A 5-day diet regimen rich in cottonseed oil (CSO) was associated with improvements in cholesterol and triglyceride levels in healthy men compared with a diet rich in olive oil (OO), according to a study published in Nutrition Research.

Researchers conducted a single-blind, randomized crossover study to evaluate the effect of a 5-day diet rich in either CSO or OO on fasting and postprandial lipid profiles in healthy-weight men (n=15) between the ages of 18 and 45 years. Participants had a body mass index (BMI) between 18 and 24.9 kg/m2 (or a body fat percentage <24%) and exercised more than 3 h/wk. The study protocol included a baseline visit at which time resting metabolic rate was recorded followed by 2 outpatient feeding trials that consisted of a 3-day introductory diet, a prediet testing visit (visit 1), a 5-day outpatient feeding protocol of either CSO or OO, and a postdiet testing visit (visit 2). Participants fasted for 8 to 12 hours prior to all visits and avoided vigorous exercise.

During the baseline visit, height, weight, and body composition measurements were recorded, followed by indirect calorimetry to measure resting metabolic weight. Participants were then provided with a lead-in diet (50% carbohydrate, 35% fat, and 15% protein intake) that they were to complete for 3 days prior to the prediet testing visit. Participants recorded their food and beverage intake on a document that was later collected for evaluation.

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Following the lead-in diet, the researchers evaluated patient anthropometric measurements and extracted a 15-mL blood sample to assess total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TGs). Participants were then provided with a high-fat liquid meal rich in either CSO or OO. Blood samples were taken at minutes 30, 60, 90, 120, 150, 180, and 240 for measurement of TG concentrations, followed by another liquid meal, followed by blood draws at minutes 270, 300, 320, 350, 380, 420, and 480. Participants then began the 5-day outpatient feeding trial of either CSO or OO, during which they consumed food prepared by the researchers and documented food intake for diet adherence. The postdiet testing visit included all of the procedures conducted in visit 1. After a 2- to 4-week washout period, the process was repeated for trial 2.

Total cholesterol was higher prediet vs postdiet in the CSO group (148.40 ± 6.39 vs 135.93 ± 6.31 mg/dL, respectively), whereas no differences were found in the OO diet (149.71 ± 6.38 vs 140.93 ± 6.92 mg /dL, prediet vs postdiet, respectively). Fasting HDL-C was lower prediet vs postdiet in the CSO group (46.67 ± 2.41 vs 50.24 ± 2.20 mg/dL, respectively); no significant change was found in the OO group (48.92 ± 2.44 vs 48.21 ± 1.92 mg/dL). Fasting LDL-C was higher prediet vs postdiet in the CSO intervention (92.20 ± 5.57 vs 78.13 ± 5.60 mg/dL, respectively) but not in the OO intervention (91.14 ± 6.87 vs 85.64 ± 6.29 mg/dL, respectively). Fasting TG levels were significantly higher prediet vs postdiet in the CSO intervention (80.11 ± 4.91 vs 56.37 ± 5.46 mg/dL, respectively), and there was a trend toward a significant difference in TG levels for the OO diet (74.51 ± 8.38 vs 64.08 ± 6.87 mg/dL, respectively).

Postdiet comparisons revealed lower LDL-C levels after the CSO diet compared with the OO diet (78.13 ± 5.60 mg/dL vs 85.64 ± 6.29 mg/dL), as well as lower TG levels (56.37 ± 5.46 mg/dL vs 64.08 ± 6.87 mg/dL).

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“The results of this study reveal significant improvements in cholesterol profiles and both fasting and postprandial TG levels after a 5-day [high-fat] diet rich in CSO,” the authors concluded. “Conversely, the 5-day [high-fat] diet rich in OO did not change either cholesterol profiles or TG levels significantly.”


Polley KR, Oswell NJ, Pegg RB, Paton CM, Cooper JA. A 5-day high-fat diet rich in cottonseed oil improves cholesterol profiles and triglycerides compared to olive oil in healthy men. Nutr Res. 2018;60:43-53.