First, some info on how teeth can get this way: Enamel is the outer layer of your teeth and is generally white to whitish-blue-gray, as well as somewhat translucent, according to dentist Harold Katz, DDS, founder of The California Breath Clinics. The layer just beneath, called dentin, becomes visible as the enamel layer becomes thinner. The color of dentin? You guessed it: yellow. RELATED: The Factor That Can Predict Exactly How Long You’ll Live Fortunately, there are some changes you can make to keep enamel stronger and prevent that dentin from peeking through—as well as reduce the food stains that can cause yellow teeth. Here are some common habits to switch up:

Here are the 6 main reasons your teeth turn yellow:

1. You’re overusing mouthwash or choosing one that’s too acidic.

One of the toughest environments for your teeth is a dry mouth, Katz says. That’s because saliva has a combination of minerals, enzymes, and oxygen compounds that keep the pH balance in your mouth neutral—reducing the acid that can wear away enamel. Saliva also bathes the teeth regularly to knock out bacteria and to prevent stains from adhering to the enamel.  How to prevent it: “What is disheartening is that many commercial types of mouthwash are very acidic, and if used very frequently, may destroy precious tooth enamel,” says Katz. So, if you’re taking frequent swigs of mouthwash to keep your breath fresh, you may want to consider other strategies, like brushing more frequently and getting regular dental cleanings. RELATED: 10 Subtle Signs Someone Has Low Emotional Intelligence — Be Aware

2. You’re loading up on acidic fruits and vegetables.

Just as more acidic mouthwash can thin out tooth enamel, so too can acids in the diet, says Katz. These include citrus fruits and juices, tomatoes, pineapples, vinegar, carbonated beverages, some sports drinks, and certain salad dressings that are vinegar-based. That doesn’t mean you need to cut all of these out of your life, but it’s a good idea to sip some water after eating or drinking them, advises Katz. How to prevent it: He suggests consuming more water to prevent staining as well, especially from choices like blueberries, dark tea, and red wine. This article was originally published at Prevention . Reprinted with permission from the author. “Sipping two or three coffees every day allows the enamel of your teeth to be in constant contact with a staining agent,” she says. Since enamel is porous, these stains can settle in and cause yellowing if they’re not regularly rinsed and brushed away.  It’s not the quantity that’s a concern, it’s the sipping that can be especially damaging, she says. How to prevent it: Drinking coffee more quickly, or even through a straw, can reduce the amount of time the staining agents linger in the mouth, she says. RELATED: 4 Dangerous Lies People Tell Themselves To Stay Unhappily Married

4. You’re a smoker.

The chemicals in cigarettes and pipe tobacco have a staining effect on teeth because they cling to enamel, says Friedman, and the longer you smoke, the more visible this becomes. Smoking has also been associated with a bevy of other oral health issues like gum disease, tooth decay, and dry mouth—so consider whiter and stronger teeth just one more reason to consider quitting. How to reverse it: Quit smoking. 

5. You skimp on good oral hygiene habits.

If you haven’t made resolutions for the new year yet, here’s a good one: floss. Friedman says that being less-than-consistent on brushing and flossing can cause an accumulation of plaque on your enamel.  This can thin that protective layer, and also cause your teeth to appear yellow from the film of bacteria. How to reverse it: A good home-care regimen, coupled with an in-office cleaning at least once a year, can go a long way toward scrubbing that yellow out, she says. “If you brush too hard or too often, you might wear away the thin enamel layer and expose the dentin layer,” he says. How to reverse it: If your teeth are already yellowing, check with your dentist for professional whitening options as well as advice about changing your habits, he suggests. There are several choices for getting your pearly whites back to a selfie-ready smile. RELATED: 9 Men Reveal The Food Dealbreakers That Make Them Run Away From A First Date Elizabeth Millard is a freelance writer focusing on health, wellness, fitness, and food.