Products claiming to be superfoods will be banned under new EU rules coming into effect on Sunday - unless the claim can be proved.
Sales of blueberries have gone up 132% in the last two years
Blueberries, salmon, spinach and soy have all been hailed as so-called superfoods - foods rich in nutrients.
Some say superfoods can protect against cancer and heart disease, but others say there is no evidence for this.
The new laws will apply to all food or drink products made or sold for human consumption within EU nations.
Onus of proof
Almost 100 products have been described as superfood, and sales of products like blueberries and spinach have soared.
But some nutritionists claim there are no proven benefits of "superfoods" and say marketing is misleading.
The new EU legislation will ban the use of the term superfood unless it is accompanied by a specific authorised health claim that explains to consumers why the product is good for their health.
However, companies will have just over two years to adjust their marketing in line with the new rules.
The legislation will also mean nutritional claims such as "low in salt" or "light" will have to meet a standardised definition agreed by the EU.
And foods that make a nutrition claim - such as being low in salt - will have to make it clear on the same label if they are also high in fat or sugar.
In addition, foods that are high in more than one nutrient will not be allowed to make a nutrition claim about another of its ingredients.
A spokeswoman from the Food Standards Agency said: "The use of general terms on food, such as 'healthy for you' or 'superfood', imply a health benefit. However, these terms do not communicate why the food is healthy or a superfood.
"So, the regulation requires they are backed up by a relevant and authorised health claim. This way the consumer knows why this food is healthy."
Kevin Hawkins of the British Retail Consortium said: "Our concern is not about the principle of this legislation.
"It is right that claims such as 'reduced fat' or 'good for your heart' are supported by science but customers must not be denied nutrition and health messages they find valuable.
"The regulation still risks unintended consequences. It could thwart national health campaigns and compromise innovation of healthier products. We will need to keep the impact of this regulation under review."