Complex sentence: From the early 2000s there was increased interest from scientists about diets that were low in or free of animal products, and in 2003 two major North American dietitians' associations approved the vegan diet as safe for all life stages.
Split into simpler sentences: From the early 2000s there was increased interest from scientists about diets that were low in, or free of, animal products. In 2003 two major North American dietitians' associations approved the vegan diet as safe for all life stages.