"These data were first published in 1924. Why has such a major medical finding, published in high-impact peer-reviewed journals, faded into obscurity?"
Possibly because the reported research results were not replicated? I wish I had the citation at hand for a finding that 50 percent or more of all medical research findings published in top peer-reviewed journals end up not being replicated. But perhaps that finding can be found in one of the sources cited in Peter Norvig's excellent article about analyzing scientific research papers,
which I recommend readers of this thread check as they consider the claims made in the submitted blog post.
After edit: Another problem at the practical level is that it may very well be that a diet optimal for recalcification of teeth (there is no controversy at all that teeth can recalcify throughout life, that's the point of fluoride treatments, but the question is by how much) may not be optimal for cardiovascular health or some other aspect of your health that is important to you. The way human evolution works is that all of your body parts are fitted by haphazard adaptation from ancestral patterns using available materials in an environment of biochemical trade-offs, and it may be a better trade-off to have teeth that decay after reproductive age and a heart that keeps beating longer than to have teeth that never need to have cavities filled. That would have to be the subject of further research, to see which diet is optimal overall. (Yes, I am aware that some research tends to show that good dental hygiene contributes to good cardiovascular health, with the hypothesized mechanism being that infected gums allow bacteria to enter the bloodstream and cause inflammation of the heart's blood vessels.)
I would posit that the diet presented in the article not only contributes to good dental health but also would contribute to good cardiovascular health.
It also corresponds to what I've read before, that a high-meat (not pure protein, but diets inclusive of bone marrows or organs like liver and stuff generally found in pâtés) and high animal fat diet can almost completely prevent the development of diabetes, and can actually get diabetics off of insulin.
I believe the theory is, is that the body uses insulin to convert glucose to glycogen, AKA 'animal starch', and every other effect (that I'm aware of) it has on the body is not considered good. Example: It promotes triglyceride production from fatty acids (high triglycerides are usually a big factor in heart disease), and decreases the metabolism of fats (I think everyone wants this one high), proteins and reduces gluconeogenesis, which can exacerbate lactose intolerance in some people.
Everything more complex than raw glucose doesn't require insulin. That's why the body largely doesn't react to fructose (which is a result of our ancestry, primates largely live in a symbiosis with the trees they feed off because larger animals like Elephants frequently kill the trees in the process of foraging, but shrieking monkeys tend to stop them) so that we do consume more of it. I think it also helps that foods high in fructose (IE fruits) are generally also high in vitamins. I mean some of the recommended RDA's for vitamin C are actually around 6,000-12,000 mg a day (30,000 mg if you're sick). Basically from what I understand, if you look at our close relatives diets (which are very similar to our ancestors diets) they essentially eat 1:1 ratio of vitamin C (in mg) to kcals. So an adult male should eat 2,500 mg of vitamin C and 2,500 kcals. Incidentally vitamin C is used in the body to produce carnitine, which moves fatty acids into the mitochondria to produce ATP.
Your average goat produces around 13,000 mg of vitamin C in normal health through biosynthesis, which has to make you wonder about WHO's RDA of 45 mg a day if a goat produces 290 times that amount. We, unfortunately don't biosynthesise vitamin C.
All carbs require insulin. Fructose and complex carbs need other "processing" first though, which spreads out their absorption, reducing spikes in insulin levels.
Actually they don't, carbs are broken down into glucose, fructose and galactose. Glucose, generally, requires insulin to be absorbed by the muscles, liver and fat cells. However Fructose doesn't, the cells then convert it into whatever form necessary, the liver usually converts it into glucose for storage. Yet muscles are capable of using fructose directly.
Glucose can directly be turned into ADP or ATP, or it is converted into Glucose-1-phosphate, which then can either be turned back into glucose or follow the path to be turned into Fructose-6-Phosphate (fructose incidentally directly turns into this). F6P is then converted into triose phosphate, a change that cannot be reversed, and can be directly converted into fat. Fats, when needed, are turned back into triose phosphate and can basically be directly converted into ATP.
Essentially fructose needs less processing than glucose to be readily stored. The aim of the human body is to increase its fat reserves for winter when food becomes scarce. Glucose is readily available and readily usable by the body, but all this depends directly on insulin to get it into cells to be useful. The notable cell that doesn't require insulin are brain cells, however these readily process fructose too.
