1
|
Rotarescu RD, Mathur M, Bejoy AM, Anderson GH, Metherel AH. Serum measures of docosahexaenoic acid (DHA) synthesis underestimates whole body DHA synthesis in male and female mice. J Nutr Biochem 2024; 131:109689. [PMID: 38876393 DOI: 10.1016/j.jnutbio.2024.109689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 06/06/2024] [Accepted: 06/09/2024] [Indexed: 06/16/2024]
Abstract
Females have higher docosahexaenoic acid (DHA) levels than males, proposed to be a result of higher DHA synthesis rates from α-linolenic acid (ALA). However, DHA synthesis rates are reported to be low, and have not been directly compared between sexes. Here, we apply a new compound specific isotope analysis model to determine n-3 PUFA synthesis rates in male and female mice and assess its potential translation to human populations. Male and female C57BL/6N mice were allocated to one of three 12-week dietary interventions with added ALA, eicosapentaenoic acid (EPA) or DHA. The diets included low carbon-13 (δ13C)-n-3 PUFA for four weeks, followed by high δ13C-n-3 PUFA for eight weeks (n=4 per diet, time point, sex). Following the diet switch, blood and tissues were collected at multiple time points, and fatty acid levels and δ13C were determined and fit to one-phase exponential decay modeling. Hepatic DHA synthesis rates were not different (P>.05) between sexes. However, n-3 docosapentaenoic acid (DPAn-3) synthesis from dietary EPA was 66% higher (P<.05) in males compared to females, suggesting higher synthesis downstream of DPAn-3 in females. Estimates of percent conversion of dietary ALA to serum DHA was 0.2%, in line with previous rodent and human estimates, but severely underestimates percent dietary ALA conversion to whole body DHA of 9.5%. Taken together, our data indicates that reports of low human DHA synthesis rates may be inaccurate, with synthesis being much higher than previously believed. Future animal studies and translation of this model to humans are needed for greater understanding of n-3 PUFA synthesis and metabolism, and whether the higher-than-expected ALA-derived DHA can offset dietary DHA recommendations set by health agencies.
Collapse
Affiliation(s)
- Ruxandra D Rotarescu
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada
| | - Mahima Mathur
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada
| | - Ashley M Bejoy
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada
| | - G Harvey Anderson
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada
| | - Adam H Metherel
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada.
| |
Collapse
|
2
|
Metherel AH, Valenzuela R, Klievik BJ, Cisbani G, Rotarescu RD, Gonzalez-Soto M, Cruciani-Guglielmacci C, Layé S, Magnan C, Mutch DM, Bazinet RP. Dietary docosahexaenoic acid (DHA) downregulates liver DHA synthesis by inhibiting eicosapentaenoic acid elongation. J Lipid Res 2024; 65:100548. [PMID: 38649096 PMCID: PMC11126934 DOI: 10.1016/j.jlr.2024.100548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 04/13/2024] [Accepted: 04/18/2024] [Indexed: 04/25/2024] Open
Abstract
DHA is abundant in the brain where it regulates cell survival, neurogenesis, and neuroinflammation. DHA can be obtained from the diet or synthesized from alpha-linolenic acid (ALA; 18:3n-3) via a series of desaturation and elongation reactions occurring in the liver. Tracer studies suggest that dietary DHA can downregulate its own synthesis, but the mechanism remains undetermined and is the primary objective of this manuscript. First, we show by tracing 13C content (δ13C) of DHA via compound-specific isotope analysis, that following low dietary DHA, the brain receives DHA synthesized from ALA. We then show that dietary DHA increases mouse liver and serum EPA, which is dependant on ALA. Furthermore, by compound-specific isotope analysis we demonstrate that the source of increased EPA is slowed EPA metabolism, not increased DHA retroconversion as previously assumed. DHA feeding alone or with ALA lowered liver elongation of very long chain (ELOVL2, EPA elongation) enzyme activity despite no change in protein content. To further evaluate the role of ELOVL2, a liver-specific Elovl2 KO was generated showing that DHA feeding in the presence or absence of a functional liver ELOVL2 yields similar results. An enzyme competition assay for EPA elongation suggests both uncompetitive and noncompetitive inhibition by DHA depending on DHA levels. To translate our findings, we show that DHA supplementation in men and women increases EPA levels in a manner dependent on a SNP (rs953413) in the ELOVL2 gene. In conclusion, we identify a novel feedback inhibition pathway where dietary DHA downregulates its liver synthesis by inhibiting EPA elongation.
