Introduction

The modern diet typically includes significant amounts of highly processed food. The term processed can be attributed to a very broad range of foods, from fresh baked bread to a chocolate bar. Essentially, if a food has been cooked or converted from base ingredients into something else, it can be considered processed. 

Adherents to a raw food diet,  also known as raw foodism, aim to remove these foods from their diets and only consume raw and uncooked ingredients. Raw fruits, vegetables, nuts, grains, and seeds make up the majority of a raw food diet, and followers typically stick to a plant-based diet.

The belief is that this is a healthier way to eat because cooking and processing food denatures many vital nutrients and enzymes that are necessary for good health. Eating food raw in its “natural” state preserves these nutrients. Proponents believe there are significant benefits, such as reduced body fat, higher energy levels, reduced risk of disease, and improved digestion. 

The raw food diet has grown in popularity in recent times and while it may be beneficial to many, it is very restrictive. If you’re considering giving it a go, it’s important to understand the scientific evidence behind its claims so that you can assess whether it’s the right thing for you. While a well-thought-out diet plan can have many benefits, it's important to be aware of any negatives that come with restricting your food intake. 

It’s advised to consult a healthcare professional before making any significant changes to your diet.

Nutritional benefits of a raw food diet

One of the main tenets behind the raw food diet is that exposing food to high temperatures denatures or degrades certain vitamins and phytonutrients within the food, reducing its nutritional value. Thus, eating the food raw preserves said nutrients and you get the full benefit.

There is evidence to back this, but it’s highly dependent on the type of nutrient, food, and cooking method. Vitamin C, for instance, is known to be highly sensitive to heat. Cooking vegetables and fruit can significantly reduce the bioavailability of the vitamin C within them.¹ The cooking method can affect how much of the nutrient is preserved. Vegetables that have been microwaved or pressure cooked have been shown to retain more vitamin C than if they were steamed or boiled.² 

However, this isn't the case for all vegetables or nutrients, and how the cooking method affects nutrient retention will vary by food and nutrient type. For instance, there is some evidence that cooked vegetables actually have higher concentrations of vitamin K than raw vegetables as heat increases the vitamin K’s bioavailability.¹

Enzyme retention

As well as vitamins, many advocates of raw foodism are concerned with enzyme retention. Enzymes are often defined as biological catalysts and are a broad category of biomolecules. They have a wide variety of different roles within the body and enable many of the biological processes that allow us to digest and absorb nutrients from food.

Enzymes that are naturally present in raw foods are sensitive to heat and are denatured by the cooking process. However, the human body produces its own digestive enzymes, and so the role of dietary enzymes in our health and whether they are beneficial is unclear. 

The theory is that consuming dietary enzymes could reduce the body's need for endogenous enzymes and reduce the body's overall energy expenditure, thus potentially leading to better digestion and nutrient absorption.³ However, there is no clear scientific consensus on whether dietary enzymes do truly have any health benefits.

Health claims and scientific evidence

Weight management 

Many people adopt a raw food diet with the intention of losing weight. Processed foods encompass a very broad range of foods, some of which are low in calories and are conducive to a weight loss diet. However many are calorically dense. Conversely, the foods typical of a raw food diet are generally all low-calorie and higher in fibre than many processed foods. \Fibre increases feelings of satiety, meaning you’ll still feel full even after consuming fewer calories. 

Essentially, you’re likely to consume fewer calories than you normally would if you adopt a raw food diet, and if you wish to lose weight, reducing your caloric intake is the only way to do so via dieting. 

Diets that include lots of fruit and vegetables, which is typical of a raw food diet, are associated with lower body weight and reduced risk of obesity.⁴ Studies have also shown that participants in a raw food diet lose significant weight, which is reflected by an improved body mass index over a period of multiple years.⁵

It is, however, important to be aware of whether you’re losing weight too quickly or if your weight drops too low. Being underweight can also be harmful. It is always advisable to consult a healthcare professional if you begin to lose weight too rapidly or your body mass index becomes to low.

