Applied nutritional investigationEffect of conjugated linoleic acid supplementation on weight loss and body fat composition in a Chinese population
Introduction
Obesity is associated with an increased risk of death from cardiovascular disease, diabetes, kidney disease, and obesity-related cancers (colon, breast, esophageal, uterine, ovarian, kidney, and pancreatic) [1]. Adults who were overweight but not obese were at a significantly increased risk of developing numerous health conditions. [2]. According to a study in the United States, from 1976–1980 to 2007–2008, the obesity prevalence increased from 15% to 34% in adults and from 5% to 17% in children and adolescents [3], [4]. From 2007 through 2008, the age-adjusted prevalence of obesity was 33.8% overall (32.2% in men and 35.5% in women) [3].
Using the criteria defined by the Department of Health in Taiwan for adults, overweight and obesity were defined as a body mass index (BMI) greater than or equal to 24 and 27 kg/m2, respectively. The age-adjusted obesity prevalences were 10.5% and 15.9% for men and 13.2% and 10.7% for women in 1993–1996 and 2000–2001, respectively [5]. A strong positive relation exists between a high BMI and increased medical care expenditure in Taiwan, although the expenditure varies according to sex, age, and socioeconomic status [6]. Thus, coping with obesity is an important public health issue in Taiwan. Patients often try different methods, including dietary supplements, to lose weight before seeking professional obesity treatment. There are many dietary supplements sold in Taiwan, including conjugated linoleic acid (CLA).
Conjugated linoleic acid is a mixture of linoleic acid isomers with conjugated double bonds. It is not produced naturally by the human body and is obtained through food. This fatty acid is, however, produced naturally in the rumen of ruminant animals by the biologic hydrogenation of linoleic acid, and it can even be produced synthetically [7]. In ruminant animals, the predominant CLA isomer produced (>90%) is cis-9,trans-11. However, the trans-10,cis-12 isomer also seems to play an important role because it has been found to affect body composition alterations in animal models [8]. In addition, CLA can decrease the amount of atherosclerosis biomarkers, cancer risk, and inflammation and improve the immune response and body composition in animal models [9], [10], [11].
Although numerous studies in animals have shown that CLA supplementation results in changes in body composition, such as a decrease in body fat mass (BFM) and an increase in lean body mass (LBM) [12], [13], [14], [15], [16], studies on humans have yielded different results [17], [18], [19], [20], [21]. This might be related to the differences in the form and doses of CLA, the treatment duration, and a subject’s body weight (BW) among the different studies.
In the present study, we tested the effect of a 50% mixture of the two active CLA isomers (cis-9,trans-11 and trans-10,cis-12; Tonalin and NaturSlim, Kuang Chuan Dairy Co. Ltd., Taiwan) on BW, body composition, and biochemical parameters in overweight and obese Chinese subjects whose work required relatively less physical strength. This is the first trial of this kind in a Chinese population. We also evaluated the changes in hepatic and renal functions, side effects reported by the subjects, and changes in blood pressure to determine the safety of CLA in Chinese persons.
Section snippets
Subjects
We performed a randomized, double-blinded, placebo-controlled dietary intervention trial from March 1, 2009 through May 31, 2009 in the E-DA Hospital and I-Shou University. All participants were members of the company staff. The study included 26 men and 54 women 18 to 60 y old with a BMI of 24 to 35 kg/m2. They needed to have a stable weight, defined as a BW variation of less 5%, in the 3 mo before the study. Exclusion criteria included cancer, severe infection, thyroid disease, diabetes
Study subjects
Sixty-three of the 80 subjects (78.75%) completed the study. Ten participants (five in the CLA group and five in the control group) withdrew during the intervention period for personal reasons. Seven participants (five in the CLA group and two in the control group) were excluded from the analysis because their data were incomplete. Thus, the main analyses were conducted with 63 participants (CLA group, n = 30; control group, n = 33; Fig. 1).
The baseline characteristics of the two study groups
Discussion
To our knowledge, this is the first randomized, double-blinded, placebo-controlled clinical trial to evaluate the effect of CLA on body fat composition in a Chinese population. The consumption of milk supplemented with CLA (3.4 g/d for 12 wk) significantly decreased the BW, BMI, BFM, fat percentage, SFM, and WHR in overweight and grade I obese subjects.