Collapse
Affiliation(s)
- Adam H Metherel
- Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada.
| | | | - Brinley J Klievik
- Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | - Giulia Cisbani
- Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | | | - Melissa Gonzalez-Soto
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | | | - Sophie Layé
- INRA, Bordeaux INP, NutriNeuro, Université de Bordeaux, Bordeaux, France
| | | | - David M Mutch
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Richard P Bazinet
- Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
3
|
Smith ME, Chen CT, Gohel CA, Cisbani G, Chen DK, Rezaei K, McCutcheon A, Bazinet RP. Upregulated hepatic lipogenesis from dietary sugars in response to low palmitate feeding supplies brain palmitate. Nat Commun 2024; 15:490. [PMID: 38233416 PMCID: PMC10794264 DOI: 10.1038/s41467-023-44388-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 12/12/2023] [Indexed: 01/19/2024] Open
Abstract
Palmitic acid (PAM) can be provided in the diet or synthesized via de novo lipogenesis (DNL), primarily, from glucose. Preclinical work on the origin of brain PAM during development is scarce and contrasts results in adults. In this work, we use naturally occurring carbon isotope ratios (13C/12C; δ13C) to uncover the origin of brain PAM at postnatal days 0, 10, 21 and 35, and RNA sequencing to identify the pathways involved in maintaining brain PAM, at day 35, in mice fed diets with low, medium, and high PAM from birth. Here we show that DNL from dietary sugars maintains the majority of brain PAM during development and is augmented in mice fed low PAM. Importantly, the upregulation of hepatic DNL genes, in response to low PAM at day 35, demonstrates the presence of a compensatory mechanism to maintain total brain PAM pools compared to the liver; suggesting the importance of brain PAM regulation.
Collapse
Affiliation(s)
- Mackenzie E Smith
- Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, ON, Canada
| | - Chuck T Chen
- Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, ON, Canada
| | - Chiraag A Gohel
- Department of Biostatistics and Bioinformatics, George Washington University, 950 New Hampshire Ave, NW, Washington, DC, 20052, USA
| | - Giulia Cisbani
- Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, ON, Canada
| | - Daniel K Chen
- Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, ON, Canada
| | - Kimia Rezaei
- Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, ON, Canada
| | - Andrew McCutcheon
- Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, ON, Canada
| | - Richard P Bazinet
- Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, ON, Canada.
