If you【D1】______smooth skin that glows with youth, the chances are that at some point you will have heard the exhortation to dri

If you yearn for smooth skin that glows with youth, the chances are that at some point you will have heard the exhortation to drink lots of water in order to flush out those evil toxins and keep your skin healthy.
    The exact amount people suggest varies. US-based advice tends to recommend eight glasses a day, while in hotter climates people are advised to drink more to compensate for higher rates of sweating. But regardless of the exact volume of water suggested, the principle behind the advice remains the same—taking extra water on board will keep your skin hydrated. In other words, water acts like a moisturiser, but from the inside out.
    This is such a common idea you might be surprised at the lack of evidence to back up. You might expect there to be countless studies where people are separated into two groups, one assigned to sip water all day, the other to drink a normal amount. Then the smoothness of the skin could be assessed a month or so later to establish whether sipping more led to smoother skin.
    In fact such studies are rare, partly because water can’t be patented, so it is hard to find anyone to fund such research when there will be no new medication or cosmetic to sell that could repay the costs. A review by the dermatologist Ronni Wolf at the Kaplan Medical Centre in Israel found just one study looking at the effect of long-term water intake on the skin. But the results were contradictory. After four weeks, the group who drank extra mineral water showed a decrease in skin density, which some believe suggests the skin is retaining more moisture, while those who drank tap water showed an increase in skin density. But regardless of the type of water they drank, it made no difference to their wrinkles or to the smoothness of their skin.