CSIC clears up most-common food myths

SPAIN'S National Research Council (CSIC) has announced a new book series seeking to debunk widely-held myths through scientific answers – including whether bread really makes you put on weight.

The latest edition in the series ¿Qué sabemos de...? ('What do we know about...?') is titled Los bulos de la nutrición ('Hoaxes about nutrition'), co-authored by researcher Miguel Herrero.

One of the most-asked questions about diet, Herrero reveals, is which part of bread is the most fattening – the crumb or the crust.

“Given that it has less water in it, the flour parts – basically, carbohydrates – are more concentrated in the crust,” the scientist explains.

“For this reason, if you take the same weight of the crust and the crumb, it's the crust that contains more calories.”

Another common grey area about nutrition involves food items described as 'anti-oxidants', which are said to flush out unwanted substances known as 'free radicals' from the body, reducing the likelihood of illness through preventing premature cell ageing and fighting infection.

“There's not enough scientific evidence on the true rôle of anti-oxidants in diet, in terms of their illness prevention effects,” Herrero cautions.

This said, “there are some indirect signs that makes you think they could have a positive effect – although we don't know to what extent – and more and more studies are being carried out into how anti-oxidants in food are metabolised in humans. 

“These will help shed more light on the subject.”

But this hitherto lack of robust evidence is no reason to stop eating blueberries and drinking green tea - “food and drink containing anti-oxidants will not do you any harm,” Herrero clarifies.

“What's not really justified is that these salads, juices and smoothies marketed as 'anti-oxidant' are more expensive, based upon that claim alone – all the ingredients naturally contain anti-oxidants anyway.”

Herrero, additionally, addressed concerns about additives in food – those used to preserve them for longer, or alter their taste, scent and colour.

“Despite their bad press, these additives play a crucial part and they're safe for consumption,” Herrero assures.

“There are food groups like honey, oils, butter, or pasta, for which the use of additives is banned or legally limited, but there are others such as wine, and pre-cooked beans and pulses in tins, where additives are necessary.” 

The new book on 'dietary hoaxes' covers how to interpret the labels on food items, containing nutritional information – including the full list of ingredients, which has been obligatory in Spain by law since 2016.

Ingredients are listed in descending order of weight or volume, meaning whichever appears first is present in the highest quantity in the food item in question.

“This means, for example, that if a label on a tin of powdered hot chocolate lists 'sugar' as the first on the ingredients list, the product contains more sugar than cocoa,” Herrero explains.

He also cautioned against claims on packaging that a food item is 'high-fibre' or 'low in calories'.

“These are voluntary messages used for marketing purposes, but their main problem is that they tend to refer to a specific component of the food item – not to the entire product – so it does not necessarily mean the product itself is healthy,” Herrero explains.