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vendredi 19 mai 2017

Liver content of vitamin C in animals

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3417664/

Red meat another time

https://profgrant.com/2017/05/16/red-meat-will-kill-you-and-make-it-look-like-an-accident/comment-page-1/#comment-29258

https://profgrant.com/2017/05/16/red-meat-will-kill-you-and-make-it-look-like-an-accident/

The recommendations are false, but the public nutrition gurus want more

http://www.oecd.org/health/health-systems/Obesity-Update-2017.pdf

Cuisez moins

D'une manière générale compte tenu de l'extraordinaire disponibilité de produits frais il est de moins en moins nécessaire de cuire.

Why observational epidemiological studies are full of biases: fruit and veggies intake association with PAD risk

If you never smoked F&V intake does not lower PAD risk

http://atvb.ahajournals.org/content/early/2017/05/18/ATVBAHA.116.308474

Salim Yusuf about cardiovascular diseases

https://youtu.be/gT9zR71KypY

https://www.youtube.com/watch?v=RwGteseHyas

Tobacco smoking
https://www.youtube.com/watch?v=Co1SisXbzr4&index=1&list=PLFL0lyNSjc4UMQ6DpLeM1lNeUO6tenivP

Genomics
https://www.youtube.com/watch?v=JHVfPEkpAFc&index=2&list=PLFL0lyNSjc4UMQ6DpLeM1lNeUO6tenivP

RCT are always needed

https://www.youtube.com/watch?v=C60eEO0Kyfc

samedi 13 mai 2017

Salt and evolution in human diet: Paleo diet was a low salt diet

Paleo diet was a low salt diet 
http://www.atlantico.fr/decryptage/sante-nouvelles-etudes-suggerent-bonne-partie-que-pensions-savoir-sel-faux-guy-andre-pelouze-3047311.html

https://www.jci.org/articles/view/88532

https://www.hsph.harvard.edu/nutritionsource/salt-and-sodium/sodium-health-risks-and-disease/

http://onlinelibrary.wiley.com/doi/10.1111/cen.12225/abstract

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4517681/
Sources of sodium: it should be cut in agro-industry factories



Clinical Perspective

What Is New?

  • This study identifies the major sources of sodium in the diets of adults from 3 geographic regions in the United States.
  • The study shows that sodium added to food outside the home accounts for more than two thirds of total sodium intake, whereas sodium added to food at the table and in home food preparation is a minor contributor to total sodium intake.
  • Study findings align with a 2010 Institute of Medicine recommendation for reduction of sodium in commercially processed foods as the primary strategy to reduce sodium intake in the United States.

What Are the Clinical Implications?

  • Commercially processed and restaurant foods should be the primary focus when educating patients on strategies for lowering sodium in the diet.
  • For packaged food products, the Nutrition Facts panel may be useful in identifying lower-sodium products.
  • When individuals eat outside the home, sodium content information for menu items should be requested and used as a guide in making food choices.
  • Limiting salt added to food at the table and in home food preparation should also be encouraged, but patients should be advised that changes in these behaviors alone may not be sufficient for achieving the recommended intake level.

Le brocoli une petite pièce du Puzzle

https://www.contrepoints.org/2017/05/13/289259-contre-cancer-mange-brocolis?utm_source=dlvr.it&utm_medium=SOCIAL&utm_campaign=Facebook-automation

mercredi 10 mai 2017

Our ancestors and alcohol

http://www.bbc.co.uk/earth/story/20170222-our-ancestors-were-drinking-alcohol-before-they-were-human

Danger et risque de cancer, une différence fondamentale

Un agent capable de causer un cancer dans certaines circonstances, représente un danger, alors qu'un risque de cancer ou d'une autre affection est une estimation des effets cancérogènes attendus de l'exposition à cet agent. Les études expérimentales ont pour but de rechercher si un cancer peut survenir dans l'exposition des animaux ou des humains à cet agent, les études cliniques ont pour but si un danger de cancer existe d'authetifier la relation causale et de quantifier le risque. La distinction entre danger et risque est importante et une étude expérimentale peut identifier un danger de cancer même lorsque les risques sont très bas aux niveaux d'exposition actuels des populations, car de nouvelles utilisations ou des expositions imprévues pourraient engendrer des risques nettement plus élevés.

