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How Do Raw Food Diets Work?
Raw food diets consist exclusively of uncooked and unprocessed plant-foods.
The bulk of the diet is therefore made up of fruits, vegetables, nuts, seeds, as well as sprouted beans, grains, and legumes. Depending on someone’s definition of ‘processed’, foods such as vegetable juices, nut milks, and fermented foods may be included.
Some variations of the raw food diet exist that include some animal products such as unpasteurized milk, and raw eggs, meat, and fish. However, as the inclusion of these foods is very rare this review will focus on plant-based foods only.
The main reason for practicing a raw food diet is to attain health, prevent illness, and to seek a more natural and healthy way of living.
The Potential Benefits of The Raw Food Diet
Below we've listed all the potential benefits that are backed with credible scientific research:
It Can Increase the Bioavailability of Some Nutrients
Cooking food can destroy some nutrients and enzymes by altering their structure, and therefore have a negative impact on their digestibility and the ability to utilize some nutrients within food.
Water-soluble and heat-sensitive nutrients seem to be affected by heating the most .
The bioavailability of some vitamins in vegetables is even reduced by as much as ~20% - especially vitamin C, folate, and potassium. Cooking processes may also negatively affect the bioavailability of some antioxidants such as polyphenols.
However, cooking food can also increase the bioavailability of some health-promoting compounds such as lycopene and certain carotenoids. Heating processes may even be effective at removing or reducing anti-nutrients - compounds that interfere with the absorption of other nutrients - such as tannins, trypsin inhibitor and phytic acid.
It May Improve Cholesterol Levels and Cardiovascular Health
Following some type of predominantly raw food diet has historically shown a preventative effect against diseases related to nutrition .
In general, an increase in fruit and vegetable intake is associated with positive health outcomes, with each increase of 1 portion of fruit or vegetables a day linked with a ~5% lower risk of ischemic stroke .
However, there is little information regarding the effect that eating only raw fruits and vegetables has upon dietary risk factors of cardiovascular diseases.
Although more data is needed, it is speculated that the significant reductions in total cholesterol and LDL cholesterol from a raw food diet likely has a beneficial impact on avoiding arterial diseases.
This is because atherosclerosis development has shown to completely diminish when there are physiologically very low concentrations of LDL cholesterol in the blood (“bad” cholesterol) - ~50-70 mg/dl . This removes some concerns that a raw food diet potentially leads to an excessive drop in LDL cholesterol.
This being said, ~50% of raw food dieters also have low HDL cholesterol (“good” cholesterol), which helps to remove cholesterol from the bloodstream . This has been documented as a concern of a raw food diet as HDL cholesterol has cardioprotective effects attributed to its role in reverse cholesterol transport. However, seen as raw food eaters consume no cholesterol, and total cholesterol in the blood is already low, the concern for low HDL cholesterol is not relevant in this context.
It May Aid Gut Health
The large focus on unprocessed plant-based foods, both soluble and insoluble, will likely help to improve the composition of the gut and the digestion of food.
Soluble fiber in particular interacts directly with gut microbes and leads to the production of metabolites such as short-chain fatty acids that modulate the microbial communities which colonize the digestive tract .
This is very important as the bacterial composition of the gut has shown to play a role in preventing diseases such as type 2 diabetes, cardiovascular disease and colon cancer .
Gut microbiome also directly influences the amount of inflammation in the body, which can provide a wide variety of different health benefits such as increasing longevity.
In addition, the high insoluble fiber content adds bulk to stools and can reduce the risks of colon cancers .
The Drawbacks of The Raw Food Diet
As you might have expected, there are some negatives to only eating raw food:
Extreme Body Weight Loss
An insufficient energy supply in nearly 50% of raw food dieters has been reported .
Due to this, a significant number of individuals on the diet experience drastic changes in body weight when they change their dietary habits in the manner.
For many diets this can be viewed as a positive outcome, however the rate of weight loss on a raw food diet can be so substantial that it can often lead to excessively low body weights – and even anorexia.
In a sense, it creates a synergistic effect for weight loss that is already common when switching to a plant-based diet.
The problem is that decreasing body weight at a faster rate is not necessarily more beneficial and will increase the chances of malnutrition result and large losses of muscle mass .
Those that do experience these issues will put themselves at a high risk for reducing bone density and developing osteoporosis .
It May Lead to Menstrual Irregularities
A specific issue for females on the diet is that being underweight, or creating nutritional deficiencies, can lead to amenorrhea - the absence of menstruation.
A worrying statistic is that 70% of women on a raw food diet have irregularities in their menstruation which was not apparent before changing their dietary habits .
Although many raw food advocates judge this as a success of their diet, since a loss of menstruation may be viewed as a natural process of “cleansing”, amenorrhea can in fact result in impaired fertility.
Loss of a females menstrual cycle may also force metabolic changes that affects bone and cardiovascular health, and increases the risk of osteoporosis and coronary heart disease in later life.
It May Cause Nutrient Deficiencies Without Supplementation
A well-balanced plant-based diet is able to hit all daily nutrient requirements with the exception of vitamin B12 which needs to be supplemented.
However, as the diet may have limited access to some nutrients it can often be harder for plant-based dieters to consume adequate amounts of other nutrients – Calcium, iron and zinc. In turn, these nutrients have a higher prevalence of deficiency in plant-based populations.
A further critique of a raw food diet is that it creates additional problems in accessing these nutrients, as they are often found in plant-foods that are typically cooked, such as tofu, lentils, beans, chickpeas, and soy. Clearly, this makes the chances of nutrient deficiencies increase.
The issue becomes even greater for raw food dieters that refuse to supplement to correct these deficiencies, due to the belief that they can get all the nutrients they need from raw foods alone.
Evidence shows that nearly 50% of raw food diet followers have a functional vitamin B12 deficiency , along with a significantly reduced bone mineral density compared to omnivorous dieters that stems from an insufficient calcium intake .
What’s more, a raw diet tends to provide very little protein - often less than 10% of an individuals total calorie intake per day. This is a concern for preserving muscle mass, especially during periods of low-calorie intake that lead to weight loss — such as can be expected on this diet .
Is A Raw Food Diet Sustainable?
The only data available for a raw food diet reports that only ~20% of people are able to adhere at least 80% to the diet .
Although more research is needed, the signs are that this is not a diet that is sustainable in the long-term.
Specifically, it is noted that the diet may cause social inconveniences if close friends and family are not following the diet, and it has also been mentioned to be labor intensive in terms of food preparation and time consumption.
The diets sustainability will largely come down to one’s individual lifestyle and beliefs.
Is A Raw Food Diet Safe?
At present, little is known about the consequences of a raw food diet on long-term health.
As mentioned, the increased chance of nutrient deficiencies on the diet can potentially cause health issues such as menstrual irregularities, anemia, nervous system damage, infertility, and poor bone health.
However, a well-planned raw food diet can be considered safe if the diet is structured in a manner where all energy and micronutrient requirements have been considered, and supplementation is taken as needed.
Raw food diets consist exclusively of uncooked and unprocessed plant-foods.
This form of dieting can effectively reduce cholesterol levels, improve heart health, and benefit the bacterial composition of the gut which may lower inflammation.
However, the extremely low-calorie intakes that are common with the style of eating can lead to rapid weight loss, menstrual irregularities, and nutrient deficiencies such as vitamin B12, calcium, iron, and zinc.
Correct planning and supplementation can make the raw food diet a viable eating plan, however current evidence suggests that it comes with too many risks and is not sustainable for the vast majority of individuals.