Thursday, March 18, 2010

Was our ancestral diet REALLY VLC and high fat?


Awareness of the ancestral human diet might advance traditional nutrition science. The human genome has hardly changed since the emergence of behaviourally-modern humans in East Africa 100–50 · 103 years ago; genetically, man remains adapted for the foods consumed then. The best available estimates suggest that those ancestors obtained about 35% of their dietary energy from fats, 35% from carbohydrates and 30% from protein. Saturated fats contributed approximately 7.5% total energy and harmful trans-fatty acids contributed negligible amounts. Polyunsaturated fat intake was high, with n-6:n-3 approaching 2:1 (v. 10:1 today). Cholesterol consumption was substantial, perhaps 480 mg/d. Carbohydrate came from uncultivated fruits and vegetables, approximately 50% energy intake as compared with the present level of 16% energy intake for Americans. High fruit and vegetable intake and minimal grain and dairy consumption made ancestral diets base-yielding, unlike today’s acid-producing pattern. Honey comprised 2–3% energy intake as compared with the 15% added sugars contribute currently. Fibre consumption was high, perhaps 100 g/d, but phytate content was minimal. Vitamin, mineral and (probably) phytochemical intake was typically 1.5 to eight times that of today except for that of Na, generally <1000 mg/d, i.e. much less than that of K. The field of nutrition science suffers from the absence of a unifying hypothesis on which to build a dietary strategy for prevention; there is no Kuhnian paradigm, which some researchers believe to be a prerequisite for progress in any scientific discipline. An understanding of human evolutionary experience and its relevance to contemporary nutritional requirements may address this critical deficiency.
A few things jump out at me:
  • The diet is roughly isocaloric for the macronutrients.
  • The dietary villain du jour --  fructose -- is well represented in fruits and honey.  Could that be why we actually have a specific enzyme for processing this nutrient? 
  • Fiber intake is huge!!
  • Fat intake is almost "low fat" levels.
I see no reason to discount the assertions in this article regarding tracing the modern human genome to Stone Age man living in NE Africa.   The meat eaters often point to the Inuit as "proof" of the ancestral value of high fat intake.   But I'm not an Inuit descendent, nor am I living in a super cold climate.  Also, those cold water fishes and seals have a fat content that in no way resembles the fat of today's farm animals -- even the grass fed variety.  

Many in the LC community point to Paleo diets to counter claims that meats are bad for us etc.  Fair and correct in general.  But many of those also consume a LOT of dairy fats -- something Paleo-Dude and Dudette had little or no access to.  IF they had access to dairy, it seems far more likely they would just drink it carbs and all.   Many also eat only the high fat cuts of meat (cooked with more fat).  Paleos ate the whole bird (including the shunned chicken breast), not just chicken wings. 

I'm not willing to give up my dairy entirely, but I take away from this to forgo the cheese over the nuts and strive to eat the whole of the whole foods.  That may not be possible, but to try to balance that prime rib with chicken breast and the like.

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