amounts of omega-3 levels offset the deleterious effects of lower amounts of PA. These effects remained significant in a subsample (n=299) controlling for overall dietary fat consumption. There were no significant additive or multiplicative benefits of higher amounts of both omega-3 and PA on cognitive performance. Our results demonstrate that a diet high in omega-3 fatty acids might mitigate the effect of lower levels of PA on cognitive performance. This study illuminates the importance of understanding dietary and PA factors in tandem when exploring their effects on neurocognitive health.

B vitamin and/or n-3 fatty acid supplementation and health-related quality of life: ancillary findings from the SU.FOL.OM3 randomized trial

Background

Despite growing attention to nutrition and quality of life in cardiovascular disease survivors, the impact of dietary factors according to disease type or to quality of life domain is poorly understood. We investigated the effects of B vitamin and/or n-3 fatty acid supplementation on health-related quality of life among survivors of stroke, myocardial infarction, or unstable angina.

Methods

We performed ancillary analyses of the SU.FOL.OM3 trial (2003–2009; France). In total, 2,501 men (mean age = 61 y) and women (mean age = 63 y) were randomized in a 2×2 factorial design to: 1) 0.56 mg 5-methyl-tetrahydrofolate, 3 mg vitamin B6, 0.02 mg vitamin B12; 2) 600 mg eicosapentaenoic and docosahexaenoic acids in a 2∶1 ratio; 3) B vitamins and n-3 fatty acids combined; or 4) placebo. Health-related quality of life was evaluated at follow-up with the Medical Outcomes Study 36-Item Short Form Health Survey. Data from 2,029 individuals were used in this analysis.

Results

After 3.1±0.4 y, no effects of supplementation with either B vitamins or n-3 fatty acids on quality of life (physical or mental health domains) were found. However, participants receiving B vitamins had slightly more activity limitations due to emotional problems compared with those not receiving B vitamins (mean difference = 3.8; 95% CI: 0.4, 7.1). A significant interaction of treatment by prior disease revealed an inverse association between n-3 fatty acids and vitality among myocardial infarction survivors (mean difference = 2.9; 95% CI: 0.5, 5.2).

Conclusions

There were no beneficial effects of supplementation with relatively low doses of B vitamins or n-3 fatty acids on health-related quality of life in cardiovascular disease survivors. The adverse effects of B vitamins on activity limitations and of n-3 fatty acids on vitality among individuals with prior myocardial infarction merit confirmation.

Content of trans fatty acids in human cheek epithelium: comparison with serum and adipose tissue

Studies pertaining to trans fatty acids (TFA), which have been implicated in development of chronic diseases, are more relevant in developing countries where nutrition transition is changing traditional habits and practices. Measuring TFA is an arduous task because of the need for fat biopsies. This study identifies a tissue, which can be easily accessed for analytical measurement of trans fatty acid. In this cross-sectional study, fatty acid in adipose tissue, cheek epithelium, and blood samples were assessed by gas chromatography. Spearman correlation coefficient was computed to study the correlation of fatty acid distribution among the three tissues. The correlation coefficient of total trans fatty acid between cheek epithelium and serum was 0.30 (P < 0.02) and between cheek epithelium and adipose tissue was 0.33 (P < 0.019). This study is the first to report trans fatty acid profile in cheek epithelium giving scope for utilizing the cheek epithelium as a tissue for objective assessment of trans fatty acid intake.

Cheek cell fatty acids reflect n-3 PUFA in blood fractions during linseed oil supplementation: a controlled human intervention study

Background

Adequate biomarkers for the dietary supply of fatty acids (FA) are FA of adipose tissue and blood fractions. In human studies, invasive sample collection is unpleasant for subjects. In contrast, cheek cell sampling can be considered as a non-invasive alternative to investigate FA status.

The aim of this study was to analyze whether cheek cell FA composition reflect the supplementation of alpha-linolenic acid (ALA) using a linseed oil mixture compared to olive oil supplementation. Additionally, it was investigated if cheek cell FA composition correlates with the FA composition of plasma, red blood cells (RBC) and peripheral blood mononuclear cells (PBMC) before and during both interventions.

