For centuries, people have enhanced their foods with various flavorings, preservatives, and dyes. But some ingredients on today’s food labels—with their complicated, chemistry set–like names—can seem downright alarming. The truth is, these ingredients are in foods for a purpose. Few foods reach today’s supermarkets free of additives—substances that do not occur naturally in a food but are added for various reasons.

These include preservatives to prevent spoilage; emulsifiers to prevent water and fat from separating; thickeners; vitamins and minerals (either to replace nutrients lost in processing or to increase nutritional value); sweeteners (both natural and artificial), salt; flavorings to improve taste; and dyes to make everything from candies to soft drinks more visually appealing. In all, North American food processors can choose from thousands of additives.

Although many people question the safety of these additives, their use is governed by stringent regulations. Authorities require extensive studies before an additive is allowed on the market. The appropriate use of additives allows us to enjoy history’s safest and most abundant assortment of foods. In short, the majority of food additives are safe to eat. However, they are generally not nutritious.

The most common additives are sugar, corn syrup, sodium, and trans fats, which can contribute to obesity, high blood pressure, heart disease, and many other health problems. So focus on whole, natural foods like fresh fruits and vegetables, whole grains, beans, and nuts. And when buying packaged foods, look for those with shorter ingredient and additive lists. In addition, while additives in general are safe, some are best left on the shelves.

The Center (CSPI) for Science in the Public Interest, a nonprofit organization, urges everyone to avoid these: Acesulfame-potassium. The organization questions the research that supported the safety of this artificial sweetener. Artificial colorings. According to the CSPI, blue no. 2, green no. 3, red no. 3, and yellow no. 6 have been linked to cancer in lab animals.

Yellow no. 5 triggers allergic-like reactions in some people. BHA (butylated hydroxyanisole). This chemical, which prevents rancidity in foods, has been linked to cancer in rodents. Caramel coloring. Found in colas, this common coloring can be contaminated with chemicals that some experts call carcinogenic. Potassium bromate. Found in some bread, bromate is linked to cancer in animals.