European Journal of Clinical Nutrition (2008) 62, 617–624 & 2008 Nature Publishing Group All rights reserved 0954-3007/08 $30.00 www.nature.com/ejcn ORIGINAL ARTICLE Effects of products made from a high-palmitic acid, trans-free semiliquid fat or a high-oleic acid, low- trans semiliquid fat on the serum lipoprotein profile and on C-reactive protein concentrations in humans RP Mensink Department of Human Biology, Maastricht University, Maastricht, The Netherlands Background: Many studies have shown that trans fatty acids have unfavorable effects on the serum lipoprotein profile. In general, however, fats were compared with different functional characteristics, which lower the practical applications of the results. Objective: The major aim of this study was to compare the effects of a high-palmitic acid, trans-free semiliquid fat with those of a high-oleic acid, low-trans semiliquid fat on the serum lipoprotein profile of healthy subjects. Subjects and design: Forty-four subjects (33 women and 11 men) consumed, in random order, two experimental diets, each for 3 weeks. Diets provided 40 energy percent (En%) from fat, while 15 En% was supplied by the experimental fats. At the end of each intervention period, concentrations of serum lipoproteins, C-reactive protein, glucose and insulin were measured. Results: When subjects consumed the high-oleic acid, low-trans semiliquid fat, intakes of stearic acid ( þ 1.3 En%), oleic acid ( þ 2.9 En%), a-linolenic acid ( þ 0.1 En%) and trans fatty acids ( þ 0.6 En%) were higher and that of palmitic acid (À4.2 En%) lower. Serum concentration of low-density lipoprotein cholesterol decreased by 0.3470.39 mmol/l (mean7s.d.; 95% confidence interval (CI), À0.46 to À0.23 mmol/l; Po0.001) and high-density lipoprotein (HDL) cholesterol by À0.0670.17 mmol/l (95% CI, À0.11 to À0.01 mmol/l; P ¼ 0.021). Also, the total to HDL cholesterol ratio was lower (À0.1570.34; 95% CI, À0.25 to À0.05; P ¼ 0.006). Other parameters did not change. Conclusions: A high-oleic acid, low-trans semiliquid fat has a more favorable effect on the serum lipoprotein profile than a trans- free semiliquid fat with comparable functional characteristics, but high in palmitic acid. European Journal of Clinical Nutrition (2008) 62, 617–624; doi:10.1038/sj.ejcn.1602756; published online 18 April 2007 Keywords: palmitic acid; trans fatty acids; semiliquid fats; serum lipids; C-reactive protein; humans Introduction high-density lipoprotein (HDL) cholesterol particles, when compared with trans monounsaturated fatty acids (Mensink Trans monounsaturated fatty acids from hydrogenated oils et al., 2003). Also, the total to HDL cholesterol ratio and increase concentrations of the atherogenic low-density triacylglycerol concentrations, which are both positively lipoprotein (LDL) particles, when compared with an iso- related to cardiovascular risk (Castelli, 1996), are more caloric amount of carbohydrates or oleic acid. In this respect, beneficially affected by palmitic acid than by trans mono- effects between trans monounsaturated fatty acids and unsaturated fatty acids from hydrogenated oils (Mensink palmitic acid (C16:0) are not very different. Palmitic acid, et al., 2003). These findings suggest that substituting however, increases concentrations of the anti-atherogenic hydrogenated oils and semiliquid fats rich in trans mono- unsaturated fatty acids for oils rich in palmitic acid will lower Correspondence: Professor RP Mensink, Department of Human Biology, cardiovascular risk. However, the optimal choice of fats and Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands. oils for food preparations does not only depend on their E-mail: [email protected] Received 12 October 2006; revised 19 February 2007; accepted 2 March health effects, but also on their functional characteristics. 2007; published online 18 April 2007 For example, preparation of French fries, snacks, meat and Semiliquid fats and serum lipids RP Mensink 618 chicken products all require a stable frying oil to prevent visits with an interval of at least 3 days after they had given as long as possible oxidation and polymerization of the oil. their written informed consent before they entered the Partially hydrogenated oils fulfill these requirements, but screening procedure. At screening, fasting blood samples have a high content of trans fatty acids. Palm fruit-based were taken for analysis of serum lipid and lipoprotein oils have therefore been promoted as a suitable alternative concentrations, and blood pressure, weight and length were for hydrogenated oils (Muller et al., 1998). However, the measured. Only at the first screening day, urinary glucose exclusive use of palm oils for frying purposes will result in a from a morning urine specimen was assessed. Subjects were substantial and undesirable increase in the consumption included in the study if they were aged 18–70 years, healthy of palmitic acid. In fact, the