Methods

During a 10-week randomized, controlled, double-blind human intervention study, 38 subjects provided cheek cell and blood samples. After a two-week run-in period, the test group (n = 23) received 17 g/d of an ALA-rich linseed oil mixture, while the control group (n = 15) received 17 g/d of an omega-3 (n-3) polyunsaturated FA (PUFA)-free olive oil. Cheek cells and blood were collected on days 0, 7 and 56 of the 8-week intervention period.

Results

Compared to olive oil, the linseed oil intervention increased ALA and also the endogenously converted long-chain n-3 metabolites eicosatetraenoic-, eicosapentaenoic- and docosapentaenoic acid in cheek cells (P ≤ 0.05). Docosahexaenoic acid remained unchanged. Reflecting the treatment, the n-6/n-3 ratio decreased in the test group. In general, cheek cell FA reflected the changes of FA in blood fractions. Independent of treatment, significant correlations (P ≤ 0.05) of n-6 PUFA and n-3 PUFA between cheek cells and plasma, RBC and PBMC were found, except for linoleic acid and ALA.

Conclusions

The changes in FA composition of cheek cells confirmed that ALA from linseed oil increased endogenously derived n-3 PUFA in cheek cell lipids. These changes in cheek cells and their correlation to the respective FA in blood fractions indicate the cheek cell FA profile as an adequate non-invasive biomarker for short-term n-3 PUFA intake and metabolism. Therefore, cheek cell FA can be used in human intervention studies or large-scale epidemiological studies, especially for assessment of the n-3 PUFA status.

Trial registration

ClinicalTrials.gov, IDNCT01317290

Fatty acid analysis by high resolution gas chromatography and mass spectrometry for clinical and experimental applications

PURPOSE OF REVIEW

Quantitative fatty acid profiles analyzed via fatty acid methyl esters (FAME) are among the most common metabolite panels and fit into the category of omics techniques. Recently, preparation and analysis methods for high throughput clinical analysis have become routine, and novel methods for structure analysis enable rapid identification of unknowns and confounded peaks.

RECENT FINDINGS

Observation of one hundred FAME in a single mixture is common with high resolution capillary gas chromatography columns. Structural analysis of FAME requires high resolution gas chromatography with specialized tandem mass spectrometry to obtain fragments indicative of structure. Covalent adduct chemical ionization provides unambiguous double bond positions, whereas electron ionization with fragmentation of the molecular ion identifies branch points. Quantitative analysis requires response calibration using external standards and/or isotopically labeled internal standards with mass spectrometry detection.

SUMMARY

Modern high throughput methods enable routine analysis of well behaved clinical samples. Careful attention to structure analysis using recent methods avoids biases due to interfering or mischaracterized fatty acids.

Current evidence and future perspectives on n-3 PUFAs

The family of polyunsaturated fatty acids (PUFAs), which can be found in most lipid classes, includes n-3 PUFAs essential for mammals and whose deficiency is associated with multiple diseases. Because of their multiple physiological actions, n-3 PUFAs play a crucial role in normal human metabolism as well as maintenance of a healthy status, with clinical effects that are not limited to the cardiovascular system but also include maternal and offspring health, growth and development, immune system disorders, cancer, cognitive function and psychological status. Multiple health organisations and scientific societies recommend increasing food-derived n-3 PUFA intake and also suggest that patients with documented coronary heart disease receive a minimum of 1000 mg/day of eicosapentaenoic acid and docosahexaenoic acid. The preventive and therapeutic effects of n-3 PUFAs appear to be largely dependent on the dosages employed and the characteristics of selected patients. So, in the era of personalised medicine, the time has come to move from generic advice to increase n-3 PUFA intake to a more evidence-based approach characterised by tailored indications to n-3 PUFA dietary or supplement consumption. This approach will require evaluation on a case-to-case basis the potential usefulness of n-3 PUFAs, taking into consideration their 'pleiotropic effects', the optimal dose for any given indication in relation to international guidelines, potential interactions with background therapy, possible side effects, differences in genetics and dietary response to supplementation, and the cost:benefit ratio, which is likely to vary as a function of differences in the range of fish intake in the diet.

