The present invention is directed to methods of reducing plasma triglyceride level in subjects by administering docosahexaenoic acid (DHA). The method can comprise administering daily to the subject a dosage form comprising docosahexaenoic acid ester substantially free of eicosapentaenoic acid (EPA), wherein the DHA is derived from an algal source. In some embodiments, the method comprises administering daily to the subject a dosage form comprising DHA ester substantially free of EPA, wherein the DHA ester is about 60% to about 99.5% (w/w) of the total fatty acid content of the dosage form. In some embodiments, the method comprises administering daily to the subject a dosage form comprising about 200 mg to about 4 g of DHA ester substantially free of EPA. In some embodiments, the foregoing methods also result in a lowering of the amount of total cholesterol in the subject.