5 healthy foods that nutritionists once thought were terrible for you

David Silverman / Getty Images

Nutritional guidelines and recommendations are constantly changing in the light of new research.

It can be difficult to keep up with which foods are healthy and which aren’t.

Here we look at five foods that have gone through the cycle of being the villains of nutritional science but are now, based on some old and some new science, apparently okay to eat again.

Eggs

For a long time, eggs were thought to be bad for your heart. A large egg contains a hefty 185mg of cholesterol.

Dietary cholesterol was believed to contribute to high blood cholesterol levels. But for the last 20 years, nutrition and medical research has shown repeatedly that at normal intakes dietary cholesterol has very little influence on a person’s blood cholesterol levels.

Although it’s taken a while, nutrition experts are now correcting the record for eggs and other foods that contain cholesterol (such as chicken liver and shellfish) by removing it as a nutrient of concern from dietary guidelines.

Eggs are an excellent source of protein, healthy fats, and several vitamins and minerals.

Fat spreads

The story of fat spreads, such as margarine and butter, is probably one of the most confusing stories in nutrition. The origin of margarine, which is made from vegetable fat, dates back to the mid-1800s.

Since that time, margarine has replaced butter as the fat spread of choice in most developed countries. This switch was driven by the lower price of margarine compared with butter as well as recommendations from health professionals to eat less saturated fat in order to prevent coronary heart disease (CHD).

While this switch away from saturated fats began to show reduced CHD incidence in the population, researchers also identified an independent link between trans fat (a fat produced when partially hydrogenating vegetable fats to make margarines) intake and CHD. Since this link between trans fat and CHD was confirmed by multiple studies regulatory agencies around the world have sought to eliminate trans fats from the diet.

The food industry was quick to respond and has been producing trans fat-free margarine for years now. However, there is still confusion among consumers as to whether vegetable, fat-based spreads are safe to eat. The short answer is yes, as long as the food label doesn’t list “partially hydrogenated vegetable oil” as an ingredient.

Modern vegetable oil-based fat spreads are a way to replace dietary saturated fat while increasing polyunsaturated fat – a dietary change that has been shown to reduce CHD in large cohort studies.

Potatoes

Potatoes are one of the few vegetables considered to be unhealthy. Because they’re a high glycaemic index food they tend to get lumped in with foods made from refined carbohydrates as foods to avoid.

But potatoes are a rich source of carbohydrates, vitamin C, some B vitamins and trace minerals.

How you prepare potatoes also changes the aspects of those starches that get a bad rap. Cooking and cooling potatoes increases the amount of resistant starch in the potatoes. This resistant starch then acts like dietary fiber which “resists” digestion in the gut, potentially having a positive impact on your gut bacteria.