Supplementation with Bovine Milk or Soy Beverages Recovers Bone Mineralization in Young Growing Rats Fed an Insufficient Diet, in Contrast to an Almond Beverage

Abstract

Background: Nondairy beverages, produced from soy, rice, oat, almond, or coconut, are increasingly being used as alternatives to dairy milk, with the perception that they are healthier and/or more sustainable products than dairy products.

Objective: The aim of this study was to compare the effects of supplementing either bovine milk, soy, or almond-based beverages to young, growing rats fed an intact-protein diet or a diet that had protein substituted with amino acids (AA-diet).

Methods: Three-week-old male Sprague-Dawley rats were randomly assigned to 5 groups (n = 10/group) and fed ad libitum for 4 wk. Two control groups were fed either standard AIN-93G food [20% casein (CN) protein] or AIN-93G with amino acids (AAs) equivalent to CN protein, and water to drink. Three treatment groups were fed AIN-93G AA and supplemented with either bovine ultra-heat treatment (UHT) milk or soy or almond UHT beverages. Rat weight gain and food intakes were recorded. During week 4, body composition was assessed using DEXA to determine lean soft tissue, fat, and bone mass. At trial end, bone biomechanical properties and blood plasma mineral concentrations were measured.

Results: At the end of the trial, animals supplemented with almond beverage were lightest (P > 0.05), with higher plasma calcium concentrations (P > 0.05) and lower bone mineral content (BMC) and bone density (P > 0.05) than animals supplemented with milk or soy beverage. Soy-supplemented animals had similar BMC and bone density compared with milk-supplemented animals, although the soy group gained most weight (P > 0.05) and had the highest fat:lean ratio (P > 0.05) compared with other groups.

Conclusions: In the model tested, supplementing rats with bovine UHT milk and soy UHT beverage provided favorable bone health outcomes. Conversely, almond UHT beverage was not an effective supplement and could be detrimental to bone mineralization and strength outcomes.

Keywords: almond drink; amino acid diet; bone mineralization; milk; soy drink.

FIGURE 1

Animal weights at the start and the end of the feeding trial. Individual animal values are shown as black circles; group data are represented as box and whisker plots, with SEDs for each time point. End-of-trial weights were analyzed by ANOVA, using start weight as a covariate, n = 10/group; boxes without a common letter denote a significant difference (P < 0.05). Trial start, grey boxes; trial end, open boxes. AA, amino acid; CN, casein; SED, SE of difference.

FIGURE 2

Fat:lean ratios. Body composition was assessed on live animals using DEXA and the fat:lean ratios were calculated for each animal. Individual animal values are shown as black circles; group data are represented as box and whisker plots, with SEDs. Data were analyzed by ANOVA, using start weight as a covariate, n = 10/group; boxes without a common letter denote a significant difference (P < 0.05). AA, amino acid; CN, casein; SED, SE of difference.

FIGURE 3

BMC and BMD of live animals measured in week 4 using DEXA. Individual animal values are shown as black circles; group data are represented as box and whisker plots, with SEDs. Data were analyzed by ANOVA, using start weight as a covariate, n = 10/group; boxes without a common letter denote a significant difference (P < 0.05). AA, amino acid; BMC, bone mineral content; BMD, bone mineral density; CN, casein; SED, SE of difference.