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Cooked vs raw balance

Ayurveda favours freshly cooked, warm, spiced food as easier on digestion (Agni) and asks that raw and cold food be limited. Studies of people on long-term strict raw-food diets in Germany found frequent underweight, menstrual disturbance in younger women and low vitamin B12 status, and human feeding studies found that cooking or processing tomatoes, carrots and spinach made lycopene and beta-carotene more available, while laboratory work shows cooking, especially boiling, lowers vitamin C. No claim reaches moderate certainty because the raw-diet evidence is cross-sectional and the cooking evidence comes from small feeding studies and laboratory measurements rather than trials of health outcomes.

  • Energy
  • Vegan

Evidence retrieved up to

What the research shows

Adults on long-term strict raw-food diets often lost substantial weight, a quarter of women and about one in seven men were underweight, and about 30% of women under 45 reported partial to complete loss of menstruation, more often at very high raw-food shares.

Low certaintyFurther research is likely to change this.
Take care: see the safety noteRisk

Who this is about

adults following long-term raw-food diets (70-100% raw food)

Practical note

Evidence comes from a self-reported questionnaire in the German Giessen Raw Food Study (513 adults) and a small Berlin comparison of 16 strict raw food eaters with vegans and omnivores; both are cross-sectional, so cause cannot be separated from who chooses the diet.

Vegan note

Most raw-food diets in these studies were mainly or wholly plant-based, so the findings bear on raw vegan eating in particular.

Safety note

The study authors concluded that a very strict raw-food diet cannot be recommended long term. Underweight and loss of menstruation are reasons to seek advice from a doctor or dietitian.

Sources

Adults on long-term strict raw-food diets frequently had low vitamin B12 status and raised homocysteine, especially those not taking a B12 supplement.

Low certaintyFurther research is likely to change this.
Take care: see the safety noteRisk

Who this is about

adults following long-term raw-food diets

Practical note

In the Giessen study 38% of 201 raw food adherents were B12 deficient; in the Berlin comparison, median B12 was 399 ng/L in raw food eaters who supplemented and 152 ng/L in those who did not.

Vegan note

This matches the wider finding that plant foods are not a reliable B12 source; see the vitamin-b12 entry.

Safety note

Low B12 status can go unnoticed for years; people on raw or vegan diets who do not use B12-fortified foods or supplements are the group these studies flag.

Sources

In small human feeding studies, lycopene from cooked tomato paste was absorbed better than from fresh tomatoes, and beta-carotene from heat-processed carrots and spinach tended to raise blood levels more than the same vegetables raw; adults on strict raw-food diets mostly had low blood lycopene.

Low certaintyFurther research is likely to change this.
No known concerns at usual amountsBenefit

Who this is about

healthy adults

Practical note

The tomato study gave a single dose of 23 mg lycopene with 15 g corn oil; the carrot and spinach study had 8 women and its threefold difference did not reach statistical significance (P = 0.09).

Vegan note

Tomatoes, carrots and spinach are plant foods, so the finding applies directly to vegan meals; the tomato study served the tomatoes with corn oil.

Safety note

No safety concern; the finding concerns how much of these carotenoids is absorbed, not a health outcome.

Sources

Laboratory studies find that cooking vegetables lowers their vitamin C, most of all with boiling, while the effect on fat-soluble nutrients such as beta-carotene depends on the vegetable and the cooking method.

Low certaintyFurther research is likely to change this.
No known concerns at usual amountsUnclear

Who this is about

adults eating cooked vegetables

Practical note

In one study vitamin C retention ranged from 0 to 91% across cooked samples, with microwaving generally retaining more and boiling the least; another found water-based cooking preserved carotenoids better than frying.

Vegan note

Vegetables and fruit are the main vitamin C source in vegan diets, so how they are cooked matters for intake.

Safety note

No safety concern; this is about nutrient content of food.

Sources

What the tradition holds

Ayurveda holds that freshly prepared, warm, cooked food is easier to digest than cold or raw food, and Ayurvedic practitioners advise that raw foods be restricted rather than eaten as the main part of the diet.

No known concerns at usual amountsBenefit

Who this is about

adults following Ayurvedic dietary guidance

The tradition's frame

Ayurveda

Ayurveda treats heat (Ushnata) as one of the factors that transform food, so food eaten warm and freshly cooked is held to support the digestive fire (Agni), while cold and raw food is held to burden it.

Practical note

The quoted sources are a focus group and a Delphi study with Ayurveda clinicians and experts designing advice for women with polycystic ovary syndrome, and an Ayurveda clinical study; they show what practitioners advise, not tested outcomes.

Vegan note

Warm, cooked plant-based meals fit a vegan diet unchanged; the vitamin B12 point in this entry applies to vegan diets whether cooked or raw.

Safety note

Favouring warm cooked meals is a low-risk dietary pattern. The scientific claims in this entry show that cooking lowers some heat-sensitive nutrients such as vitamin C, so the tradition's restriction on raw food is not a scientific finding that raw food is harmful in ordinary amounts.

Sources

Ayurvedic practitioners recommend freshly cooked food that is light to digest and hot in potency, with added spices such as cumin, asafoetida, turmeric, ginger and pepper.

No known concerns at usual amountsBenefit

Who this is about

adults following Ayurvedic dietary guidance

The tradition's frame

Ayurveda

Ayurveda classes foods and spices by potency (virya); food that is freshly cooked, light and hot in potency, with warming spices, is held to kindle Agni.

Practical note

The source records advice given by Ayurveda clinicians to women with polycystic ovary syndrome seeking weight management; this entry holds no trial of spiced cooked food against unspiced or raw food.

Vegan note

The spices named are plant foods. The same source also lists ghee, buttermilk and warm milk among recommended additions, which are not vegan.

Safety note

Culinary amounts of common spices are low-risk for most adults; people with reflux or sensitivity to hot spices may find strongly spiced food uncomfortable.

Sources