The observation of a lower BFM in the CLA group than in the placebo group was similar to that reported in previous studies involving the same
Conclusions
We found that supplementation with CLA 3.4 g/d for 12 wk in healthy overweight and grade I obese subjects resulted in a decrease in obesity indices, with no obvious adverse effects. These changes were noticeable in grade I obese women. The levels of TC, TG, LDL, and Glu-AC increased, whereas those of HDL deceased after 3 mo of CLA treatment. The changes in these levels were slight, within the normal range, and not significantly different from the baseline values.
Acknowledgments
The authors are very thankful to Ting-Ting Wu for facilitating the recruitment of patients and to Yi-Chieh Hsieh and Yi-Hsuan Chang for their assistance with data collection.
References (42)
- et al.
Conjugated linoleic acid and atherosclerosis in rabbits
Atherosclerosis
(1994) - et al.
The combination of dietary conjugated linoleic acid and treadmill exercise lowers gain in body fat mass and enhances lean body mass in high fat-fed male Balb/C mice
J Nutr
(2005) - et al.
Conjugated linoleic acid reduces body weight gain in ovariectomized female C57BL/6J mice
Nutr Res
(2010) - et al.
Effect of conjugated linoleic acid on body fat accretion in overweight or obese children
Am J Clin Nutr
(2010) - et al.
Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans
Am J Clin Nutr
(2004) - et al.
Supplementation with conjugated linoleic acid for 24 months is well tolerated by and reduces body fat mass in healthy, overweight humans
J Nutr
(2005) Effect of conjugated linoleic acid on body composition and plasma lipids in humans: an overview of the literature
Am J Clin Nutr
(2004)- et al.
Opposing effects of cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid on blood lipids in healthy humans
Am J Clin Nutr
(2004) - et al.
Effects of dairy products naturally enriched with cis-9, trans-11 conjugated linoleic acid on the blood lipid profile in healthy middle-aged men
Am J Clin Nutr
(2006) - et al.
Conjugated linoleic acid supplementation for twelve weeks increases lean body mass in obese humans
J Nutr
(2007)
Cause-specific excess deaths associated with underweight, overweight, and obesity
JAMA
Impact of overweight on the risk of developing common chronic diseases during a 10-year period
Arch Intern Med
Prevalence and trends in obesity among US adults, 1999–2008
JAMA
Prevalence of high body mass index in US children and adolescents, 2007–2008
JAMA
Prevalence of obesity in Taiwan
Obes Rev
Association between obesity and medical care expenditure among Taiwanese adults
Asia Pac J Clin Nutr
Conjugated linoleic acid and the control of cancer and obesity
Toxicol Sci
Dietary conjugated linoleic acid and body composition
Am J Clin Nutr
Effects of dietary conjugated linoleic acid on lymphocyte function and growth of mammary tumors in mice
Anticancer Res
Effects of conjugated linoleic acid on body fat and energy metabolism in mouse
Am J Physiol Regul Integr Comp Physiol
Evidence that the trans-10, cis-12 isomer of conjugated linoleic acid induces body composition changes in mice
Lipids
Cited by (65)
Dietary fatty acids activate or deactivate brown and beige fat
2023, Life SciencesConjugated linoleic acid (CLA) as a functional food: Is it beneficial or not?
2023, Food Research InternationalConjugated linoleic acid supplements preserve muscle in high-body-fat adults: A double-blind, randomized, placebo trial
2020, Nutrition, Metabolism and Cardiovascular DiseasesCitation Excerpt :Conjugated linoleic acid (CLA) is a collective term that refers to a group of positional and geometrical isomers of linoleic acid naturally found in the fat, milk, and meat from ruminant animals [7]. Accumulating studies have evaluated the effect of CLA supplementation on body composition in humans [8], some of which showed reductions in body fat [9–11] or increased/sustained body muscle/lean mass [12–15], while others showed no significant effect [16,17]. Of note, most of those studies included people with a body mass index (BMI) ≥ 25 kg/m2.
Conjugated Linolenic Acid (CLnA) vs Conjugated Linoleic Acid (CLA): A Comprehensive Review of Potential Advantages in Molecular Characteristics, Health Benefits, and Production Techniques
2024, Journal of Agricultural and Food Chemistry
This study was supported by the Kuang Chuan Dairy Co., Ltd., Taiwan.