{"id":{"repo_id":"ubc","oai_identifier":"oai:circle.library.ubc.ca:2429/2373"},"canonical_url":"https://search.dev.ndltd.org/etd/ubc/oai:circle.library.ubc.ca:2429/2373","repository":{"repo_id":"ubc","name":"University of British Columbia","base_url":"http://circle.library.ubc.ca/oai/request"},"display":{"title":"The dietary essentiality of n-3 polyunsaturated fatty acids in infant nutrition","abstract":"Docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) are deposited in large amounts in membrane phospholipids of the developing central nervous system (CNS). High levels of 22:6n-3 are found in synaptic terminals and retina, and are important for normal visual development and function. 20:4n-6 and22:6n-3 are supplied in human milk. In contrast, infants fed formula rely completely on endogenous synthesis of 20:4n-6 and 22:6n-3 from linoleic (18:2n-6) and a-linolenic (18:3n-3) acid, respectively. Levels of 22:6n-3 in the blood lipids of infants fed formula are lower than in infants fed human milk. Concern over the supply of 22:6n-3 led to clinical trials in which premature infants were fed formulas containing fish oils as a source of 22:6n-3. Piglets, which have a similar lipid metabolism and perinatal timing of the brain growth spurt to humans, have a lower percentage of 22:6n-3 in blood, liver and CNS tissues when fed formula with 30% of fatty acids as18:2n-6 and 0.8% 18:3n-3, compared to sow milk. It was hypothesized that the low blood and tissue 22:6n-3 in formula-fed piglets was due to inappropriate quantities and/or ratios of dietary 18:2n-6 and 18:3n-3 limiting the synthesis of 22:6n-3. Thus, the main objectives of this thesis were to determine. (1) if 22:6n-3 is an essential dietary nutrient for the term gestation piglet, (2) if appropriate quantities and ratios of 18:2n-6 and 18:3n-3 in formula will support CNS membrane accretion of 20:4n-6 and 22:6n-3, comparable to piglets fed varying amounts of 22:6n-3 in natural milk, and (3) if lower blood phospholipid 22:6n-3 consistently reflects reduced 22:6n-3 in the CNS. Initial studies (Experiment I) showed that formula with 4% 18:3n-3 supported a similar percentage of22:6n-3 in piglet liver and CNS membrane lipids to sow milk, but was associated with lower brain weight. Deposition of 22:6n-3 in brain was influenced by the formula 18:3n-3 content. The 18:2n-6:18:3n-3 ratio (22:1and 37:1) seemed to be important, however, when formulas contained 1% 18:3n-3. Low levels of fish oil in formula, similar to those used in clinical trials, were effective in supplying 22:6n-3 to the developing piglet brain (Experiment II). The efficacy of 18:3n-3 in supporting the deposition of 22:6n-3 in the brain was estimated to be at least 20% that of dietary 20:5n-3 plus 22:6n-3. With increasing dietary fish oil, however, levels of eicosapentaenoic acid (20:5n-3) increased and 20:4n-6decreased in plasma, liver and retina, but not brain (Experiment III). This suggests regulatory mechanisms may exist to maintain relatively constant levels of 20:4n-6 and 20:5n-3 in brain. Milk 22:6n-3 varies with maternal intake of 22:6n-3. The effect of milk 22:6n-3 content was studied in piglets fed milk with 0.1% or 1.5% 22:6n-3 obtained from sows fed usual pig diets containing vegetable fats without or with fish oil, respectively (Experiment IV). Consumption of 1.5 vs 0.1% 22:6n-3 from sow milk resulted in 300% higher 22:6n-3 in liver and blood phospholipids and 11% higher 22:6n-3 in cerebrum of nursing piglets. Despite similar milk 20:4n-6, the % 20:4n-6 in tissues other than the brain was lower in piglets fed high22:6n-3 sow milk. Thus, high intakes of n-3 fatty acids decrease 20:4n-6 in piglet liver and blood lipids. The blood phospholipid % 22:6n-3 in piglets fed formulas containing 18:2n-6 and 18:3n-3 but not their long-chain derivatives, was lower than in piglets fed 22:6n-3 in natural milk, consistent with published findings in formula-fed infants. However, in contrast to circulating lipids, formulas with 4% 18:3n-3 maintained similar levels of 22:6n-3in the piglet CNS compared to milk. These studies show that blood phospholipid 22:6n-3 and 20:4n-6 are not specific indices of effects in CNS lipids. This thesis has shown (1) 22:6n-3 is not essential in the diet of the term piglet, if adequate 18:3n-3 is given, (2) fish oils are an effective source of 22:6n-3 for deposition in the developing brain, (3) high dietary n-3fatty acids interfere with 20:4n-6 metabolism, and (4) blood lipid 20:4n-6 and 22:6n-3 do not accurately reflect CNS fatty acids.","abstract_html":"Docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) are deposited in large amounts in membrane phospholipids of the developing central nervous system (CNS). High levels of 22:6n-3 are found in synaptic terminals and retina, and are important for normal visual development and function. 