vendredi 5 mai 2017

Primary prevention could be summed by a poem

http://www.bmj.com/rapid-response/2011/10/30/polypill-life%E2%80%A6in

Polypill a life…in

Instead of delicious butter margarin
For bad cholesterol statin
For thick blood aspirin
For diabetes metformin
For high blood pressure nicardipin
As I stopped smoking a full patch of nicotin
And tomorrow a nightmare, imagine !
Don’t be foolish !
Take fresh spinach and fatty fish
Roquette, nuts, kiwis and have a large meal
Pour your glass with wine and make a deal
After a snap I will go running
Work a bit and get light dining
Smoke a big havana once a year
And forget doctors for ever

Grosse manipulation journalistique au sujet du thon en boîte

Un tissu de mensonges. Un exemple: la moitié de la valeur réglementaire c'est parfaitement réglementaire. Des manipulateurs.

mercredi 3 mai 2017

Chronobiology of food intake: the truth and the myths

Figure 1. The day-night cycles set the regular oscillations of eating (purple line) and locomotor activity (blue line), which are coupled during a healthy state. Intake of hypercaloric diets, leading in obesity, disrupts the eating daily patterns, producing small but frequent bouts of ingestion even during the normal resting period. The locomotor activity and eating pattern rhythms are uncoupled in an obese state. The effects of a hypercaloric diet over the rhythmicity of the reward system are unknown but as the evidence suggest that the rhythmicity in the hypothalamus is mainly unaffected (blue dotted line), the reward system might be influencing the disturbances of the daily eating patterns (purple dotted line). In the diet-induced obese state, the rhythmicity of the peripheral organs are altered (green line), causing an internal desynchrony of central and peripheral oscillators (green dotted line).


http://journal.frontiersin.org/article/10.3389/fnins.2017.00023/full

This clearly proven. Other relationships between more specific food intakes and chronobiology are not backed by solid experimental or clinical studies.
This study (http://ajpregu.physiology.org/content/308/5/R337.long) is considering those issues:

"This review has focused on the effects of fatty acids and sugar on the circadian clock. Studies have shown that high-fat and high-sugar intake can lead to alterations in clock gene expression in peripheral tissues, in non-SCN brain nuclei, as well as in the SCN. Putative mechanisms through which this can occur were discussed with an important role for signaling components that link nutrient status to the molecular clock mechanism. Indeed, it was shown that alterations in circulating levels of fatty acids and glucose can affect various nutrient sensing mechanisms, which can affect the molecular clock, thereby linking fat and/or sugar intake to the circadian clock. Furthermore, many studies have focused on how altered energetic status can affect the clock. Current evidence supports the idea that the amount of nutrients may be more important for resetting the molecular clock than the source of nutrients, but it remains elusive whether the specific metabolites of fatty acids and sugar can contribute to alterations in the circadian clock and whether there are differential mechanisms through which fatty acids and sugar regulate the clock."

Breast-feeding is better for preterm babies

http://www.jpeds.com/article/S0022-3476(16)30411-5/pdf

mercredi 26 avril 2017

Vitamin D skeptics

https://www.nytimes.com/2017/04/10/health/vitamin-d-deficiency-supplements.html?_r=0

Added sugars according to Bob Lustig

Katelin Walling wrote this paper about added sugars,

http://www.nymetroparents.com/article/the-negative-health-effects-of-too-much-added-sugar





Consuming too much added sugar is detrimental to our health—here’s why, and what you can do about it.

