Scientific Opinion on the substantiation of health claims related to chitosan
and reduction in body weight (ID 679, 1499), maintenance of normal blood
LDL-cholesterol concentrations (ID 4663), reduction of intestinal transit
time (ID 4664) and reduction of inflammation (ID 1985) pursuant to Article
13(1) of Regulation (EC) No 1924/2006[sup]1[/sup]
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2, 3
European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe:
Chitosan
LDL-cholesterol
body weight
fibre
health claims
inflammation
intestinal transit time
3. Naukowe uzasadnienia wpływu na zdrowie człowieka -
3.1. Redukcja masy ciała (ID 679 and 1499)
The references provided for the scientific substantiation of the claim included narrative reviews and book chapters which did not provide original data for a scientific evaluation, one human intervention study which investigated the effects of a combination of chitosan and glucomannan on body weight, and one intervention study using chitosan which did not report on body weight. Two references on internal reports were not available to the Panel even after every reasonable effort had been made to
retrieve them. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claim.
In addition, one meta-analysis of randomised controlled trials (RCTs, Ernst and Pittler, 2000), one Cochrane systematic review and meta-analysis of RCTs (Ni Mhurchu et al., 2005) and seven human intervention studies on the effect of chitosan on body weight were provided. The Panel notes that all of the intervention studies provided, and those included in the systematic review and meta-analysis, were considered in a more recent update of the Cochrane systematic review (Jull et al., 2008), which was considered by the Panel for the scientific evaluation of the claim. This systematic review was restricted to RCTs which assessed the effects of chitosan on body weight, compared to placebo or standard care in adult overweight or obese males and females, and which had a minimum duration of four weeks. A total of 15 studies out of 42 identified met the inclusion criteria, and these studies comprised a total of 1,216 participants (640 allocated to chitosan and 640 to placebo) with a mean age of 44 years (range 18 to 70 years). Mean trial duration was 8.3 weeks (range 4-24 weeks) and mean study size was 81 subjects (range 24 to 250). All trials compared chitosan at doses ranking from 0.24 g/day to 15 g/day (mean 3.7 g/day) to placebo, but five studies did not report any dose (Colombo and Sciutto, 1996; Giustina and Ventura, 1995; Sciutto and Colombo, 1995; Veneroni et al., 1996; Woodgate and Conquer, 2003). Sufficient data on body weight were available only for 13 trials, which were considered for data analysis (Colombo and Sciutto, 1996; Giustina and Ventura, 1995; Ho et al., 2001; Kaats et al., 2006; Macchi, 1996; Ni Mhurchu et al., 2004; Pittler et al., 1999; Schiller et al., 2001; Sciutto and Colombo, 1995; Veneroni et al., 1996; Williams, 1998; Woodgate and Conquer, 2003; Zahorska-Markiewicz et al., 2002). Seven studies (Colombo and Sciutto, 1996; Girola et al., 1996; Giustina and Ventura, 1995; Kaats et al., 2006; Sciutto and Colombo, 1995; Veneroni et al., 1996; Woodgate and Conquer, 2003) used treatment preparations which contained other active ingredients in addition to chitosan, while the remainder used chitosan alone. The treatment preparations contained, in addition to chitosan, guar gum, ascorbic acid and other micronutrients (Colombo and Sciutto, 1996; Giustina and Ventura, 1995; Sciutto and Colombo, 1995; Veneroni et al., 1996), glucomannan, fenugreek, Gymnema sylvestre and vitamin C (Woodgate and Conquer, 2003), Garcinia cambogia extract and chrome (Girola et al., 1996), and beta-glucan, snow white oat fibre, betamine HCL and aloe saponins (Kaats et al., 2006). The Panel considers that no conclusions can be drawn from these studies, and thus from the meta-analysis in which they were included, for the scientific substantiation of the claim.
When the analysis was limited to trials which used chitosan alone as intervention (Ho et al., 2001; Macchi, 1996; Ni Mhurchu et al., 2004; Pittler et al., 1999; Schiller et al., 2001; Wuolijoki et al., 1999; Zahorska-Markiewicz et al., 2002), a small but statistically significant weight loss of -0.9 kg (95 % CI -1.4 to -0.4, p=0.0009) was observed with chitosan compared to placebo. However, when the analysis was limited to trials that met the allocation concealment quality criteria (Ni Mhurchu et al., 2004; Pittler et al., 1999; Schiller et al., 2001), no significant differences between the effect of chitosan and placebo on body weight changes were observed (-0.6 kg, 95 % CI -1.3 to 0.1, p=0.09). Similar results were obtained when the analysis was limited to studies of six months duration (Ni Mhurchu et al., 2004; Zahorska-Markiewicz et al., 2002). The Panel notes that this meta-analysis does not show an effect of chitosan consumption on body weight loss.
The mechanism by which chitosan is presumed to exert the claimed effect is by binding to negatively charged lipids and hence reducing their gastro-intestinal uptake, and these effects were observed in some animal studies (Deuchi et al., 1995; Sugano et al., 1980; Zacour et al., 1992). However, the effects of chitosan on 24 h faecal fat excretion in healthy human volunteers at doses of about 3 g daily were not statistically significant, and thus were unlikely to have an impact on body weight (Guerciolini et al., 2001).
In weighing the evidence, the Panel took into account that a meta-analysis of RCTs, which included all the individual human intervention studies submitted for the scientific substantiation of the claim
and which investigated the effects of chitosan consumption on body weight, did not show a significant effect of chitosan when only studies that met the allocation concealment quality criteria were considered for analysis.
The Panel concludes that a cause and effect relationship has not been established between the consumption of chitosan and reduction in body weight.
