Why onions make you cry: The truth behind strange effects of certain foods

Natural food may be healthier than processed, but some can have strange effects on our bodies.

A British graduate chemist and secondary school teacher has created a number of infographics to explain the unexpected chemistry behind some foods – revealing why coffee tastes bitter and chocolate is toxic to dogs.

The anonymous blogger started publishing his infographics nine months ago after creating some posters to brighten up his classroom and hopes to explain the chemistry of everyday substances.

‘Chemistry gets a pretty bad reputaion at times, with the word “chemicals” too often used to denote something bad. I want to show that chemicals are in fact in everything, in all the foods we eat and responsible for some pretty interesting effects,’ he told MailOnline. He also sells his creations from his Compound Interest blog.

See the infographics of some foods including their various effects

None of the compounds that cause people’s eyes to water are present in an intact onion, but when the cell walls are damaged by chopping, an enzyme released produces a range of compounds as a defence mechanism, which act as irritants

Asparagus causes the urine of some – but not all – people to smell and for 40 years scientists have tried to pinpoint the chemical compounds responsible. While there is no definite verdict, it is thought they are all a form of asparagusic acid

Feeling hot: The spiciness of chilli is due to the presence of compounds called capsaicinoids, which cause a burning sensation when they come into contact with mucous membranes

In the mood: Phenylethylamine is called the ‘love drug’ and occurs in the brain – as well as in chocolate. It is known to cause feelings of contentment but as the compound is broken down after it is eaten, scientists believe it doesn’t have an aphrodisiac effect

The sour taste of lemons is caused by organic acids, the most prevalent of which is citric acid, followed by Malic acid, which adds to the fruit’s tangy taste

A strong cup of tea contains some 180mg to 240mg of polyphenol compounds, which are shown to have beneficial effects on cardiovascular health

Grapefruit meddling: The juice of the fruit is known to interact with medicines because of compounds which inhibit some forms of an enzyme responsible for breaking down drugs in the body

Feeling bitter: Chlorogenic acids make coffee taste bitter and account for up to eight per cent of unroasted coffee beans. Its content decreases when they are roasted.

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