So it's actually possible to completely remove glucose from the body, in the event it was ever needed then fructose can be back-stepped into glucose-1-phosphate. However, the body can more than adequately produce energy directly from fats, so it would seem extremely rare that the body would need glucose.
Interesting that you mention that given that dental health is already directly linked to cardiovascular health, via incidence of inflammation and gum disease.
Study after study has shown that read meat increases the chances of dying early, both from cardiovascular problems and cancer. Just one of the recent studies :-
After some research, it apears that May and Edward Melanby were published several times in high profile, peer reviewed journals (BMJ, the Lancet) on the topic of the impact of nutrition on health.
Looking at the citations, it seems that the effect of diet on tooth healing have been forgotten more than disporoved. They are cited in papers focusing on tooth developement in children (but not regeneration later on), and on the role of Vitamin D and other food in Rickets. But tooth regrowth is a well documented process in animals, and, according to these papers, it also happens in humans.
BTW, the linked blog post has it wrong. White flour is the least Ca++ chelating cereal (once again, according to E. Mellanby). Oatmeal appears to be the worst (see 1).
Side note for fun: It looks like bad OCR software reinvented l33t sp34k. This is what you get when you copy/paste the title of the first paper referenced here:
THE RELATION OFDIET TO HEALTH
AND DISEASE.
S4OMlJE 1E'E XET !NVESTIW.41T!ONS).
BY
EDWARI) MA1iT,LANBY, M.A. M.D.C.kMn.l
F.R.C.P., F.R.S.,
PROFESSOR OF PHARMACOILOC', XJNTVERSITY OF SHEFFIELD.
There's a reasonable amount of evidence that following (generally) a diet as outlined in the article would be beneficial to one's health across the spectrum. Google 'paleolithic diet' (alternative spelling, 'palaeolithic') for further information.
who is a professor of zoology specializing in Paleolithic fauna and an accomplished artist and bow hunter. He cites all the best primary research literature on Paleolithic life in the notes in his book. One fact Guthrie points out is that the lifespan for Paleolithic Homo sapiens was only forty years.
The main cause of early death was injuries and infections following injury. Disease was relatively low because the population was dispersed. Contrary to much belief, startvation was also rare, it was an anthropologist who coined the term "the original leisure society" for hunter-gatherers; Google the term in quotes for many references.
Lifespan at birth or at adulthood? I thought it was accepted that lifespan at adulthood for hunter-gatherer types was often essentially of modern length, and it was agriculture that lowered it (while increasing number of children) until modern times?
Wikipedia agrees with you, for values of "not very long" that are about 60 at mid-life. Since that includes essentially no medical care, however, I'm not sure how much of it is attributable to diet.
> lifespan for Paleolithic Homo sapiens was only forty years.
That is 10 years longer that people in Swaziland.
40 is not that bad if you think that most hunter gatherer societies abandon old people (since food is a scarcity). So the life expectancy in those times was basically the modern day retirement age.
Actually average life expectancy has consistently been inaccurate. If half our species died at birth, and the rest lived until 80 years old, our average life expectancy is only 40 years. Anyone notice a problem?
The length of a human life has usually rested around 70 years, which is actually seen in nomadic people today. Their life expectancy can be appallingly low due to their environment, it doesn't mean everyone's dropped dead by the time they're 40, it means lots were lost at a ridiculously young age.
During the industrial revolution 75% of children in London died before 5 years old. This meant that life expectancy was only around 30 years, despite the fact that poor houses were predominantly old people. The UK instituted the Old Age Pension Act in 1909 to deal with this problem and the claiming age was 70 years, which means people were expected to work until this age. If people were really only living until 30, why would people have invented a pension for 70 year olds?
IIRC the breakdown for the Paleolithic was, at birth life expectancy was ~33 years. If you lived to 15, your life expectancy was, on average, actually between 39-55 and I wouldn't doubt that if you lived to 55 you had a solid chance of making it to 70.
During the Bronze Age life expectancy at birth was 18, this was due partly to wars, population densities and essentially the plagues caused by such (this is the essential reason why Europeans had diseases that wiped out 70-80% of Native Americans). At about 1000 BC we hit our average of 30 years again, although for Greece and Rome it actually ended up being 20-30 years because again of wars and some diseases (although by this time we were more disease resistant).
