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(Looking at the Science on Raw vs. Cooked Foods--continued, Part 2H)

Does cooking render minerals "inorganic"
or less assimilable?

One claim made by a number of raw "experts" is that "cooking makes all minerals inorganic," i.e., cooking converts all the (organic) minerals in food into an inorganic form. The further claim is then made that the inorganic form cannot be used by the body. This section will examine the validity (or lack thereof) of the first claim, as the second (regarding assimilation of inorganic minerals) depends somewhat on the first.

An old claim, but what is its origin? The idea that cooking converts organic minerals to an inorganic form is fairly common in rawist circles--one can find natural hygienists, fruitarians, and others making the claim. It is sometimes attributed to Herbert Shelton or T.C. Fry (raw/predominantly raw diet advocates of the past), but apparently neither actually originated the claim. The earliest citation for the claim that could be located for the present write-up is one found in the book Uncooked Foods and How to Use Them, by Mr. and Mrs. Eugene Christian, published in 1904. From pp. 77-78:

When we apply it [fire] to our food in the process of cooking, it results in such a change as destroys the elementary plant form, and the mineral elements return to their inorganic condition.

Thus it appears that the claim originated long ago, before the days of Shelton or Fry, though the above book could be described as having (approximately) a "traditional" natural hygiene orientation. This suggests the claim may have originated in the 1800s (or earlier), perhaps as part of the nature cure movement, or in the earliest days of the natural hygiene movement. (If any reader is aware of citation(s) regarding an earlier origin for this claim, don't hesitate to forward the information to one of the site editors.)

What is actually meant by
"organic" vs. "inorganic" minerals?

The first point to note is that the claim about the difference between "organic" vs. "inorganic" minerals is relatively vague. The terms used are never defined, thus many readers--or raw-fooders themselves--may not know exactly what the claim means. So let's begin by defining terms.

[Detailed definitions are available via]

The term mineral is still not as precise as one would like; one might ask whether metals are minerals or not. By definition (1) under the last bullet above, metals are minerals, but by definition (2) they might not be. Because of this fine point, we give counterexamples below for both metals and minerals.

Another fine point concerns the value of the minimum temperature in the definition of cooking. A few potential minimum temperatures that come to mind are:

Thus one can argue for a definition of "cooked" in the range 90-100°C (194-212°F). For convenience here, we will adopt 95°C (203°F) as the standard for cooked food: at this temperature, food is "cooked" according to criteria that many raw-fooders share: most enzymes are degraded, and the food is leukocytic if one believes old research by Kouchakoff [1930, 1937].

Restating the claim in more precise language

We can now clarify the claim: Cooking food--heating it to 95°C (203°F)--will cause chemical changes to any/all organic molecules (present in the food) that include or are chemically bound to minerals, such that all the minerals in the organic compound(s) are converted into inorganic form (i.e., inorganic compounds and/or free ions). The term "mineral" as used here can follow either definition above.

At this point most readers with even a limited knowledge of organic chemistry are probably chuckling with mirth, as the claim is, quite frankly, ridiculous. However, let's continue to take it seriously, and thoroughly assess it.


Because the claim alleges that ALL minerals are converted to inorganic form, all that is needed to disprove it is a counterexample of an organic compound that includes a mineral (or metal) that is at least partially heat-stable at 95°C (203°F), i.e., can be heated to 95°C and does not completely break down. A few select counterexamples follow.


Cobalt is a metal, hence a mineral by definition (1) above, but not necessarily by definition (2) above. Cobalt is an essential part of cobalamin, a compound better known as vitamin B-12. Herbert et al. [1984] reports that vitamin B-12 was heated to 200°C (392°F) for 6 days, with only 15% loss. That is, 85% of the vitamin B-12 survived the heating. This is a counterexample to the claim above, since if the claim were true, 100% of the B-12 should degrade due to loss of cobalt.

Copper: For an example from the plant world, Neumann et al. [1995] discuss how the plant Armeria maritima binds a heavy metal (copper, from natural copper in the soil near a copper mine) into heat-stress proteins within the plant, which are stable and extracted for analysis at 95°C.

Non-metallic minerals

Sulfur: Two important sulfur-containing amino acids, methionine and cysteine (both found in many plant foods, see Giovanelli [1987]) survive--to a large extent--after cooking. See Clemente et al. [1998] and Chau et al. [1997] for two research papers reporting the survival of these amino acids with cooking. Note that although there is some loss of sulfur-based amino acids in cooking, the claim the cooking makes minerals inorganic, if it were true, would require (nearly) 100% loss of methionine and cysteine. As that does not happen, these two common amino acids are counterexamples to the claim. (Note: the claim, if it were true, would require the consumption of at least some raw (rather than cooked) protein, as otherwise all the sulfur-based amino acids would be lost, including methionine, an essential amino acid.)

Additional examples

Phytates and tannins are common antinutrient compounds in certain plant foods. Phytate contains phosphorus (a metal), and also forms complexes with metal ions. Phytates and the phytic acid-metal ion complex are only partially destroyed by heat. Similarly, various tannins are known for forming complexes with minerals/metals, especially iron, and for being at least partially heat-resistant. We conclude, in this case, that cooking makes part, but not all, of the minerals inorganic.

