Seasonal Variability - Hadza Example

[Russ]

So by now y'all know I'm on a kick right now w/r variability on the possibility that it's not necessarily about fats vs carbs, but how things like that vary and then correspond to changing human moody state over time. In other words, maybe it's not about being in one state (e.g. ketosis) OR another, but one state THEN another?

In that context, I offer this fairly recent paper on seasonal variability in the oft-studied Hadza hunter-gatherers of east Africa. Note that to the best of my knowledge we have no data either way on APOE status of the Hadza, so keep that in mind (although other regional HG tribes we know are high in E4's (e.g. pygmies, khoisan)). [I upload the paper as it's most frequently found behind paywalls although I found one site with the full pdf and wanted to make sure we had this in case that is ever removed.]

Tubers as Fallback Foods and Their Impact on Hadza Hunter-Gatherers
Frank W. Marlowe* and Julia C. Berbesque

ABSTRACT The Hadza are hunter-gatherers in Tan- zania. Their diet can be conveniently categorized into five main categories: tubers, berries, meat, baobab, and honey. We showed the Hadza photos of these foods and asked them to rank them in order of preference. Honey was ranked the highest. Tubers, as expected from their low ca- loric value, were ranked lowest. Given that tubers are least preferred, we used kilograms of tubers arriving in camp across the year as a minimum estimate of their availability. Tubers fit the definition of fallback foods because they are the most continuously available but least preferred foods. Tubers are more often taken when berries are least available. We examined the impact of all foods by assessing variation in adult body mass index (BMI) and percent body fat (%BF) in relation to amount of foods arriving in camp. We found, controlling for region and sea- son, women of reproductive age had a higher %BF in camps where more meat was acquired and a lower %BF where more tubers were taken. We discuss the implica- tions of these results for the Hadza. We also discuss the importance of tubers in human evolution. Am J Phys Anthropol 140:751–758, 2009. VC 2009 Wiley-Liss, Inc.

tubers_and_fallback_foods_hadza_21040_ftp.pdf

Moderator note - I deleted the attached paper (DOI: 10.1002/ajpa.21040) because our copyright infringement policy prohibits it. Members in jurisdictions for which access to Sci-Hub is legal may want to search for the paper there.

Although the whole thing is quite good, if nothing else, I invite you to scan Figures 2, 3, 4 and 5. Here you will see that dietary composition indeed varies quite a bit by season, and seasonal body fat% varies for women but not so much for men. Note that all charts on diet composition are in terms of weight (kg), not energy (calorie) percentages.

Highlights (for me):
1. Hadza get carbs from berries when available, but then backfill with tubers when berries are out of season.
2. Tubers are slightly but not deeply roasted before eating (only 5 in) - Resistant starch more available?
3. The honey is gathered by men who eat ~50% of their haul before bringing back to camp - Short term energy for the hunt?
4. But not much honey is available 5-7 months of the year…and in those same months meat consumption is highest. Seasonal ketosis?
5. Overall diet looks like it was about 20-30% meat (again by weight), but was down to abut 5% in February and as high as about 55% in Sept. Seasonally in and out of ketosis?
6. There was a bias for both men and women to more strongly prefer the foods they were most active in acquiring (honey/meat for men, and berries for women). Connection between fuel and activity type, or true need based?
7. Male body fat was largely stable (~10% over time), but women's body fat went up a bit in Sep-Nov (from ~17% to about 20%) (when tuber consumption was lowest). Maybe men's diets match energy consumption throughout cycle, but women have more storage-driven needs?

If nothing else, this looks like a very good example of how you can't simply represent diets with annual averages. I continue to find it at least plausible if not likely that this variability is actually important for health, but of course that really hasn't been studied as far as I know (yet).

[Julie G]

Really interesting, Russ. I'll look forward to reading the paper. I know that the ApoE4 allele is well-represented in Africa. Can we assume that the Hadza are primarily E4 carriers?

FWIW, I strongly agree that E4's ability to deal with variability, based purely upon evolution, appears to be the characteristic that has lent to it's survivability. Failure to recognize our genetic/environmental mismatch is certainly driving high rates of chronic illness (including Alzheimer's, CAD/CVD) in Western civilization. Our challenge is HOW to apply that understanding to our daily regimen

[Russ]

As you know, I don't like to assume anything. So whereas I would say that prior probabilities favor Hadza having high E4 incidence, they could actually be low for all we know? Others we do know include: Khoisan (37%), Pygmies (41%), Burundi Tursi (39%), Rawanda Hutu (24%), Zaire (33%).

[Welcomeaboard]

I don't know how close those tribes live to the equator, but the one article I mentioned said the closer to the equator the higher the apoe4. So if the Hadza are closer figure as high or higher, if father away then these then figure lower to maybe near the same depending on distance calculations.

[Welcomeaboard]

Here is another thing that I wonder. These African tribes do not have any schools like Harvard or Yale or private elementary, etc. So as we have seen that higher education is considered a prevention or protection are they seeing more AD if these Hadza and others have the lifespans to reach 70 or more years. They may die in their 50's or 60's? So if so are they dying due to diet or lifestyle and lack of health care as if it is diet that is killing them off then we don't want to follow that choice. As well if they don't live long enough then we don't know if their AD rate would be 100 percent based on their diet.