    
Fifty-six. That’s how many different names the food industry uses for sugar.
Here’s another number: 19½. That’s, on average, how many teaspoons of added sugar each person in the U.S. consumes each day. To be clear: We’re talking about added sugar—the sugar the food industry adds to foods, not the sugar found naturally in foods. The daily maximum recommendation from the American Heart Association? Six teaspoons for women, 9 teaspoons for men, less than 6 teaspoons for children ages 2-18, and zero for children ages 2 and younger.
Ready for another? One-quarter: the number of pounds of added sugar Americans are consuming daily, on average, which equates to 90-100 pounds of added sugar annually. “The problem is you’re really supposed to be consuming zero [added sugar], but you could consume an ounce or an ounce and a half,” says Robert Lustig, M.D., a pediatric endocrinologist, professor of pediatrics in the Division of Endocrinology at University of California, San Francisco, and author of Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease.
So, why is it a big deal that we’re consuming so much added sugar? Dr. Lustig—who was also featured prominently in the 2015 documentary Sugar Coated (available on Netflix) and is a member of the SugarScience team, an authoritative source for the scientific evidence about sugar and its impact on health—shares what we need to know and think about before saying “Yes” to sugary foods.
    

Glucose vs. Fructose

There are two main sugars found in foods, and it’s important to know the difference because one is necessary and one isn’t.
Glucose, which is found in starch, is the energy of life, according to Dr. Lustig. “Glucose is so important that if you don’t consume it, your body makes it,” he says. The liver has a way of turning fat into glucose called gluconeogenesis. So while it’s necessary for life, it’s not necessary to eat.
Fructose, on the other hand, is an entirely different molecule. “There’s no animal cell on the planet that needs fructose for any reaction at all,” Dr. Lustig explains, adding that it’s sweet, it’s energy, and it’s calories, but it’s not nutrition.
    

Effects of Too Much Sugar

Acutely, too much sugar doesn’t have significant effects on the body. It’s the long-term effects that are the issue.
Dr. Lustig says there are three things fructose does to our bodies that glucose does not:
    
Liver fat: “Because of the way fructose is processed, it goes to the liver and excess gets turned into liver fat, and that liver fat gums up the workings of the liver. When that happens, you end up with a phenomenon called insulin resistance. You have a situation where the liver’s not responding to the insulin signal so the pancreas has to make extra,” Dr. Lustig says, which raises insulin levels all over the body and leads to hyperinsulinemia.
Excess insulin, Dr. Lustig explains, does two things in your body to make you gain weight: It turns energy into fat cells, and it blocks leptin, the hormone that sends a signal to the brain when you’ve had enough to eat. Continued insulin secretion is also one of the major factors involved in chronic metabolic diseases, such as cardiovascular disease, Type 2 diabetes, cancer, and dementia. “All of those are referred to in total as metabolic syndrome. Some people will get some of those diseases, some people will get others of those diseases, and some unfortunate people will get all of them,” Dr. Lustig says. “Anything that drives insulin is going to drive those, and because of the liver fat issue, fructose drives it.”
Aging: Have you ever thought of why bananas brown? It’s a chemical reaction called the Millard reaction—the aging reaction. “All carbohydrates bind to proteins, all carbohydrates cause a mild reaction. But because of fructose’s unique chemistry, it causes that mild reaction to occur seven times faster and generate a hundred times the number of oxygen radicals called oxidative stress that damage proteins and lipids inside cells,” Dr. Lustig says. “So basically sugar drives aging faster than other carbohydrates.”
    
Dopamine: Fructose causes the reward system to release dopamine, the reward response. When dopamine is released, it fosters continued consumption, according to Dr. Lustig. “That’s something only fructose does. So you get into a vicious cycle of consumption and disease.”
    
To paint a clearer picture, Dr. Lustig compares fructose to alcohol: “Alcohol is calories, but it’s not nutrition. Consumption of alcohol is dangerous in two ways: It’s dangerous acutely, and it’s dangerous chronically. Fructose is not dangerous acutely, but it is dangerous chronically for the same reason that alcohol is. In fact, fructose and alcohol are metabolized exactly the same in the liver, and that’s why kids are getting the disease of alcohol—Type 2 diabetes and fatty liver disease—without alcohol. Fructose sugar is the alcohol of the child. While we have the capacity to metabolize a limited amount of alcohol, excess is dangerous. While we have a limited capacity to metabolize the sugar in our diet, excess is dangerous.”
    

What Happens When You Cut Sugar From Your Diet?

