7 Side Effects Drinking Too Many Smoothies, According to Dietitians 7 Side Effects Drinking Too Many Smoothies, According to Dietitians Smoothies can be a great way to power pack nutrients, especially if you are short on time or on-the-go. Plus, they can work as an entire meal, snack, or pick me up. But they can easily go from a health drink to a health disaster depending on their ingredients. "A smoothie is only as healthy as the ingredients used to make it," says Brenda Braslow, MS, RDN, registered dietitian nutritionist for MyNetDiary. "You can use a lot of veggies and make it a nutritional powerhouse, or you can add a lot of juice and added sugar that results in too many calories."