| |
Collapse
|
4
|
Metherel AH, Klievik BJ, Cisbani G, Smith ME, Cumberford G, Bazinet RP. Blood and tissue docosahexaenoic acid (DHA, 22:6n-3) turnover rates from Ahiflower® oil are not different than from DHA ethyl ester oil in a diet switch mouse model. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159422. [PMID: 37977491 DOI: 10.1016/j.bbalip.2023.159422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/19/2023]
Abstract
Ahiflower® oil is high in α-linolenic and stearidonic acids, however, tissue/blood docosahexaenoic acid (DHA, 22:6n-3) turnover from dietary Ahiflower oil has not been investigated. In this study, we use compound-specific isotope analysis to determine tissue DHA synthesis/turnover from Ahiflower, flaxseed and DHA oils. Pregnant BALB/c mice (13-17 days) were placed on a 2 % algal DHA oil diet of high carbon-13 content (δ13C) and pups (n = 132) were maintained on the diet until 9 weeks old. Mice were then randomly allocated to a low δ13C-n-3 PUFA diet of either: 1) 4 % Ahiflower oil, 2) 4.35 % flaxseed oil or 3) 1 % fish DHA ethyl ester oil for 1, 3, 7, 14, 30, 60 or 120 days (n = 6). Serum, liver, adipose and brains were collected and DHA levels and δ13C were determined. DHA concentrations were highest (p < 0.05) in the liver and adipose of DHA-fed animals with no diet differences in serum or brain (p > 0.05). Based on the presence or absence of overlapping 95 % C.I.'s, DHA half-lives and synthesis/turnover rates were not different between Ahiflower and DHA diets in the liver, adipose or brain. DHA half-lives and synthesis/turnover rates from flaxseed oil were significantly slower than from the DHA diet in all serum/tissues. These findings suggest that the distinct Ahiflower oil n-3 PUFA composition could support tissue DHA needs at a similar rate to dietary DHA, making it a unique plant-based dietary option for maintaining DHA turnover comparably to dietary DHA.
Collapse
Affiliation(s)
- Adam H Metherel
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada.
| | - Brinley J Klievik
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Giulia Cisbani
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Mackenzie E Smith
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Greg Cumberford
- Natures Crops International, Kensington, Prince Edward Island, Canada
| | - Richard P Bazinet
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
5
|
Chen DK, Metherel AH, Rezaei K, Parzanini C, Chen CT, Ramsden CE, Horowitz M, Faurot KR, MacIntosh B, Zamora D, Bazinet RP. Analysis of omega-3 and omega-6 polyunsaturated fatty acid metabolism by compound-specific isotope analysis in humans. J Lipid Res 2023; 64:100424. [PMID: 37572791 PMCID: PMC10507585 DOI: 10.1016/j.jlr.2023.100424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 08/07/2023] [Accepted: 08/08/2023] [Indexed: 08/14/2023] Open
Abstract
Natural variations in the 13C:12C ratio (carbon-13 isotopic abundance [δ13C]) of the food supply have been used to determine the dietary origin and metabolism of fatty acids, especially in the n-3 PUFA biosynthesis pathway. However, n-6 PUFA metabolism following linoleic acid (LNA) intake remains under investigation. Here, we sought to use natural variations in the δ13C signature of dietary oils and fatty fish to analyze n-3 and n-6 PUFA metabolism following dietary changes in LNA and eicosapentaenoic acid (EPA) + DHA in adult humans. Participants with migraine (aged 38.6 ± 2.3 years, 93% female, body mass index of 27.0 ± 1.1 kg/m2) were randomly assigned to one of three dietary groups for 16 weeks: 1) low omega-3, high omega-6 (H6), 2) high omega-3, high omega-6 (H3H6), or 3) high omega-3, low omega-6 (H3). Blood was collected at baseline, 4, 10, and 16 weeks. Plasma PUFA concentrations and δ13C were determined. The H6 intervention exhibited increases in plasma LNA δ13C signature over time; meanwhile, plasma LNA concentrations were unchanged. No changes in plasma arachidonic acid δ13C or concentration were observed. Participants on the H3H6 and H3 interventions demonstrated increases in plasma EPA and DHA concentration over time. Plasma δ13C-EPA increased in total lipids of the H3 group and phospholipids of the H3H6 group compared with baseline. Compound-specific isotope analysis supports a tracer-free technique that can track metabolism of dietary fatty acids in humans, provided that the isotopic signature of the dietary source is sufficiently different from plasma δ13C.
