The Vitamins – Part 1
The average North American is exposed each day to food with many different nutrients, preservatives, toxins, colourings, flavouring agents, and numerous miscellaneous other additives. While many of these items are individually designated ‘GRAS’ (generally regarded as safe), no studies have considered them in combination, or looked at their cumulative effect. Since a connection cannot be made between these items and specific findings in patients, comments in this article must hence be general rather than specific.
Almost by definition, nutrients are necessary for good health. This has led to the hypothesis that reduced nutrient levels may be associated with asthma. Sub-optimal intake of vitamins, magnesium, sodium and selenium are recognized as potential risk factors for asthma.1 Further, a reduced intake of essential nutrients may be associated with increased airway inflammation and subsequent heightened bronchial hyperreactivity. However, insufficient data are currently available to denote any of them as causal.
Many studies have addressed the topic of diet and its role in asthma. This brief review will attempt to summarize recent findings with respect to essential nutrients in diet and their possible role in asthma.
Vitamins A, C and E
- a free radical scavenger, it converts oxygen radicals to less reactive forms
- is found in tissue membranes
- comes as beta-carotene or provitamin A
- is an antioxidant
- reduces airway obstruction
- levels are inversely associated with airway obstruction
Research-based conclusion: Beneficial. Patients with brittle asthma had statistically significant lower dietary intakes of Vitamin A.
Vitamin C 1-5 * a free radical scavenger, it converts oxygen radicals to less reactive forms * is a major antioxidant * is found in extracellular lung fluid and lipid membranes * defends airways against oxidant attack * is related to lung function * causes a significant decrease in thesputum and cellular levels of mild asthmatics * raises FEV 1 levels as its intake increases * has a short-term protective effect on airway responsiveness
Research-based conclusion: Beneficial. Lowest intake of vitamin C increased BHR seven-fold and doubled the risk of adult-onset wheezy illness. Levels are significantly lower in brittle asthma. The literature does not support definite instructions for its use in asthma. Evidence from randomised-controlled trials is inadequate to recommend vitamin C in the treatment of asthma. 6
- inhibits IgE response to allergic stimuli
- isprotective against atopy
- tocopherol isoforms have opposing regulatory function
- γ-tocopherol is associated with lower lung function and increased allergy induced inflammation
- daily dietary intake of γ-tocopherol has anti-inflammatory effect particularly in neutrophilic asthma
- α-tocopherol is associated with improved lung function and decreased allergy induced inflammation
- higher intake (of vitamin E) was associated with lower serum IgE concentrations and a lower frequency of allergen sensitization
- dietary intake is positively correlated with lung function. Every 1-mg increase in daily intake resulted in a mean increase of 54 ml in FEV 1
Research-based conclusion: Beneficial. Lowest intake of vitamin E increased risk of adult-onset wheezy illness by five-fold.
Antioxidants, which include vitamins A, C and E, have been the focus of a number of studies. When looking at brittle asthma, Baker et al. 2 found that while subjects with asthma had lower intakes of Vitamin A and D than the other vitamins, they did not find much difference with other nutrients. Intake of magnesium, vitamins A and C below the safe level were more likely to be found in patients with brittle asthma.
A systematic review and meta-analysis was conducted by Allen and colleagues 10 to determine whether the vitamins A, C and E, measured as dietary intake or serum levels were associated with asthma. Their findings are shown in Table 1. They concluded that low dietary intake of the A and C vitamins was significantly associated with increased odds of asthma and wheeze while vitamin E did not relate to the status of asthma.
