Does Your Fruit Smoothie Harm Your Teeth?
Researchers have found that some fruit smoothies wear away dental enamel and cause tooth decay.
Five smoothies tested
The researchers, from Scotland’s Dundee Dental School and Hospital, studied five different types of fruit smoothies. They were purchased from from local smoothie shops to their laboratory for extensive analysis. At issue was whether – and if so which – fruit smoothies could wear away at the enamel lining of the teeth.
Their laboratory analyses judged the tested the smoothies for their pH and their relative acidity. They also measured the smoothie’s effects upon microsurfaces that mimicked the hardness and profile of human teeth.
The pH of enamel averages about 5.5. A food that is lower has the potential of eroding the teeth enamel assuming the enamel is exposed.
A pH that is higher than 7 is considered alkaline, while pH lower than 7 is considered acidic. The 7 pH is the approximate level of drinking water.
They also compared the smoothie’s effects to mineral water and orange juice. In addition they compared the commercial smoothies with “homemade” versions.
pH and teeth enamel
The researchers discovered that all but two of the drinks tested were at a pH that was less than the pH of enamel – giving them the potential of eroding enamel. The two drinks that had a higher pH than enamel’s 5.5 was the mineral water and a yogurt-based smoothie with honey and vanilla bean.
However, even those that were below the pH of enamel resulted in little actual erosion upon testing, except for two smoothies – the cranberry-blueberry-cherry smoothie and the strawberry-banana homemade smoothie. The others resulted in little if any dental erosion.
In terms of surface depth loss, the smoothie with the greatest effect upon the dental surfaces was the kiwi-apple-lime smoothie. Certainly kiwis and limes also have significant total acidity, while apples render malic acid.
The researchers also determined that they could quite easily reduce and eliminate erosion potential by removing or adding certain foods/fruits.
They concluded that:
“Within the limitations of this study some fruit smoothies have the potential to bring about dental erosion if consumed irresponsibly. This can be influenced by ingredient variations.”
Consider your smoothie ingredients
Not all smoothies are healthy. The take-away here is making a wise choice regarding the smoothie ingredients. A sweet syrupy smoothie can taste great, but is it healthy for our teeth? What about our oral probiotics? What about the relative acidity of our saliva?
Even the researchers suggest that a smoothie offers a convenient way to get our five-plus servings of fruits and vegetables every day:
“Recent health promotion campaigns have encouraged the public to consume at least five portions of fruit and vegetables per day. Many see consuming fruit smoothies as a way of achieving this.”
As the research suggests, adding yogurt to our smoothies can significantly reduce its dental erosion potential. Incremental to that, adding other pH-positive (more alkaline) ingredients such as flax seeds, greenfoods, yeast powder and other supplements can neutralize the acidic elements and render a pH balanced smoothie.
These supplements also bring about a more nutritionally complete smoothie as well.
Commercial smoothies sometimes add yogurt, but many are notorious for adding sugar or high fructose corn syrup to their smoothie mixes. These elements can not only increase dental erosion, but can feed our pathogenic yeast and bacteria.
Saliva pH and probiotics
The relative pH of our saliva and the population of probiotics and other bacteria significantly contribute to the ability of our foods eroding the enamel as well. This is something we can control with our diet and lifestyle factors.
In general, the most acidic fruits include citrus, followed by kiwis, cherries and cranberries. Plums, apples, pears and apricots follow in acidity. Sweeter fruits approach neutrality, including watermelon, figs, mangoes and peaches.
Most vegetables are neutral to alkaline, but this can vary. Spinach, for example, is typically slightly acidic.
This type of alkalinity and acidity is often confused with the body’s relative acidity or alkalinity following the eating of certain foods. While this form of acidity can affect the teeth enamel, the body will reach a higher state of alkalinity in response to eating fresh fruits and vegetables in general, regardless of their relative pH.
This is because these foods also contain phytonutrients and antioxidants that serve to neutralize the acid-forming free radicals within the body. As those oxidative free radicals are neutralized, the body reaches a more neutral state of pH.
Blacker SM, Chadwick RG. An in vitro investigation of the erosive potential of smoothies. Br Dent J. 2013 Feb 22;214(4):E9.
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Case Adams is a California Naturopath and a Board Certified Alternative Medicine Practitioner with a PhD in Natural Health Sciences, and diplomas in Homeopathy, Aromatherapy, Bach Flower Remedies, Blood Chemistry, Clinical Nutritional Counseling and Colon Hydrotherapy. He has authored 26 books on natural healing strategies.