Collapse
Affiliation(s)
- Daniel K Chen
- Temerty Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | - Adam H Metherel
- Temerty Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | - Kimia Rezaei
- Temerty Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | - Camilla Parzanini
- Temerty Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | - Chuck T Chen
- Temerty Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | - Christopher E Ramsden
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging and National Institute on Alcohol Abuse and Alcoholism, NIH, Baltimore, MD, USA
| | - Mark Horowitz
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging and National Institute on Alcohol Abuse and Alcoholism, NIH, Baltimore, MD, USA
| | - Keturah R Faurot
- Department of Physical Medicine and Rehabilitation, Program on Integrative Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Beth MacIntosh
- Department of Physical Medicine and Rehabilitation, Program on Integrative Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA; Metabolic and Nutrition Research Core, UNC Medical Center, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Daisy Zamora
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging and National Institute on Alcohol Abuse and Alcoholism, NIH, Baltimore, MD, USA; Department of Psychiatry, UNC School of Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Richard P Bazinet
- Temerty Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada.
| |
Collapse
|
6
|
Klievik BJ, Tyrrell AD, Chen CT, Bazinet RP. Measuring brain docosahexaenoic acid turnover as a marker of metabolic consumption. Pharmacol Ther 2023:108437. [PMID: 37201738 DOI: 10.1016/j.pharmthera.2023.108437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/02/2023] [Accepted: 05/15/2023] [Indexed: 05/20/2023]
Abstract
Docosahexaenoic acid (DHA, 22:6n-3) accretion in brain phospholipids is critical for maintaining the structural fluidity that permits proper assembly of protein complexes for signaling. Furthermore, membrane DHA can by released by phospholipase A2 and act as substrate for synthesis of bioactive metabolites that regulate synaptogenesis, neurogenesis, inflammation, and oxidative stress. Thus, brain DHA is consumed through multiple pathways including mitochondrial β-oxidation, autoxidation to neuroprostanes, as well as enzymatic synthesis of bioactive metabolites including oxylipins, synaptamide, fatty-acid amides, and epoxides. By using models developed by Rapoport and colleagues, brain DHA loss has been estimated to be 0.07-0.26 μmol DHA/g brain/d. Since β-oxidation of DHA in the brain is relatively low, a large portion of brain DHA loss may be attributed to synthesis of autoxidative and bioactive metabolites. In recent years, we have developed a novel application of compound specific isotope analysis to trace DHA metabolism. By the use of natural abundance in 13C-DHA in food supply, we are able to trace brain phospholipid DHA loss in free-living mice with estimates ranging from 0.11 to 0.38 μmol DHA/g brain/d, in reasonable agreement with previous methods. This novel fatty acid metabolic tracing methodology should improve our understanding of the factors that regulate brain DHA metabolism.
Collapse
Affiliation(s)
- Brinley J Klievik
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Aidan D Tyrrell
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Chuck T Chen
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Richard P Bazinet
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8.
| |
Collapse
|
7
|
Lacombe RJS, Smith ME, Perlman K, Turecki G, Mechawar N, Bazinet RP. Quantitative and carbon isotope ratio analysis of fatty acids isolated from human brain hemispheres. J Neurochem 2023; 164:44-56. [PMID: 36196762 DOI: 10.1111/jnc.15702] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/22/2022] [Accepted: 09/29/2022] [Indexed: 02/04/2023]
Abstract
Our knowledge surrounding the overall fatty acid profile of the adult human brain has been largely limited to extrapolations from brain regions in which the distribution of fatty acids varies. This is especially problematic when modeling brain fatty acid metabolism, therefore, an updated estimate of whole-brain fatty acid concentration is necessitated. Here, we sought to conduct a comprehensive quantitative analysis of fatty acids from entire well-characterized human brain hemispheres (n = 6) provided by the Douglas-Bell Canada Brain Bank. Additionally, exploratory natural abundance carbon isotope ratio (CIR; δ13 C, 13 C/12 C) analysis was performed to assess the origin of brain fatty acids. Brain fatty acid methyl esters (FAMEs) were quantified by gas chromatography (GC)-flame ionization detection and minor n-6 and n-3 polyunsaturated fatty acid pentafluorobenzyl esters by GC-mass spectrometry. Carbon isotope ratio values of identifiable FAMEs were measured by GC-combustion-isotope ratio mass spectrometry. Overall, the most abundant fatty acid in the human brain was oleic acid, followed by stearic acid (STA), palmitic acid (PAM), docosahexaenoic acid (DHA), and arachidonic acid (ARA). Interestingly, cholesterol as well as saturates including PAM and STA were most enriched in 13 C, while PUFAs including DHA and ARA were most depleted in 13 C. These findings suggest a contribution of endogenous synthesis utilizing dietary sugar substrates rich in 13 C, and a combination of marine, animal, and terrestrial PUFA sources more depleted in 13 C, respectively. These results provide novel insights on cerebral fatty acid origin and concentration, the latter serving as a valuable resource for future modeling of fatty acid metabolism in the human brain.
