Swapping saturated fats for polyunsaturated fats instead of the more often featured monounsaturated fats may allow for the greatest reduction of triglycerides and improvements in endothelial function in patients with the metabolic syndrome, according to findings from The Muffin Study.
These beneficial effects were independent of the weight loss achieved with the change in intake of polyunsaturated versus monounsaturated fats, as reported online ahead of print in the Journal of Clinical Lipidology.
“The main clinical implication is that polyunsaturated fats [PUFA], as derived from safflower, sunflower, and soybean oils are a metabolically worthy substitute for saturated fat,” said lead author Michael Miller, MD, who is professor of cardiovascular medicine at the University of Maryland School of Medicine in Baltimore.
“Subjects in this six-month study lost an average of 10-pounds after consuming the tasty, heart-healthy muffins supplemented with other PUFA-enriched fats, in addition to walking regularly, and maintaining a mild caloric restriction,” said Dr. Miller.
Prospective, Open-Label Study
The prospective, open-label, parallel group design study involved 39 people with the metabolic syndrome (mean age, 60.8 years; 79% African American, 60% female). The patients were on the American Heart Association step 1 stabilization diet at baseline and were encouraged to walk at least 3 days per week for 30-45 minutes.
Changes in metabolic syndrome parameters were evaluated at baseline and after 6 months of a dietary intervention in which participants were randomized eat 3 muffins daily that were enriched with either monounsaturated fat (high-oleic sunflower oil) or polyunsaturated fat (safflower oil) with additional supplementation to achieve 25%–50% increases in dietary fat intake from these sources with a comparable decrease in saturated fat. Medications and dosage regimens were unchanged throughout the 6-month study.
Both groups showed weight loss at 6-months, but the difference from baseline was significant only in the polyunsaturated fat group (Table). The polyunsaturated fat group also showed significant improvements from baseline and compared with the polyunsaturated group in reductions in triglycerides levels and improved flow mediated dilation, a marker of endothelial function (Table).
“Consumption of polyunsaturated fats may result in greater increases in the anorexigenic hormone peptide YY compared to monounsaturated fats or saturated fat,” Dr. Miller said. “Improvement in flow mediated dilation may in part reflect reduced saturated fat intake that is associated with impairment in flow mediated dilation. Polyunsaturated fat lowers triglycerides in part, by reducing very low density lipoprotein secretion.”
Clinical Implications of the Findings
“Polyunsaturated fat may be the preferential unsaturated fat of choice for substitution of saturated fat,” Dr. Miller said.
“This study demonstrated that a diet enriched in polyunsaturated fats may lead to a greater reduction in triglycerides and diastolic blood pressure in patients with metabolic syndrome, when compared to a diet enriched in monounsaturated fats,” commented Deena Adimoolam, MD, Assistant Professor, Endocrinology, Diabetes & Metabolism Icahn School of Medicine at Mount Sinai, New York, NY.
“The metabolic syndrome is quite complex and varies among all patients. Not every patient with metabolic syndrome will have diabetes, lipid abnormalities, and obesity. There are multiple combinations of metabolic derangements that can define the metabolic syndrome (as can be seen below with the definition of the metabolic syndrome where only 3 of 5 traits need to be present [See Table]) and diet plans need to be created accordingly. ” Dr. Adimoolam noted.
“Based on this study’s data, I might suggest a diet higher in polyunsaturated fats versus monounsaturated fats to a patient with metabolic syndrome dominated by severe hypertriglyceridemia or high diastolic blood pressure given its large reduction in both metabolic parameters,” Dr. Adimoolam said.
Dr. Adimoolam added that the findings are limited by the use of a food record recall to assess dietary intake. “A more sensitive metric for dietary intake would have been providing study participants with prepared meals throughout the study,” she said.
Helping Patients Make Better Food Choices
Dr. Adimoolam suggested that the first step in helping patients with metabolic syndrome make better food choices is to review their current diet, food preferences, and access to healthy food. Diets need to be personalized based on these findings, she said.
“When it comes to fats, I advise patients to limit trans fats which can be found in many fast foods and processed foods. I then focus on limiting saturated fats (especially animal derived saturated fats), which are associated with an increased risk of cardiovascular disease. I suggest limiting saturated fats to 5% of one’s total daily calories. Animal-derived saturated fats include beef, lamb, poultry with skin, butter, cheese, etc,” Dr. Adimoolam said.
“Monounsaturated and polyunsaturated fats are considered ‘heart-healthy healthy foods’ and I recommend 2-3 servings of fish, oil, and/or nuts daily. Given the results of this study with a decrease in two major components of metabolic syndrome (triglycerides and diastolic blood pressure), it might be beneficial to increase intake of polyunsaturated fats with corn oil, sunflower oil, salmon, herring, mackeral, trout, etc,” Dr. Adimoolam noted.
Miller M, Sorkin JD, Mastella L, et al. Poly is more effective than monounsaturated fat for dietary management in the metabolic syndrome: The Muffin Study. J Clin Lipid. 2016. http://dx.doi.org/10.1016/j.jacl.2016.04.011
ATP III Guidelines At-A-Glance Quick Desk Reference. ATP III Guidelines At-A-Glance Quick Desk Reference. http://www.nhlbi.nih.gov/files/docs/guidelines/atglance.pdf. Accessed June 22, 2016.