Effects of n-3 polyunsaturated fatty acids on glucose homeostasis and blood pressure in essential hypertension. A randomized, controlled trial

Ann Intern Med. 1995 Dec 15;123(12):911-8. doi: 10.7326/0003-4819-123-12-199512150-00003.

Abstract

Objective: To determine whether dietary supplementation with fish oil adversely affects glycemic control in patients with hypertension.

Design: Randomized, double-blind, placebo-controlled study.

Patients: 78 persons with untreated hypertension recruited from a population survey.

Intervention: Participants were randomly assigned to receive eicosapentaenoic and docosahexaenoic acids, 4 g/d, or corn oil placebo, 4 g/d, for 16 weeks.

Measurements: An oral glucose tolerance test; assessments of insulin release, glucose disposal, and insulin sensitivity done using the hyperglycemic clamp technique to keep plasma glucose levels at 10 mmol/L for 180 minutes; assessment of insulin sensitivity done using a euglycemic hyperinsulinemic clamp technique (infusing insulin and glucose to keep plasma glucose levels at 5 mmol/L); assessments of lipid levels and blood pressure. Measurements were done before and after intervention.

Results: Changes in integrated glucose and insulin response after the oral glucose challenge did not differ between the fish oil and corn oil groups after intervention (-0.6 +/- 0.7 compared with -1.0 +/- 0.6 mmol/L [P > 0.3] for integrated glucose and 143 +/- 76 compared with 169 +/- 84 pmol/L [P > 0.3] for insulin response). Changes in first-phase insulin release (34 +/- 72 pmol/L in the fish oil group compared with 191 +/- 112 pmol/L in the corn oil group [P > 0.3]), second-phase insulin release (179 +/- 66 pmol/L compared with 257 +/- 122 pmol/L [P > 0.3]), and insulin sensitivity index (-0.03 +/- 0.01 compared with -0.01 +/- 0.01 [mumol/kg.min divided by pmol/L]; P > 0.3) were also similar in both groups after treatment. Fish oil lowered systolic blood pressure by 3.8 mm Hg more than control (P = 0.04) and lowered diastolic blood pressure by 2.0 mm Hg more than control (P = 0.10). After fish oil treatment, triglyceride levels decreased by 0.28 +/- 0.08 mmol/L more than control (P = 0.01), and very-low-density lipoprotein cholesterol levels decreased by 0.13 +/- 0.04 mmol/L more than control (P = 0.01).

Conclusion: Fish oil, in doses that reduce blood pressure and lipid levels in hypertensive persons, does not adversely affect glucose metabolism.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Glucose / drug effects*
  • Blood Glucose / metabolism
  • Blood Pressure / drug effects*
  • Docosahexaenoic Acids / adverse effects*
  • Docosahexaenoic Acids / blood
  • Double-Blind Method
  • Eicosapentaenoic Acid / adverse effects*
  • Eicosapentaenoic Acid / blood
  • Female
  • Hemostasis / drug effects
  • Humans
  • Hypertension / blood*
  • Insulin / blood
  • Lipids / blood
  • Male
  • Middle Aged
  • Phospholipids / blood

Substances

  • Blood Glucose
  • Insulin
  • Lipids
  • Phospholipids
  • Docosahexaenoic Acids
  • Eicosapentaenoic Acid