One interesting factor with much of Patrick Holford‘s work it the sheer amount of time that it takes to check its claims properly. Dealing with Holford’s statements in one, short, Manchester Evening News article has lead to me reading more than I’d ever wanted about fish cooking and Shinga doing some detailed reading and writing about MSM. This article just gives and gives, though – Coracle, from the awayfromthebench blog – has carried out a review of Holford’s claims in the Manchester Evening News. And, very kindly, e-mailed it to me to post here. So here it is – enjoy:
Not that long ago Patrick Holford was extensively quoted in an article about allergic rhinitis in the Manchester Evening News. In the article Mr Holford makes claims for a number of supplements he believes to be effective in the management of allergic rhinitis. It has already been pointed out that some of his advice is dubious, it therefore follows that the other claims by him should be subjected to critical analysis. Here I will attempt an amateur systematic review of the evidence for the recommended supplements.
The terms used in the original article were used to search the pubmed database (www.ncbi.nlm.nih.gov/pubmed) in conjunction with the phrase “allergic rhinitis”. Where freely available, full text articles were retrieved. When full text articles were not available abstracts alone were used. Previous reviews of the area were not included although observational studies were.
Vitamin C Three clinical trials involving ascorbic acid for allergic rhinitis were identified. Each trial measured different outcomes and were of small size. Bucca et al (1990) found that 2g of vitamin C a day improved forced expiratory volume. A small trial using a range of doses found no benefit for vitamin C up to doses of 4 g a day when testing histamine response and skin wheal (Fortner et al, 1982). The largest trial found an improvement in allergic symptoms when treated with vitamin C (Podoshin et al, 1991). However, the details of this study are particularly sparse, it is not clear whether the trial was placebo controlled, what dose or doses of vitamin C were administered, nor for how long. A single observational study failed to find an association between plasma vitamin C levels and allergic rhinitis (Kampauer et al, 2006).
|Reference||n||Dose (g)||Measured outcome||Favoured Intervention|
|Fortner||6||1, 2 or 4||Skin wheel/ histamine||Neither|
Table 1: Summary of evidence for Vitamin C in allergic rhinitis. FEV, forced expiratory volume. NR, not reported.
Searching for omega 3 and allergic rhinitis returned the greatest number of hits for any of the interventions. Four observational studies and two clinical trials were identified. The results of the trials were equivocal, the larger trial found no benefit for fish oils in comparison to an olive oil placebo (Thien et al, 1993) when looking at occupational and recreational antigen challenge. The smaller of the two trials found benefit for EPA when compared to no dose in direct antigen challenge. The two studies used very similar doses of EPA and the larger trial was conducted for longer and in a real-world environment rather than a clinical setting. The four observational trials identified produce no clear pattern of benefit for omega-3 oils. The smallest trial found benefit for omega-3 with odds-ratio of 0.5 for the highest qurtile intake compared to the lowest quartile intake (Hoff et al, 2005). Kompauer et al (2005) failed to find any relationship between allergic rhinitis and omega-3 intake in a study of 740 adults. In a survey of 4104 children an increased risk of wheezing was associated with higher intake of fats in the form of margarine and butter (Farchi et al, 2003). The largest of the observational studies found that high ratios of n6:n3 omega fatty acids increased the risk of hay fever in males, and a higher total fat intake was associated with increased risk of hay fever in females (Trak-Fellermeier et al, 2004).
|Reference||n||dose (g)||Measured Outcome||Favoured Intervention||Type|
|Thien||37||3.5 EPA/day, 6 months||Histamine levels||None||Placebo controlled trial|
|Rangi||7||3.5 EPA/day, 8 weeks||Nasal blood flow, eosinophils, symptoms||omega-3||Placebo controlled trial|
|Kompauer||740||N/A||Hayfever, allergic sensitisation, total IgE||No benefit for omega-3||observational|
|Farchi||4104||N/A||Wheezing and allergic rhinitis||Increased risk with increased fat intake||observational|
|Trak-Fellermeier||802||N/A||Hayfever, allergic sensitisation||Higher risk associated with higher n6:n3 ratio||observational|
Table 2: Summary of evidence for omega 3 oils in allergic rhinitis. EPA, Eicosapentanoic acid. N/A, not applicable.