When sugar is cut from your diet, “your metabolic primers get better, and you feel better, and your metabolic parameters improve, and you detox, and you don’t crave it as much. Everything gets better,” Dr. Lustig says, referring to a study his team published in October 2015.
For that study, the research team studied the diets of 33 Latino and African-American kids with metabolic syndrome (obesity plus at least one other chronic medical condition) to determine a home-baseline diet. Then, for the next 10 days, sugar was cut from the kids’ diets. “What we did was we gave them starch instead so they would not loose weight. We took pastries out, and we put the bagels in. … We took the chicken teriyaki out, and we put turkey hotdogs in. We gave them processed foods, but there were no added-sugar foods,” Dr. Lustig explains.
After those 10 days, the kids were assessed, and “every aspect of their metabolic health improved and their liver fat reversed. That is without any change in calories or any change in weight. This shows fructose is the primary driver because when we gave them extra glucose instead of fructose, it got better unrelated to calories and unrelated to weight,” Dr. Lustig says. “That proves that sugar is the driver of these metabolic diseases. It may not be the only driver, but it certainly is the primary driver, and the one that children are exposed to.”
    

Easy Tips for Cutting Sugar

When working the following tips into your family’s lifestyle, the first thing to keep in mind is to cut back gradually and make realistic goals for your family. “It’s really hard to go to an extreme. I work with families that want to cut everything all at once, and that’s usually unsuccessful,” says Nicole Silber, R.D., a pediatric nutritionist based in New York City. “Meet your child where they’re at, engage them in the plan, and cut back slowly, which I think will end up yielding more success than to cut back drastically.”
    
Be weary of foods labeled as fat-free. “There are a bunch of fat-free items that tend to be loaded with sugar to compensate for the loss of fat in the product, especially in baked goods,” Silber says.
    
Opt for fresh fruit over dried fruit or fruit sauce. With dehydrated fruit and sauces, it’s a matter of the source of sugar being concentrated, Silber says. For example, when you dehydrate a plum, what’s left is the fiber and natural fruit sugar. “It ends up being much smaller, so you could eat five prunes, which will fill your stomach the same amount as one plum, but you’re consuming five times the amount of sugar because you’re essentially eating five plums,” Silber explains. The same thing happens with applesauce. “It will take a child a few minutes to eat a whole apple, which has the skin, the fiber, the liquid. When you boil it down and puree it into a sauce, you can probably have four or five apples in the same amount of time it would take to eat one whole apple,” Silber adds.
    
Choose plain yogurt over flavored. Yogurt can be unhealthy if you’re not picking the right one, Silber says. “If a child is used to high-sugar yogurts, you can add in your own fruit, jam, maple syrup, honey,” she advises. “You can even add in your own white sugar. I’m confident you will add in less than the food companies.” And make sure you check the labels on baby yogurts; Silber says some brands are really high in added sugar.
    
Preventatively, don’t introduce infants to juice or sweetened foods in their first year. Silber advises to give babies more veggies and less fruit to accustom their taste buds to less sweet foods. When shopping for baby foods or making your own, opt for blends that have one or no fruit.
Cut down your weekly dessert intake. Wherever your family is now, cut back one to two servings per week, Silber advises. “If a family has dessert every night, I would say cut back to five nights per week,” Silber says. Another option is to substitute fresh fruit and eat the fruit when it’s extra ripe because it will taste sweeter.
    
Drink water rather than sweetened beverages. Nearly two-thirds of kids in the U.S., ages 2-19, consumed at least one sugar-sweetened beverage per day, and roughly 30 percent of children consumed two or more, between 2011-2014, according to a study published in January by the Centers for Disease Control and Prevention’s National Center for Health Statistics. That includes soda, fruit drinks, sports and energy drinks, and sweetened coffees and teas.
Silber says most kids don’t need to consume beverages aimed toward athletes. “Usually water and a nutritious snack before and after will be sufficient to restore the nutrition and hydration,” she says.
    