Reduced risk of chronic disease

Because a raw food diet necessitates eating a lot of plant-based foods that are nutrient-rich, high in vitamins, minerals, and antioxidants, it is thought that the diet can reduce the risk of developing chronic diseases like cancer, cardiovascular disease, and diabetes. Oxidative stress is a contributing factor to many chronic diseases, and so a diet high in antioxidants is beneficial to overall health. 

Diets high in fruits and vegetables are associated with lower rates of heart disease and stroke.⁶ The high levels of fibre associated with a raw food diet are also beneficial. High-fibre diets are associated with healthy blood sugar levels and a lower risk of developing type-2 diabetes.⁷

Potential drawbacks and nutritional concerns

Nutrient deficiencies 

While a raw food diet may have high levels of certain nutrients, which can have many benefits, it is very restrictive and thus is low in other types of nutrients. If not carefully planned and managed, you could put yourself at risk of certain deficiencies.

Nutrients such as iron, calcium, vitamin B12, and omega-3 fatty acids are largely found in animal products, and it can be difficult to consume adequate amounts from a purely plant-based raw food diet. B12 in particular is almost exclusively found in animal products, and so supplementation should be strongly considered if you intend to follow this diet. B12 is essential for nerve health and function, as well as red blood cell and DNA production. A deficiency in B12 can cause serious health problems like anaemia and neurological issues.⁸

Food safety concerns 

A major benefit of cooking food is that high heat will kill off any potentially dangerous pathogens, making the food safe to consume. This is more of an issue with raw meat and other animal products than it is with plant-based foods, consuming raw or undercooked animal products significantly increases the risk of infection from foodborne illnesses like E.coli and salmonella.⁹ 

Many practitioners of a raw food diet generally stick to plant-based foods anyway, but if you do intend to consume raw animal products, it is crucial to ensure with certainty that they do not harbour harmful pathogens and to practice thorough food hygiene with high levels of care.

The role of cooking in enhancing nutritional value

One of the core theories behind the raw food diet is that it preserves nutrients that are otherwise destroyed in the cooking process. However, while cooking may degrade some nutrients, it can enhance the bioavailability of others.

We mentioned earlier that the bioavailability of vitamin K is increased by cooking, another example is lycopene. Lycopene is an antioxidant found in tomatoes and is associated with lower rates of heart disease and prostate cancer and also has higher bioavailability when tomatoes are cooked than when they are raw.¹⁰

If some nutrients are degraded by cooking, but the bioavailability of others is enhanced, a balance of both cooked and raw foods may be a more efficient way of getting a full suite of nutrients from your food. 

Balancing raw and cooked foods for optimal health

The raw food diet has benefits. It encourages you to primarily consume foods that are high in fibre and are nutrient-dense, and completely removes highly processed foods, which can be sub-optimal for your health. Fruits, vegetables, nuts, seeds, and whole grains are healthy options to include in any diet.

The issue is that it is extremely restrictive, meaning you may be missing out on foods that are also healthy and can contribute essential nutrients to a well-balanced diet. In fact, if you were to follow a raw food diet that is poorly planned and executed, you would be at significant risk of becoming deficient in certain nutrients, like vitamin B12. 

Considering the bioavailability of certain nutrients is actually increased by cooking, a better strategy may be to simply reduce your intake of processed foods while maintaining a healthy balance of cooked and raw foods. 

Summary

The raw food diet is an interesting case in that in many ways it can genuinely improve a person's health, via weight loss if they are overweight, and by introducing more high-fibre and nutrient-dense foods.

The issue is that there is no unequivocal evidence that raw foods are inherently healthier than cooked foods. The raw food diet essentially forces you to remove processed foods from your diet but takes it to such an extreme that it also restricts perfectly healthy foods. The diet can be so restrictive that it then puts you at risk of nutrient deficiencies.

A more balanced approach that still focuses on whole foods such as fruit, vegetables, grains, nuts, and seeds and reduces highly processed foods but allows for some animal products or supplementation and allows both raw and cooked foods may provide a more comprehensive approach to a healthy diet. 

If you are considering giving the raw food diet a go, it is advisable to consult a healthcare professional before making any major changes to your diet.