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Updated 23 May 2016

Is raw food really better for us?

'Eating raw' is once again in fashion. DietDoc explains the pros and cons of a raw food diet.

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I am always fascinated by the changing face of modern nutrition and new concepts that pop up out of the blue. The “raw versus cooked” controversy been around for a long time, but seems to be experiencing an upsurge of late.

“Eating raw” is one of the diet fads currently in vogue. The adherents of raw food can be very persuasive, and argue that as modern diets include more and more processed foods, we need to return to eating raw, real foods like our remote ancestors before the advent of cooking.

Raw diets

Most raw diets encourage their adherents to eat only plant foods, i.e. fruits, vegetables, unsifted, uncooked or unbaked grains (usually in the form of sprouted seeds), raw honey, and nuts in their raw state.

Read: Eating nuts lowers cholesterol

Raw meat and fish

Many people baulk at the idea of eating raw meat, but raw fish for example is consumed in sushi, which is very popular in western countries.

Meat can actually be eaten raw, as lovers of steak tartare, carpaccio and sashimi, will attest – and most steak enthusiasts prefer their meat red or pink in the middle anyway. Anyone who has ever watched famous chefs at work will know that judges frown upon meat that is not dripping with juices.

Read: Cooked meat better

Totally raw poultry dishes and underdone pork are, however, not acceptable in the culinary industry. This may be due to fear of bacterial contamination like Salmonella, or worm infestations such as tapeworm. These meats are safer for human consumption when cooked right through. Generally speaking, protein foods are safer cooked than raw. 

The brain size theory

In the past few decades anthropologists and proponents of evolution theory have suggested that it was the discovery of fire and how to cook food that led to the dramatic and relatively fast (in evolutionary terms) development of the human brain – which increased by up to 50% in H. erectus compared to the brain of its predecessor H. habilis. At the same time, tooth size in H. erectus decreased more than ever before or after. 

Read: How predictable is evolution?

These changes occurred about 1.6 million to 1.9 million years ago, and modern anthropologists attribute this unprecedented expansion in brain size, which allowed us to develop into modern humans, to various theories linked to what H. erectus ate, and the concept that they cooked their food.

According to Richard Wrangham, a biological anthropologist, species that eat only raw plant foods and minimal quantities of raw meat, such as gorillas and chimpanzees, spend so much time chewing and digesting the hard, fibrous roots, leaves and wild fruits that make up their diets that they are not able to ingest sufficient energy to fuel brain growth.

The discovery and control of fire for cooking purposes, made digestion easier and faster and also permitted greater uptake of important nutrients. Consequently, not only the teeth, but also the gut of modern humans is much smaller than those of our ancestors.

Wrangham has calculated that members of the H. erectus species, who had a similar body size to modern humans but ate wild, raw foods, would have had to eat about 5,5 kg of these foods a day to survive and keep their brains going. Even if H. erectus just ate raw meat, he would have needed 6 or more hours a day to chew the tough meat of active, wild animals, to obtain sufficient energy and nutrients.

Read: Alcohol slows rich food digestion

Wrangham has suggested that by eating cooked food, which was more digestible and made nutrients more absorbable, our ancestors were able to provide sufficient energy and nutrients for their brains to grow in size and complexity.

Until recently, little or no proof existed that humans or their ancestors had been able to control and use fire for cooking 1.9 million years ago, when that period of unprecedented brain expansion took place. This caused many anthropologists and paleologists to believe that it was not the fact that our predecessors knew how to cook food, but that they managed to catch and kill animals to obtain marrow from the bones and brain tissue which is rich in nutrients and essential fats, to fuel the growth spurt in human brains.

Wonderwerk Cave

As often seems to be the case, proof that our human ancestors knew how to control fire possibly for the purposes of cooking nearly 200,000 years earlier than previously believed, was discovered in South Africa in the Wonderwerk Cave in the Northern Cape province.

Humanoids and humans inhabited this cave for 2 million years and it is here that the first plausible evidence was found that our ancient human ancestors were using fire and cooking food at an early stage.

Read: Don't be a fire-starter

The team of scientists led by Boston University archaeologist Paul Goldberg, were able to determine that the bones found in an ashy layer of the Wonderwerk Cave had been charred by a small fire made of twigs and grasses burning at temperatures between 400oC and 700oC, and not by a bush fire outside the cave.

Still exploring

So although we are still waiting for some patient archaeologist to find proof that humans or their ancestors were capable of controlling fire and cooking food round about the time of the great expansion in human brain size and complexity, Wrangham’s theory that cooking fuelled our evolution, still remains only a theory at present.

However, if we consider that cooked food provides 30% more energy from oats, wheat or potato starch compared to the raw varieties, and up to 78% of the protein in a cooked egg, then perhaps we need to take the findings of archaeology seriously and combine raw and cooked foods in our diets.

According to Wrangham, studies of modern raw food adherents showed that they tend to be underweight, and up to 50% of females had stopped menstruating. The weight loss effect is emphasised in some of the raw food websites, one of which for example states that “weight loss is almost certain on this diet”.

In view of the above, it is important to make sure that you and your children eat a balanced, nutrient-rich diet that consists of both raw and cooked foods for optimum health.

Read more:

Evolution driven by environment

Big brains are pricey

Rules for a balanced diet

References:

Adler J (2013) Why fire makes us human. Cooking may be more than just part of your daily routine, it may be what made your brain as powerful as it is.

Bestofrawfood, 2016. Raw food diet plan.

Gibbons A, (2012). Raw food not enough to feed big brains

Gorman R M, 1008. Cooking up bigger brains

Miller K (2013). Archaeologists find earliest evidence of humans cooking with fire.

Mott N (2012). What makes us human? Cooking, study says.

Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Health24.com. Read more of her articles.

 
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