Leave sugar out of recipes when possible. With cooking, Silber suggests cutting the sugar from the recipe entirely, or cutting it in half. “I do this a lot where I see a recipe for a marinade that has a lot of honey or white sugar that I will eliminate and I still think the recipe comes out tasty,” she says.
For baking, Silber says to look for recipes that use more natural forms of sugar, such as honey, agave, or maple syrup because they’re more concentrated, so you’ll use less of it. And remember: “There is a time and a place for [sweets],” Silber says. “Just because it doesn’t have the white sugar doesn’t mean it’s a food that should be given all the time.”
Read and understand the Nutrition Facts labels on packaged foods. The Food and Drug Administration announced a new Nutrition Facts label in May 2016, which among other changes includes an “Includes X g Added Sugars” field. Food manufacturers will need to implement the new label by July 26, 2018, while smaller companies will have an additional year to comply, according to the FDA.
Until then, Silber suggests thinking about it in terms of a sugar packet, which is approximately 4 grams of sugar. If you choose a food product that has 8-12 grams of sugar per serving, “envision yourself opening up two or three sugar packets and pouring that into your dish. That can become quite alarming,” she says.
Silber recommends choosing condiments (ketchup, salad dressing, and marinades) with less than 5 grams of sugar per serving, and foods (breads, yogurts, cereals, etc.) with no more than 10 grams of sugar per serving.
An easy way to keep track of your added sugar intake is to convert the grams per serving into teaspoons. There are 4.2 grams of sugar per teaspoon, Dr. Lustig says. That comes out to less than 25 grams per day for children and teens, 25.2 grams for women, and 37.8 grams for men. “We’re currently at about 90 [grams per day] on average. That’s a big difference,” Dr. Lustig says.

lundi 24 avril 2017

Les Chimane de Bolivie/Tsimane of Bolivia

http://www.sciencedirect.com/science/article/pii/S0140673617307523
https://wn.com/tsimane_and_atherosclerosis

https://wn.com/tsimane_reborn

http://time.com/4705247/healthy-diet-heart-disease/

https://www.nytimes.com/2017/04/10/well/live/learning-from-our-parents-heart-health-mistakes.html?rref=collection%2Fsectioncollection%2Fhealth&action=click&contentCollection=health&region=rank&module=package&version=highlights&contentPlacement=9&pgtype=sectionfront&_r=0

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4317610/



FAQ

"Tsimane are a homogenous ethnic group. Could it be genetic? What happens to Tsimane individuals in a westernized living situation? Anecdotes are not science."


It is why results of observational studies are not a proof of causal relationship.


"The meat eaten by the Tsimane tribe cannot be compared to that eaten in the US. They are hunting & eating wild animals, not the factory-farmed ones fed the wrong diet with antibiotics thrown in, and having limited to no exercise. Factory farmed animals are raised to increase the fat levels in their meat. The meat eaten by the Amazon tribe comes from foraging animals and is very lean. Because they eat meat and are healthy cannot be used to justify a meat-eating diet in the US as good for the heart."


Yes they eat less fat than us but does it matter?


"How much exercise?"
15 000 to 17 000 steps id est 5 miles


"LE"
53 after 1990
https://www.ncbi.nlm.nih.gov/pubmed/17421012

http://www.sciencedirect.com/science/article/pii/S0140673617307523

Summary of the study 

The Chimanes of Bolivia have arteries that do not age ...
It seems that the Chimane way of life protects their arteries

Guy-André Pelouze


1 / Is there still in the world tribes living as in the Paleolithic?

The indigenous peoples who live far from the agro-industrial civilization following a lifestyle close to that of the Paleolithic (-2.3 million to -10000 years ago) are very few today. They are of considerable interest from the anthropological as well as the medical point of view, since many chronic diseases can not be understood without the perspective of evolution. Anthropologists have studied several tribes to analyze what the way of life could be in the Paleolithic. Such tribes are found in Papua New Guinea, the Andaman and Nicobar Islands (India), the Philippines, Africa and South America (Amazonia).
In the 1990s a Swedish researcher, Staffan Lindeberg, studied the inhabitants of Kitava, one of the Trobriand Islands of Papua New Guinea. He observed that sudden cardiac death, stroke, and chest pain associated with exercise (angina) never occur in Kitava; By deepening his research he concludes that the essential element is their palaeolithic diet.
The study of the Bolivian population of the Chimane who live on the Andean foothills, particularly along the Maniquí River is a project that began in 2001. It is a fantastic anthropological research project, And the numerous publications with this link (https://www.unm.edu/~tsimane/index.html).
The 6000 Chimane constitute small communities of 20 to 30 families. They practice hunting, fishing, gathering and subsistence farming.
In March 2017 the results of an original study of cardiac risk in Chimane is published in the Lancet (http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)30752-3/fulltext? Elsca1 = tlpr). She is interested in the cardiac risk measured by the so-called calcium score. This is the measurement by the thoracic CT scan of the amount of calcium deposited in the walls of the arteries of the heart. Depending on the quantity present, a score is calculated which reliably predicts the risk of an atheromatous involvement of the coronary arteries (formation of a plaque in the wall of the artery, the progression of which obstructs blood circulation and rupture Leads to myocardial infarction)

