Nutritional Therapists have long been aware that the role of single nutrient therapy in the prevention or resolution of common rhino Viruses has had poor research conclusions but plenty of anecdotal support. In addition to Vit C Vit D and others the long-time favourite is Zinc.
The Cochrane reviews a well-respected albeit confrontational group that does meta-analysis of studies – sort of reinventing others work without having to do the study and then pronouncing a collective opinion have fallen on the side of the humble nutrient Zinc.[1]
They conclude:
Zinc administered within 24 hours of onset of symptoms reduces the duration and severity of the common cold in healthy people. When supplemented for at least five months, it reduces cold incidence, school absenteeism and prescription of antibiotics in children. There is potential for zinc lozenges to produce side effects. In view of this and the differences in study populations, dosages, formulations and duration of treatment, it is difficult to make firm recommendations about the dose, formulation and duration that should be used.
Of course making recommendations about which form, dose and cofactor nutrients is exactly the role of Nutritional Therapists. We all recognise genetic variability in the need for zinc and in the tolerance of the format and also understand that the zinc taste test is a useful clinical tool for identifying need and repletion status.
None of these studies used the ZTT prior to supplementing and this raises the question, would supplementation to meet the individuals actual need produce a better immune outcome than a simple across the board supplement, and would additional nutrients that interact with zinc such as copper and vitamin A and C.
Typical symptoms linked to zinc deficiency
Because of the link between zinc and the taste-related protein called gustin, impaired sense of taste and/or smell are common symptoms of zinc deficiency. Depression, lack of appetite, growth failure in children, and frequent colds and infections can also be symptomatic of insufficient dietary zinc.
Comment
There remains a sense in research that nutrients should be tested like medicines – in isolation against a set endpoint. Useful though this may be nutrients do not operate in isolation and individual needs based on Dr Ames Triage theory means that minimum RDA levels will not satisfy unique genetic requirements. Complex nutrient combinations designed to counter adverse effects and to assist absorption in the face of compromised digestive function as well as well-designed cofactors is what mostly sets apart professional supplement manufacturers from those offering cheap poorly tolerated formats.
Explain that zinc reduced the average duration of cold symptoms by nearly a day when taken within 24 hours of symptom onset, and also eased symptom severity.
Reference
[1] Singh M, Das R “Zinc for the common cold” Cochrane Database Syst Rev 2011; DOI: 10.1002/14651858.CD001364.pub3. View Abstract