Collapse
Affiliation(s)
- R J Scott Lacombe
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Mackenzie E Smith
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Kelly Perlman
- McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, Quebec, Canada
| | - Gustavo Turecki
- McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, Quebec, Canada.,Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - Naguib Mechawar
- McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, Quebec, Canada.,Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - Richard P Bazinet
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
8
|
Smith ME, Cisbani G, Metherel AH, Bazinet RP. The Majority of Brain Palmitic Acid is Maintained by Lipogenesis from Dietary Sugars and is Augmented in Mice fed Low Palmitic Acid Levels from Birth. J Neurochem 2021; 161:112-128. [PMID: 34780089 DOI: 10.1111/jnc.15539] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 11/04/2021] [Accepted: 11/10/2021] [Indexed: 11/28/2022]
Abstract
Previously, results from studies investigating if brain palmitic acid (16:0; PAM) was maintained by either dietary uptake or lipogenesis de novo (DNL) varied. Here, we utilize naturally occurring carbon isotope ratios (13 C/12 C; δ13 C) to uncover the origin of brain PAM. Additionally, we explored brain and liver fatty acid concentration, total brain metabolomic profile, and behaviour. BALB/c dams were equilibrated onto either a low PAM diet (LP; <2%) or high PAM diet (HP; >95%) prior to producing one generation of offspring. Offspring stayed on the respective diet of the dam until 15-weeks of age, at which time the Open Field test was conducted in the offspring, prior to euthanasia and tissue lipid extraction. Although liver PAM was lower in offspring fed the LP diet, as well as female offspring, brain PAM was not affected by diet or sex. Across offspring of either sex on both diets, brain 13 C-PAM revealed compared to dietary uptake, DNL from dietary sugars contributed 68.8%-79.5% and 46.6%-58.0% to the total brain PAM pool by both peripheral and local brain DNL, and local brain DNL alone, respectively. DNL was augmented in offspring fed the LP diet, and the ability to upregulate DNL in the liver or the brain depended on sex. Anxiety-like behaviours were decreased in offspring fed the LP diet and were correlated with markers of LP diet consumption including increased liver 13 C-PAM, warranting further investigation. Altogether, our results indicate that DNL from dietary sugars is a compensatory mechanism to maintain brain PAM in response to a LP diet.
