The raw diet has been around for a while (e.g. forever). If you wanted to label the start of scientific interest in the raw diet you could say it originated in the Victorian period (1800), during the natural hygiene movement. Recently it gained traction through the strength of celebrity endorsement (Gwyneth Paltrow, Miranda Kerr and Venus Williams) and quick fix culture (detoxes and juice cleanses).
What is the raw diet?
You eat most if not anything raw, this diet is usually a plant-based diet, focusing on either vegetarian or even completely vegan. The focus is also on unprocessed foods, so lovely fermented foods are out, and if super strict, canned foods.
Having all your vegetables and fruit raw is marketed as a way to make sure you get all the vitamins, minerals and phytochemicals intact. It is implied that eating raw makes all the vitamins and minerals in food more bioavailable.
Is this true though?
First off there is nothing wrong with eating a lot of your vegetables raw, and I would probably imagine that most people eat raw fruit although, stewed and canned fruit could be more affordable. So raw isn’t bad, but is all raw good, or better?
Secondly, we should try and remember cooking is a form of chemistry, causing a series of reactions from the type of heat used, temperature reached, and other ingredients present. As such different methods will have an impact on the water- and fat-soluble vitamins, minerals and phyto-chemicals contained in the food. Sometimes beneficial, sometimes not. However, it doesn’t make that food useless, it may make it taste better, and allow you to eat more of it. It could also make it more digestible, and easier on your digestive system to break down.
To raw or not to raw
Let’s start with the obvious benefits of not following a strictly raw diet. Some foods, especially ones that we obtain dried are easier to eat and digest when they have been cooked or processed to a certain extent.
Beans are a little obvious, canned they have been processed to a certain extent, likely cooked (boiled). Alternatively, you can purchase them dried, dried beans are impossible to eat.
Lentils are also a legume that are canned or bought dried. Here is a rather useless fact. Beans and peas are slightly higher in protein when cooked. Which is great, although not relevant as you couldn’t them raw unless you harvested some types fresh.
Peas, part of the legume family, can be eaten fresh. This means cooking these little guys makes them a slightly better source of plant protein.
Cooking pea[CC1] s almost doubles the available digestible amino acids. Peas are also an ok source of the branch chained amino acid leucine[CC2] [CC3] , which is important for building muscles. Great news if you are vegetarian and find it hard to eat enough protein. Cook and eat your peas.
Most of these require cooking, and the cooking method can change the form the starch and non-digestible fibre take. Grains are an important part of the diet, they provide a great range of vitamins and minerals. The fibre is very important for gut health and blood sugar regulation. Not cooking your foods, leaves out this essential food group.
A study in the journal Molecules [CC4] found that cooking tomatoes, onion and garlic in olive oil (using the traditional sofrito method) may make the phytonutrients more bioaccesible and bioavailable. How come? These foods are a good source of fat-soluble polyphenols and carotenoids (a pre-formed version of vitamin A). During cooking, these phytonutrients are leached into the olive oil and prevented from oxidising in the food matrix.
Why does this help? The specific polyphenols and carotenoids are fat soluble. This means that they are made up of molecules that don’t bond with water based molecules (hydrophobic) and they can be oxidised, like fats can be oxidised. Oxidation of fat soluble nutrients is not great, they become rancid and can cause more oxidative stress in the body.
Cooking foods in a medium made up of fats, the food breaks down more which is good. These fat soluble molecules are protected and even transported out of the food matrix into the olive oil. As such making the molecules easily accessible when eaten.
The authors of the paper theorise that this may be one of the reasons the Mediterranean diet is so protective for people. As the foods that make up the diet are good for you, but the cooking methods extract the best out of those foods.
A study in the Journa[CC5] l of Nutritional Science and Vitaminology found that roasting vegetables can make the free amino acids more readily available. A good option for vegetarians and vegans to get more protein out of their foods. This method specifically increases the free amino acid GABA.
The roasting as opposed to boiling also reduces the amount of water soluble vitamins lost. A benefit that the raw movement would have you believe can only be achieved through eating raw vegetables.
Brassica and Asian vegetables
The brassica family includes broccoli, cauliflower, brussel sprouts and cabbages. They are a family that are rich in the antioxidant called glucosinate. This antioxidant is particularly important in energy production in the body. Glucosinate are also integral in regenerating vitamin C to it’s antioxidant state, after vitamin C has reacted with a free radical in the body. Meaning it can neutralise more free radicals.
