Calcium Absorption and Retention From Marine Products
Condition: Calcium Metabolism
Study type: Interventional

Summary: 
      The purpose of the study is to determine the uptake of calcium from fish bone meal from
      salmon and cod in 12 healthy volunteers. A test meal labelled with trace amounts of a
      radioactive calcium isotope (Ca47) will be given after an overnight fast and whole body
      retention of calcium will be measured on day 13, 21, and 24 after the test meal day.
    

Detailed description: 
      Background:

      Up till now little attention has been given the exploitation of marine by-products from the
      fishing industry. Calcium in fish is found mainly in bone and skin. By-products from these
      sources are limited to production of gelatine. Small fish, which can be eaten whole with
      bones included, are traditionally considered to be a good source of calcium. Until recently,
      bioavailability of this calcium was not known. Two recent studies from Denmark have shown
      that the absorption of calcium from small soft-boned fish was comparable to that of skimmed
      milk both in rats and in humans.

      Calcium fortified foods are likely to play an important role in helping consumers to achieve
      calcium requirements aimed at reducing the risk of developing osteoporosis. Experimental
      evidence show a positive effect of calcium supplementation on bone mineral accretion in
      children, and combined calcium and vitamin D supplementation has resulted in reduced bone
      loss and fracture incidence in older men and women.

      This protocol describes a project on the nutritional utilisation of calcium from fish bone
      waste. The main objective is to maximise the use and the added value of marine by-products
      with special emphasis on utilisation of fish bone as a calcium source and determine its
      bioavailabiliy in humans.

      Study design :

      This study will follow a 3x7 weeks ransomised crossover design, where the calcium absorption
      and retention will be measured form meals labelled with 47Ca. The test meals will be digested
      in the morning after a 12h fast and bloodsampling. Whole body retention will be measured on
      day 15, 22 and 26, and calibrated against a background measurement from the day prior to
      ingestion of the test meal. The subjects will receive an ordinary standardised diet for 2
      days prior and 3 days after the test meals. This diet will be standardised to match the
      subjects' individual calcium intake.

      Test meals:

      Two types of fish bone meal (from salmon and cod fish) and a control (CaCO3) will be tested.
      Amounts equivalent of 800 mg Ca will be baked into bread, which will be labelled with 47Ca
      and served with 500 mL of ultra pure water at the department.

      Isotopes and labelling procedure:

      Isotopes (47Ca) will be ordered from Risø National Laboratory, Radiation Research Department,
      Denmark. The department of Human Nutrition will recieve the prepared doses of isotopes the
      day before the test meal. A dose of 0.2 MBq/ml will be used. The doses will be used to
      extrinsically label the test meals by drop-wise adding 1 ml of isotope solution in the
      afternoon on the day before intake of test meals and stored at 5 degree C until ingested.

      Since each subject will recieve labelled meals on three occasions, a total dose of 0.6 MBq
      will be ingested during the study.

      Measurement of calcium retention:

      The whole body retention of calcium will be measured with a whole body counter at the
      Copenhagen University Hospital, Denmark. All measurements of calcium retention will be
      corrected for physical decay back to the time of administration.

      Chemical analyses:

      Serun calcium, phosphorus and vitamin D concentrations will be determined in before each test
      meal. Plasma levels of PTH will be determined before the first test meal only.
    

Intervention name(s): Calcium controlled diet
Intervention type(s): Behavioral
Intervention MeSH terms: Calcium
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Calcium absorption; D-vitamin status; Whole body calcium retention; Calcium intake; PTH status