Vegetable oils were brought into our lives in about 1910 when the processing of them became cheap. Make no mistake, these oils are a food technology that should never have been.

I have a rule of thumb; if the oil comes from something that is not obviously oily then don’t eat it, ever.

Canola, soybean, corn oil, cottonseed, safflower, margarines, often hydrogenated, sunflower, see a comprehensive list.

Olives, avocados and coconuts are all fruits and obviously oily. So that’s two reasons why they escape my rule and are therefore not something you need to avoid.

With lots of cottonseed oil, but no demand, it was added illicitly to animal fats and lards. There was no evidence that this was, in any way safe for human consumption.

By the 1990s, these trans fats that the AHA and the CSPI told us were supposed to be so healthy for us were implicated as major risk factors for heart disease.

Unsurprisingly, natural fats, whether they come from animal (meat, dairy) or plant sources (olive, avocado, nut) are generally healthy. Highly processed, industrial seed oils tend to be unhealthy. Let’s face the facts — we ate vegetable oils because they were CHEAP, not because they were healthy.

Most people share at least the following traits: they want to be healthy; they like animals; and they value clean air and water. Yet relatively few Americans connect those concerns with their food. As more people start making the link (especially if they’ve seen graphic video footage of industrial animal operations), many decide it’s time to stop eating foods from factory farms. This is a guide for doing just that.

I’ve been a vegetarian for more than twenty years. Unlike the fits and starts described in Jonathan Safran Foer’s autobiographical book Eating Animals, the day I decided to quit eating meat was the last time I ever did.