Don't want to break the flow of the discussion which is very interesting but can I just ask Skotkonung - in that case do you use other fats apart from saturated to make up the ratio of fat:protein:carb? What are the sources?
Or do you feel that the amount you get from beef is enough?
What does everyone else do about this?
To be honest, I pay most attention to food source percentage as opposed to a specific macro-nutrient ratio. My reasoning behind this is that a diet comprised primarily of fats, while containing some benefits from a clinical dietitian's perspective, is not supported by the anthropological literature. Since the goal of the paleolithic diet is to a follow a regimen of eating and perhaps exercising that closely resembles the patterns of those who lived during the preagricultural period (pre 10,000 BP), it makes sense to strongly consider what we know from anthropology.
Based on recorded history and anthropological evidence, we know the following fat sources weren't available to paleolithic humans:
- Dairy, specifically butter and cheese. (c 6,100–5,500 BP)
- Refined vegetable oils such as shortening, margarine, etc. (1897 AD)
- Vegetable oils (c 5,000–6,000 BP, widely available starting 1910 AD)
- Fatty, feedlot-produced meats (1860 AD)
Incidentally, this is the origin for most modern sources of dietary fat.
Fatty acids fall into one of three major categories: (1) saturated fatty acids (SFA), (2) monounsaturated fatty acids (MUFA), and (3) polyunsaturated fatty acids (PUFA). PUFA occur in two biologically important families, the n-6 PUFA and the n-3 PUFA.
Substantial evidence now indicates that for preventing the risk of chronic disease the absolute amount of dietary fat is less important than the type of fat. Beneficial, health-promoting fats are MUFA and some PUFA, whereas most SFA and trans fatty acids are detrimental when consumed in excessive quantities. Further, the balance of dietary n-6 and n-3 PUFA is integral in preventing the risk of chronic disease and promoting health.
The six major sources of SFA in the U.S. diet are fatty meats, baked goods, cheese, milk, margarine, and butter. Five of these six foods would not have been components of hominin diets before the advent of animal husbandry or the Industrial Revolution. Because of the inherently lean nature of wild-animal tissues throughout most of the year and the dominance of MUFA + PUFA in their muscle and organ tissues, high dietary levels of SFA on a year-round basis would have been infrequently encountered in preagricultural diets.
Since the western diet frequently contains excessive saturated and trans fatty acids and has too little n-3 PUFA relative to its n-6 PUFA, it is my opinion that individuals following the paleo diet would experience better health if they avoided the above listed food sources and instead emphasized the consumption of grass fed and free range animals, which incidentally more closely resemble their wild peers as opposed to feedlot beef.
So the big question isn't the total amount of fat, but the total quantity of meat consumed as that was the primary source of dietary fats in the paleolithic diet. While this number likely varied per region, we can approximate an average by reviewing the data of modern hunter-gatherer tribes and carbon signatures from paleolithic era bone samples.
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9 downloadsThe data in the table above indicates that most hunter gatherer tribes consumed somewhere around 60-65% of their food intake from low SFA animal sources. Similarly, our own evolution indicates a high intake of animal product. The following excerpt is pulled from the above attached study:
The development of stone tools and the increased dietary reliance on animal foods
allowed early African hominins to colonize northern latitudes outside of Africa where
plant foods would have been seasonally restricted. Early Homo skeletal remains and
Oldowan lithic technology appear at the Dmanisi site in the Republic of Georgia (40°
N) by 1.75 Mya (Vekua et al., 2002), and more recently Oldowan tools dating to
1.66 Mya have been discovered at the Majuangou site in North China (40° N; Zhu
et al., 2004). Both of these tool-producing hominins would likely have consumed
considerably more animal food than prelithic hominins living in more temperate
African climates.
In addition to the fossil evidence suggesting a trend for increased animal food
consumption, hominins may have experienced a number of genetic adaptations to
animal-based diets early on in our genus's evolution analogous to those of obligate
carnivores such as felines. Carnivorous diets reduce evolutionary selective pressures
that act to maintain certain anatomical and physiological characteristics needed to
process and metabolize high amounts of plant foods. In this regard, hominins, like
felines, have experienced a reduction in gut size and metabolic activity along with a
concurrent expansion of brain size and metabolic activity as they included more energetically
dense animal food into their diets (Leonard and Robertson, 1994; Aiello
and Wheeler, 1995; Cordain, Watkins, and Mann, 2001). Further, similar to obligate
carnivores (Pawlosky, Barnes, and Salem, 1994), humans maintain an inefficient ability
to chain elongate and desaturate 18 carbon fatty acids to their product 20 and 22
carbon fatty acids (Emken et al., 1992). Since 20 and 22 carbon fatty acids are essential
cellular lipids, then evolutionary reductions in desaturase and elongase activity
in hominins indicate that preformed dietary 20 and 22 carbon fatty acids (found
only in animal foods) were increasingly incorporated in lieu of their endogenously
synthesized counterparts derived from 18 carbon plant fatty acids. Finally, our species
has a limited ability to synthesize the biologically important amino acid, taurine,
from precursor amino acids (Sturman et al., 1975; Chesney et al., 1998), and vegetarian
diets in humans result in lowered plasma and urinary concentrations of taurine
(Laidlaw et al., 1988). Like felines (Knopf et al., 1978; MacDonald, Rogers, and
Morris, 1984), the need to endogenously synthesize taurine may have been evolutionarily
reduced in humans because exogenous dietary sources of preformed taurine
(found only in animal food) had relaxed the selective pressure formerly requiring
the need to synthesize this conditionally essential amino acid.
Based on this information, I consume upwards of 60% of my food intake from animal products such as free-range chickens, and grass fed beef, deer, and bison. The rest of my calories comes from fresh, organic, fruits and vegetables. To a limited extent (less than 10%), some of my calories come from nuts.
Edited by Skotkonung, 19 May 2009 - 07:56 PM.