Burden of proof

Without evidence, claims are simply speculation. The above counterexamples neatly disprove the claim. However, one might argue that disproof is not required here, because the promoters of the claim have never put forth any credible proof FOR the claim--they are simply speculating. Strictly speaking, the burden of proof is on those who make the claim, and in this case, no proof has ever been presented.

In order to understand this point, consider what credible proof for such a claim would look like. Basically, proof for the claim should be a voluminous database, whose entries would show:

Obviously, developing such a database would be a very large research project. However, instead of the above credible proof, what the raw-fooder receives/offers as "proof" are the unsupported/unscientific assertions of alleged raw "experts."

Old, speculative, and/or unscientific claims often accepted as "raw truth" without evidence or proof. Now consider the apparent age of the claim, and that the claim has been not only uncritically accepted but, further, actively promulgated down to the present day by raw "experts," despite the apparent lack of even a semblance of legitimate scientific proof. Consider the credibility of the raw diet "experts" who promote as "fact" what is really unsupported speculation on their part. What does this suggest about their credibility on other points, especially if they claim that their raw diets are cure-alls, will work for everyone, are "ideal," etc.?

The above is just one example of the burden of proof--when you hear raw "experts" claiming that "spices are toxic," "wheatgrass juice is toxic," etc., the burden of proof is on those making the claims. Also, due to the prevalence of crank science in raw, it is wise to check any "proofs" offered up by the "experts," if any are given. An interesting situation highlighted by the issue of burden-of-proof is that some of the allegedly "scientific" raw vegan "experts" accept the claim above with no proof whatsoever, while simultaneously angrily demanding "proof" for every criticism of their diet. Is that irony, hypocrisy, or both?

Rationalizations to defend the claim

As convenient rationalizations are easily spun when idealistic theories are at issue, two potential rationalizations to watch for here are:

RATIONALIZATION: The counterexamples cited above were not heated high enough. If you heat something hot enough, it will turn to ash and the minerals will then be inorganic.

REPLY: This is an attempt to change the claim. The claim is that cooking converts minerals to inorganic form, not that incineration converts minerals to inorganic form. It is true that given enough heat, carbon can be driven off and one gets an inorganic molecule. However, there is a big difference between cooking something via baking, and heating it to the point that the item is incinerated. As mentioned above, phytate is an antinutrient that contains phosphorus. Phytate is common in wheat, and sufficiently heat-stable that significant quantities of phytate can and do survive the bread-baking process [Buonocore et al. 1977]. Hence phytate provides a counterexample to the claim.

RATIONALIZATION: The claim is not ALL minerals, but only that MOST minerals are converted to inorganic form by cooking.

REPLY: This is really speculation; once again, the burden of proof is on those who make this claim. Without a comprehensive database of organic compounds in foods that contain minerals, and information on the temperatures at which they break down into inorganic forms, one cannot even say "MOST."

Absorption of organic and inorganic
minerals in the human body

It is appropriate to briefly comment on the topic of minerals in the human body. The human body includes both:

Obviously, you would die without hemoglobin (organic iron) and salt (inorganic sodium, a metal/mineral). Additionally, the body can certainly use inorganic iron; see Fomon et al. [1995], Abrams et al. [1996], and Cook and Reddy [1995] for experimental verification.

Thus we note that the body needs and/or can use both organic and inorganic minerals, and the raw-foodist claim that the body cannot use any/all inorganic minerals is simply nonsense. Once again, the burden of proof applies to those who make this claim.

Are inorganic minerals "toxic"? Some raw-fooders make the extreme claim that all inorganic minerals are "toxic." (And note here that, as with the failure to define "organic" vs. "inorganic," advocates are usually also quite sloppy in their use of the word "toxic.") Such claims are an example of the narrow, binary thinking common in the raw community. The fact that a substance (e.g., a specific inorganic mineral) is toxic in isolation and in huge doses does not mean it is toxic at the levels encountered in a particular food, nor does it mean the food is "toxic." One should beware of the raw "experts" who see toxins everywhere, except, of course, in the very few foods they promote.

Conclusion on the nutritiousness
of raw vs. cooked food

Considering trade-offs rather than spurious black-and-white divisions. We see from the many considerations above that there is no clear-cut conclusion that can be stated with confidence about the question of raw vs. cooked foods as a whole. However, if we break the question down into simpler aspects, there are several general observations that can be made. First, the two major overarching considerations are:

"Net value" of a food depends on assessing the cost/benefit trade-offs. Putting the two above points together means that one must consider the cost/benefit trade-offs--that is, the nutrients present vs. the "cost" to get them--the latter determined by both absorbability and antinutrient concerns.


(PART 3: Discussion--100% vs. Predominantly Raw)

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GO TO PART 1 - Is Cooked Food "Toxic"?

GO TO PART 2 - Does Cooked Food Contain Less Nutrition?

GO TO PART 3 - Discussion: 100% Raw vs. Predominantly Raw

Back to Research-Based Appraisals of Alternative Diet Lore

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