Searching for Quercitin returned two clinical trials. One, involving a combination antihistamine had no abstract and so was excluded from analysis (Miller, 1963). The other was a trial of Artemisia abrotanum L. extract in 12 patients (Remberg et al, 2004). No control group is reported. Reductions in nasal and conjunctival symptoms were reported. The concentration of flavenols, of which Quercitin is one, was reported at 2.5 microg/ml. No estimation of total Quercitin content or delivered dose is reported in the abstract.
A single clinical trial of Methylsulphonylmethane was retrieved from Pubmed. 55 subjects were recruited for an open-label trial for 30 days. Significant decreases in allergic symptoms were found in comparison to baseline (Barrageret al, 2002). Glutamine No reports were returned when searching for Glutamine and allergic rhinitis. Bromelain Only one experimental paper involving Bromelain for allergic rhinitis was found. One Rather than use as an anti-allergic agent, in this research Bromelain was used as an aggravating agent in mice. Inhibited and active forms of Bromelain were investigated and active forms were more potent in inducing sneezing and nasal rubbing (Suzuki et al, 2006).
Allergic rhinitis is an unpleasant condition that affects approximately 16% of the UK population (Savage and Roy, 2005) and is increasingly common (Gupta et al, 2007). Dietary interventions have been recommended for the management of allergic rhinitis symptoms in areas of the lay press. The provision of evidence-based advice is important for the relief of symptomatic suffering. Here I have systematically reviewed the evidence for dietary intervention. Six dietary interventions were examined in the management of allergic rhinitis. The evidence base is generally poor, clinical trials are generally of small sizes and not always placebo controlled or blinded. The most evidence exists for vitamin C and omega 3 fatty acids. However, these trials are not uniform in the outcomes measured or their results. Only two clinical trials were reported for omega-3 oil intervention and the larger of the two reported no benefit for omega-3. The results of the observational studies were similarly conflicting with the largest study reporting increased risk of hay fever with increased fat intake. Of the other interventions the evidence was limited and of poor quality. Some reported benefit was found for Quercitin and MSM and the recommendation of Bromelain intervention appears to be counter-intuitive. No evidence was found for the non-essential amino-acid and the therapeutic rationale for taking supplements of crystalline glutamine, that could otherwise be provided by a balanced diet, is unclear. This study has been limited by the lack of full text articles. All analysis on the results has been based on content provided by the text of the report abstracts. Further information provided by full text articles may have provided a clearer picture of the results. The possibility of abstract bias, in which positive outcomes may be emphasised in the the abstract, cannot be discounted. However, abstract-bias cannot likewise estimated without full text availability. In conclusion there is insufficient evidence to recommend any of the dietary supplements suggested by Patrick Holford.
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Bucca, C, G Rolla, A Oliva, and J C Farina. 1990. Effect of vitamin C on histamine bronchial responsiveness of patients with allergic rhinitis. Annals of allergy 65, no. 4 (October): 311-4.
Farchi, S, F Forastiere, N Agabiti, G Corbo, R Pistelli, C Fortes, et al. 2003. Dietary factors associated with wheezing and allergic rhinitis in children. The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology 22, no. 5 (November): 772-80.
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Hoff, S, H Seiler, J Heinrich, I Kompauer, A Nieters, N Becker, et al. 2005.Allergic sensitisation and allergic rhinitis are associated with n-3 polyunsaturated fatty acids in the diet and in red blood cell membranes. European journal of clinical nutrition 59, no. 9 (September): 1071-80.
Kompauer, Iris, Hans Demmelmair, Berthold Koletzko, Gabriele Bolte, Jakob Linseisen, and Joachim Heinrich. 2005. Association of fatty acids in serum phospholipids with hay fever, specific and total immunoglobulin E. The British journal of nutrition 93, no. 4 (April): 529-35.
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Thien, F C, J M Mencia-Huerta, and T H Lee. 1993. Dietary fish oil effects on seasonal hay fever and asthma in pollen-sensitive subjects. The American review of respiratory disease 147, no. 5 (May): 1138-43.
Trak-Fellermeier, M A, S Brasche, G Winkler, B Koletzko, and J Heinrich. 2004. Food and fatty acid intake and atopic disease in adults. The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology 23, no. 4 (April): 575-82.