Dietary α‐Linolenic Acid (ALA) is Sufficiently Converted to Docosahexaenoic Acid (DHA) to Increase Bioactive Lipids Derived from DHA
Bibliographic record
Abstract
Background There is considerable debate on whether α‐linolenic acid (ALA) can be sufficiently converted to docosahexaenoic acid (DHA) for optimal health. DHA has beneficial health effects and is critical for tissues such as the retina and brain. It produces bioactive lipids, such as resolvins, protectins and hydroxy DHA (HDoHE) with anti‐inflammatory, vasodilatory, anti‐aggregatory and anti‐proliferative effects. Many organizations worldwide provide recommendations for minimal DHA intake, but vegans, who consume little or no DHA, have shown no apparent detrimental health effects. Moreover, the Institute of Medicine Dietary Reference Intakes do not provide a minimum recommendation for DHA, and only have a recommendation for adequate ALA intake. Although dietary ALA generally does not significantly alter DHA levels, tissue fatty acid levels are not always an accurate indication of bioactive lipid levels. Therefore, the objective of this study was to determine whether dietary ALA can alter levels of DHA derived bioactive lipids (oxylipins) in normal rat tissues. Methods Weanling Sprague‐Dawley rats were provided diets based on the AIN93G diet. The isocaloric and isolipidic diets had oils (soy, olive, flax) containing adequate levels of ALA (0.3 g/100 g diet) or higher ALA (3.4 g/100 g diet), with ALA replacing monounsaturated fatty acids in the latter diet. Male and female rats were provided the diets ad libitum for 6 weeks, after which livers, kidneys and serum were collected for oxylipin analysis. Phospholipid fatty acids were purified from lipid extracts using TLC and quantified as fatty acid methyl esters by GLC. Oxylipins were extracted in methanolic solutions containing deuterated internal standards. After solid phase extraction, lipidomic analysis of >150 oxylipins was performed by HPLC/MS/MS, and those above the limit of quantification (LOQ) were quantified using the stable isotope dilution method. Approximately 100 oxylipins above the LOQ were detected in each of the 3 tissues. Results Consistent with many prior studies, providing a higher ALA diet resulted in higher phospholipid ALA and eicosapentaenoic acid (EPA) in all 3 tissues, and DHA concentrations were only higher in liver, but not in the kidney or serum. Providing higher dietary ALA also resulted in higher levels of all ALA derived oxylipins detected, and most of the EPA derived oxylipins in all 3 tissues. With respect to DHA oxylipins, however, despite not altering DHA levels, in the kidney 12 DHA oxylipins were (~20–100%) higher in rats provided high ALA. Similarly in serum, 9 DHA oxylipins were (~20–100%) higher in rats provided high ALA. In liver, despite differences in DHA, only 2 oxylipins derived from this fatty acid were altered by dietary ALA level. Conclusions These results illustrate that although dietary ALA may not alter tissue DHA concentrations, it does increase the levels of many oxylipins derived from DHA in kidney and serum. This indicates that the conversion from ALA to DHA is sufficient to increase production of DHA derived bioactive lipids in these tissues. These findings may have implications for dietary recommendations of n‐3 fatty acids. Support or Funding Information Natural Sciences and Engineering Research Council of Canada (NSERC)
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".