2 / This study published in the newspaper The Lancet shows that the Chimane, a people of Bolivians living in the Amazon have coronary functions at the same state at 80 years as Americans at 50 years. What explains in our respective lifestyles that our heart system is more damaged and we are more prone to heart attacks?

What is striking in this very detailed study is that the Chimane have a very low calcium score throughout their life. And indeed at 80 years the Chimanes have an average calcium score that is that of North American 50 years.
The investigators then studied their cardiovascular risk factors as we understand them today. Almost no obesity, no diabetes, low blood pressure and lipid particles in the blood that are not atherogenic especially LDL particles are low. The Chimanes have a low risk profile and their arterial tree ages much less quickly: 85% of them all have no cardiovascular risk markers and have a normal calcium score. But mostly they are only 13% to have a coronary risk and it is low. According to the authors their lifestyle is the main explanation: they are physically very active, hunt, fish and build their house. They do not smoke. In terms of food, they eat almost no cereals, no sugar, no dairy products and, of course, virtually no industrial product. In addition, they consume less fat than French or northern Americans, but with 38 g of fat per day, 11 g / d of saturated fat (29%), 14 g / d of monounsaturated fat (37%). , And 8 g of polyunsaturated fat (21%), the proportion of saturated fat is higher than ours.



3 / What are the health consequences of this sedentary lifestyle where we no longer have enough sports, or are we feeding badly?

Our energy expenditure collapsed when humanity sat down and physical work was replaced by motorized machinery. The Chimanes make 15000-17000 steps a day on average. In our country, recreational physical activity did not replace the efforts that our parents and our ancestors made. At the same time the diet has sharply and profoundly transformed. We live in abundance of product foods which leads to excessive consumption of calories. Moreover, these calories are present in industrial products very high in simple carbohydrates or which are rapidly transformed into simple carbohydrates after ingestion and the metabolic mechanisms of storage of these carbohydrates lead to obesity and type 2 diabetes. Both factors, abundance and important part of the sugars characterise our diet. 

4 / What lessons have we learned from the mistakes of our parents in their way of life? Can a return to a lifestyle closer to that of the Tsimane be observed? There is no doubt that we are underestimating the potential for lifestyle change in the prevention of cardiovascular disease. For reasons related to our allopathic drug model and also because these changes require full responsibility of the patients. In this respect it is necessary to remember that it is not necessary to obtain results to make extraordinary changes: not to smoke, to have a normal weight, to consume a minimum of sugars (simple sugars or starches) and to do every day a Physical activity outdoors that results in shortness of breath requires no additional means or medical advice. Our elders did it not so long ago. What this study tells us is that physical activity is about 8 kilometers per day. Obviously this is very far from the average physical activity of the French (file: //localhost/Users/GuyAndrePelouze/Desktop/poster_ICDAM_2009_2.pdf). 

5 / What are the limitations of this study? First, it is an observational study and not an interventional study. Therefore the conclusions in particular the causes of this health of the arteries in the Chimanes remain uncertain. We must be careful with the correlations observed. However, from a medical point of view, the cardiovascular health of Chimane is remarkable. We also know that their lifestyles also produce similar changes in patients in developed countries and the most effective prevention of cardiovascular events. We must not underestimate the questions of genetics and epigenetics, that is to say differences which would participate in causality in arterial atheromatous disease. Especially for us European. This question remains very open. Further work is needed to highlight possible genetic differences with Europeans that could explain some of this cardiovascular health alongside lifestyle. Finally, given the inflammation observed in Chimane, inflammation in relation to endemic parasitism, we must certainly question the model of atheroma that we use. Chronic inflammation has been shown to be associated with progression of atheroma in populations in developed countries. This is not what we observe among the Chimanes without our knowing why.

