Protein Requirement During Lactation
Condition: Pregnancy
Study type: Interventional

Summary: 
      It is well established that a breast-feeding women need more protein in their diet compared
      to non-lactating women, but how much additional protein is needed remains unclear. There is
      reason to believe that the current Dietary Reference Intake (DRI) recommendations for
      breast-feeding women are too low. To gain better understanding, we plan to study healthy
      breast-feeding women 20 - 45 yrs, between 3 - 5 months lactation and 6 - 8 months lactation.
      We will use the indicator amino acid oxidation technique (IAAO), which is a modern, quick and
      safe research method.
    

Detailed description: 
      Purpose:

      To determine the dietary protein intake requirement in healthy lactating women during the
      exclusive breast-fed period (3 - 5 months lactation) and during weaning (6 - 8 months
      lactation).

      Hypothesis:

      Recent stable isotope-based research using the IAAO technique indicate that current protein
      intake recommendations are underestimated in adults by ~40 %, in school aged children ~75 %
      and pregnant women during early and late gestation by ~39 % and ~73 %, respectively.

      Therefore we hypothesize that that protein requirements will be increased during both phases
      of lactation above that of the current recommendations

      Justification:

      The WHO advocates that all newborn infants are exclusively breast-fed for the first 6 months
      of life, followed by a period of weaning, with appropriate complementary feeds, which is
      recommended to continue until the child's second birthday. The period of lactation from the
      mother's perspective of up to 2 years for each child, represents a considerable period of
      adult life. Adequate protein intake during lactation is important - if a woman's dietary
      intake of protein is inadequate, her own lean mass will be depleted to support the growth of
      the infant. Currently, dietary protein intake recommendations are based on nitrogen balance
      studies conducted in men and recommendations for breast-feeding women are extrapolated from
      these studies, and there is little breast-feeding specific data.

      Objectives:

      To determine the protein requirements during lactation and examine whether protein needs are
      significantly altered during exclusive breastfeeding (~3 - 5 mo post parturition) and partial
      breast feeding (~6 - 8 mo post parturition).

      Research design:

      A minimum of 10 women will be recruited. Each mother will participate in up to 8 study days,
      4 during the exclusively breast-fed period and 4 during the partial breast-fed period, for a
      total of 40 data points (study days) during each lactation period. We hope to retain the same
      women for all 8 study days to minimize data variability.

      Potential participants will meet us for a preliminary assessment where we will evaluate their
      eligibility to participate in the study. The preliminary assessment will take approximately 1
      hour during which we will examine body composition (Bioelectrical impedance, skin-fold
      measurements, height and weight), resting energy expenditure (by indirect calorimetry) and
      medical history (questionnaire). We will collect a 3 day food diary, to determine usual food
      intake and food preferences. Based on the 3 day food record we will prescribe a standardized
      diet two days prior to the study day to ensure protein intake of 1.5 g/kg/day and 1.7 x
      resting energy.

      During each study day, the participants will randomly receive 1 of 40 test protein intakes.
      Each subject will participate in one study day at approximately 14, 16, 18, 20 weeks
      postpartum and 24, 28, 30 and 32 weeks postpartum, respectively, for a total of up to 8 study
      days.

      The test protein intakes will be administered in an experimental diet. The study day diets
      will consist of 8 isocaloric and isonitrogenic meals provided hourly, each meal presenting
      1/12 of the daily energy requirement. Study day diet is composed of a crystalline amino acid
      mixture based on the composition of egg-protein, flavored with orange Tang, orange Kool-aid
      crystals and corn oil.

      A stable isotope tracer will be added to the 5th - 8th meal. We will measure the rate of
      oxidation of this tracer expired in breath (F13CO2), and flux of this tracer by its
      enrichment in urine.
    

Intervention name(s): Dietary supplement: Protein intake
Intervention type(s): Dietary Supplement
Intervention description(s): Oral consumption of houly experimental meals. Includes 4 meals containing a mixture of free amino acids, carbohydrates from a flavored liquid, fat from corn oil and protein free cookies.
The last 4 meals will in addition contain labelled labelled 13C phenylalanine.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: Protein requirement