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Acording to a Swedish study that says dog ownership could reduce heart disease.A study of 3.4 million people between the ages of 40 and 8 0 found that having a dog was associated with a 23% reduction in death fr om heart disease and a 20% lower risk of dying from any cause over the 12 years of the study. Previous studies have suggested dogs relieve social isolation and depres-sion both linked to an increased risk of heart disease and early death.

Dog owners show better responses to stress，have higher levels of physical activity and slightly lower cholesterol(胆固醇)levels.The American Heart Asociation was sufficiently swayed by a review of dozens of studies to release a statement in 2013 saying that owning a dog" was probably associated with a reduced risk of heart disease: Their reluctance to more strongly approve dog ownership is because most studies are w hat is called observational-researchers note an as-sociation?but can't prove causation.This means that other factors might explain why dog owners are healthier than,say goldfish owners-for cxample,perhaps only people who are fit in the first place buy pets that need daily walkies.

Tove Fall, an epidemiologist (流行病学家)and the leading author of this latest study, says they tried their bestto allow for any differences in education,existing ilhea 1th and lifestyles between those with and without dogs. The study found the biggest positive impact of having a dog was on people living alone.“It seems that a dog can be asubstitute for living with other people in terms of reducing the risk of dying,"says Fall.'’Dogs encourage you to walk,they provide social support and they make life more meaningful.If y ou have a dog,you inleract more with other people. If you do get ill and go into hospital and you have a dog,there’s ahuge motivation to try to get back home."