Speaking of fad diets (like the paleo diet), what about the green smoothie diet? This fad diet uses a meal replacement strategy where dieters replace two meals a day with green smoothies in order to lose weight and “detoxify” in order to reduce their incidence of nonspecific symptoms supposedly brought on by exposure to chemicals in modern diets.

Although there are some proven benefits to green smoothies, many of them are overstated, and there is a potential for green smoothies to damage your teeth, especially if they’re acidic.


Acidity of Green Smoothies

The acidity of green smoothies depends largely on the ingredients they contain. Let’s evaluate the acidity of some popular recipes, using an estimated pH value from the FDA’s analysis of the pH of common ingredients.

Collard Green Smoothie with Mango and Lime:

  • 2 tablespoons lime juice (pH 2)
  • 2 cups collard greens or spinach (6.2)
  • 1 ½ cups mango (4.1)
  • 1 cup green grapes (3.4)

This is a pretty acidic smoothie recipe, and will likely yield a smoothie with a pH in the lower 4 range, which is a concern because this is low enough to significantly erode your tooth enamel.

Spinach, Grape, and Coconut Smoothie

  • 1 cup green grapes
  • 1 cup spinach
  • ½ cup ice (7)
  • ¼ cup coconut milk (6.6)

The addition of the neutral coconut milk and ice helps balance out the acidity of the grapes, resulting in a more moderate pH, probably in the 5 range, which may result in mild enamel damage, but isn’t too bad.

Kale Smoothie with Pineapple and Banana

  • ½ cup coconut milk
  • 2 cups stemmed and chopped kale or spinach (6.7 for kale)
  • 1 ½ cups pineapple (3.6)
  • 1 ripe banana (4.8)

Although the pineapple is acidic, the coconut milk and greens can help balance it out, especially if you use the more neutral kale. This smoothie likely has a pH in the upper 5 or lower 6 region, which is considerably safer for teeth.

Some people specifically seek out alkaline smoothies, but how do they measure up? Here’s a popular recipe:

  • 4 cups organic spinach
  • 1 cup filtered water
  • 1 medium avocado
  • 2 whole peeled limes or the juice of 1 red grapefruit (3.2)
  • 1 English cucumber (5.4)
  • 1 or 2 cups ice
  • 1 inch piece of raw creamed coconut (6.7)
  • Stevia (6-8 depending on formulation)

This smoothie is very likely in the neutral pH range, probably pretty close to 7, depending on the pH of your water.

Avoid Smoothie Damage

Because of the individual variability of fruits and vegetables, your smoothies may end up being slightly different from the estimates we came up with here. If you want to avoid damage to your teeth from smoothies, follow these tips:

  • Don’t replace more than one meal a day with a green smoothie.
  • Choose more alkaline smoothie recipes
  • Add ice or water to smoothies
  • Use a straw to minimize smoothie contact with teeth
  • Drink water or rinse mouth with water after finishing a smoothie to minimize contact

Following these tips will reduce the damage caused to your teeth from green smoothies, and reduce the likelihood that your teeth will suffer damage that may require restorative dentistry, as well as potential staining that may result in the need for teeth whitening.