Another example of this is the USA. People in the US have a lower life expectancy than many other countries, which aside from my problem with privatized health care (which is primarily a quality of life, not a quantity of life issue), is mainly due to the US having an appalling infant mortality rate... however if you actually survive infancy you're good to go.
IMO stating life expectancies is very misleading, due to the fact that it creates the impression of a Logan's Run environment where you're dead at 21. Only in modern society has life expectancy surpassed 40 years, but Genghis Khan died at age 72 (IIRC) due to an infection after his horse bucked returning from war. Apparently this was no mean feat in the Mongol armies as many of his generals were as old, if not older, than him as they'd been with him since the beginning.
"the US having an appalling infant mortality rate" do you have any sources? or more specifically articles or papers researching the cause of this high infant mortality rate?
I'll say this here: Sorry, I stated the US had an appalling infant mortality rate, and in fact it actually has a very good one. I was thinking of the Per Capita Infant Mortality rate, which IIRC the formula goes Per Capita GDP / 1,000 x IMR. This places the US rate as almost double of the UK's rate (IIRC), due to the fact that the US economy should be capable of providing better health care to infants than the UK. This test is only really good for developed nations as poor countries can end up looking the best, due to the fact that they can have Per Capitas below $1000.
Iceland IMR (the lowest) is 2.9, and the US is 6.3. Wow! That means twice as many kids in the US die as Iceland! That's appalling! But we're in the noise floor here. 0.03% vs 0.06% is noise floor, It's certainly not appalling.
> People in the US have a lower life expectancy than many other countries,
The USA's life expectancy is 78.06 years – this is not far from the European Union average of 78.7 years and it is higher than some Scandinavian countries (such as Denmark) .
> is mainly due to the US having an appalling infant mortality rate
The infancy mortality rate (under five) of the USA is 7.8 per 1000 life births. This again is not that much worse than European countries (UK is at 6.0).
Now for my defence of the USA health system. Firstly, what are the leading causes of death in developed countries? They are listed below (with the number of people who died per year):
Ischaemic heart disease 3,512,000
Stroke 3,346,000
Chronic obstructive pulmonary disease 1,829,000
Lower respiratory infections 1,180,000
Lung cancer 938,000
Car accident 669,000
Stomach cancer 657,000
High blood pressure 635,000
Tuberculosis 571,000
What are some causes of Ischaemic heart disease ? Here are some:
There is limited evidence for population screening, but prevention (with a healthy diet and sometimes medication for diabetes, cholesterol and high blood pressure) is used both to prevent IHD and to decrease the risk of complications. “
For the second leading cause of death high cholesterol and cigarette smoking is also a contributing factor (you can see where I am going with this).
You can see that the average health of an American is therefore far worse off due to his/her lifestyle (diet, etc...). How can you compare the health system in the USA with one in Norway (8.3%), Denmark (9.5%) or Canada (14.3%) that does not have to contend with this obesity rate?
The health system in the USA is amazing for bringing the average life expectancy of the USA close to European levels with such a high rate of obesity.
We have just talked about obesity – there are quite a few other things that contribute to a larger death rate. A few examples is smoking (which is much more regulated in the EU, car safety (which is stricter in the EU) and AIDS prevalence. The AIDS prevalence for the USA is 0.6% which is higher than all the Western European countries.
Is that the diet about not eating bread or pasta or rice because the hunter gathers did not eat those foods?
See, if evolution is about the survival of the fittest, then would have not those hunter-gathers who got unhealthy because of eating pasta not pass on their genes?
What I mean is: have we stopped evolving since hunter- gathering times?
* I wish I had the citation at hand for a finding that 50 percent or more of all medical research findings published in top peer-reviewed journals end up not being replicated. *
That's just general skepticism, which is great, and certainly should be the default reaction to an article like this.
But when you said "It's not spam, it's just so very wrong." you made it sound like you must know of some hard evidence that actually debunked the article, rather than just the same general skepticism that tokenadult already expressed.
I'm pretty sure Femur was asking you for some more details of that evidence.
I think where you and I and Femur disagree is what constitutes skepticism.
For me an experiment who's results can't be replicated, indeed have not been replicated since 1924, is as wrong as wrong can be. It is 2 + 2 = 5
For you and Femur it is perhaps merely reasonable skepticism.