Broccoli [CC6] is high in glucosinates, and by boiling you can increase the anti-oxidant activity of it’s glucosinate content. This happens by inactivating the enzyme myrosinase which reduces the glucosinates into another molecule.
Chinese cabbage and pakchoi are common vegetables in some Asian cuisines, they are increasingly available in other countries. These vegetables are a good source of antioxidants, including glucosinates. The particular cooking method that is ideal for these vegetables is the traditional method of stir frying, using very little oil and a high heat in a wide deep pan.
A study [CC7] in Plant Based Foods for Human Nutrition found that stir frying inactivated the enzyme myrosinase at the start of frying due to the high heat. This method also prevents the loss of any water-soluble vitamins, as it does not use water. Some water-soluble vitamins can be damaged by heat, however stir frying is a quick method and without prolonged cooking, the loss to heat damage shouldn’t be too bad.
Another study [CC8] looking at antioxidants activity and polyphenol levels in vegetables found that frying them increased antioxidant activities and polyphenol levels significantly. Without going into all the vegetables, we can see that a variety of cooking methods bring out a variety of nutrient profiles in foods.
Should we cook everything?
As we stated in the beginning, cooking is a fun, and at times less confusing world of chemistry. Everything we do changes the chemical make-up of food. Some foods that have more-fat soluble anti-oxidants benefit from the presence of fat and some cooking methods. Whereas foods high in water soluble vitamins, benefit from being eaten raw, cooking in low temperatures and specific methods such as steaming and not boiling.
We should also realise that you have no control over some parts of food processing, and these will always change the availability of vitamins and minerals. This is just a side effect of our modern food production.
A lot of foods are frozen and then thawed before being displayed, and this definitely changes nutrient profiles. While some foods come long distances, and have to be stored in specific ways. You cannot control every aspect unless you grow everything from home. Good on you if you can, but that’s not realistic for many.
This can all seem a bit overwhelming, but to us, it simply suggests that we really just need to focus on variety. A variety of vegetables, cooked and raw, as well as other food groups are all part of a healthy eating pattern. By ensuring you eat 2 serves of fruit and 5 or more serves of vegetables and some whole grains, cooked in a variety of ways, you will have a very healthy diet.
We also need to be less nutrient focussed, yes each different method produces a variety of results. However to get caught up in which is best and not can be mentally exhausting.
Aim for variety, and you should hit benefits for each type and method throughout your week. Overall leading to a healthy diet and the benefits that come from that.
Calm your farm, eat your vegetables however you want. If you prefer some cooked, others not then just eat them that way. Over all it’s best to just eat your vegetables.
[CC1]Burd, N. A. et al., (2019, June 6). Dietary protein quantity, quality, and exercise are key to healthy living: A muscle-centric perspective across the life span. Frontiers in Nutrition, 6: 83
[CC3]Gorrisen, S. M.H. (2018, August 30). Protein content and amino acid composition of commercially available plant-based protein siolates. 50(12): 1685-1695
[CC4]Rinaldi de Alvarenga, J. et al. (2019, April 9). Using extra virgin olive oil to cook vegetables enhances polyphenol and carotenoid extractability: A study applying the sofrito technique. Molecules, 24(8): 1555
[CC5]Ito, H., Kikuzaki, H., & Ueno, H. (2019). Effects of cooking methods on free amino acid contents in vegetables. Journal of Nutritional Sciene and Vitaminology, 65(3): 264-271.
[CC6]Ng, Z. X., Chai, J. W., & Kuppusamy, U. R. (2011, Jan 20). Customized cooking methods improves total antioxidant activity in selected vegetables. International Journal of Food Sciences and Nutrition, 62(2): 158-163
[CC7]Nugtahedi, P. Y. at al. (2017, Noc 13). Stir-frying of Chinese cabbage and pakchoi retains health-promoting glucosinates. Plant Foods for Human Nutrition (Dordreant, Netherlands), 72(4): 439-444.
[CC8]Murador, D., Braga, A. R., Da Cunha, D., & De Rosso, V. (2018, Jan 22). Alterations in phenolic compound levels and antioxidant activity in response to cooking technique effects: A meta-analytic investigation. Critical Reviews in Food Science Nutrition, 58(2): 169-177