With the remains of goat fur found on this site, one might intuitively suggest that goat meat was a significant component of the Ice Man’s diet. However, if this were the case, the stable nitrogen isotope composition of his hair should have been 3‰ enriched
relative to the goat d15 N value, and clearly this is not so. Rather, the d15N value for the Ice Man’s hair is approximately 3‰ enriched relative to the d15 N values of plants, indicating that plants were likely a primary component of his diet at the time of his death. The stable nitrogen isotope composition of the Ice Man is consistent with that observed for modern vegetarians with low levels of animal protein in their diet (Table 1) and who are depleted in 15 N by several per milligram relative to modern humans on omnivorous diets. The goat should reﬂect the vegan diet, being enriched by 3‰ over primary production. In all likelihood it does, but represents an integration of browsing on a variety of terrestrial plants, some of which may be more depleted in 15 N owing to nitrogen ﬁxation. The fact that the d 13 C value of the Ice Man was depleted in 13 C reﬂects a high percentage of grains in the diet that can be attributed to plants that utilized the C-3 pathway for photosynthesis (Table 1). In general, C-3 plants (e.g., wheat, rice, legumes) are depleted in 13 C by 5 to 15% relative to C-4 plants (e.g., corn) due to differences in enzymes used for the primary ﬁxation of carbon (e.g., ref 23). A similar preference for C-3 plants (or for organisms that subsisted on C-3 plants) was reﬂected in the diets of the other omnivores, all of which are expected to be enriched in 13 C by a few per milligram relative to their respective C-3 sources. Strict adherence to only vegetation is not suggested,however. Small amounts of animal protein in the diet, as well as variation in the isotopic signals of potential plant and animal foods, could be masked by the consumption of large amounts of plant proteins.
I have no doubt that it is in the interest of the diabetic (especially type 2 diabetic) to reduce the consumption of carbohydrates as needed. But I find it really comical whenever I see the insistence that man's original diet was near-zero-carb animal food based and that all, including non-diabetics should adopt this diet .