20:4n-6 and22:6n-3 are supplied in human milk. In contrast, infants fed formula rely completely on endogenous synthesis of 20:4n-6 and 22:6n-3 from linoleic (18:2n-6) and a-linolenic (18:3n-3) acid, respectively. Levels of 22:6n-3 in the blood lipids of infants fed formula are lower than in infants fed human milk. Concern over the supply of 22:6n-3 led to clinical trials in which premature infants were fed formulas containing fish oils as a source of 22:6n-3. Piglets, which have a similar lipid metabolism and perinatal timing of the brain growth spurt to humans, have a lower percentage of 22:6n-3 in blood, liver and CNS tissues when fed formula with 30% of fatty acids as18:2n-6 and 0.8% 18:3n-3, compared to sow milk. It was hypothesized that the low blood and tissue 22:6n-3 in formula-fed piglets was due to inappropriate quantities and/or ratios of dietary 18:2n-6 and 18:3n-3 limiting the synthesis of 22:6n-3. Thus, the main objectives of this thesis were to determine. (1) if 22:6n-3 is an essential dietary nutrient for the term gestation piglet, (2) if appropriate quantities and ratios of 18:2n-6 and 18:3n-3 in formula will support CNS membrane accretion of 20:4n-6 and 22:6n-3, comparable to piglets fed varying amounts of 22:6n-3 in natural milk, and (3) if lower blood phospholipid 22:6n-3 consistently reflects reduced 22:6n-3 in the CNS. Initial studies (Experiment I) showed that formula with 4% 18:3n-3 supported a similar percentage of22:6n-3 in piglet liver and CNS membrane lipids to sow milk, but was associated with lower brain weight. Deposition of 22:6n-3 in brain was influenced by the formula 18:3n-3 content. The 18:2n-6:18:3n-3 ratio (22:1and 37:1) seemed to be important, however, when formulas contained 1% 18:3n-3. Low levels of fish oil in formula, similar to those used in clinical trials, were effective in supplying 22:6n-3 to the developing piglet brain (Experiment II). The efficacy of 18:3n-3 in supporting the deposition of 22:6n-3 in the brain was estimated to be at least 20% that of dietary 20:5n-3 plus 22:6n-3. With increasing dietary fish oil, however, levels of eicosapentaenoic acid (20:5n-3) increased and 20:4n-6decreased in plasma, liver and retina, but not brain (Experiment III). This suggests regulatory mechanisms may exist to maintain relatively constant levels of 20:4n-6 and 20:5n-3 in brain. Milk 22:6n-3 varies with maternal intake of 22:6n-3. The effect of milk 22:6n-3 content was studied in piglets fed milk with 0.1% or 1.5% 22:6n-3 obtained from sows fed usual pig diets containing vegetable fats without or with fish oil, respectively (Experiment IV). Consumption of 1.5 vs 0.1% 22:6n-3 from sow milk resulted in 300% higher 22:6n-3 in liver and blood phospholipids and 11% higher 22:6n-3 in cerebrum of nursing piglets. Despite similar milk 20:4n-6, the % 20:4n-6 in tissues other than the brain was lower in piglets fed high22:6n-3 sow milk. Thus, high intakes of n-3 fatty acids decrease 20:4n-6 in piglet liver and blood lipids. The blood phospholipid % 22:6n-3 in piglets fed formulas containing 18:2n-6 and 18:3n-3 but not their long-chain derivatives, was lower than in piglets fed 22:6n-3 in natural milk, consistent with published findings in formula-fed infants. However, in contrast to circulating lipids, formulas with 4% 18:3n-3 maintained similar levels of 22:6n-3in the piglet CNS compared to milk. These studies show that blood phospholipid 22:6n-3 and 20:4n-6 are not specific indices of effects in CNS lipids. This thesis has shown (1) 22:6n-3 is not essential in the diet of the term piglet, if adequate 18:3n-3 is given, (2) fish oils are an effective source of 22:6n-3 for deposition in the developing brain, (3) high dietary n-3fatty acids interfere with 20:4n-6 metabolism, and (4) blood lipid 20:4n-6 and 22:6n-3 do not accurately reflect CNS fatty acids.","abstract_has_math":false,"creators":["Arbuckle, Lucille D."],"institution":"University of British Columbia","degree_name":"Doctor of Philosophy - PhD","degree_level":"doctoral","degree_discipline":"Family and Nutritional Sciences","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1993,"date_issued":"1993","date_published":"1993","updated_at":"2026-07-24T05:07:30Z","subjects":[],"languages":["eng"],"rights":["For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2429/2373","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Arbuckle, Lucille D."