Our pH test of 19 drinks

A pH of 7 is neutral (for example, tap water); the lower the pH, the more acidic the drink. A pH less than 5.5 increases the risk of dental erosion. The majority of products in our test had a pH below 5.5.

Eight of the drinks contained citric acid, naturally present in oranges and other fruit, and added to beverages as a preservative and for flavour. The most acidic drink was Pure NZ Herbal Sparkling Drink, which had a pH of 2.7. The manufacturer said the drink’s been discontinued but we were able to find old stock in a Wellington supermarket.

Next were Ch’i’s sugar-free offering and OVI Hydration Citrus (it contains ascorbic acid), both with a pH of 2.9. That compares with 2.4 for Coca-Cola.

Five others — VitalZing Water Drops Lemon Lime, Vitasport Water Booster Lemon Lime, Mizone Sports Water Lime, Glaceau Vitamin Water Dragonfruit and Caliwater Cactus Water (it contains lemon juice) — were more acidic than the Keri Orange Juice we tested as a comparison.

The only drinks that had a pH above 5.5 were Pump Water, H2Coco Coconut Water Cocoespresso and Ararimu Valley Alkaline Water. The two plain coconut waters we tested had a pH of 5.4.

New Zealand Dental Association senior oral health educator Dr Deepa Hughes says the acidity of drinks is a hidden danger. “We should drink plain water, not sugary or acidic drinks for hydration. Any other drinks, even if they have ‘diet’ or ‘water’ in their name are best for occasional treats,” Dr Hughes says.

GUIDE TO THE TABLE PRODUCTS are listed in each category by energy (kJ) (lowest to highest). ^AThese products were included as a baseline comparison. ^BThe manufacturer advises this product has been discontinued. pH was tested by an independent laboratory. The lower the pH the more acidic the drink.

Dental erosion

Dental erosion, a gradual wearing away of the enamel that can leave your teeth sensitive to hot or cold food or drinks, isn’t the same as tooth decay. Decay is caused by acid produced by bacteria feeding on fermentable carbohydrate, such as sugar, in your mouth. Erosion occurs as the acidic drink washes over the whole tooth surface, which dissolves the tooth enamel in the process. Once the enamel is lost, it’s lost forever.

You can minimise the harm to your teeth by only drinking acidic and sugary drinks during meals when your mouth is producing plenty of saliva to wash the sugar and acid away. You should also drink these drinks quickly — not sip them over a long period of time — or use a straw to reduce direct contact with the teeth.