Carnivores diets

Figure 10.2. Schematic diagram showing how restricted conversion of fatty acids to amino acids influences the fractionation between collagen and CO3 of bone apatite LI = lipid component, PR = protein, T = total isotopic composition AP = COj component of apatite, a) Herbivorous diet (Cj plants only) b) Carnivorous diet, assuming rj = 1 (no barrier to fatty acid conversion to AAs) c) Carnivorous diet, assuming ri < 1 note that carbonate-collagen fractionation is smaller.

The difference in the spacing arises from the combination of two effects that of protein routing (no difference is seen if protein is scrambled), and the difference in the spacing between Dp and Dn in herbivore and carnivore diets. In fact, for the rat diets recorded by Ambrose and Norr (1993), there is a clear linearity between 5 C and (Dp — Dn). 

Vitamin A (retinol), present in carnivorous diets, and the provitamin (P-carotene), found in plants, form retinaldehyde, utilized in vision, and retinoic acid, which acts in the control of gene expression. Vitamin D is a steroid prohormone yielding the active hormone derivative calcitriol, which regulates calcium and phosphate metaboUsm. Vitamin D deficiency leads to rickets and osteomalacia. 

Hipkiss, A. R. (2005). Glycation, ageing and carnosine Are carnivorous diets beneficial Mech. Ageing Dev. 126,1034-1039. 

Hipkiss, A. R. (2006c). Would carnosine or a carnivorous diet help suppress aging and associated pathologies Ann. N. Y. Acad. Sci. 1067,369-374. 

Lipids are a second major source of carbon in most animal diets, perhaps the major source in some carnivorous diets Lipids are metabolized for energy requirements, although somewhat more slowly than carbohydrates Lipids tend to be depleted in by about 2 0/00 or more relative to carbohydrates in any particular food (data in 6 7 9) Virtually all lipid carbon is ultimately... 

Carbohydrates are almost negligible in pure carnivore diets, the only significant source being glycogen stored in the cells of the meat eaten It is unlikely that this glycogen is sufficient in quantity to significantly affect the isotopic composition of blood bicarbonate or bone apatite ... 

It is possible that we are not yet perfectly adapted to such a high carbohydrate diet. Some students of tooth decay point out that dental caries is rare among primitive Eskimos and the meat eaters of the Great Rift Valley in Africa. Many seem to feel that the human race made a mistake in giving up its primitive, carnivorous diets and that dental ailments are the price we have paid for adoption of carbohydrate foods (49). However this may be, all indications are that carbohydrates are here to stay. Indeed, unless science can provide some alternative that is not yet in sight, the growth of even United States population may be expected eventually to force us by stages up toward the 85% carbohydrate level of the orientals. 

Osteopenia can be induced in adult cats by immobilization, by feeding a low calcium diet, or by feeding a high phosphorus diet. Indeed, bone disease is a common clinical problem in cats fed all-meat diets unsupplemented with calcium. On the other hand, their carnivorous diet denotes a capacity to buffer the large metabolic acid load generated by a high protein intake without depletion of bone buffers. 

Exposure to estrogenic compounds through diet will differ for herbivores and carnivores, the latter being most likely to encounter endogenous steroids in their prey. Efficient uptake of steroids in mammals is illustrated by the use of the contraceptive pill, but routes of absorption in invertebrates remain to be determined. The relationship between endocrine disruption and metabolic toxicity, with reduced reproductive viability a secondary consequence of metabolic disturbance, also merits further study in invertebrate species. 

Vitamin Bjg is not synthesized by animals or by plants. Only a few species of bacteria synthesize this complex substance. Carnivorous animals easily acquire sufficient amounts of Bjg from meat in their diet, but herbivorous creatures typically depend on intestinal bacteria to synthesize Bjg for them. This is sometimes not sufficient, and certain animals, including rabbits, occasionally eat their feces in order to accumulate the necessary quantities of Big. 

Study, ancient Maya diet shows a A N of 4.5%o (humans-herbivores). The 8 N values for mixed-diet humans in Schoeninger et al. (1983) seem always somewhat too positive for their supposed food European agriculturalists are about 8-10%o. Also, Bocherens et al. (1991) and Lubell et al. (1994) give similar values (aroimd +9%o) for medieval French and Neolithic humans from Portugal, respectively. The 8 N values (+9.3 and 11.6%o) of two human (Neanderthal) samples (Fizet et al. 1995) are very similar to those of associated carnivores but are only slightly higher than those of Neolithic humans. 

Table 3.2 shows the 5 Cu and 5 Cc values of herbivores, omnivores, carnivores and humans. The (climate-corrected) trophic level effect between herbivores and carnivores is 0.90%o. Human values are closer to carnivore and omnivore values than to herbivore 5 Cc values. The human 5 Cc values are on average 0.66%o more positive than the herbivore 5 Cc values, a good estimate for a carnivore effect in humans (see section on trophic level effects, below). The average human 5 Cc value is -19.92 1.28%o,which would indicate that Holocene humans in Europe had a diet that consisted of C3 terrestrial foods, whieh is as might be expected. By looking at the humans separate from the total bone data set, we notice potential human food selection (Fig. 3.3) we can see a non-climatic pattern, which is much less uniform than in the total bone data set (Fig. 3.2b). Italy (6 Cc = -21.3%o) has a much more negative 8 Cc value than the Czech Republic (8 Cc =-18.7%o), Spain (8 Cc = -19.3%o) and Greece (-18.9%o but the 8 N of 9.0%odoes not indicate marine food), while the northern European coimtries are closer to a 5 Cc value of-20%o. What the actual causes are for this pattern in the human samples is not clear to better understand these variations it is best to consider, where possible, the 8 N values with the 8 Cc values. 

Most accounts of the larger A,p.,.o in carnivores have attributed this effect to higher proportion of lipids in the diet of carnivores. This arises because carnivores obtain all or most of their nutrition from the flesh of other animals, a significant part of which is composed of lipid. By contrast, lipids make up a much smaller fraction of the total carbon pool in the diet of herbivores, particularly mminants which get much of their energy from digestion of cellulose. Humans who selectively use seeds and grains as food sources obtain a... 

Herbivores typically eat diets with high carbohydrate and low protein and lipid. F is about 0.15, and the protein is mainly plant derived and not very different in S C from the non-protein (i.e., Dp is close to Dn). For carnivores, F is typically 0.5 or over, and carbohydrate is low. Animal protein is generally isotopically heavier, while the non-protein is much higher in lipid, so that Dp - Dn is generally quite large (>5%o). The spacing, Bcolla Bcarb. for the two diets is evaluated according to the equation above. 

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