The Effect of Chymosin on the Intestinal Absorption of Calcium
Condition: Osteoporosis; Osteopenia
MeSH terms: Osteoporosis; Bone Diseases, Metabolic
Study type: Interventional
Phase: Phase 1

Summary: 
      An adequate calcium intake is important for bone turnover and the risk of developing
      osteoporosis. Yet many studies have documented that supplementation with calcium tablets are
      often associated with a poor compliance, therefore it is important to explore ways to better
      calcium influx.

      Calcium consumed through dairy products must first be cleaved from the molecules which it is
      bound to before it can be absorbed. Chymosin is an enzyme which cleaves the protein binding
      between some amino acids in κ-casein. The reaction occurs after ingestion of milk and causes
      a process whereby the time the milk is staying gastrointestinal tract is extended, this can
      lead to enhanced uptake of calcium.

      When the body's calcium balance is in equilibrium excretion in urine (24 h) in roughly the
      size of the intake, whereby a measurement of circadian urine excretion of calcium can
      determine the amount of calcium absorbed from the intestine.

      The investigators want to clarify whether the addition of chymosin to milk increases calcium
      absorption. Secondary to explore issues of significance for this effect, including vitamin D
      status and amount of daily calcium intake and whether a change in calcium absorption has
      immediate effects on bone turnover (measured as plasma osteocalcin, bone specific alkaline
      phosphatase (BSAP), and the renal excretion of cross-linked N-terminal telopeptide of type 1
      collagen (NTx/Cr) ratio) and on the parathyroid function (measured as PTH). Finally we will
      explore relations between bone mineral density (BMD) and the measured parameters (in terms of
      P-PTH, P-25OHD, P-1,25(OH)2D, P-osteocalcin, P-BSAP, and U-NTx/Cr).
    

Detailed description: 
      Background:

      Osteoporosis is a frequent disease. Allegedly, more than 500,000 Danes are diagnosed with
      osteoporosis and, in consequence, seems every year more than 20,000 fractures. A number of
      factors are known to increase the risk of osteoporosis, including a low daily intake of
      calcium.

      Several clinical trials with calcium supplements for adults (with or without simultaneous
      supplementation of vitamin D) have shown an increase in bone mineral density (Bone Mineral
      Density, BMD) and reduction the risk of fractures. Similarly, several studies have shown that
      high milk intake during childhood and adolescence may increase bone mass and reduce the risk
      of fractures later in life.

      Since an adequate calcium intake is important for bone turnover and the risk of developing
      osteoporosis, it is important to explore ways to better calcium influx. Several studies have
      documented that supplementation with calcium tablets are often associated with a poor
      compliance - people do not remember to take the tablets. It is therefore desirable to find
      methods that can increase the intake of the amount of calcium which occurs naturally in the
      diet.

      Calcium consumed through dairy products must first be cleaved from the molecules which it is
      bound to before it can be absorbed. Various methods have been tried to optimizing the amount
      of calcium absorbed from dairy products, including the addition of so called
      fructo-oligosaccharides (FOSS) and casein phosphopeptides (CPPs).

      Chymosin is an enzyme which cleaves the protein binding between some amino acids in κ-casein.
      The reaction occurs after ingestion of milk and causes a process whereby the time the milk is
      staying gastrointestinal tract is extended, this can lead to enhanced uptake of calcium. When
      the body's calcium balance is in balance the excretion in urine (24 h)is in roughly the size
      as the intake. Therefore a measurement of circadian urine excretion of calcium can determine
      the amount of calcium absorbed from the intestine.

      Purpose and hypothesis:

      Primarily the study intends to clarify whether the addition of chymosin to milk increases the
      intestinal calcium absorption. Secondary to explore issues of significance for this effect,
      including vitamin D status and amount of daily calcium intake, and whether a change in
      calcium absorption has immediate effects on bone turnover (measured as plasma osteocalcin,
      plasma bone specific alkaline phosphatase, and the renal excretion of cross-linked N-terminal
      telopeptide of type 1 collagen (NTx/Cr) ratio) and on the parathyroid function (measured as
      PTH). Finally we will explore relations between bone mineral density (BMD) and the measured
      parameters (in terms of P-PTH, P-25OHD, P-1,25(OH)2D, P-osteocalcin, P-BSAP, and U-NTx/Cr).

      Design:

      The study is conducted as a randomized double-blinded controlled cross-over trial in which
      125 healthy subjects will be asked to drink a glass of milk with or without added chymosin at
      two occasions. The two time two test days will be separated by 10-18 days. Neither study
      participants nor the staff conducting the investigation (investigator) will while the trial
      will be conducted know on which day of the trial which milk contains chymosin
      (double-blinded). About chymosin added to milk on the first or second test day will be
      determined by lot (randomized study).

      Study Population:

      Healthy participants in the agegroup of 25-40 years old are recruited. From the central
      personal register (CPR register) a list of young people living in the Aarhus area is drawn
      up, followed by sending out a direct letter asking for participation in the study. At the
      same time a questionnaire will clarify whether participation is possible, i.e. whether the
      criteria for participation in the survey are meet.
    

Intervention name(s): Drug A Chymosin; Drug B: Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Five drops of chymosin is added to ½ a liter of milk. This is to be consumed during breakfast.; B: Five drops of placebo (water) is added to ½ a liter of milk. This is to be consumed during breakfast.
Other intervention name(s): Chy-max plus IMCU200; Water
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Chymosin; 24H urine calcium excretion; Calcium absorption; Intestinal Absorption of Calcium