World Health Organization has as indicated by a medical questionnaire, not pregnant or concluded that there is convincing evidence that the breast feeding, weight stable and had a body mass index saturates myristic acid and palmitic acid, when consumed (BMI) below 32 kg/m2, a diastolic blood pressure below 95 in elevated quantities, will increase the risk to develop and systolic blood pressure below 160 mm Hg, no indication cardiovascular diseases (Report of a Joint WHO/FAO Expert for treatment with cholesterol-lowering drugs according to Consultation, 2002). Replacing hydrogenated fats – high the Dutch Cholesterol Consensus (1998) and a serum in trans fatty acids, but low in palmitic acid – by palm oil, triacylglycerol concentration below 4.0 mmol/l. Subjects virtually free of trans fatty acids, but high in palmitic acid – with a history of atherosclerotic disease or glucosuria or for cooking and baking is nevertheless a possibility for who were using medications known to affect blood lipids several applications such as frying and for the production of were excluded from the study. Blood donation or participa- low-fat bakery products and snacks. However, there may tion in another biomedical trial was not allowed within 4 also be some technological disadvantages in this respect. For weeks before the start of the study or during the study. None example, for some specific food production processes, the of the subjects used vitamin supplements, fish-oil capsules or crystallization rate, melting curve and the stability of palm products enriched with plant sterol or stanol esters within 3 oils may not be as good as that of hydrogenated fats. weeks before the start or during the study. The Medical Recently, a new generation of hydrogenated oils and fats Ethics Committee of the Maastricht University had approved have been developed using novel technologies, resulting in a the study. significant reduction (up to 80%) in trans fatty acid content All subjects, 11 men and 33 women, completed the of oils and fats (Dijkstra, 2006). In this type of oil, the protocol. During the screening period, these men were 2 structuring fatty acid is stearic acid (C18:0), a saturated fatty 41711 years (mean7s.d.), had a BMI of 24.071.8 kg/m ,a acid with hardly any impact on LDL cholesterol (Mensink systolic blood pressure of 13277.3 and a diastolic blood et al, 2003), while it also has a higher content of oleic acid pressure of 8575.6 mm Hg. The women were 41718 years of 2 (cis-C18:1) as compared with the traditional hydrogenated age, had a BMI of 23.873.3 kg/m , had a systolic blood oils. This new development combines a good crystallization pressure of 126710.6 and a diastolic blood pressure of rate with a good oxidative stability. Effects of these new 8176.6 mm Hg. For the male subjects, the mean fasting types of oils on cardiovascular risk marker have never been concentrations of serum total cholesterol, LDL cholesterol, studied. We have therefore compared the effects of two HDL cholesterol and triacylglycerol were respectively semiliquid fats on the serum lipoprotein profile of healthy 5.4070.64, 3.4770.66, 1.2070.23 and 1.6270.75 mmol/l. volunteers. One fat was high in palmitic acid and contained For women, these values were 5.3170.67 for total cholesterol, virtually no trans monounsaturated fatty acids. The other 3.0570.62 for LDL cholesterol, 1.5470.43 for HDL cholesterol semiliquid fat was high in oleic acid and contained a small and 1.5670.67 mmol/l for triacylglycerol. Thirteen women fraction of trans monounsaturated fatty acids. As recent were postmenopausal and nine used oral contraceptives. None studies have also indicated that trans monounsaturated fatty of the subjects smoked. acids increases biomarkers of low-grade systemic inflamma- tion (Baer et al., 2004; Mozaffarian et al., 2004; Lopez-Garcia et al., 2005), effects of the two fats on C-reactive protein Experimental design and diets (CRP) concentrations were also studied. Finally, effects on The study had a double-blind, randomized, crossover design glucose and insulin concentrations were examined. and consisted of two dietary periods of 3 weeks, interrupted by a washout period of 1 week during which time subjects consumed their habitual diets. One experimental fat was rich Subjects and methods in a fat high in palmitic acid, which contained virtually no trans fatty acids (high-palmitic, trans-free diet), while Subjects another experimental fat was high in oleic acid and provided Healthy men and women were recruited via advertisements a small amount of trans fatty acids (high-oleic acid, low-trans in local newspapers and a university hospital newsletter and diet). Fats were incorporated into margarines (80% fat via posters in university buildings. People who were inter- (w/w)), cookies (17% fat), muffins (24% fat), chocolate paste ested were fully informed about the purposes and require- (35% fat) and chips (23% fat).