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teaser Sun, Mar-26-17 10:00

Oral health in transition: The Hadza foragers of Tanzania

Conventional wisdom holds that a decline in oral health accompanies the transition from hunting and gathering to agriculture, given increased consumption of carbohydrates. This widely touted example of the mismatch between our biology and modern lifestyle has been intuited largely from the bioarchaeological record of the Neolithic Revolution in the New World. Recent studies of other populations have, however, challenged the universality of this assertion. Here, we present the first comprehensive study of oral health among a living population in transition from the bush to village life, the Hadza hunter-gatherers of Tanzania, to test the hypothesis that the shift from foraging to farming, or agricultural intensification, inevitably leads to increased periodontal disease, caries, and orthodontic disorders. Our results showed that women living in villages consuming a mostly agricultural diet exhibited more caries and periodontal disease than those living in the bush consuming a mostly wild-food diet. Furthermore, men living in the bush consuming mostly a wild-food diet had more than those living in the village consuming a mostly agricultural diet. These findings are explained by the high incidence of maize consumption in village settings, along with previously recognized variation in rate of caries between men and women. The unexpected discovery of high caries incidences for men in the bush is likely explained by heavy reliance on honey, and perhaps differential access to tobacco and marijuana. These data support the notions that mechanisms of cariogenesis are multifactorial and that the relationships between oral health and the shift from a predominantly wild-food diet to one dominated by cultigens are nuanced.

Sometimes I find I've wandered into some blog extolling the virtues of honey, referencing high seasonal consumption among the Hazda. I think when it comes down to it, the null hypothesis should be that naturally refined sugars are still refined sugars. There may be contexts where a diet high in honey doesn't lead to obesity--like the Hadza. But unless you convince some Hadza to switch the honey for sucrose, and see what happens, they can't be used as an example of how honey is superior to sucrose, I think the null hypothesis should be to be just as suspicious of honey as you are of sucrose or high fructose corn syrup.

Nicekitty Sun, Apr-16-17 11:31

That's interesting. I've recently switched to using small amounts of honey for sweetening (like in my coffee, etc..), as part of a switch to a more "natural", ancestral foods way of eating.

I became very suspicious of all artificial sweeteners and even stevia, after my dog almost died from ingesting xylitol (it sends their insulin levels very high). That experience, combined with information from The Obesity Code has made fake sweeteners of any kind very unappealing to me. Honey at least has been ingested by humans for a very long time. I'd also like to think that honey might have other compounds in it that are helpful as opposed to the emptiness of sugar or corn syrup.

I'm very curious as to why the Hadza men eat so much more honey than the women--are they out in the bush taking it directly from the hive?

teaser Sun, Apr-16-17 11:55

I'd like to think that there are wonderful protective factors in honey as well. But I don't. :) At least, I don't seem to be protected vs. binging on honey. Honey might have been ingested by humans for a very long time. But not in massive quantities, except for seasonally for groups like the Hadza.

Men eating more honey might be just a division of labour thing, the accounts of honey gathering all seem to involve men, they probably eat a fair bit right away when they come across a hive. I'm thinking they aren't any more protected against binging on honey than I am.

Something I thought was a mistake was when folk like Kurt Harris started talking about "paleo re-enactment" as if it were a bad thing. If we knew exactly why a people like the Hadza do as well as they do while eating a fair amount of honey, we could just say, okay do just that. Honey is protective? Get lots of sunlight? Do a certain kind of exercise? Eat "safe" starches that aren't wheat? Fermented foods? It's hard to be certain just what it is about their diet and lifestyle that works. We know something does. If there are twenty differences between one group and another, and one has a better result, the best result might not come from thinking that you know how things work--but from re-enactment, change those twenty things, and without knowing why the new way of eating/lifestyle works, it seems fairly likely that there will be improvement. As long as the protection doesn't come from genetic or multigenerational differences. A very long winded way for me to say that I'm not sure how I could safely eat honey without going full-Hadza.

WereBear Sun, Apr-16-17 12:12

Also, it is seasonal.

You could make a case that we have both sugar burning and fat burning mechanisms because it was once vital to put weight on in fall, to actually live on over the winter.

teaser Mon, Aug-28-17 11:41

More evidence that our intestinal microbes are profoundly influenced by the foods we eat -- or don't: The gut ecosystems of members of a small group of hunter-gatherers inhabiting Tanzania's Rift Valley show a strong cyclicality consistent with the population's seasonally changing diet.

A study led by researchers at the Stanford University School of Medicine is the first to look at seasonal variations in the gut-microbial composition, or microbiota, of the Hadza, one of the world's few remaining traditional hunter-gatherer populations. The findings confirm that the Hadza microbiota is more diverse than, and substantially different from, that of industrialized countries' urban-dwelling denizens.

The study is also the first to show that the microbiota of the Hadza population varies seasonally, and that this variation corresponds to their seasonally fluctuating dietary intake. And the research suggests that sweeping changes in the average person's diet over the past 10,000 years could be the key driver in the loss of microbial diversity in the typical modern gut.

