An interesting debate this one-
A lot of the ingredients in functional food are actually naturally - derived (ingredients from plants/ seeds etc) rather than being 'unnatural chemicals'. In food labelling terms everything has to have a technical description, so even 'salt' has an 'E' number...
Coronary heart disease is one of (if not THE) UK's greatest cause of death. A diet high in saturated bad is a major contributing cause.
The reason butter is so hard is that it is very high in saturated fat. This is not such a problem for children who can more rapidly metabolise it, and indeed need a certain percentage of fat for growth. The fat also carries essential A & D vitamins. However not so good in later life, when your arteries can begin to get 'furred up' - restricting the passage of blood to your heart.
Spreads are usually made from vegetable oils which are high in polyunsaturated (e.g. Sunflower)or monounsaturated (e.g. Olive oil) fats. These are broadly better for you. They haven't been shown to contribute to the development of coronary heart disease, like butter, and they may have significant beneficial effects.
I always find it interesting that people who are staunchly anti-margarine and anti- added chemicals have often already switched from lard or hard cooking fats to oil, and probably popped a whole load of Folic Acid when pregnant...
Have to say, I wouldn't be looking to the Two Fat Ladies for my dietary advice
(Actually sadly, isn't there just ONE Fat Lady now - didn't one die??)