The theory behind the raw foodism diet started already in the 1800s when a Swiss doctor Maximilian Bircher-Benner eligibly cured many of his patients with by given them only raw foods. The popularity of the raw foods has since spread and evolved over the decades to sushi (raw fish), carpaccio (meat), cold pressed juices and unpasteurized milk. 

Should we eat all our foods raw? 

Many raw plant-based foods like fruits, vegetables, nuts/seeds, wholegrains are packed with natural vitamins, phytonutrients, and enzymes, which can easily be destroyed by the heat especially highly sensitive vitamins like C and B complex. 

Yet, not all raw food has equal nutritional advantage over cooked. A study found that a higher amount of the antioxidant lycopene is released from tomatoes when they’re cooked (1). The British Journal of Nutrition also found that people following a 100% raw food diet had low levels of lycopene (2). Similar benefits have been reported in mushrooms and asparagus that their content of phytochemicals quercetin, lutein, and zeaxanthin increases when cooked (3). 

Evidence from other non-plant-based foods like meat, egg and fish show little health and nutritional benefit from being eating raw vs cooked. There have been some conflicting studies suggesting nutritional quality like healthy omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid may slightly degrade when fish is cooked at very high heats. However, animal products like fish, milk and meat are highly prone to grow pathogen bacteria like Listeria, E coli which are potentially deadly and therefore does not weigh up its little health benefits.

What are the benefits of eating raw foods?

Many studies have found a strong links between eating a raw diet and weight loss. One theory is that raw (unprocessed) wholefoods contain a much higher amount of indigestible dietary fibres mainly plant-based foods like nuts, fruits and vegetables. These fibres stimulate the gut hormones like GLP-1, PYY that suppresses your “hunger” hormones like leptin, ghrelin i.e. suppresses your appetite. Another health benefit found by eating raw wholefoods is that it leads to a lower calorie intake as many macronutrients are “bypassing” absorption in the small intestinal. 

A study published last month in Nature Microbiology investigated how raw vs cooked foods alters the composition the guts microbiome and its health benefits (4). They discovered the influence of meat was the same regardless of whether it was cooked or not. Whereas raw plant-based foods like beets, corn, carrots altered the gut microbiota and positive metabolic pathways; leading to a lower absorption of calorie and altered carbohydrates metabolism and weight loss.

The take home message:

A raw plant-based food diet can lead to weight loss, higher intake of vitamins/enzymes and promote a healthier gut microbiome; however, there can be nutritional and health consequences associated with eliminating all cooked foods. For a well-balanced diet eat no more than 80% raw plant-based foods and preferable cook most of your non-vegetarian foods such as meat, fish and seafood. 

References:

1. Dewanto V, Wu X, Adom KK, Liu RH. Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity. J Agric Food Chem. 2002;50(10):3010-3014.

2. Garcia AL, Koebnick C, Dagnelie PC, et al. Long-term strict raw food diet is associated with favourable plasma beta-carotene and low plasma lycopene concentrations in Germans. Br J Nutr. 2008;99(6):1293-1300.

3. Fanasca S, Rouphael Y, Venneria E, Azzini E, Durazzo A, Maiani G. Antioxidant properties of raw and cooked spears of green asparagus cultivars. Int J Food Sci Technol. 2009;44(5):1017-1023.

4. Rachel N. Carmody, Jordan E. Bisanz, Benjamin P. Bowen, Corinne F. et al. Cooking shapes the structure and function of the gut microbiome. Nature Microbiology. 2019.

This is a guest post. The opinions expressed are the writer’s own.