(in french)


Le mode de vie des Chimane de Bolivie protègent leurs artères


Les Chimane de Bolivie ont des artères qui ne vieillissent pas…
Il semble que le mode de vie des Chimane protègent leurs artères

Guy-André Pelouze


1/Existe-t-il encore dans le monde des tribus vivant comme au paléolithique ?

Les populations indigènes qui vivent à l’écart de la civilisation agro-industrielle suivant un mode de vie proche de celui du paléolithique (-2,3 millions à -10000 ans avant notre ère) sont très peu nombreuses aujourd’hui. Elles présentent un intérêt considérable du point de vue anthropologique mais aussi médical car nombre de maladies chroniques ne peuvent être comprises sans la perspective de l’évolution. Les anthropologues ont étudié plusieurs tribus pour analyser ce que le mode de vie pouvait être au paléolithique. De telles tribus se trouvent en Papouasie-Nouvelle-Guinée, dans les îles Andaman et Nicobar (Inde), aux Philippines, en Afrique et en Amérique du Sud (Amazonie).
Dans les années 90 un chercheur suédois, Staffan Lindeberg, étudie les habitants de Kitava, l'une des îles Trobriand de Papouasie-Nouvelle-Guinée. Il observe que la mort subite d’origine coronarienne, les accidents vasculaires cérébraux et les douleurs thoraciques liées à l'effort (angine de poitrine) ne se produisent jamais chez les Kitava; en approfondissant ses recherches il conclue  que l’élément essentiel est leur régime alimentaire paléolithique.
L’étude de la population bolivienne des Chimane qui vivent  sur le piémont andin, en particulier le long de la rivière Maniquí est un projet qui a débuté en 2001. Il s’agit d’un fantastique projet de recherche anthropologique dont on retrouvera les étapes et les nombreuses publications avec ce lien (https://www.unm.edu/~tsimane/index.html).
Les 6000 Chimane constituent de petites communautés de 20 à 30 familles. Ils pratiquent la chasse, la pêche, la cueillette et une agriculture de subsistance.
En mars 2017 les résultats d’une étude originale du risque cardiaque chez les Chimane est publiée dans le Lancet (http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)30752-3/fulltext?elsca1=tlpr). Elle s’intéresse au risque cardiaque mesuré par ce que l’on appelle le score calcique. Il s’agit de la mesure par scanner thoracique de la quantité de calcium déposée dans les parois des artères du cœur. En fonction de la quantité présente on calcule un score qui prédit de manière très fiable le risque d’une atteinte athéromateuse des artères coronaires (constitution d’une plaque dans la paroi de l’artère dont la progression obstrue la circulation du sang et la rupture conduit à l’infarctus du myocarde)

2/ Cette étude publiée dans le journal The Lancet montre que les Chimane, un peuple de Boliviens vivants en Amazonie possèdent des fonctions coronariennes au même état à 80 ans que des Américains à 50 ans. Qu'est-ce qui explique dans nos modes de vie respectifs que notre système cardiaque soit plus abîmé et que nous soyons plus exposé a des accidents cardiaques ?

Ce qui frappe dans cette étude très détaillée c’est que les Chimane ont un score calcique très bas tout au long de leur vie. Et en effet à 80 ans les Chimane ont un score calcique moyen qui est celui de nord américains de 50 ans.
Les investigateurs ont ensuite étudié leurs facteurs de risque cardiovasculaires au sens où nous l’entendons aujourd’hui. Presque pas d’obésité, pas de diabète, une tension artérielle basse et des particules lipidiques  dans le sang qui ne sont pas athérogènes en particulier les particules LDL sont basses. Les Chimane ont un profil de risque bas et leur arbre artériel vieillit bien moins vite: 85 % d’entre eux tous âges confondus n’ont aucun marqueur de risque cardiovasculaire et présente un score calcique normal. Mais surtout ils ne sont que 13% à avoir un risque coronarien et il est faible. Selon les auteurs leur mode de vie est la principale explication: ils sont physiquement très actifs, chassent, pêchent et construisent leur maison. Ils ne fument pas. Sur le plan alimentaire ils ne mangent presque pas de céréales, pas de sucre, pas de produits laitiers et bien sur quasiment aucun produit industriel. Ajoutons qu’ils consomment moins de gras que les français ou les américains du nord mais avec
38 g de gras par jour, 11 g/j de graisse saturée (29%), 14 g/j de graisse mono-insaturée (37%), et 8 g de graisse polyinsaturée (21%), la proportion de graisse saturée est plus élevée que la notre.



