Who says breakfast is the most important meal of the day? And why does spinach make you strong? It sounds like conventional wisdom, but most of it was cooked up by ad men

What came first, the chicken-is-healthy study or the eggs-are-unhealthy study? Nutritional advice is notoriously nebulous, and food groups regularly alternate between demonisation and deification. Fat makes you fat; fat makes you thin; carbs are basically crack; carbs are back. Corporate agendas are behind much of this confusion. But, more worryingly, they’re also behind many of the food “facts” we take for granted. Much conventional health wisdom is actually commercialised wisdom: the result of canny marketing campaigns or industry-funded studies. Even if you think you’re above advertising, immune to the seductions of pseudoscience, you would be surprised how many marketing myths you may have inadvertently swallowed.

Breakfast of chumps



Let’s start with breakfast. There’s no conclusive evidence a morning meal makes you lose weight and feel great, but the idea that breakfast is the most important meal of the day is widely ingrained. This is largely thanks to the efforts of grain companies. Kellogg’s, for example, funded an influential study that linked breakfasting on cereal with lower BMI. And The Quaker Oats Center of Excellence financed research showing that a daily breakfast of porridge reduces cholesterol.

Big Cereal isn’t alone in bigging up breakfast with biased science; bacon is also to blame. In the 1920s, PR man Edward Bernays was tasked with increasing bacon consumption in the US. At the time, most Americans ate a light breakfast; Bernays figured a good way to increase bacon consumption would be to increase breakfast consumption. So, he asked doctors to confirm that “a hearty breakfast was better than a light breakfast to replace the energy lost by the body at night”; 4,500 doctors agreed and Bernays got the media to report the results, strategically placing bacon adverts by the headlines. Today, 70% of bacon eaten in the US is eaten at breakfast.

Squeezing the truth



Orange juice’s position as part of a healthy breakfast is the fruit of a marketing man’s imagination. In 1908, California faced a surplus of oranges; if citrus growers (organised under the brand Sunkist) didn’t increase consumption, they would go bust. At the time, Americans didn’t drink fresh orange juice, but an ad agency decided to change that. It invented a cheap juice extractor, which it publicised in adverts extolling the health benefits of drinking an orange. “We asked 3,000 physicians about orange juice for babies,” reads one Sunkist ad. The physicians were all for it. The campaign led to a massive increase in juice consumption and created a health halo around fruit juice that has only recently started to slip.

Caffeinated kids



You may have heard that caffeine stunts growth; this is unsubstantiated nonsense. The short story is that it’s a tall tale spread by Postum, a caffeine-free morning beverage invented in the late 1800s. Postum marketed itself as an alternative to coffee by demonising its competitor, suggesting coffee stunted a child’s mental and physical development. One Postum ad shows a small boy struggling at school: “Held back by coffee … this boy never stood a fair chance.”

Eight is not the magic number



Drinking eight glasses of water a day is great if you enjoy urinating, but generally it’s unnecessary. The eight-a-day myth seems to derive from old guidelines stating that, while people need 2.5 litres of water a day, we get most of that from our regular diet. Only half of that information seems to have stuck. Bottled water companies have helped reinforce existing hydration misinformation through exaggerated health marketing, and we lap it up. Consumption of bottled water has shot up – in the UK, it’s now 100 times higher than in 1980.

The military-industrial-carrot complex



Some food myths go deep into the upper levels of government. The idea that carrots imbue you with night vision originated in the second world war, when the British government dealt with an oversupply of carrots via propaganda suggesting carotene was the source of the RAF’s night-flying abilities. The actual source was radar, but that was sort of classified. It’s unlikely the Luftwaffe bought the carrot-vision story, but the British public did and millions of carrots were consumed in the hope of being able to see better in a blackout.

Spinach spinmeisters



Rumours of spinach’s iron content have been greatly exaggerated. The blame for this has traditionally been cast on clumsy German scientists who put a decimal point in the wrong place, bestowing spinach with 10 times more iron than it has. However, the decimal-point myth has itself been debunked. So, by the way, has Popeye’s iron enthusiasm; Popeye liked spinach for the Vitamin A. Despite all the debunking, however, both spinach and Popeye are still strongly associated with iron. Marketing may not be responsible for this particular fallacy, but it does demonstrate how hard it is to overturn misinformation once it gets out there. Which is something many marketers understand when they push exaggerated claims.

Pinching salt



Statistics show that, eventually, 100% of us will die. Whether we should avoid carbs, fat, chicken or eggs in order to postpone that demise is not so clear cut. Nevertheless, looking at who funds the research behind health headlines is always advisable; many supposedly scientific studies are best taken with a heavy pinch of salt. Although, you know, that may have been an expression invented by the sodium lobby.