Collapse
Affiliation(s)
| | - Giulia Cisbani
- University of Toronto, Department of Nutritional Sciences, Toronto
| | - Adam H Metherel
- University of Toronto, Department of Nutritional Sciences, Toronto
| | | |
Collapse
|
9
|
Metherel AH, Irfan M, Klingel SL, Mutch DM, Bazinet RP. Higher Increase in Plasma DHA in Females Compared to Males Following EPA Supplementation May Be Influenced by a Polymorphism in ELOVL2: An Exploratory Study. Lipids 2020; 56:211-228. [PMID: 33174255 DOI: 10.1002/lipd.12291] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/26/2020] [Accepted: 10/28/2020] [Indexed: 12/22/2022]
Abstract
Young adult females have higher blood docosahexaenoic acid (DHA), 22:6n-3 levels than males, and this is believed to be due to higher DHA synthesis rates, although DHA may also accumulate due to a longer half-life or a combination of both. However, sex differences in blood fatty acid responses to eicosapentaenoic acid (EPA), 20:5n-3 or DHA supplementation have not been fully investigated. In this exploratory analysis, females and males (n = 14-15 per group) were supplemented with 3 g/day EPA, 3 g/day DHA, or olive oil control for 12 weeks. Plasma was analyzed for sex effects at baseline and changes following 12 weeks' supplementation for fatty acid levels and carbon-13 signature (δ13 C). Following EPA supplementation, the increase in plasma DHA in females (+23.8 ± 11.8, nmol/mL ± SEM) was higher than males (-13.8 ± 9.2, p < 0.01). The increase in plasma δ13 C-DHA of females (+2.79 ± 0.31, milliUrey (mUr ± SEM) compared with males (+1.88 ± 0.44) did not reach statistical significance (p = 0.10). The sex effect appears driven largely by increased plasma DHA in the AA genotype of females (+58.8 ± 11.5, nmol/mL ± SEM, n = 5) compared to GA + GG in females (+4.34 ± 13.5, n = 9) and AA in males (-29.1 ± 17.2, n = 6) for rs953413 in the ELOVL2 gene (p < 0.001). In conclusion, EPA supplementation increases plasma DHA levels in females compared to males, which may be dependent on the AA genotype for rs953413 in ELOVL2.
Collapse
Affiliation(s)
- Adam H Metherel
- Department of Nutritional Sciences, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Maha Irfan
- Department of Nutritional Sciences, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Shannon L Klingel
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - David M Mutch
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Richard P Bazinet
- Department of Nutritional Sciences, University of Toronto, Toronto, ON, M5S 1A8, Canada
| |
Collapse
|
10
|
Lacombe RJS, Bazinet RP. Natural abundance carbon isotope ratio analysis and its application in the study of diet and metabolism. Nutr Rev 2020; 79:869-888. [PMID: 33141222 DOI: 10.1093/nutrit/nuaa109] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Due to differences in carbon assimilation pathways between plants, there are subtle but distinct variations in the carbon isotope ratios of foods and animal products throughout the food supply. Although it is well understood that the carbon isotope ratio composition of the diet influences that of the consumers' tissues, the application of natural abundance carbon isotope ratio analysis in nutrition has long been underappreciated. Over the past decade, however, several studies have investigated the utility of carbon isotope ratio analysis for evaluation of nutritional biomarker status, primarily focusing on its application as an objective indicator of sugar and animal protein intake. More recently, research investigating the application of natural abundance measurements has been extended to study fatty acid metabolism and has yielded encouraging results. Collectively, data from large-scale observational studies and experimental animal studies highlight the potential for carbon isotope ratio analysis as an additional and effective tool to study diet and metabolism. The purpose of this review is to provide an overview of natural abundance carbon isotope ratio analysis, its application to studying nutrition, and an update of the research in the field.
Collapse
Affiliation(s)
- R J Scott Lacombe
- Dell Pediatric Research Institute, University of Texas at Austin, Austin, Texas, USA.,Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Richard P Bazinet
- Dell Pediatric Research Institute, University of Texas at Austin, Austin, Texas, USA
| |
Collapse
|
11
|
Lacombe RJS, Lee CC, Bazinet RP. Turnover of brain DHA in mice is accurately determined by tracer-free natural abundance carbon isotope ratio analysis. J Lipid Res 2020; 61:116-126. [PMID: 31712249 PMCID: PMC6939594 DOI: 10.1194/jlr.d119000518] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Indexed: 01/04/2023] Open
Abstract
The brain is highly enriched in the long-chain omega-3 (n-3) PUFA DHA. Due to the limited capacity for local DHA synthesis in the brain, it relies on a continual supply from the circulation to replenish metabolized DHA. Previous studies investigating brain DHA turnover and metabolism have relied on isotope tracers to determine brain fatty acid kinetics; however, this approach is cumbersome and costly. We applied natural abundance carbon isotope ratio analysis via high-precision gas chromatography combustion isotope ratio mass spectrometry, without the use of labeled tracers, to determine the half-life of brain DHA in mice following a dietary switch experiment. Mice fed diets containing either α-linolenic acid (ALA) or DHA as the sole dietary n-3 PUFA were switched onto diets containing ALA, DHA, or ALA + DHA at 6 weeks of age, while control mice were maintained on their respective background diet. We measured brain DHA carbon isotope ratios (reported as δ13CDHA signatures) over a 168-day time course. Brain δ13CDHA signatures of control mice maintained on background diets over the time course were stable (P > 0.05). Brain δ13CDHA signatures of mice switched to the DHA or ALA + DHA diet from the ALA diet changed over time, yielding brain incorporation half-lives of 40 and 34 days, respectively. These half-lives determined by natural abundance carbon isotope ratio analysis were consistent with estimates from kinetic isotope tracer studies. Our results demonstrate the feasibility of natural abundance carbon isotope ratio analysis in the study of fatty acid metabolism without the use of isotopically labeled fatty acid tracers.
