Is a raw vegan diet healthy?

The objection

“Cooking wrecks vitamins and turns starchy food into compounds like acrylamide, and raw-food eaters are slim with low cholesterol to show for it. If a vegan diet is healthy, surely the purest version, eaten raw, is the healthiest of all.”

The answer

A vegan diet doesn’t have to be raw to be healthy, and a strict raw diet carries real risks. Studies of people who have eaten raw for years find low energy intakes, weight loss, lost periods, eroded teeth and lower bone density, along with a shortage of vitamin B12 in those who skip supplements. The studies are small snapshots of volunteers, mostly in Germany, and can’t prove the diet caused these problems, but the harms they report all point the same way.

The objection isn’t wrong about everything. Among 201 raw-food eaters in the Giessen Raw Food Study (2005), none had high triglycerides and only 14% had high LDL cholesterol, though 46% had low HDL, the “good” cholesterol [1]. Raw vegetarians studied at Washington University in St Louis (2005) had lower C-reactive protein, a marker of inflammation, than matched controls [2], and a 2020 study from Tehran of 59 raw vegans found healthier gums than in 59 controls, which its authors put down to better oral care and lifestyle [3]. In a Finnish trial (1998), people with rheumatoid arthritis randomised to an uncooked vegan diet rich in lactobacilli said their symptoms eased, though measures of disease activity didn’t differ significantly from the control group’s, and half had nausea or diarrhoea on the diet and stopped early [20]. A 2019 systematic review of diet trials in fibromyalgia, two of them of raw vegetarian diets, found that pain seemed to ease on such a diet but that the studies were too few and too poor in quality to draw conclusions from [21]. Heat also costs some vitamins, as the second section below shows.

What happens to people who eat only raw food?

Many lose a lot of weight, and many women lose their periods. In the Giessen Raw Food Study’s questionnaire survey (1999) of 513 people who had eaten 70 to 100% of their food raw for 3.7 years on average, the women said they had lost 12 kg on average since starting and the men 9.9 kg [4]. A quarter of the women (25.0%) and 14.7% of the men were underweight, with a body mass index (BMI) below 18.5, and BMI was lower the more raw food people ate and the longer they had eaten it [4]. About 30% of the women under 45 had partly or completely lost their periods, more often among those eating over 90% raw, and the authors concluded that a very strict raw diet can’t be recommended in the long term [4].

Their teeth showed more erosion as well. Dentists at the same university in Giessen examined 130 people who ate more than 95% of their food raw, as part of a larger diet study, and compared them with 76 of their own patients matched for sex and age (Ganss et al., 1999) [5]. Of the raw-food eaters, 60.5% had at least one severely eroded tooth, against 31.6% of the patients, and only 2.3% had no erosion at all, against 13.2% [5]. They ate citrus fruit a median of 4.8 times a day, though within the group no food or oral-hygiene measure was significantly linked to erosion [5].

A small US study found low bone mass in long-term raw-food eaters too. Eighteen people who had eaten a raw vegetarian diet for 3.6 years on average had lower bone mineral content and density at the lumbar spine and hip than matched controls on a typical American diet, and a mean BMI of 20.5 against 25.4 (Fontana et al., 2005) [2]. Their markers of bone turnover were similar to the controls’ and their vitamin D levels were higher [2].

Vitamin B12 is the other weak point, because plants don’t provide it [6]. In the Giessen study’s 2005 report, 38% of the 201 raw-food eaters were short of B12 [1]. A 2022 study from Germany’s Federal Institute for Risk Assessment compared 16 strict raw-food eaters (four fully vegan, four vegetarian and eight who ate some raw meat or fish) with 32 vegans and 27 meat-eaters from an earlier study [7]. The raw-food eaters took in less energy, protein, calcium and iodine than either group, and had the lowest BMIs [7].

Finding	Raw-food eaters	Comparison group
At least one severely eroded tooth (Ganss, 1999) [5]	60.5% of 130	31.6% of 76 matched patients
Average BMI (Fontana, 2005) [2]	20.5	25.4 in matched controls
Took B12, at least now and then (Abraham, 2022) [7]	56% (9 of 16)	94% of vegans
Homocysteine above 12 µmol/L (Abraham, 2022) [7]	50% (8 of 16)	6.3% of vegans, 7.4% of meat-eaters

Raised homocysteine can signal a shortage of B12, B6 or folate, and three of the raw-food eaters who took no supplement had B12 levels too low to measure [7]. The authors expected B12 to be the main harm of a raw vegan diet without supplements, and noted that supplements easily prevent it, as the vegans’ results showed [7]. Every vegan needs a reliable source of B12, raw or not [6].

