1. Eggs.
There was a time not very long ago when eggs were looked upon as cardiovascular time bombs. High in dietary cholesterol, it was said that eating a lot of eggs would result in gummed-up arteries and a high risk of heart attack. Most recent studies, however, cast these assumptions aside. Unless you are diabetic, there is no evidence that dietary cholesterol results in plaque building up in your arteries (studies on diabetics have shown possible correlation but nothing definitive).
2. Saturated fat/red meat.
Good and bad news about saturated fat has been bouncing to and fro like a ping-pong ball for several decades. One of our primary sources of saturated fat is red meat (burgers, steaks, beef hot dogs and the like). From the early- to mid-20th century, we were encouraged to consume lots of meat because it was a great source of protein, B vitamins and numerous other nutrients. However, in the 1960s, studies began to link saturated fat with heart disease and cancer.
3. Butter.
Butter’s stock has gone up and down for 150 years. As far back as 1855, people were told to use oil instead of butter. Like a close-fought basketball game, the duel between margarine and butter has been classic, but it seems that butter has finally gained the upper hand.
4. Coffee.
For many years, coffee was the victim of flawed studies linking it to cancer and heart disease. Problem was, these studies did not take into account other factors, like coffee-drinkers might also be cigarette smokers. The result was that many people gave up coffee, albeit reluctantly.
5. Avocados.
Only a few decades ago the avocado was considered a sinful treat. As studies coming out in the 1970s and ’80s extolled the dangers of fat, the poor avocado suffered in silence as it was swept up in the low-fat tsunami of scientific opinion.
Source: salon.com