The campaign, run by the Food Standards Agency (FSA), supports traffic light front-of-pack labelling, which allows shoppers to see at a glance if a food product is high, medium or low in certain nutrients.
The FSA argues that the red, amber and green colour coding used in the traffic light system provides easy-to-understand advice on foods that have high, medium and low amounts of saturated fats, sugars and salt.
The fourth 10-second ad will be seen on ITV, satellite channels, and a Welsh version will be broadcast on S4C.
"Our extensive and published research demonstrates that the use of traffic light colours is key to helping people interpret nutritional information on foods," said FSA chair Deirdre Hutton.
"We want to highlight to shoppers that these labels are now out there and really can help us all to make healthier choices.
"Our new labelling TV ads, like the traffic light approach, are clear and simple - with the beauty being that these labels speak for themselves."
The debate over nutritional labelling remains highly polarised however. Some of the UK's biggest food manufacturers including Danone, Kellogg's, Kraft, Nestle and PepsiCo and retailers Tesco and Morrisons recently joined together to launch a £4m campaign to promote GDA (guideline daily amount) labels, which they claim will help people 'make better-informed decisions about the food they eat'.
The GDA system tells consumers the percentage of the adult male Guideline Daily Amount of the four key nutrients that each product contains.
Certainly, the campaign for the hearts and minds of consumers is well underway. Earlier FSA traffic light ads started running on 17 January, and posters have been used outside some supermarkets during February.
Ads have also appeared in the national press and in women's weekly magazines since late January.
But while many speculate the two systems are on a collision course, Hutton's recent comments appear to suggest the FSA traffic light system and the GDA system may actually be complimentary.
"Most manufacturers and retailers are now using front-of-pack nutritional labelling and this is good news," she said.
"Some shoppers find extra GDA information useful and all industry needs to do is add traffic light colours to their GDA schemes to ensure the consumer gets the best of both worlds."
Results of independent research into the impact and effects of front of pack labelling on shoppers' behaviour will be released next year.