Cholesterol Metabolism After Bariatric Surgery in Grade 3 Obesity

Differences between malabsorptive and restrictive procedures

  1. Antonio E. Pontiroli, MD1,2
  1. 1Dipartimento di Scienze della Salute, Universita degli Studi di Milano, Milan, Italy
  2. 2Dipartimento di Medicina Interna, Ospedale San Paolo, Milan, Italy
  3. 3Dipartimento di Medicina Sperimentale, Universita degli Studi di Milano Bicocca, University of Milan Bicocca, Milan, Italy
  4. 4Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Universita degli Studi di Milano, Milan, Italy
  5. 5Istituto Nazionale per la Chirurgia dell'Obesita and Unita Operativa di Chirurgia Generale, Istituto Clinico Sant'Ambrogio, Milan, Italy
  1. Corresponding author: Antonio E. Pontiroli, antonio.pontiroli{at}unimi.it.

Abstract

OBJECTIVE Malabsorptive bariatric surgery (biliopancreatic diversion and biliointestinal bypass [BIBP]) reduces serum cholesterol levels more than restrictive surgery (adjustable gastric banding [AGB]), and this is thought to be due to greater weight loss. Our aim was to evaluate the changes of cholesterol metabolism induced by malabsorptive and restrictive surgery independent of weight loss.

RESEARCH DESIGN AND METHODS In a nonrandomized, self-selected, unblinded, active-comparator, bicenter, 6-month study, glucose metabolism (blood glucose and serum insulin levels and homeostasis model assessment of insulin resistance [HOMA-IR] index) and cholesterol metabolism (absorption: serum campesterol and sitosterol levels; synthesis: serum lathosterol levels; catabolism: rate of appearance and serum concentrations of serum 7-α- and serum 27-OH-cholesterol after infusions of deuterated 7-α- and 27-OH-cholesterol in sequence) were assessed in grade 3 obesity subjects undergoing BIBP (n = 10) and AGB (n = 10). Evaluations were performed before and 6 months after surgery.

RESULTS Subjects had similar values at baseline. Weight loss was similar in the two groups of subjects, and blood glucose, insulin levels, HOMA-IR, and triglycerides decreased in a similar way. In contrast, serum cholesterol, LDL cholesterol, non-HDL cholesterol, serum sitosterol, and campesterol levels decreased and lathosterol levels increased only in BIBP subjects, not in AGB subjects. A significant increase in 7-α-OH-cholesterol occurred only with BIBP; serum 27-OH-cholesterol decreased in both groups.

CONCLUSIONS Malabsorptive surgery specifically affects cholesterol levels, independent of weight loss and independent of glucose metabolism and insulin resistance. Decreased sterol absorption leads to decreased cholesterol and LDL cholesterol levels, accompanied by enhanced cholesterol synthesis and enhanced cholesterol catabolism. Compared with AGB, BIBP provides greater cholesterol lowering.

  • Received August 27, 2012.
  • Accepted November 6, 2012.

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  1. Diabetes Care vol. 36 no. 6 1443-1447
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