Comment by mikeyouse

The key results from the paper:

    After adjustment for sociodemographic and health-related
    characteristics, sugar-sweetened soda consumption was 
    associated with shorter telomeres (b = –0.010; 95% 
    confidence interval [CI] = −0.020, −0.001; P = .04).
    Consumption of 100% fruit juice was marginally associated
    with longer telomeres (b = 0.016; 95% CI = −0.000, 0.033;
    P = .05). No significant associations were observed between
    consumption of diet sodas or noncarbonated SSBs and 
    telomere length.

Shortened telomeres are one way to measure genetic 'age'. So they saw 'aging' with sugar-sweetened soda, the opposite with fruit juice, and no significant difference with diet sodas or non-carbonated sugary sodas.

The study was pretty substantial with ~5,300 participants with no history of cardiovascular disease or diabetes. It's nice to have another datapoint against some of the bro-sciencey "Fruit juice has as much sugar as soda" arguments.

Late Edit:

Here's a pretty good summary of telomere aging:

http://learn.genetics.utah.edu/content/chromosomes/telomeres...