Phytic acid and the bioavailability of minerals in common plant foods
On the absorption of tooth-friendly phosphorus and other minerals from seeds, nuts, beans and grains
Another possibly important puzzle piece in the dental health equation is phytic acid aka phytate. While you may never have heard these names before, they are nevertheless ubiquitous compounds found in some of the foods considered by many to rank among the healthiest - nuts, beans, seeds and whole grains...
Minerals in a bind
In addition to calcium, phosphorus in phytate form constitutes a major part of the hard structure of teeth and bones.
Certain plant tissues (the hulls of seeds, nuts, beans and grains) mainly store phosphorus in a chemical form called phytic acid (aka phytate, for instance when present as a [chemically speaking] salt molecule).
To "extricate" the bound phosphorus from the phytate molecule, enzymes called phytases are required which most animals including humans don't naturally produce. In other words, the phosphorus contained in these foods otherwise considered healthy is, according to which source you read, either "generally unavailable" or "only at a ratio of about 50%" (take your pick :-). Thankfully phosphorus is found in most any food since it is crucial to all living organisms (hence dairy, fish and meat are rich sources but phosphorus also occurs in wheat, nuts etc. so eating a varied diet should typically furnish adequate amounts of bioavailable phosphorus).
Of greater consequence than its "strong attraction" to phosphorus is the fact that phytic acid also shows a strong binding capacity for other essential minerals such as calcium, iron, magnesium and zinc. Any such mineral bound to phytic acid becomes insoluble and thus inabsorbable during its passage through the intestines. This characteristic can create deficiencies in essential minerals if no additional sources of minerals are ingested to make up for the loss incurred by the phytic acid "bind".
Techniques helping to reduce phytic acid content
Thankfully, several traditional food preparation techniques help to reduce the phytic acid in the above-listed foods.
To achieve this effect, the best methods are considered to be sprouting (which has the additional benefit of increasing a number of nutrients), lactic acid and other fermentation (incl. sourdough- and yeast-leavened bread) and soaking in an acidic medium. In fact a healthy intestinal flora harbouring probiotic lactobacilli and other good bacteria may also help. These organisms among other things according to one source produce the above-mentioned phytase enzymes required to release the phosphate from phytate. Cooking and baking itself serves to somewhat reduce the phytic acid.
In other words, to avoid mineral losses in the course of digestion, whole grains for instance can be consumed but preferably exclusively after having been sprouted, subjected to leavening and/or cooked.6
Early research: reversing tooth decay by abandoning grains?
Dr Herbert Shelton writes that "[i]nvestigations have revealed that those races whose diets include no cereals have teeth and mouths practically free of any kind of disease"1. As early as the 1920s, research done on children showed a connection between eating grains and cavities and discontinuing grains and the healing of tooth decay.
To establish whether a diet low in cereals and high in vitamin D would cure active tooth decay (as this seemed a possibility after some successful research on dogs' secondary dentine), researcher May Mellanby worked with a group of 62 children with active tooth decay, separating them into three dietary groups for a half year study period. While the first group continued eating their normal diet but enriched with oatmeal (a rich source of phytic acid), the second group received their normal diet enriched with vitamin D and the third group received a grain-free diet plus vitamin D.
The results were very interesting. The first group had continued to develop new cavities. In the second group, the addition of vitamin D made most cavities disappear with fewer new ones forming. Group 3 who had eaten no grains (but some sugary foods!) while also receiving supplementary vitamin D showed the most dramatic healing effects with virtually all tooth decay gone and only a few new cavities formed.
Whether is was the "unmitigated" phytic acid content or some other characteristic of grains' metabolism in the human body that led to the second group showing less dramatic caries healing benefits, in any case this research is worthy of note (the original can be downloaded - after free registration - from the British Medical Journal at http://www.bmj.com/cgi/reprint/2/3322/354).2
It also tallies with reports such as the one here telling about the disappearance of gum disease after grains were abandoned, and it reminds me of a personal experience I've repeatedly had after eating whole rice dishes or whole-grain noodles: what frequently happened is that a distinctly unpleasant film had formed on my teeth after eating (which I rarely experience after eating other food).
In any case, as shown above, there are techniques allowing to reduce phytic acid content in grains and other phytate-containing foodstuffs so unless you feel it is right for you personally, I would not abandon foods that after all boast many nutritional (in addition to culinary) qualities.
In fact, that cavities cannot just be the fault of high-phytic-acid-grain consumption, can also be seen from the following:
In his search for peoples all over the world who had managed to keep healthy teeth and bodies, Dr. Weston A Price3 also studied and included as an example of superb health Gaelic communities living in the Islands of the Outer Hebrides (Coast of Scotland), one of whose staplefoods was ... oats! Quoting from Price's book Nutrition and Physical Degeneration discussing the nutrition of these "isolated Gaelics":
"The basic foods of these islanders are fish and oat products with a little barley. Oat grain is the one cereal which develops fairly readily, and it provides the porridge and oat cakes which in many homes are eaten in some form regularly with each meal."4
It is also worth mentioning that German natural dental health pioneer, dentist Johann Georg Schnitzer, bases his anti-caries diet heavily upon grains consumed both raw and cooked as well as upon much raw food.
Last but not least and for what it is worth, Dr Ralph Steinman demonstrated in rat experiments that the addition of whole wheat to a cariogenic diet (two thirds of whole wheat, one third cariogenic diet) dramatically decreased (but did not eradicate) caries incidence in the rat population while the addition of white flour had no beneficial effect.5 Similarly, he raised his three children on a diet of exclusively whole grains, milk, vegetables and fruit with hardly any sugar and none of them ever developed a cavity (while both parents who had been brought up on a conventional diet had a mouth full of restorations).
So perhaps it's only in a diet comprising denatured items such as sugar (as the children in the above study consumed) that grains will furnish the straw that breaks the camel's back? Maybe the combination of grains and sugar (which I have seen described as inducing alcoholic fermentation in the intestines) is one of the mechanisms at work? Whatever the reason might be, the answer may be different for each person.
1 Compare Dr. Herbert Shelton on the true causes of tooth decay.
2 Interestingly, a number of similar research findings have been published in respected professional journals decades ago, see for instance the Journal of Dental Research at http://jdr.sagepub.com/ which publishes all issues since March 1919. It makes you wonder why these empowering research findings have never been widely circulated to the public...
3 See Introduction to Dr. Weston A Price's work.
4 Additionally, oatmeal is frequently mentioned as a staple food by people in their eighties and upward and most highly recommended as a basic food item by the late erudite Father Thomas Häberle, an outstanding natural healer. You can read about his books here (scroll to More books on healing with cabbage leaf poultices (and much more!).
5 Healing Teeth Naturally does not support animal experimentation. Many reasons for this are being discussed for instance at Animal Experimentation Unscientific, On Differences Between Species, Better Science: Benefits of Using Non-Animal Tests The Harms to Humans from Animal Experimentation and Better Science: Limitations of Animal Tests.
6 Compare this helpful Cereal & pulses cooking tip.