1 Sweet foods

When you consume more sugar than your cells are able to process, the excess sugar molecules combine with proteins, triggering a process that can damage the skin's collagen (the protein that keeps skin firm and youthful). Moreover, as is well known, sugar attacks the teeth, causing decay and discolouration.

2 Alcohol

"When the liver is functioning well, toxins that could affect the skin are naturally expelled through the body. But if toxins build up in the liver and are not broken down properly, the skin can develop a range of problems, such as acne and wrinkles," Ostad explains.
Alcohol also causes dehydration, which leads to poor sleep. "Insufficient sleep is linked to wrinkles, uneven pigmentation and reduced skin elasticity."

3 Charred meat

The black, charred parts of grilled meat contain pro-inflammatory hydrocarbons that could lead to collagen damage in the skin, Ostad explains. There is no need to ban the barbecue altogether, but it is essential to remove the charred parts from food and to clean the grill thoroughly after use.

4 White wine

White wines can damage tooth enamel and stain teeth. Here is what not to do: brush your teeth immediately after drinking (the same applies to any acidic drink). Brushing already-acidic teeth can promote enamel erosion. "You need to give teeth time to remineralise after being bathed in an acidic drink," explains Maureen McAndrew of the New York University College of Dentistry. "After drinking wine, it is better to wait an hour before picking up a toothbrush."

5 Salty foods

Salty foods retain water and give the body a "bloated" appearance. It is better to use little salt at the table and to always choose fresh foods rather than preserved or ready-made ones.

6 Processed meats

Sausages, bacon, frankfurters and so on. "Many of these meats contain sulphites and other preservatives that can trigger skin inflammation and accelerate the onset of ageing," said Ostad. They also tend to be high in salt.

7 Hydrogenated fats

As well as being dangerous for heart health, trans fats can age the skin. "They promote inflammation," states Dr Ostad. They can also make skin more vulnerable to UV rays. It is best to avoid products that list hydrogenated oil on the label.

8 Red meat

"Fatty meat generates free radicals," states Ostad. These are molecules that possess a single electron rather than two, which makes them highly unstable and drives them to steal the missing electron from other molecules, in turn transforming those molecules into unstable compounds that then begin to behave in the same way. Free radicals damage the skin's ability to protect itself and produce collagen. Ostad recommends eating leaner meats, such as turkey and chicken, and eating plenty of fruit and vegetables, which are rich in antioxidants.

9 Spicy food

According to Ostad, it worsens rosacea (couperose), and can cause damage during the menopause, a time when the skin's blood vessels become more reactive. There is no need to cut spicy food out of the diet entirely, but it is certainly better not to consume it regularly, so as to avoid varicose veins, swelling and redness.

10 Energy drinks

They provide a boost but have an ageing effect on teeth. If you really need an energy drink, it is better to remember to sip it through a straw, to limit contact with the teeth.

11 Caffeine

"Caffeine, like any other diuretic, can flush out fluids and deplete the body of moisture," says Dr Hirsch. "This can dehydrate the skin, making it look aged."

12 Coffee

Beyond the dehydration caused by caffeine, coffee is also accused of damaging teeth. "Acidic drinks can create microscopic pores on the enamel surface, causing erosion," says McAndrew. To avoid cutting out this food, which also has several positive health effects, it is enough to drink a glass of water after having a coffee. "Water has a neutral pH, which washes away the acid," says McAndrew.

13 Sweetened lemonade

According to experts, lemonade can also damage tooth enamel. The advice to sip a little water after drinking it applies here too, as does waiting an hour before brushing your teeth — but above all, avoid adding sugar to lemonade, so as not to compound the problem with sugar plaque as well.

14 Black tea

Due to its high tannin content, heavy tea drinkers may experience problems with tooth staining. A study published in the Journal of Dental Hygiene found, however, that the casein in milk reduces this type of staining, while the citric acid in lemon, by making enamel more porous, could make teeth more susceptible to stains.