The first industrially prepared baby formula that supposedly contained enough nutrients to replace breast milk successfully was invented in the mid-19th century by German chemist Baron Justus von Liebig. Even though his formula was promoted as a perfect meal, it soon turned out that breast milk wasn’t as easily duplicated as it seemed. The recipe lacked crucial ingredients such as vitamins since their nutritional value still hadn’t been recognised.

The list of known nutrients needed for a child’s healthy development has lengthened further over the years. The role of omega-3 fatty acid was recognised as late as the 1970s. In 2006 chemist Bruce German and his colleagues discovered another interesting trait in breast milk.

It may sound strange, but human milk contains substances that the child isn’t able to digest. These include complex sugars called oligosaccharides (HMO), which constitute the third most prominent ingredient of human milk. Because it passes through the child’s digestive system without any apparent benefits, it wasn’t clear why it was there in the first place.

The bad proteins and the good carbohydrates

Bruce German’s hypothesis was it was there to feed the bacteria in the child’s digestive system. He sent samples of breast milk oligosaccharides to his friend David Mills’ laboratory to check which bacteria fed on the sugars. After much testing, Mills’ team discovered a strain of intestinal bacteria Bifidobacterium infantis that thrived on the nutrients babies weren’t able to digest.

Further research showed that a layer of these bacteria prevents harmful microorganisms from reaching the child’s intestines. Because breast milk contains a significant amount of their food, the bacteria multiply and take over much of the child’s lower intestines, preventing other potentially harmful bacteria from developing in the colon.

The years spent discovering the role of the many different ingredients of breast milk indicate just how unreliable diet plans can be. A diet will typically claim to strike the right balance between various elements of nutrition – fats, carbs, vitamins, minerals and so on. It’s problematic to divide food into good and bad because the list of ingredients considered harmful and those thought beneficial has kept changing throughout history.

In the early 1900s proteins were proclaimed as something we needed to avoid to remain healthy. The most famous critic of protein was Dr John Harvey Kellogg, a prominent member of the Seventh-day Adventist Church that promoted vegetarianism. The most common problem with digestion at the time was constipation: Dr Kellogg saw the cause of this complaint in the intestinal bacteria feeding on half-digested meat. These evil meat-eating bacteria supposedly produced illness-inducing toxins, and people came to Kellogg’s sanatorium from all over the world to benefit from his various techniques and colon-cleansing diets.

John Kellogg also tried to change the habits of regular citizens who couldn’t necessarily afford a stay at his sanatorium. He wanted to replace the traditional bacon-and-eggs breakfast with something that adhered to his principles. So he asked his brother Will to invent a new, healthier kind of food to be used as a morning meal. Will Kellogg came up with cornflakes – soon a firm favourite on the American breakfast table – and made a fortune.

It eventually became clear that Dr Kellogg’s anti-protein and pro-carb movement was wrong, but his approach to diet – hailing some nutrients and demonising others – is still widely in evidence.

Bad fats and cholesterol

A few decades ago the role of the main bad guy was taken over by saturated fats. They started to gain notoriety in the 1950s when scientists tried to find the cause for the rise of cardiovascular diseases. Cholesterol was found to be the primary molecule responsible for narrowing and blocking the veins. The body needs this molecule and produces it on its own, but the problem is that when we have too much of it, it gets deposited on the walls of our blood vessels, causing arteries to narrow and clog up, eventually with fatal consequences.

After studying the eating habits of many different ethnic groups all over the world, statistics indicated a correlation between eating more dairy and meat products and the development of cardiovascular disease. They found out cholesterol levels increased the more saturated fats people ate. In the 1970s, new healthy diet guidelines were introduced, stating that fatty foods shouldn’t comprise more than 30% of all caloric intake. They advised people to eat less red meat, more fish and poultry, and to cut down on dairy products.

But the meat and the dairy lobbies managed to turn this very reasonable advice into a guideline, encouraging people only to eat less saturated fat. This again meant there was an evil nutritional component that needed to be avoided; and yet, an abstract enemy that couldn’t be seen or felt. The food industry exploited our desire for healthy eating by launching a series of products containing less saturated fats but more added sugars and other ingredients that were potentially even more harmful than saturated fats. Eating fatty foods did decrease with time, but levels of carbohydrate intake rose dramatically.

The food industry began to make massive use of industrially processed vegetable fats called trans fats because they are cheaper and last longer. But in the 1990s it turned out that trans fats were even worse than saturated fats. Advising people to eat less saturated fats has therefore done more harm than good.

The secret of a healthy diet

Michael Pollan, the author of many renowned books on healthy food, is firmly against an approach to healthy eating that reduces food to a list of balanced chemical ingredients. This approach, nutritionism as he calls it, understands each meal as the sum of its constituent molecules or nutrients. A carrot here equals a certain amount of beta-carotene, vitamins, fibre and sugars. These chemical compounds are supposed to represent everything a carrot has to offer. To eat healthy food, one needs to gather enough of the individual dietary components that the food experts of the day define as healthy.

Nutritionism is a way of thinking that looks to the balance between a food’s nutrients or components. Food is regarded as the sum of its nutrients. Because of this approach, something as simple as eating has become very complicated.

Nutritionism is primarily promoted by the food industry. Companies that make processed food tend to brag about removing harmful components from food and adding good ones. Adding vitamins and eliminating fats is the most popular way of making a product that corresponds to the current healthy food standards.

The main issue with nutritionism isn’t the fact that it perceives food as a carrier of individual nutrients, it is the fact that we aren’t able to see or feel these components of food. The consumer is supposed to read the list of ingredients and the content analysis, as well as trust the experts to have correctly identified which nutrients and how much of them we need for a healthy diet.

In his long years of research on healthy eating, Pollan adopted a simple rule that successfully refrains from naming any nutrients: Eat food. Not too much. Mostly plants.