The key to heart health isn't cutting down on pasta or potatoes, new evidence suggests; it's not even a low-fat diet. A study that tracked nearly 200,000 men and women in the US for around 30 years has now found that some low-fat and low-carb diets are better for heart health than others. The key was the quality of the food itself, not the quantity of carbs or fats. The research, led by public health researchers at Harvard University, suggests that if a diet contains too many processed foods