Using a random sample of 2,633 adults, Fogarty et al studied the relationship between dietary vitamin E, serum IgE and atopy. They found that higher concentrations of vitamin E intake were associated with lower serum IgE concentrations and lower frequency of positive skin tests. Their conclusions are cautious and do not suggest an increase in Vitamin E consumption; rather, they say merely that “. . .effect of vitamin E on IgE on atopy . . . justify closer investigation”. They did note that dietary ingestion of vitamin E was associated with a reduced occurrence of allergy and asthma. 9
Vitamin E in the isoform γ-tocotrienol has been found to be protective in allergic asthma. 11 Patients with mild atopic asthma who were given a high dose (1500 I.U.) oral supplement of acetate-conjugated d-α-tocopherol had improved airway responsiveness to a methacholine challenge. 7
According to a study on exercise-induced asthma by Kurti and colleagues, 12 both Vitamin C and E supplements had a beneficial effect on lung function after exercise by significantly improving
- FVC at the 5 minute mark
- FEV 1, PEFR and FEF25-75 at the 15 minute mark
- FEV1 and FEF25-75 at the 30 minute mark
Additionally, Vitamins B, C, D and E and polyunsaturated fatty acids may modify the negative effects of air pollution. 13
Consider the Vitamin D hypothesis that postulates an inverse correlation between serum vitamin D and asthma severity. Vitamin D 7 affects the immune system by
- enhancing the epithelial barrier function
- heightening chemokine secretion
- increasing production of antimicrobial peptides in macrophages
- inhibiting B cells and Ig production
Research-based conclusion: Serum vitamin D levels were found to be lower in patients with severe asthma compared to patients with mild or moderate asthma. It has thus been suggested that serum vitamin D may be useful in predicting the severity of asthma. 14 After Fares et al 15 did a systematic review of the benefits and harms of Vitamin D supplementation in pediatric asthma, they concluded that the current available evidence did not provide adequate information for a consensus either way.
. . . to be continued
- Baker JC, Ayres JG. Diet and asthma. Respir Med. 2000;94(10):925-34 Doi:10.1053/rmed.2000.0873
- Baker JC, Tunnicliffe WS, et al. Dietary antioxidants and magnesium in type 1 brittle asthma: a case control study. Thorax. 1999; 54: 115-118.
- Smit HA. Chronic obstructive pumonary disease, asthma and protective effects of food intake: from hypothesis to evidence? Respir Res 2001; 2(5):261-4
- Seaton, Devereux G. Diet, infection and wheezy illness: lessons from adults. Ped Aller Immunol 2000; 11(S13):37-40
- Kongerud J, Crissman K, et al. Ascorbic acid is decreased in induced sputum of mild asthmatics. Inhal Toxicol. 2003 Feb;15(2):101-9.
- Kaur B, Rowe BH, Arnold E. Vitamin C supplementation for asthma. Cochrane Database Syst Rev. 2009 Jan 21;(1):CD000993. doi: 10.1002/14651858.CD000993.pub3.
- Hernandez ML, Wagner JG et al. Vitamin E gamma-tocopherol reduces airway neurtophil recruitment after inhaled endotoxin challenge in rats and in healthy volunteers. Free Radic Biol Med. 2013 Jul; 60: 10.1016/j.freeradbiomed.2013.02.001.
- Fogarty A, Lewis S, Weiss S, Britton J. Dietary vitamin E, IgE concentrations and atopy. Lancet 2000; 356 (9241): 1573-4
- S Allen, J R Britton, J A Leonardi-Bee. Association between antioxidant vitamins and asthma outcome measures: systematic review and meta-analysis. Thorax 2009;64: 610-619 doi:10.1136/thx.2008.101469
- Peh HY, Ho WE, et al. Vitamin E Isoform γ-Tocotrienol down regulates house dust mite-induced asthma. J Immunol. 2015 Jul 15;195(2):437-44. doi: 10.4049/jimmunol.1500362.
- Cook-Mills JM, Avila PC. Vitamin E and D regulation of allergic asthma immunopathogenesis. Int Immunopharmacol. 2014 Nov;23(1):364-72. doi: 10.1016/j.intimp.2014.08.007.
- Kurti SP, Murphy JD, et al. Improved lung function following dietary antioxidant supplementation in exercise-induced asthmatics. Respir Physiol Neurobiol. 2016 Jan;220:95-101. doi: 10.1016/j.resp. 2015.09.012.
- Péter S, Holguin F et al. Nutritional solutions to reduce risks of negative health impacts of air pollution. Nutrients. 2015 Dec 10;7(12):10398-416. doi: 10.3390/nu7125539.
- Ismail AM, Aly SS, et al. Serum 25-hydroxyvitamin D and CD4+CD25(+high) FoxP3+ Regulatory T cell as predictors of severity of bronchial asthma in children. Egypt J Immunol. 2015;22(1):9-18.
- Fares MM, Alkhaled LH, et al. Vitamin D supplementation in children with asthma: a systematic review and meta-analysis. BMC Res Notes. 2015 Feb 3;8:23. doi: 10.1186/s13104-014-0961-3.