We’ve all heard the tales of post-lunch onion-breath or apologising to co-workers for coffee-breath but they’re the least of your problems.

And there could be a simple culprit for your halitosis - your lack of bread and carbohydrates.

Nutritionist and Lifestyle expert Amanda Hamilton commented: “Popular high protein and high fat diets, such as this season’s Paleo Diet, and post work-out drinks with a high protein content can also affect breath. This is because eating a lot of protein can cause an increase in levels of ammonia in the mouth which carries an unpleasant odour.”

What’s more, according to a recent study from mouthwash company CB12, a quarter of the nation admit to skipping breakfast on a regular basis, which may be leading to unpleasant breath1. The body produces less saliva at night which dries out the mouth creating the perfect environment for bacteria to grow, hence the phrase “morning breath”.

Commenting on the results of the study, dentist Dr Luke Thornley said: “Eating breakfast helps to stimulate saliva production which removes bacteria from the tongue keeping your breath fresh. When asked, just under a fifth of people said they would stop skipping breakfast if they knew it was causing foul breath.”

[Read more: The gadget that detects intolerances from your breath]

So what else can cause bad breath? We look at four of the biggest – and most surprising – smelly culprits.

Sugar

Yet another reason to give up the sweet stuff: it can give you bad breath. The bacteria that cause bad breath use sugars as a super fuel, and sweets, mints and chewing gum that contain sugar do not help to eliminate it.

In fact, the sugar in most breath mints actually causes bad breath bacteria to become super active and create even more offensive, sulphur compounds; the strong mint of fruit flavouring only masks the smell.

Protein

Dairy, meat and fish contain dense proteins used as a food source for bad breath bacteria. Eggs, nuts and seeds also fall into this category as do beans and lentils. As for peanut butter, it’s known as the halitosis-causing paste.

Acidic foods

It’s a scientific fact that acids encourage bacteria to reproduce much faster. To slow this down, avoid eating or drinking acidic foods or beverages, ranging from pasta sauce, olives, butter and chocolate to tomato juice and fizzy drinks.

[Read more: Is your diet making you ill? 6 unwanted side effects of trying to lose weight]

Supplements

They may well be helping your body but most supplements contain garlic oil or powder, which is loaded with a sulphide that gives garlic it’s instantly recognisable odour.

As your body digests a helping of garlic oil, this sulphide goes into your blood and eventually escapes through your sweat glands and mucus membranes. The result? Bad breath and body odour.

Like this story? Why not share it with your friends by clicking the orange plus sign?