However, some types of soy milk do have a major nutritional disadvantage because of their added sugar content. Added sugars boost your calories without offering nutritional value, and increase your risk of cardiovascular disease. Select unsweetened soy milk to minimize added sugar -- it contains just 1 gram of naturally occurring sugars and no added sugar. Chocolate and vanilla flavored soy milks, in contrast, contain 18 and 6 grams of added sugar per serving, respectively.