Total Serum Fatty Acid Analysis by GC-MS: Assay Validation and Serum Sample Stability

Analysis of n3 fatty acids in serum samples has clinical applications in supplementation trials, but the analysis can be challenging due to low levels, stability issues and intra-individual variation. This study presents the single laboratory validation of a gas chromatographic-mass spectral (GC-MS) assay for analysis of fatty acid methyl esters (FAME) using sensitive single ion monitoring and provides data on fatty acid stability under different sample handling conditions. Recovery of total fatty acids from serum with Folch extraction was optimized and parallelism tests with spiked samples indicated that the serum matrix did not interfere with mass spectral quantitation. Precision and accuracy of the assay at the lowest limit of quantitation and at low, medium and high levels met with accepted guidelines for single laboratory validation. Several storage conditions that can be encountered with clinical samples also were evaluated for impact on fatty acid levels in serum. Serum from blood that was stored refrigerated for 3 days yielded similar results as serum that was prepared and frozen at -80°C immediately. Serum storage at room temperature for 3-24 hours and serum subjected to one freeze/thaw cycle had minimal effects on fatty acid levels. The intra-individual variability in pregnant women was reasonably small, with significant correlation coefficients ranging from 0.35 to 0.76 for blood drawn between 12-20 weeks versus 34-36 weeks of gestation. These results indicate that GC-MS with single ion monitoring is valid for the analysis of total fatty acids in clinical samples, even when blood processing cannot be performed in a timely manner.

Development and validation of a robust automated analysis of plasma phospholipid fatty acids for metabolic phenotyping of large epidemiological studies

A fully automated, high-throughput method was developed to profile the fatty acids of phospholipids from human plasma samples for application to a large epidemiological sample set (n > 25,000). We report here on the data obtained for the quality-control materials used with the first 860 batches, and the validation process used. The method consists of two robotic systems combined with gas chromatography, performing lipid extraction, phospholipid isolation, hydrolysis and derivatization to fatty-acid methyl esters, and on-line analysis. This is the first report showing that fatty-acid profiling is an achievable strategy for metabolic phenotyping in very large epidemiological and genetic studies.

Efficient and specific analysis of red blood cell glycerophospholipid fatty acid composition

Background

Red blood cell (RBC) n-3 fatty acid status is related to various health outcomes. Accepted biological markers for the fatty acid status determination are RBC phospholipids, phosphatidylcholine, and phosphatidyletholamine. The analysis of these lipid fractions is demanding and time consuming and total phospholipid n-3 fatty acid levels might be affected by changes of sphingomyelin contents in the RBC membrane during n-3 supplementation.

Aim

We developed a method for the specific analysis of RBC glycerophospholipids. The application of the new method in a DHA supplementation trial and the comparison to established markers will determine the relevance of RBC GPL as a valid fatty acid status marker in humans.

Methods

Methyl esters of glycerophospholipid fatty acids are selectively generated by a two step procedure involving methanolic protein precipitation and base-catalysed methyl ester synthesis. RBC GPL solubilisation is facilitated by ultrasound treatment. Fatty acid status in RBC glycerophospholipids and other established markers were evaluated in thirteen subjects participating in a 30 days supplementation trial (510 mg DHA/d).

Outcome

The intra-assay CV for GPL fatty acids ranged from 1.0 to 10.5% and the inter-assay CV from 1.3 to 10.9%. Docosahexaenoic acid supplementation significantly increased the docosahexaenoic acid contents in all analysed lipid fractions. High correlations were observed for most of the mono- and polyunsaturated fatty acids, and for the omega-3 index (r = 0.924) between RBC phospholipids and glycerophospholipids. The analysis of RBC glycerophospholipid fatty acids yields faster, easier and less costly results equivalent to the conventional analysis of RBC total phospholipids.