"Surviving hunter-gatherer populations are the closest available proxy to a time machine we in the modern industrialized world can climb into to learn about the ways of our remote human ancestors," said Justin Sonnenburg, PhD, associate professor of microbiology and immunology at Stanford.

Sonnenburg is the senior author of the multi-institution study, to be published Aug. 25 in Science. Lead authorship is shared by Sonnenburg's former graduate student Samuel Smits, PhD, and Jeff Leach, director of the Human Food Project in Terlingua, Texas.

The life inside our guts

For more than 15 million years, human beings have co-evolved with thousands of microbial species that take up residence in the lowermost part of the intestine, earning their keep by helping us digest food components we're unable to break down by ourselves, chiefly dietary fiber; manufacturing vitamins and other health-enhancing molecules; training our immune system and fostering the maturation of cells in our gut; and guarding our intestinal turf against the intrusion of all-too-eager competing microbial species including pathogens.

The advent of agriculture about 10,000 to 15,000 years ago has radically altered our diet. In the past century alone, the typical person's lifestyle has undergone further vast alterations: labor-saving devices' encouragement of a sedentary existence, the introduction of antibiotics and of birth by cesarean section, and the gradual supplanting of fiber-filled whole grains, fruits and vegetables by increasingly processed and fiber-free foods.

These environmental changes have wrought corresponding shifts in our microbial exposures, and in our intestines' ability to serve as hospitable hosts for our single-celled symbionts. But it's been hard to apportion the relative contributions of technological and societal innovations to the loss of microbial diversity in modern populations.

The new study adds evidence that diet is a major factor.

The Hadza number just over 1,000 people, fewer than 200 of whom adhere to the traditional hunter-gatherer lifestyle, which includes a diet composed mainly of five items: meat, berries, baobab (a fruit), tubers and honey. While Western diets are pretty much the same throughout the year, the Hadza lifestyle doesn't include refrigerators and supermarkets. So the population's diet fluctuates according to the season, of which there are two in the Rift Valley: dry, when meat, baobab and tuber consumption play a relatively larger role; and wet, during which berries, tubers, honey and baobabs prevail. (Tubers and baobab are available year-around.)

"The 100 to 200 Hadza sticking to this routine will possibly lose it in a decade or two, maybe sooner. Some are using cell phones now," Sonnenburg said. "We wanted to take advantage of this rapidly closing window to explore our vanishing microbiota."

Tracking the variation

The investigators collected 350 stool samples from 188 separate Hadza individuals over a roughly one-year period encompassing a bit more than one full seasonal cycle. A thorough analysis of the samples' microbial contents revealed that the gut microbiota varied seasonally, in harmony with the Hadza dietary intake. In particular, a subset of microbial species' populations diminished in the wet season, when honey accounted for a significant portion of caloric intake, and rebounded in the dry season, when consumption of fiber-rich tubers peaked.

That made sense, Sonnenburg said. "Our own microbiota can change significantly from day to day, or even within hours, in response to what we've been eating."

Samples collected during the same season, but a year apart, contained essentially identical microbial populations, indicating resilience to transitory dietary disruptions.

More surprisingly, the bacterial species whose numbers diminish to sub-detectable levels in the wet season, only to bounce back robustly in the next dry season, appear to be the same ones that -- although shared by hunter-gatherers in locations as diverse as modern-day Africa and South America -- are resoundingly absent in the guts of the vast majority of those who populate the industrialized world.

This observed seasonal cyclicality, in combination with results of a previous study led by two of the study's co-authors, offers a possible hint about the case of the missing microbes.

A 2016 study, published in Nature and led by Sonnenburg and senior research scientist Erica Sonnenburg, PhD, showed that while depriving mice of dietary fiber greatly reduced their gut-microbial species diversity, this diversity was restored when the dietary-fiber restriction was lifted. But if this fiber deprivation was maintained for four generations, microbial species that had initially bounced back robustly became permanently lost.

Could this be happening, or could it have already happened, in us?

"Fiber's all that's left at the very end of our digestive tract where these microbes live, so they've evolved to be very good at digesting it," said Sonnenburg. "The Hadza get 100 or more grams of fiber a day in their food, on average. We average 15 grams per day."

nawchem Tue, Aug-29-17 19:12

Also, who among us hasn't taken antibiotics?

Ms Arielle Sat, Jul-21-18 13:15

How do we bring back the microflora of old???

Read a book some years ago about how much we have lost. ANd for some people a transfer of fecal matter is a medical procedure to save their lives .......

It makes me think that we are now living in the margines of deprivation.....can other people provide what we have lost??

The doctor also talked about the minute amount of antibiotics in commercial milk and the effects; and the downside of a ceasarian section such that the baby is not innoculated with the mothers natural flora down under.... and how docs can assist with this.

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