3/ Quelles sont les conséquences pour la santé de ce mode de vie sédentarisé où nous ne faisons plus assez de sport, ou nous nous alimentons mal ?

Notre dépense énergétique s’est effondrée quand l’humanité s’est assise et que les travaux physiques ont été remplacés par des machines motorisées. Les Chimane font 15000-17000 pas par jour en moyenne. Chez nous l’activité physique de loisirs n’a pas du tout remplacé les efforts que nos parents et nos ancêtres faisaient. Dans le même temps l’alimentation s’est brutalement et profondément transformée. Nous vivons dans l’abondance de produits alimentaires ce qui conduit à une consommation excessive de calories. De surcroît ces calories sont présentes dans des produits industriels très riches en glucides simples ou qui sont rapidement transformés en glucides simples après ingestion et les mécanismes métaboliques de stockage de ces glucides conduisent à l’obésité et au diabète type 2. Les deux facteurs, abondance et part importante des sucres caractérisent notre régime alimentaire.

4/ Quelles leçons avons-nous tiré des erreurs de nos parents dans leur façon de vivre ? Est-ce qu'un retour à un mode de vie plus proche de celui des Tsimane peut s'observer ?
Il est certain que nous sous estimons les possibilités d’un changement de mode de vie dans la prévention des maladies cardiovasculaires. Pour des raisons liées à notre modèle allopathique médicamenteux et aussi parce que ces changements demandent une pleine responsabilité des patients. A ce sujet il faut rappeler qu’il n’est pas nécessaire pour obtenir des résultats de faire des changements extraordinaires: ne pas fumer, avoir un poids normal, consommer un minimum de sucres (sucres simples ou amidons) et faire tous les jours une activité physique à l’extérieur qui entraîne un essoufflement ne nécessite ni moyens supplémentaires ni avis médical. Nos ainés le faisaient il n’y a pas si longtemps. Ce que nous apprend cette étude c’est que l’activité physique est d’environ 8 kilomètres par jour. Évidemment c’est très loin de l’activité physique moyenne des français (file://localhost/Users/GuyAndrePelouze/Desktop/poster_ICDAM_2009_2.pdf).



5/ Quelles sont les limites de cette étude ?
Tout d’abord il s’agit d’une étude observationnelle et non d’une étude interventionnelle. Donc les conclusions en particulier les causes de cette santé des artères chez les Chimane restent incertaines. Nous devons être prudent avec les corrélations observées. Il reste que du point de vue des paramètres médicaux la santé cardiovasculaire des Chimane est remarquable. Nous savons aussi que leur mode de vie produit aussi chez les patients des pays développés des changements similaires et la prévention la plus efficace des accidents cardiovasculaires.
Il ne faut pas sous estimer les questions de génétique et d’épigénétique c’est à dire des différences qui participeraient à une causalité dans l’atteinte artérielle athéromateuse. En particulier pour nous européens. Cette question reste très ouverte. D’autres travaux sont nécessaires pour mettre en évidence d’éventuelles différences génétiques avec les européens notamment qui pourraient expliquer une partie de cette santé cardiovasculaire à côté du mode de vie.

Enfin compte tenu de l’inflammation observée chez les Chimane, inflammation en rapport avec un parasitisme endémique il faut certainement s’interroger sur le modèle de l’athérome que nous utilisons. Il a été démontré que l’inflammation chronique était associée à une progression de l’athérome dans les populations des pays développés. Ce n’est pas ce que l’on observe chez les Chimane sans que nous sachions pourquoi.