Annotated Medical Bibliography
By Dr. Alan Inglis, MD

Digging deeper into the vitamin A story was an eye opener. And here I want to emphasize that the main emphasis is on the active “retinoid” form of vitamin A, not the “pre-vitamin A” carotenoid forms found in fruits and vegetables. The active retinoid form is found animal foods -- mainly dairy foods and organ meats. The problem with the “pre vitamin A” found in fruits and vegetables is that in many people it is not successfully converted to the active “retinoid” form. I discuss this important insight in more detail in our vitamin A blog.

Research into vitamin A as an immune system booster and anti-infectious agent dates all the way back to the 1800s. And here’s where the story becomes really interesting. That’s because doctors and researchers focused their attentions on Cod Liver Oil! I still have patients tell me that yes, their mothers used to make them take cod liver oil because it was supposed to be good for you. Guess what’s in Cod Liver Oil? That’s right -- large amounts of vitamins A and D.   

By far the best writing and research I came across in my studies on these two vitamins are two companion articles Drs. Ash and Levine. I have heard Dr. Ash speak and he is a brilliant doctor and scientist as well as a fine lecturer. Here’s an excellent summary statements about the relationship between these two vitamins by his brilliant colleague, Dr. Steven Levine: “Most important, vitamins D and A are an ancient and inseparable team that evolution has honed through time. They must be supplemented together in order to not create a functional deficiency of either one. Excess D will create a “relative” deficiency of A, even when dietary levels are adequate. And vice versa.” (FOCUS August 2010)

So you can there are good reasons we’ve teamed up high potency doses of both Vitamin A and D in Dr. Schnuffie’s COLD + FLU. 

These two articles are supported by an excellent, extensive bibliography, if wish to study the subject even further:

Ash, Michael DO Vitamin A: The Key To a Tolerant Immune System FOCUS: Allergy Research Group August 2010and Levine, Steven PhD Why Vitamin D Is Not Enough FOCUS: Allergy Research Group August 2010

-- Dr. Alan Inglis


Calder PC, Kew S. The immune system: a target for functional foods? Br J Nutr. 2002 Nov; 88 Suppl 2:S165-77.

Cameron, HC The effect of vitamin A upon incidence and severity of colds among students. J. Am. Dietet. Assoc. 1935 11:189-204

Semba, RD, Clin Infect Dis. 1994 Sep;19(3):489-99. Vitamin A, immunity, and infection.

Sommer, Alfred Vitamin a deficiency and clinical disease: an historical overview. J Nutr , 2008 J. Nutr. April 1, 1999 vol. 129 no. 4 783-791

Wintergerst ES1, Maggini S, Hornig DH., Contribution of selected vitamins and trace elements to immune function. Ann Nutr Metab. 2007;51(4):301-23. Epub 2007 Aug 28.