LED lights give strawberries special diet powers, reveal Scots researchers


They are the sweet taste of summer and, if you can live without smothering them in double cream, are already known to pack a healthy punch.

Now Scottish researchers believe they may have discovered how to boost strawberries’ existing health qualities in a way that may bring fresh benefits for diabetics and slimmers.

The discovery has come at the flick of a light switch: research carried out at the James Hutton Institute near Dundee had set out to explore how shining certain LED lights on strawberries might produce better fruits and boost farmers’ crops.

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But they were surprised by the extent of the findings, that showed that not only did the light therapy produce sweeter tasting berries, it also turbo-charged existing digestive benefits that help limit calorific assimilation – raising hopes they might become a weapon in the battle against diabetes and obesity.

Strawberries are already known to be rich in antioxidants with natural anti-inflammatory agents that can help support healthy blood pressure.

The researchers found using particular light-emitting diodes (LED) in the red, far-red and blue regions of the spectrum ignited even more positive chemical reactions in the plants.

As well as boosting fruit yield, the LED lights produced berries with significantly enhanced antioxidants and antioxidant activity, plus higher levels of vitamin C.

The most striking finding was the realisation that soft fruit’s existing abilities to inhibit certain digestive enzymes which help slow down digestion with benefits to calorific assimilation, had been ‘supercharged’ by the LED lights.

That raises the prospect that a hearty post-meal bowl of LED-enhanced strawberries could have an improved impact on sugar and fat levels in the blood.

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The study is believed to be the first of its kind and has raised hopes among the researchers that the same positive impacts can be achieved using the same LED lighting conditions to grow other soft fruits such as raspberries and blueberries and crops such as salad leaves.

The newly-published research was carried out at the James Hutton Institute in connection with Seahills Farm, a fruit growers based near Arbroath. The farm contributed almost £65,000 to the research with a further £130,000 grant from Innovate UK.

It feeds into wider studies into molecular breeding of strawberries and other fruit and vegetables, which involves scientists using natural processes to tweak the plant’s genetic makeup to produce better crops.

The next stage is likely to see the LED light-enhanced strawberries put to the test in human trials.

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That would see volunteers consume the ‘super’ berries after a heavy meal followed by blood tests to see whether their blood sugar and fat levels react positively.

Dr Robert Hancock, Senior Biochemist and Plant Physiologist at the James Hutton Institute, said the scale of the positive impacts from using the LED lighting had taken them by surprise.

“We know that strawberries are good for you and, of course, people like to eat and enjoy them, but we wanted to manipulate the quality of the fruit.

“You can do that by breeding, but that is long term, time consuming and difficult to apply.

“An alternative is to take cultivars that are on the supermarket approved list, recognised by consumers and that growers know how to grow well and manipulate their environment.

“We know light is one of the most important things in a plants’ environment, and it’s something we can manipulate fairly easily using narrow spectrum LED.

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“The question was could we use the capacity of plants’ response to certain regions of the spectrum to improve quality?”

They set up narrow band red, far red and blue LED lighting at a range of densities to study how the plants would react to each.

In all cases, the plants showed positive chemical responses and produced enhanced antioxidants, vitamin C and anthocyanins, the natural pigments which some studies have associated with boosting heart health, lowering cholesterol, fighting obesity and lowering cancer risks.

The berries showed also increases in the capacity to inhibit the digestive enzymes pancreatic lipase and α-amylase.

That has been linked to slowing down the rate fat and sugar are absorbed, potentially leading to a lower glycaemic load and reducing the calorific value of a meal.

Diets with a low glycaemic index have been associated with improvements in insulin sensitivity and weight loss.

Dr Hancock said human tests could see volunteers consume meals of, for example, steak and chips followed by strawberries, in the hope the LED grown fruit would have a positive impact.

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“We would test that by providing volunteers with a meal and strawberries and take blood samples to see if there is an increase in lipids or sugars, or if the ingestion of strawberries inhibits that.

“Strawberries are pretty good at this anyway,” he added, “but we are improving their capacity to do the same thing, and making them healthier.”

Having proven the concept, he said ‘super’ berries could soon become available to consumers, assuming supermarkets regarded them as sufficiently attractive to consumers and farmers were willing to invest in LED light equipment.

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However, the findings are likely to be welcomed by commercial growers and, in particular, growing numbers of urban vertical farms.

“Conditions for strawberry growers become more difficult with supermarkets competing against each other,” he added. “They have two options: if they don’t want to compete on price, then they have to compete on quality.

“Through marketing healthy strawberries that provide something beneficial to consumers on top of the flavour.”


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