Thanks for providing that, Kallyn.
I can see the reasoning for this precaution. The comments by the foundation indicate that the letter was written early in his career, before coming across groups who were eating high meat & fat diets, which explains the over-emphasis on grain foods recommendations.
I'd like to emphasize this excerpt from the WAPF recent response to the Cannell/D-camp recommendation to avoid cod liver oil (and indirectly all foods high in pre-formed retinols):
The statement that preformed vitamin A is unnatural is ludicrous in the light of what we know about traditional diets. The chief source of calories in the traditional Inuit diet, for example, is seal oil, which Weston Price found to be higher in vitamin A than cod liver oil. Fish heads, extremely rich in vitamin A, are a staple in the Japanese diet. Many cultures consume liver, often in high amounts—yet the authors of the review paper imply that liver is toxic. Tell that to the Frenchman enjoying his foie gras, the Englishman consuming liver and onions, or the South Sea Islander who submits to great danger to obtain shark liver for men and women, in order to ensure healthy children. The truth is that pre-formed vitamin A is more plentiful in traditional foods than vitamin D, yet politically correct nutrition insists that we must obtain vitamin A through the laborious process of converting carotenes.
Price documented that the Inuit were able to produce excellent offspring evidenced by their wide facial structure and excellent dental arches and sturdy healthy bodies. Consumption of seal oil on probably a daily basis with all the rich pre-formed retinols (vitamin A), it seems logical to conclude, played a role in this success and did not play a detrimental role in the presence of other synergistic elements found in the whole foods they consumed.
I consume small portions of beef liver on an almost daily basis, and I always find that I feel better by doing so, almost immediately. I also don't appear to be experiencing signs or symptoms of vitamin A toxicity, as I also ensure I'm obtaining adequate minerals and the other synergistic fat-soluble activators D & K2.
I realize I'm coming off as a bit of a WAPF-fanatic, but the principles they put forth make a lot of sense to me, and put into practice have only helped to increase my level of health.
I'm more inclined to believe the accounts of Price on real living people living off traditional diets than the studies presented by Cannell and the D-camp that rely mostly on studies using isolated nutrients (at times synthetic) and experiments that by their very nature do not take into account the full complexity of the human body.
As a personal testament, I can confidently say that I observe expression of VDR activation with adequate vitamin D supplementation even when I continue to consume a diet fortified with nutrient-dense foods like liver and many egg yolks that also contain higher levels of pre-formed vitamin A. This again makes it difficult for me to believe the claims by the D-camp that pre-formed vitamin A intake directly antagonizes the action of vitamin D in the body. Again, the explanations provided by the WAPF regarding nutrient synergy win out for me again, unbiasedly based on actual personal observation.