Significance: Investigating this negative feedback pathway is of great importance in providing evidence to support n-3 PUFA DRIs. EPA and DHA are ecologically sensitive with their major source coming from unsustainably farmed fish stocks and having a set DRI may help to limit the overconsumption of these nutrients. conditions: Nutrition, Healthy studyType: INTERVENTIONAL phases: NA allocation: RANDOMIZED interventionModel: PARALLEL interventionModelDescription: Double blinded, randomized, control, dose-response supplementation trial primaryPurpose: BASIC_SCIENCE masking: DOUBLE maskingDescription: For randomization we will use the Research Electronic Data Capture (REDCap) program. Following successful completion of informed consent, the questionnaire and anthropometric assessment participants will be randomized into groups, of a possible six, using a blocked (Latin squares) randomization. These groups will represent DHA0 (0mg/d), DHA1 (100mg/d), DHA2 (200mg/d), DHA3 (400mg/d), DHA4 (800mg/d), and DHA5 (1000mg/d) groups. The Latin square sequences will be randomly allocated to participants with a similar number of participants allocated to each treatment sequence. The participants will only be randomized once all information is collected, informed consent has been obtained and questionnaires have been filled out following the first study call/zoom meeting. Then following their first study in person visit and post blood sample extraction they will be given their DHA capsules, which have been organized by a lab member not directly involved in the study. whoMasked: PARTICIPANT whoMasked: INVESTIGATOR count: 72 type: ESTIMATED name: docosahexaenoic acid (DHA) name: soybean oil placebo measure: Changes in omega-3 polyunsaturated fatty acid (n-3 PUFA) blood levels measure: Changes in the delta carbon 13 (δ13C) n-3 PUFA signatures measure: Measure of n-3 LC PUFA turnover rates measure: Measure of n-3 LC PUFA half-lives measure: Increased intake of dietary α-Linolenic acid (ALA) and the inhibition of long chained omega-3 polyunsaturated fatty acids (LC n-3 PUFA) synthesis measure: Comparing the potential change in omega-3 long chained polyunsaturated fatty acids (n-3 LC PUFA) levels between male and female participants measure: Comparing the potential change in n-3 LC PUFA δ13C signatures between male and female participants measure: Comparing the potential change in n-3 LC PUFA levels between genetic variations measure: Comparing the potential change in n-3 LC PUFA δ13C signatures between genetic variations measure: Changes in cardiovascular disease (CVD) biomarkers (BMI in kg/m^2) measure: Changes in cardiovascular disease (CVD) biomarkers (Waist circumference in cm/inch) measure: Changes in cardiovascular disease (CVD) biomarkers (blood pressure in mmHg) measure: Changes in cardiovascular disease (CVD) biomarkers (heart rate in beats per minute) measure: Changes in cardiovascular disease (CVD) biomarkers (blood lipid profile changes in mmol/L) measure: Changes in δ13C DHA signature levels to document adherence sex: ALL minimumAge: 18 Years maximumAge: 50 Years stdAges: ADULT facility: Clinical Nutrition and Risk Factor Modification Centre status: RECRUITING city: Toronto state: Ontario zip: M5C 2T2 country: Canada name: Amy Symington, PhD student role: CONTACT email: dhatrial@unityhealth.to name: John Sievenpiper, MD, PhD, FRCPC role: CONTACT email: john.sievenpiper@alumni.utoronto.ca name: Richard Bazinet, PhD role: SUB_INVESTIGATOR name: John Sievenpiper, MD, PhD, FRCPC role: PRINCIPAL_INVESTIGATOR lat: 43.70011 lon: -79.4163 hasResults: False