Eur J Nutr (2004) 43 : 61–68 DOI 10.1007/s00394-004-0441-y ■ Summary Background Milk fer- mented with Lactobacillus helveti- cus (L. helveticus) has been shown to lower blood pressure and to in- crease bone mineral content in Received: 23 April 2003 Accepted: 9 July 2003 Published online: 6 January 2004 M. Narva, MSc · R. Nevala, MD · R. Korpela, PhD Institute of Biomedicine, Pharmacology Helsinki University Helsinki, Finland M. Narva, MSc · R. Korpela, PhD Valio Research Centre Valio, Finland T. Poussa, MSc Stat-Consulting Tampere, Finland Dr. Riitta Korpela () Institute of Biomedicine, Pharmacology P.O. Box 63 00014 Helsinki University, Finland Tel.: +358-10/3813026 Fax: +358-10/3813019 E-Mail: riitta.korpela@valio.fi spontaneously hypertensive rats. The effect of L.helveticus may be due to better calcium availability. Aim of the study In the present study the effect of milk fermented with L. helveticus on acute changes in calcium metabolism and bone resorption in postmenopausal women was studied. Methods The study was performed as a ran- domised double-blind crossover study of 20 postmenopausal women (mean age 65, range 50–78). The study was carried out in two parts. Firstly, L. helveticus fermented milk was compared to a control milk. Secondly, juice con- taining peptides formed with L. helveticus bacteria was compared to a control juice. The acute effect on calcium metabolism was mea- sured during the study day by serum ionised calcium (iCa), parathyroid hormone (PTH), cal- cium (Ca), phosphate (P), and uri- nary calcium. A direct marker of bone turnover, carboxyterminal telopeptide of type I collagen (ICTP), was measured from the serum. Results L. helveticus fer- mented milk reduced serum PTH (405.3 ± 37 ng/l vs. 454.9 ± 37, p = 0.012) and increased serum cal- cium (19.1± 0.2 mmol/l vs. 18.8 ± 0.2, p = 0.031) compared to the control milk. L. helveticus- derived peptides had no significant acute effect on calcium metabo- lism, in fact, ionised calcium was lower and PTH higher after the juice containing peptides com- pared to the control juice. Conclu- sions Fermentation of milk with Lactobacillus helveticus had a posi- tive acute effect on calcium metab- olism. This effect was not explained by the small peptides formed by L. helveticus. ■ Key words calcium metabolism – L. helveticus – bioactive peptides – postmenopausal women ORIGINAL CONTRIBUTION Mirkka Narva Riikka Nevala Tuija Poussa Riitta Korpela The effect of Lactobacillus helveticus fermented milk on acute changes in calcium metabolism in postmenopausal women Introduction Calcium is needed throughout life to ensure bone growth during adolescence and to support bone mass when age-related bone loss occurs [1]. In western coun- tries the main source of calcium in the diet is milk prod- ucts, accounting for up to 75% of calcium intake [2, 3]. However, the use of milk products has been declining over the past decade [4], thus increasing the risk groups of low-calcium intake [5]. In the prevention of osteo- porosis it is vital to increase calcium intake by augment- ing the intake of milk products, by calcium fortification or with calcium supplements. These methods are not al- ways successful because of dietary preferences and lack of compliance [1].A further possibility is to improve cal- cium availability.Better calcium availability would com- pensate for the lower use of milk products and ensure an adequate supply of calcium to the bone. Milk-derived caseinophosphopeptides (CPP), formed in the gastrointestinal tract or during fermenta- tion enhance calcium absorption by preventing the for- EJN 441