[Russ]

WA, As I read it in the below link, the mortality curves for the Hadza are similar to 'industrialized' peoples…

http://www.theskinnywhitebuddha.com/201 ... erers.html

…and perhaps worth reminding… that in that context, everything I have ever seen suggests pretty much zero incidence of dementia in any hunter-gatherer society. So indeed maybe it's all the E4's that die first in such cultures (of other causes), or E4 is not an underlying problem in that context.

[Welcomeaboard]

Nice article Russ. Shows men eat more meat than women and that is pretty much the same in western culture as well. They said non of the hunter gatherers lived past 90 and we know the western or eastern society have people that live into the 116 at highest, record was 122 and the rest never beat 116, so 116 looks as of now as the oldest to expect if you can get there.
The other thing was they only ate like five things, honey, meat, a Tuber. Fruits, so it would be a simple repetitive diet, if you wanted to follow it as a male start with honey and meat and then add in some of the other in your seasonal plan. Kinda kills all the vegans ideas as they are largely meat eater in males and when meat is available to the women after a hunting trip they throw all the carbs in the trash and eat meat. Shows that ancient man and women prefer meat and it does not kill them faster than vegans.

[Russ]

Listening to Robb Wolf's podcast from this week with Terry Wahl's this morning that may be broadly interesting to many in this community...

http://robbwolf.com/2014/12/30/episode- ... oimmunity/

…but relevant here is that this 'seasonal variability' thing came up shortly after 50 min….

"Terry: Well I think a lot about this as well. As I look at the traditional societies, the arctic Inuit are hailed as the ultimate ketogenic eater, but even those guys are not in ketosis all the time on their traditional diets. They have more carbs for two months out of the year. And we have societies that never have to be in ketosis in equatorial Africa, you might have been in ketosis sometimes but you're more likely had access to some carbs year round.

I think we may discover is that ketosis intermittently is the normal state and that every society would spend who had ketosis because we’re in winter, would be in ketosis every winter for one six months or ten months span how far towards the pole you were. But you also got to come out of ketosis during your summer period.

Biologically when we’re in ketosis, our biological systems are set more towards repair and maintenance. When we have more carbs in our diet our biological process is set more towards reproduction. So it’s not that one is necessarily better than the other, I'm beginning to think that we’re probably best of experiencing both during the year so that I'm beginning to wonder if with the average Jane or Joe, being in ketosis part of the year is a very good idea. Being out of ketosis would a low glycemic index diet is fine. But then you should go back into ketosis.

If you're trying to conceive, you probably don’t want to be in ketosis. You want to have a low glycemic index diet. And I’d also made the observation that we’re all unique set of DNA enzymes, a unique set of microbiome that live in our guts and help in digest our food, a unique set of toxins. So how we respond to these interventions will vary. And it’s really up to us to pay very close attention and be willing to make minor adjustments based on our observations."

The whole idea fits with what I've been reflecting on, but hadn't really thought of this idea that the length of the extended ketotic period being a function of latitude before. Makes me also wonder if there's not an important co-variable with sunlight and e.g. vitamin D with carb/fat metabolism as well? I recall that seasonal timing of carbs and sunlight have been emphasized by Jack Kruse.

Also seems to imply some interplay with your own personal genetic heritage as well… i.e. what would matter more - the latitude your ancestors evolved at, or the one you presently live at? Also logical questions as to whether such strategies might be different for those of us in post-productive years… although cyclical building and cleaning cycles still seem to make sense?

Just so as to not overemphasize on the long slow seasonal variability, also seems that frequency of short-duration cycles in and out of ketosis might be important as well?

[Tincup]

If you're trying to conceive, you probably don’t want to be in ketosis.

I recall reading about a doc in Florida very successfully treating infertile women with a ketotic diet though.

Gundry is certainly all over the time-of-year cycles, too, since he eats 1x/day for 5 ish months (Dec-May as I recall).

What I get out of these papers is that the hunter gatherer people ate whatever they could find, but have preferences if they have a choice. The common thing is none of the foods are processed. A great difference between them & us is that they don't appear to have metabolic derangement (since they've not eaten SAD since birth & they don't appear to continually overeat). In one of the American Gut interviews and also a comment by Wahls is that they ate ~200 different plants over a year. They also have a different gut biome than we do as a consequence.

[Russ]

Sure - I agree one common thing is unprocessed foods, but may also be significant that they were also all variable as the seasons changed. So they never ate the same thing all year round - even in equatorial regions rainy/dry seasons effect availability. May also be relevant that the simultaneous variation in other attributes of those doing the eating - e.g. of vitamin D status and exercise that went along with those seasonal patterns also matched up? Of course the implication is that all of our dialogue on high vs low fat may be missing a key variable?

Perhaps worth noting that even though I had been largely a whole food only person for about 3 yrs, although I did not feel and perform quite as good while in deep ketosis for ~3 months, I absolutely feel fabulous after adding some (but not a lot) of carbs back in. Strikes me that it may have taken me through some kind of metabolic threshold into a new state? Maybe doing so periodically rather than all the time is the magic? Although should note I've done this out of cycle (ketotic during peak of summer).