For some, there's no escape from the daily grind According to a study in the Journal of Caffeine Research , the negative effects of caffeine can go unrecognised, and cases of problematic caffeine use may call for treatment. The study summarised the results of previously published caffeine research and found that more than half of regular caffeine consumers report difficulty quitting or reducing caffeine use. Study co-author Laura Juliano advises that healthy adults should limit caffeine consumption to no more than 400mg per day, or about two to three 240ml cups of coffee. Pregnant women should consume less than 200mg per day. Voice may change after nose surgery Getting a nose job not only changes your appearance, but may also change the sound of your voice, according to a new study in the journal Plastic and Reconstructive Surgery . These voice changes after rhinoplasty are perceptible to patients as well as experts, but generally don't cause problems with speech function, say the researchers from Mashhad University of Medical Sciences, Iran. The study analysed changes in voice quality in 27 rhinoplasty patients at two hospitals in Iran; about a fifth of the patients used their voice professionally. An increase in "hyponasality" was found post-surgery, similar to the voice of a person with a stuffy nose. Certain probiotics could help women to lose weight Certain probiotics could help women lose weight and keep it off, reports a study in the British Journal of Nutrition . Researchers from Université Laval in Quebec put 125 overweight men and women through a 12-week weight-loss diet, followed by a 12-week period aimed at maintaining body weight. Throughout the study, half the participants took two pills daily containing probiotics from the Lactobacillus rhamnosus family, while the other half received a placebo. At the end of the study, women who consumed probiotics lost twice as much weight as those who didn't.