Collapse
Affiliation(s)
- R J Scott Lacombe
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Chi-Chiu Lee
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Richard P Bazinet
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
| |
Collapse
|
12
|
Metherel AH, Irfan M, Klingel SL, Mutch DM, Bazinet RP. Compound-specific isotope analysis reveals no retroconversion of DHA to EPA but substantial conversion of EPA to DHA following supplementation: a randomized control trial. Am J Clin Nutr 2019; 110:823-831. [PMID: 31204771 DOI: 10.1093/ajcn/nqz097] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/29/2019] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND It has long been believed that DHA supplementation increases plasma EPA via the retroconversion pathway in mammals. However, in rodents this increase in EPA is likely due to a slower metabolism of EPA, but this has never been tested directly in humans. OBJECTIVE The aim of this study was to use the natural variations in 13C:12C ratio (carbon-13 isotopic abundance [δ13C]) of n-3 PUFA supplements to assess n-3 PUFA metabolism following DHA or EPA supplementation in humans. METHODS Participants (aged 21.6 ± 2.2 y) were randomly assigned into 1 of 3 supplement groups for 12 wk: 1) olive oil control, 2) ∼3 g/d DHA, or 3) ∼3 g/d EPA. Blood was collected before and after the supplementation period, and concentrations and δ13C of plasma n-3 PUFA were determined. RESULTS DHA supplementation increased (P < 0.05) plasma EPA concentrations by 130% but did not affect plasma δ13C-EPA (-31.0 ± 0.30 to -30.8 ± 0.19, milliUrey ± SEM, P > 0.05). In addition, EPA supplementation did not change plasma DHA concentrations (P > 0.05) but did increase plasma δ13C-DHA (-27.9 ± 0.2 to -25.6 ± 0.1, P < 0.05) toward δ13C-EPA of the supplement (-23.5 ± 0.22). EPA supplementation increased plasma concentrations of EPA and docosapentaenoic acid (DPAn-3) by 880% and 200%, respectively, and increased plasma δ13C-EPA (-31.5 ± 0.2 to -25.7 ± 0.2) and δ13C-DPAn-3 (-28.9 ± 0.3 to -25.0 ± 0.1) toward δ13C-EPA of the supplement. CONCLUSIONS In this study, we show that the increase in plasma EPA following DHA supplementation in humans does not occur via retroconversion, but instead from a slowed metabolism and/or accumulation of plasma EPA. Furthermore, substantial amounts of supplemental EPA can be converted into DHA. δ13C of n-3 PUFA in humans is a powerful and underutilized tool that can track dietary n-3 PUFA and elucidate complex metabolic questions. This trial was registered at clinicaltrials.gov as NCT03378232.
Collapse
Affiliation(s)
- Adam H Metherel
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Maha Irfan
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Shannon L Klingel
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David M Mutch
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Richard P Bazinet
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|