To make sure that your salad dressing is heart-healthy, start with the base. Vinaigrettes are generally made with a mild-tasting vegetable oil such as soybean, canola or corn. (Bonus: these oils are also inexpensive.) They're considered heart-healthy because they're naturally occurring and unhydrogenated, meaning they don't contain trans-fatty acids. They also contain polyunsaturated or monounsaturated fats (the good ones) and may help lower your LDL, or "bad," cholesterol levels.
If you want to step up the heart-healthy effects of your dressing, however, consider one made with olive oil. Besides adding great flavor, olive oil is high in antioxidants called polyphenols. Pick up some virgin or extra-virgin olive oil for the highest levels of polyphenols -- they aren't processed as much as regular olive oil.
Oils such as sesame, walnut or macadamia have many of the same health benefits as olive oil. They're expensive and high in fat, but a little bit goes a long way, so you could mix a small amount of one of these flavored oils with another type of oil.
And what about heart-healthy creamy dressings? Finding them is a bit trickier, as creamy dressings tend to get their texture from dairy products that are high in saturated fats. If you really want to get some heart-healthy benefits from your salad dressing, forget the bottled stuff and make your own. You can find mayonnaise made with olive oil, which would work well as a base.
Choosing a heart-healthy salad dressing when in a restaurant is also difficult; it's best to stick to a basic vinegar-and-oil, which most restaurants stock. If that's unavailable, try Italian or another type of vinaigrette. Unless the salad dressings are made in-house, your server may not be able to provide you with detailed ingredients.