What you eat and drink has a direct effect on your teeth and gums. The good news is that protecting your teeth does not mean giving up everything you enjoy. It mostly means changing when you have sugar, and choosing better snacks and drinks between meals.
How sugar causes tooth decay
Plaque is a sticky film of bacteria on your teeth. When you eat or drink something containing sugar, those bacteria turn the sugar into acid. The acid dissolves minerals from the enamel, and for up to an hour your teeth are under attack. Saliva then slowly neutralises the acid and helps put minerals back.
If this happens three times a day at meals, your teeth have time to recover in between. If you sip a sweet drink or snack all day, they never do. Over months, the enamel weakens and a cavity forms. That is why the World Health Organization names free sugars as a main cause of tooth decay.
What counts as "free sugar"?
Free sugars are sugars added to food and drinks by the manufacturer, the cook or you, plus the sugars naturally found in honey, syrups and fruit juice. The sugar inside whole fruit and plain milk does not count, because it is released more slowly and comes with fibre, water or protein.
WHO recommends that adults and children keep free sugars below 10 percent of their daily energy, and suggests that below 5 percent, roughly 25 grams or 6 teaspoons a day for an adult, brings further benefits. One bottle of soda can contain more than that on its own.
The biggest culprits
- Soda and energy drinks. They combine sugar with acid, and are often sipped slowly. Even sugar-free versions are acidic and can wear enamel.
- Fruit juice. Freshly squeezed juice is still free sugar, and citrus juice is acidic too.
- Sweetened tea and coffee sipped through the day. Two or three teaspoons of sugar in each cup adds up quickly.
- Sweets, biscuits and mandazi eaten as snacks between meals.
- Sticky foods such as toffee and dried fruit, which cling to teeth for longer.
- Sucking sweets and sugarcane chewed over a long time, which keep sugar in the mouth for many minutes.
Foods that help your teeth
- Water, the best drink between meals. It rinses food away and keeps saliva flowing.
- Milk, plain yoghurt, ikivuguto and cheese, which provide calcium and phosphate and help neutralise acid.
- Eggs, fish, beans and groundnuts, which are rich in protein and minerals and low in sugar.
- Vegetables, including leafy greens like isombe and crunchy vegetables like carrots, which make you chew and increase saliva.
- Whole fruit such as bananas, avocado, mango and passion fruit, better than juice because the sugar is not free.
- Sugar-free chewing gum after a meal, which increases saliva for 20 minutes or so.
Smart swaps
| Instead of | Try |
|---|---|
| Soda at lunch or through the afternoon | Water, or one soda with a meal instead of sipping it over hours |
| Tea with 3 teaspoons of sugar, several times a day | Cut down one teaspoon at a time; taste adjusts within weeks |
| Fruit juice for children | Whole fruit and water; keep any juice to mealtimes, diluted |
| Biscuits or mandazi as a mid-morning snack | Groundnuts, a boiled egg, plain yoghurt or a banana |
| Sweets after school | Fruit, cheese or ikivuguto, with sweets kept for after a meal |
| A sweet drink at bedtime | Water only after brushing at night |
Timing matters as much as what you eat
- Keep sugary food and drinks to mealtimes, when saliva flow is higher and the attack happens once, not all day.
- Aim for no more than four eating or drinking occasions a day other than water.
- Finish a meal with something that neutralises acid, such as cheese, milk or water.
- After acidic food or drinks such as soda, juice or citrus fruit, wait about an hour before brushing. Enamel is briefly softer, and brushing straight away can wear it.
- Nothing but water after brushing at night.
Dry mouth and your teeth
Saliva is your mouth's natural defence. It washes away food, neutralises acid and delivers minerals back to the enamel. Many medicines, some medical conditions, and not drinking enough water can reduce it. If your mouth often feels dry, sip water through the day, chew sugar-free gum, and mention it at your next visit. Dry mouth raises the risk of decay and we can help you manage it.
Diet works together with your routine
No diet can replace brushing twice a day with fluoride toothpaste, cleaning between your teeth, and regular check-ups. Put them together and most tooth decay can be prevented. Our five daily habits explain the routine, and our guide to children's teeth covers feeding and snacks for little ones.
If you are worried about decay, or want advice for your family, book a check-up.
Frequently asked questions
Is fruit bad for my teeth?
Whole fruit is fine, and much better than juice. The sugar in whole fruit is not counted as free sugar. Enjoy it with meals or as a snack, and rinse with water after very acidic fruit such as oranges or lemons.
Is honey better for teeth than sugar?
No. Honey counts as free sugar and causes decay in the same way. Use it sparingly and at mealtimes.
Are diet sodas safe for teeth?
They do not cause decay, but they are acidic and can wear enamel over time. Water is the safest drink between meals.
Does drinking through a straw help?
It can reduce contact between the drink and your front teeth, so it helps a little with sugary or acidic drinks. Cutting down how often you have them helps much more.
Sources
- 1.Guideline: sugars intake for adults and children (opens in a new tab), World Health Organization (2015)
- 2.Oral health: fact sheet (opens in a new tab), World Health Organization
- 3.Diet and my teeth (opens in a new tab), Oral Health Foundation
- 4.Tooth decay (opens in a new tab), NHS
This article is for general information and does not replace advice from a dentist who knows your health history.
