Many of our favourite foods are high in sugar, fat, salt and calories, which we all know are bad for us in large amounts. Here, Dr. Melissa Lem shares unexpected and surprising reasons to avoid some commonly enjoyed foods.

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Breakfast Sandwich: Cold Hands

In a 2012 study, researchers from the University of Calgary fed students 2 breakfast sandwiches, then measured the speed of blood flow in their arms. Just two hours later it was 20 per cent lower! Surprisingly, saturated fat and salt can have an instant negative effect on the stretchiness of your blood vessels, which in cooler weather can mean freezing fingers.

Salt and Vinegar Potato Chips: Facial Sweating

The scientific name for this embarrassing phenomenon is gustatory hyperhidrosis. Gustatory sweating is brought on while eating, thinking or even talking about foods that make you produce a lot of saliva, like sour foods. Scientists think this is caused when the nerve fibres to your salivary glands are inconveniently connected with your sweat glands

Italian Sausage: Lactation

Italian sausage is traditionally flavoured with large amounts of the herbs anise and fennel, which in large quantities can actually make you lactate. Both herbs contain anethole, a chemical that is thought to increase your levels of prolactin, a hormone that causes breast milk production in both women and men.

Chocolate: Cough Suppressant

Chocolate lovers rejoice: in a 2004 British study, participants inhaled capsaicin (chilli-pepper spice), then were given possible cough remedies. Amazingly, researchers found that theobromine, a derivative of chocolate, worked even better than codeine to stop coughing!

Macaroni and Cheese: Constipation

This popular comfort food gives you double the toilet trouble. First, macaroni is low in fibre, making it less bulky when digested and harder to pass through your intestines. Adding insult to injury is the cheese, which contains casein—a milk protein that's been shown in animal studies to slow down bowel activity.

Citrus Soda Pop: Memory Loss

Your IQ is actually going to drop if you drink too much soda pop. The culprit here is brominated vegetable oil (BVO), which prevents oily citrus flavouring from separating out of soft drinks and sports drinks. BVO is added to about 10 per cent of drinks sold in the U.S. and typically makes them look cloudy and opaque. But pop drinkers beware: a 1997 case study in the Journal of Toxicology described a 40-year-old man who was hospitalized with memory loss, headaches and poor coordination after drinking 2-4 litres of soda per day!

For more dirty secrets of your favourite foods, including coffee, ice cream and donuts, click here.