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1993"]},{"key":"dc:publisher","label":"Institution","values":["University of British Columbia"]},{"key":"dc:type","label":"Dc Type","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Family and Nutritional Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy - PhD"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of British Columbia"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["For non-commercial purposes only, such as research, private study and education. 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Levels of 22:6n-3 in the blood lipids of infants fed formula are lower than in infants fed human milk. Concern over the supply of 22:6n-3 led to clinical trials in which premature infants were fed formulas containing fish oils as a source of 22:6n-3. Piglets, which have a similar lipid metabolism and perinatal timing of the brain growth spurt to humans, have a lower percentage of 22:6n-3 in blood, liver and CNS tissues when fed formula with 30% of fatty acids as18:2n-6 and 0.8% 18:3n-3, compared to sow milk. It was hypothesized that the low blood and tissue 22:6n-3 in formula-fed piglets was due to inappropriate quantities and/or ratios of dietary 18:2n-6 and 18:3n-3 limiting the synthesis of 22:6n-3. Thus, the main objectives of this thesis were to determine. (1) if 22:6n-3 is an essential dietary nutrient for the term gestation piglet, (2) if appropriate quantities and ratios of 18:2n-6 and 18:3n-3 in formula will support CNS membrane accretion of 20:4n-6 and 22:6n-3, comparable to piglets fed varying amounts of 22:6n-3 in natural milk, and (3) if lower blood phospholipid 22:6n-3 consistently reflects reduced 22:6n-3 in the CNS. Initial studies (Experiment I) showed that formula with 4% 18:3n-3 supported a similar percentage of22:6n-3 in piglet liver and CNS membrane lipids to sow milk, but was associated with lower brain weight. Deposition of 22:6n-3 in brain was influenced by the formula 18:3n-3 content. The 18:2n-6:18:3n-3 ratio (22:1and 37:1) seemed to be important, however, when formulas contained 1% 18:3n-3. Low levels of fish oil in formula, similar to those used in clinical trials, were effective in supplying 22:6n-3 to the developing piglet brain (Experiment II). The efficacy of 18:3n-3 in supporting the deposition of 22:6n-3 in the brain was estimated to be at least 20% that of dietary 20:5n-3 plus 22:6n-3. With increasing dietary fish oil, however, levels of eicosapentaenoic acid (20:5n-3) increased and 20:4n-6decreased in plasma, liver and retina, but not brain (Experiment III). This suggests regulatory mechanisms may exist to maintain relatively constant levels of 20:4n-6 and 20:5n-3 in brain. Milk 22:6n-3 varies with maternal intake of 22:6n-3. The effect of milk 22:6n-3 content was studied in piglets fed milk with 0.1% or 1.5% 22:6n-3 obtained from sows fed usual pig diets containing vegetable fats without or with fish oil, respectively (Experiment IV). Consumption of 1.5 vs 0.1% 22:6n-3 from sow milk resulted in 300% higher 22:6n-3 in liver and blood phospholipids and 11% higher 22:6n-3 in cerebrum of nursing piglets. Despite similar milk 20:4n-6, the % 20:4n-6 in tissues other than the brain was lower in piglets fed high22:6n-3 sow milk. Thus, high intakes of n-3 fatty acids decrease 20:4n-6 in piglet liver and blood lipids. The blood phospholipid % 22:6n-3 in piglets fed formulas containing 18:2n-6 and 18:3n-3 but not their long-chain derivatives, was lower than in piglets fed 22:6n-3 in natural milk, consistent with published findings in formula-fed infants. However, in contrast to circulating lipids, formulas with 4% 18:3n-3 maintained similar levels of 22:6n-3in the piglet CNS compared to milk. These studies show that blood phospholipid 22:6n-3 and 20:4n-6 are not specific indices of effects in CNS lipids. This thesis has shown (1) 22:6n-3 is not essential in the diet of the term piglet, if adequate 18:3n-3 is given, (2) fish oils are an effective source of 22:6n-3 for deposition in the developing brain, (3) high dietary n-3fatty acids interfere with 20:4n-6 metabolism, and (4) blood lipid 20:4n-6 and 22:6n-3 do not accurately reflect CNS fatty acids."]},{"key":"dc:format","label":"Dc Format","values":["8147185","application/pdf"]},{"key":"dc:title","label":"Title","values":["The dietary essentiality of n-3 polyunsaturated fatty acids in infant nutrition"]}]}],"canonical_facts":{"dc:creator":["Arbuckle, Lucille D."],"dc:date":["1993"],"dc:description":["Docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) are deposited in large amounts in membrane phospholipids of the developing central nervous system (CNS). High levels of 22:6n-3 are found in synaptic terminals and retina, and are important for normal visual development and function. 