3.2. Utrzymanie prawidłowego stężenia cholesterolu LDL we krwi (ID 4663)
Five animal studies and one human intervention study on the effects of chitosan on blood lipids were provided for the scientific substantiation of the claim.
The Cochrane systematic review (Jull et al., 2008) cited in section 3.1. also reported on the effects of chitosan on blood lipids and included the only human intervention study submitted for the scientific substantiation of the claim (Macchi, 1996).
Statistical analyses combining the nine trials that provided data on total cholesterol concentrations (Colombo and Sciutto, 1996; Ho et al., 2001; Kaats et al., 2006; Macchi, 1996; Ni Mhurchu et al., 2004; Pittler et al., 1999; Veneroni et al., 1996; Wuolijoki et al., 1999; Zahorska-Markiewicz et al., 2002) were reported in the meta-analysis. However, the Panel notes that some of these studies used treatment preparations which contained other active ingredients in addition to chitosan, and considers that no conclusions can be drawn from these analyses for the scientific substantiation of the claim. When the trials were limited to those that used chitosan alone as intervention (Ho et al., 2001; Macchi, 1996; Ni Mhurchu et al., 2004; Pittler et al., 1999; Zahorska-Markiewicz et al., 2002), a small but statistically significant reduction in total cholesterol concentrations of -0.15 mmol/L (95 % CI -0.23 to -0.07, p=0.0002) was observed. Similar results were obtained when the analyses were limited to trials that met the allocation concealment quality criteria (Ni Mhurchu et al., 2004; Pittler et al., 1999) (-0.15 mmol/L; 95 % CI -0.23 to -0.07, p=0.0004). The I2-statistic indicated substantial heterogeneity (I2=59.5 %).
Statistical analyses combining the seven trials that included data on LDL-cholesterol concentrations (Colombo and Sciutto, 1996; Ho et al., 2001; Kaats et al., 2006; Ni Mhurchu et al., 2004; Veneroni et al., 1996; Wuolijoki et al., 1999; Zahorska-Markiewicz et al., 2002) were provided in the meta-analysis. However, the Panel notes that four of these trials used treatment preparations which contained other active ingredients in addition to chitosan (Colombo and Sciutto, 1996; Kaats et al., 2006; Veneroni et al., 1996; Wuolijoki et al., 1999), and that no separate analysis of the trials using chitosan alone was provided. The Panel notes, however, that whereas the studies by Ho et al. (2001) and Zahorska-Markiewicz et al. (2002), including 68 and 32 subjects respectively, did not show a significant effect on LDL-cholesterol concentrations, the largest study, by Ni Mhurchu et al. (2004), which included 250 subjects (125 per group), observed a small but statistically significant reduction in LDL-cholesterol concentrations in favour of chitosan (-0.12 mmol/L, 95 % CI -0.19 to -0.05). Similar results were obtained when the analysis was limited to the two studies of 6 months duration (-0.14 mmol/L, 95 % CI -0.19 to -0.06) (Ni Mhurchu et al., 2004; Zahorska-Markiewicz et al., 2002).
Statistical analyses combining the seven trials that provided data on HDL-cholesterol concentrations (Colombo and Sciutto, 1996; Ho et al., 2001; Kaats et al., 2006; Macchi, 1996; Ni Mhurchu et al., 2004; Veneroni et al., 1996; Zahorska-Markiewicz et al., 2002) were also provided. The Panel notes that three of these trials used treatment preparations which contained other active ingredients in addition to chitosan (Colombo and Sciutto, 1996; Kaats et al., 2006; Veneroni et al., 1996), and that no separate analysis of the trials using chitosan alone was provided in the meta-analysis. The Panel also notes that only the smallest study using chitosan alone showed a statistically significant increase in HDL-cholesterol concentrations compared to placebo (0.15 mmol/L, 95 % CI 0.03 to 0.27; 10 subjects per group) (Macchi, 1996), whereas no significant differences between chitosan and
placebo were observed in any of the other three studies, including the largest study by NiMhurchu et al. (2004), which had the longest duration (6 months).
The Panel notes that while chitosan consumption at doses of about 3 g/day showed, in the meta- analysis by Jull et al. (2008), a small but statistically significant effect on the reduction of both total (combining five studies) and LDL-cholesterol (combining two studies) concentrations, no effect was observed on HDL-cholesterol concentrations.
The mechanism by which chitosan is presumed to exert the claimed effect is by binding to negatively charged lipids and hence reducing their gastro-intestinal uptake, and these effects were observed in some animal studies (Deuchi et al., 1995; Sugano et al., 1980; Zacour et al., 1992). The effects of chitosan on 24 h faecal fat excretion in healthy human volunteers at doses of about 3 g daily were not statistically significant (Guerciolini et al., 2001), and it is unclear whether this could play a role on the claimed effect.
In weighing the evidence, the Panel took into account that a meta-analysis of RCTs, which investigated the effects of chitosan consumption on blood lipids, showed a small but statistically significant reduction in total and LDL-cholesterol concentrations.
The Panel concludes that a cause and effect relationship has been established between the consumption of chitosan and maintenance of normal blood LDL-cholesterol concentrations.
3.3. Skrócenie czasu pasażu jelitowego (ID 4664)
Only one reference was provided in relation to the claim.
In a double-blind, placebo-controlled study, Kaats et al. (2006) evaluated the safety and efficacy of chitosan on body composition in a group of 134 overweight/obese adults. The Panel notes that the study did not address outcome measures related to the claimed effect, and considers that no conclusions can be drawn from this study for the scientific substantiation of the claim.
The Panel concludes that a cause and effect relationship has not been established between the consumption of chitosan and reduction of intestinal transit time.