Early Life Sugar Consumption Affects the Rat Microbiome Independently of Obesity

A recent study published in The Journal of Nutrition utilized a rodent model to assess the impact of early-life added sugar consumption on the composition of the gut microbiome, caloric intake, and weight gain. Researchers divided 42 juvenile male Sprague-Dawley rats (post-natal day 26) into 4 groups that were maintained on identical diets with varying sugar water solutions (11% wt:volume) until post-natal day 92. Their dietary intakes are described in the table below. Fecal samples were collected and sequenced on post-natal day 80 to measure changes in the microbiome.

  % Fructose % Glucose Diet
Group One


35 65 Lab Diet 5001

29.8% kcals from protein

13.4% kcals from fat

56.7% kcals from carbohydrate

Group Two


65 35
Group Three


50 50
Group Four [Control]


0 0

Researchers found that there was no significant difference between groups for body weight gain, overall caloric intake, body fat, lean mass, or overall adiposity index. Rats that consumed sugar water consumed less of the solid food. As a result of this well-established compensatory behavior in Sprague-Dawley rats, all three sugar groups consumed a significantly lower percentage of energy from fat and protein compared to the control.

The 16s rRNA sequencing of fecal samples taken at post-natal day 80 revealed a distinct clustering pattern when comparing the sugar to non-sugar fed rats. Interestingly, when comparing the 3 different fructose-to-glucose ratio groups, there was no distinct clustering pattern observed. Researchers detail a number of shifts in the microbiome at the phylum, class, order, family, and genus level. For example, at the phylum level, Proteobacteria and Actinobacteria were elevated in the sugar consuming groups. At the class level, Actinobacteria, Bacilli, Alpha-, Beta- and Gamma-Proteobacteria were significantly elevated in the sugar consuming group.

Researchers conclude “that the gut microbiome is affected by added-sugar consumption during the juvenile and adolescent stage of development and that these differences are independent of obesity status and caloric intake. Moreover, the monosaccharide ratio of fructose to glucose did not significantly contribute to the overall effects of sugar consumption on microbial populations.”