20:4n-6 and22:6n-3 are supplied in human milk. In contrast, infants fed formula rely completely on endogenous synthesis of 20:4n-6 and 22:6n-3 from linoleic (18:2n-6) and a-linolenic (18:3n-3) acid, respectively. Levels of 22:6n-3 in the blood lipids of infants fed formula are lower than in infants fed human milk. Concern over the supply of 22:6n-3 led to clinical trials in which premature infants were fed formulas containing fish oils as a source of 22:6n-3. Piglets, which have a similar lipid metabolism and perinatal timing of the brain growth spurt to humans, have a lower percentage of 22:6n-3 in blood, liver and CNS tissues when fed formula with 30% of fatty acids as18:2n-6 and 0.8% 18:3n-3, compared to sow milk. It was hypothesized that the low blood and tissue 22:6n-3 in formula-fed piglets was due to inappropriate quantities and/or ratios of dietary 18:2n-6 and 18:3n-3 limiting the synthesis of 22:6n-3. Thus, the main objectives of this thesis were to determine. (1) if 22:6n-3 is an essential dietary nutrient for the term gestation piglet, (2) if appropriate quantities and ratios of 18:2n-6 and 18:3n-3 in formula will support CNS membrane accretion of 20:4n-6 and 22:6n-3, comparable to piglets fed varying amounts of 22:6n-3 in natural milk, and (3) if lower blood phospholipid 22:6n-3 consistently reflects reduced 22:6n-3 in the CNS. Initial studies (Experiment I) showed that formula with 4% 18:3n-3 supported a similar percentage of22:6n-3 in piglet liver and CNS membrane lipids to sow milk, but was associated with lower brain weight. Deposition of 22:6n-3 in brain was influenced by the formula 18:3n-3 content. The 18:2n-6:18:3n-3 ratio (22:1and 37:1) seemed to be important, however, when formulas contained 1% 18:3n-3. Low levels of fish oil in formula, similar to those used in clinical trials, were effective in supplying 22:6n-3 to the developing piglet brain (Experiment II). The efficacy of 18:3n-3 in supporting the deposition of 22:6n-3 in the brain was estimated to be at least 20% that of dietary 20:5n-3 plus 22:6n-3. With increasing dietary fish oil, however, levels of eicosapentaenoic acid (20:5n-3) increased and 20:4n-6decreased in plasma, liver and retina, but not brain (Experiment III). This suggests regulatory mechanisms may exist to maintain relatively constant levels of 20:4n-6 and 20:5n-3 in brain. Milk 22:6n-3 varies with maternal intake of 22:6n-3. The effect of milk 22:6n-3 content was studied in piglets fed milk with 0.1% or 1.5% 22:6n-3 obtained from sows fed usual pig diets containing vegetable fats without or with fish oil, respectively (Experiment IV). Consumption of 1.5 vs 0.1% 22:6n-3 from sow milk resulted in 300% higher 22:6n-3 in liver and blood phospholipids and 11% higher 22:6n-3 in cerebrum of nursing piglets. Despite similar milk 20:4n-6, the % 20:4n-6 in tissues other than the brain was lower in piglets fed high22:6n-3 sow milk. Thus, high intakes of n-3 fatty acids decrease 20:4n-6 in piglet liver and blood lipids. The blood phospholipid % 22:6n-3 in piglets fed formulas containing 18:2n-6 and 18:3n-3 but not their long-chain derivatives, was lower than in piglets fed 22:6n-3 in natural milk, consistent with published findings in formula-fed infants. However, in contrast to circulating lipids, formulas with 4% 18:3n-3 maintained similar levels of 22:6n-3in the piglet CNS compared to milk. These studies show that blood phospholipid 22:6n-3 and 20:4n-6 are not specific indices of effects in CNS lipids. This thesis has shown (1) 22:6n-3 is not essential in the diet of the term piglet, if adequate 18:3n-3 is given, (2) fish oils are an effective source of 22:6n-3 for deposition in the developing brain, (3) high dietary n-3fatty acids interfere with 20:4n-6 metabolism, and (4) blood lipid 20:4n-6 and 22:6n-3 do not accurately reflect CNS fatty acids."],"dc:format":["8147185","application/pdf"],"dc:identifier":["http://hdl.handle.net/2429/2373","http://circle.library.ubc.ca/bitstream/2429/2373/1/ubc_1993_fall_phd_arbuckle_lucille.pdf"],"dc:language":["eng"],"dc:publisher":["University of British Columbia"],"dc:rights":["For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."],"dc:title":["The dietary essentiality of n-3 polyunsaturated fatty acids in infant nutrition"],"dc:type":["Text"],"thesis:degree_discipline":["Family and Nutritional Sciences"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Doctor of Philosophy - PhD"],"thesis:institution_name":["University of British Columbia"]},"updated_at":"2026-07-24T05:07:30Z"}