Perhaps you were expecting some proof that it is wrong, not just lack of proof that it is right?
In science inability to reproduce is where the buck stops. There are no further attempts to actually prove wrongness.
I appreciate your correction. I value the more wordy opinions on HN, short ones tend to remind me of reddit, and I strive to stay away from pithy posts.
The fact that teeth could heal themselves was unknown to me for quite some time. I thought that if you had a cavity, you had to have it filled.
I used to have horrid teeth (and the diet to match). I stopped drinking soda and my dentist recommended a product called Recaldent (http://en.wikipedia.org/wiki/Recaldent). This concentrated paste helped most of my teeth strengthen and recalcify.
I did not eat the paste. I applied the paste to my teeth with my finger and let it set for approximately 30 minutes. I did this once a day for several months right before I went to bed.
Much of the American population (including a majority of pregnant women) are deficient in vitamin D. Odds are good that you are too.
A big contributing factor is insufficient exposure to sunlight. Some have speculated that seasonal winter flu season is attributable to vitamin D levels.
What I don't understand is that no one addresses the bacterial component of cavities. I just had some work done and my dentist clearly stated that cavities are caused by bacteria eating through the enamel. I get that poor diet contributes to calcium loss and so the body will re-strengthen teeth given improved nutrition, however this will not do anything to address the bacterial infection problem.
Bacteria don't actually hurt the teeth directly - they just sit there and they make an acid that can etch the teeth, but if the teeth are strong they resist the acid, plus repair any areas that are eroded.
Also saliva contains immune components that can stop the bacteria. Bacteria may be the final component, but the causes of decay lie elsewhere.
It's not really an infection either, anymore than the gazillions of bacteria living on skin are.
The bacteria don't eat the enamel. They feed on sugars (and other carbs, but especially sugars) in the mouth, then excrete an acid that attacks tooth enamel. They live on teeth, especially in the crevices where they won't get knocked off, so that's where the acid is concentrated. Diet can help reduce the incidence of decay in the first place by reducing sugars in the mouth.
I am from Finland and Xylitol has been hugely popular for as long as I can remember, mostly as chewing gum. How popular are Xylitol products in other countries?
Hard to get in the UK. Some chewing gums have xylitol but don't say how much and they still have other stuff like sorbitol and maltitol. I'm not sure why it's commercially unpopular - expensive, perhaps?
There is a lot more to this story, but briefly, the pH of the mouth. The more acidic and the longer it is acidic, the more likely you are to get caries.
Also, just because Diet 3 is a lot better than Diet 1 (and 2 for that matter), that doesn't mean that Diet 3 is the ideal/best diet. We would need to research this more using Diet 3 as the starting point.
In my life, I have eaten very little refined/added sugar (i.e. very rarely do I eat such things). Aged 30 I have no fillings: the only dental work I have had done was having my teeth straightened and having eight of them removed (yes eight, though not all at once) that didn't fit in my mouth (I have big teeth). When I was a child, my dental hygiene wasn't always very good.
A single data point doesn't tell you anything. But there it is, anyway.
Possibly because the reported research results were not replicated? I wish I had the citation at hand for a finding that 50 percent or more of all medical research findings published in top peer-reviewed journals end up not being replicated. But perhaps that finding can be found in one of the sources cited in Peter Norvig's excellent article about analyzing scientific research papers,
http://norvig.com/experiment-design.html
which I recommend readers of this thread check as they consider the claims made in the submitted blog post.
After edit: Another problem at the practical level is that it may very well be that a diet optimal for recalcification of teeth (there is no controversy at all that teeth can recalcify throughout life, that's the point of fluoride treatments, but the question is by how much) may not be optimal for cardiovascular health or some other aspect of your health that is important to you. The way human evolution works is that all of your body parts are fitted by haphazard adaptation from ancestral patterns using available materials in an environment of biochemical trade-offs, and it may be a better trade-off to have teeth that decay after reproductive age and a heart that keeps beating longer than to have teeth that never need to have cavities filled. That would have to be the subject of further research, to see which diet is optimal overall. (Yes, I am aware that some research tends to show that good dental hygiene contributes to good cardiovascular health, with the hypothesized mechanism being that infected gums allow bacteria to enter the bloodstream and cause inflammation of the heart's blood vessels.)