The Giessen study took raw-food eaters of every kind, and in its main blood-test group the diets were vegan, vegetarian or mixed [7], so its findings describe raw eating in general, with raw vegans among them. The authors of the 2022 study saw the same trends in B12, homocysteine and HDL cholesterol as that 1990s work, and judged energy the second big problem after B12, shown by the low BMIs [7].

Doesn’t cooking destroy nutrients?

Cooking destroys some nutrients and makes others easier to absorb, and for many plant foods it is what makes them safe or edible at all. The losses are real: in a 2018 laboratory study of vegetables cooked four ways, the share of vitamin C kept ranged from none to 91.1%, generally lowest after boiling and highest after microwaving, while some cooked vegetables held more beta-carotene and vitamin E than raw ones (Lee et al.) [8].

The best-known example of heat helping is lycopene, the red pigment in tomatoes, though the evidence is mixed. In a 1997 trial, a single serving of tomato paste eaten with oil gave a peak of lycopene in the blood 2.5 times as high as the same amount of lycopene in fresh tomatoes [9], while a five-person study of cherry tomatoes in 2004 found no significant rise in blood lycopene after either the raw or the home-cooked fruit [10]. In a 2008 study of 198 strict raw-food eaters in Germany, 77% had lycopene levels below the reference values for healthy people, while 63% had beta-carotene at the level linked to lower risk of chronic disease (Garcia et al.) [11]. The main predictor of their carotenoid levels was how much fat they ate [11].

Beans are the starkest case. Soaking cut lectins by at most about 5% in a 2018 study of Canadian pulses, while cooking cut them further [12]. Phytate was harder to shift: soaking had no effect on it, and in common beans and soya beans cooking did no better [12]. Red kidney beans are dangerous raw: as few as four or five can cause severe stomach ache, vomiting and diarrhoea, and Australia’s Food Safety Information Council advises soaking them for at least five hours, then boiling them briskly in fresh water for at least 10 minutes [13]. There is more in the answer on lectins and antinutrients.

Going without heat also narrows the menu. Potatoes need cooking to make them harmless, and rice, pasta and bread only become edible once cooked or baked [7]. Between them, the 16 strict raw-food eaters in the 2022 study ate from only 23 of 57 food groups, and nine ate more than a kilo a day from a single group [7].

Isn’t cooked food full of acrylamide?

Cooking at high heat does create acrylamide, and raw-food eaters carry less of it, though still about half as much as meat-eaters. Acrylamide forms when starchy foods such as potatoes and bread are baked, fried, grilled, toasted or roasted above 120°C, and the Food Standards Agency (FSA) says it has the potential to cause cancer in humans, though it isn’t possible to estimate by how much it raises the risk [14]. In a 2024 German study, the median blood marker of acrylamide in strict raw-food eaters was 13.3 pmol per gram of haemoglobin, 48% of the meat-eaters’ 27.7, while the vegans had the highest level at 39.7, all among non-smokers [15]. The authors took the raw-food eaters’ remaining level as evidence that the body makes some acrylamide itself [15]. The study measured exposure and didn’t look at health outcomes [15]. The FSA’s advice, which applies to vegans as much as to anyone, is to aim for a golden yellow colour or lighter when frying, baking, toasting or roasting starchy foods, and boiling and steaming aren’t among the ways of cooking it lists [14].

Is a raw diet safe for children or in pregnancy?

Nothing in the studies of raw-food eaters suggests a raw diet can meet the needs of a growing child or a pregnancy. The NHS says a child brought up vegan needs a wide variety of foods to provide the energy and vitamins they need for growth, and that a vegan who is pregnant or breastfeeding has to get enough vitamins and minerals for the baby to develop healthily [16]. The raw-food studies found shortfalls in exactly those things: too little energy, lost weight, lost periods in about 30% of women under 45, and B12 deficiency in 38% of the 201 raw-food eaters tested for it in the Giessen study [1][4][7]. Raw sprouts carry a risk of their own: they were the most likely source of a large outbreak in Germany in 2011 of haemolytic uraemic syndrome, caused by a toxin-producing strain of E. coli [22].

If your periods have stopped, see a GP. The NHS lists sudden weight loss and too much exercise among the causes, and advises seeing a GP if you’ve missed three periods in a row, or missed one and lost weight [17]. If eating raw has become a way of restricting how much you eat, a GP or an eating-disorder charity can help: Beat in the UK (beateatingdisorders.org.uk), Bodywhys in Ireland (bodywhys.ie), ANAD in the US (anad.org), NEDIC in Canada (nedic.ca) and the Butterfly Foundation in Australia (butterfly.org.au), while in New Zealand EDANZ (ed.org.nz) supports families and carers.

Raw fruit, salad, nuts and seeds have a place alongside cooked beans, grains, tofu and vegetables. Dietitians’ bodies in the UK, Ireland and Canada say a well-planned vegan or plant-based diet can suit every age [6][18][19], and the NHS says pregnancy and early childhood need particular care [16].