Brilliant Ideas that will Never Work: food price controls that make the healthiest food the most affordable

Some countries (I think France is one of them) have price controls on basic staple foods to ensure that things like bread and milk remain affordable to even the poorest citizens. I don't know exactly how this words, but obviously there is a mechanism for the state to put a ceiling on the price of food. The state can also make goods prohibitively expensive by taxing them (c.f. alcohol, tobacco). So what they should do is harness this power to make the healthiest foods the most affordable, and the least healthy foods the least affordable.

You would calculate how healthy a food is by working out the nutrition per calorie. Take the percentage recommended daily intake of each good nutrient, and divide it by the number of calories in a serving. This ratio could then be weighted so that foods with less bad fats and other bad things get a lower score than healthier foods. It's complex and I'm not a nutritionist so I can't come up with the formula myself - they'd need to take into consideration things like the fact that some fat is necessary, but too much is bad, and trans fat is unconditionally bad, or that some sodium is necessary but too much sodium is bad. Or fibre is good, but it isn't a nutrient strictly speaking. The formula would also have to be adjusted so it doesn't favour food that's low calorie, but has very few nutrients.

Anyway, my point is they work out a system so that healthier foods have a higher score and less healthy foods have a lower score. A big old tub of pure trans fat with no redeeming qualities would have a score of 0, and the single most efficient food in the world would have a score of 100. Then they put a cap on the amount that one serving of the healthiest foods cost, with the price cap being lower the healthier the food is. They would do this for, say, foods with a healthiness score of 65 and over. They could pay for this by incrementally increasing the taxes on foods with a healthiness score of, say, 35 and under. Since the price cap is per serving, using the standard Food Guide servings, you wouldn't have to worry about the fact that yes, one apple is cheap, but it won't fill you up nearly as much as one bag of chips.

They'd obviously need to check a few things first (like what if all the foods that were price-capped ended up being fruits and vegetables, with no protein in the mix?) but if they could implement this it would ensure that even the poorest can afford a healthy diet, and may help improve the health of the population as a whole.