Can a Healthy Diet Protect Us from Air Pollution?
Air pollution can be highly localized and has the potential to affect us all. The Air Pollution Quality Index website provides real-time data on air quality in a particular location based on the PM2.5 particle size, which refers specifically to fine particles in the air that have a diameter smaller than 2.5 micrometers. Fine particles are considered to be more dangerous than larger particles such as dust, as their small size means that they can lodge deep in the lungs. While there are many substances in the air that can reduce its quality, PM2.5 particles make up one of six “indicators” of air quality according to the US EPA, the others being the nitrogen oxides, carbon dioxide, sulfur dioxide, lead and ozone.
The Air Pollution Quality Index measures the quality of the air outside and is primarily affected by the amount of traffic and the types of emissions from combustion activities by industry. Indoor air quality, on the other hand, can be greatly affected by the use of open fires in the home (which is estimated to affect around half the world’s population, according to the World Health Organisation), and poor ventilation. Air pollution causes 4.3 million premature deaths each year, mostly from pneumonia, stroke, heart disease, chronic obstructive pulmonary disease and lung cancer. Asthma and some allergies are also affected by air pollution and are a considerable health issue in their own right.
One way to reduce the health effects of PM2.5 particles is to prevent them from being released into the air in the first place. Various options exist to reduce the use of open fires in developing countries, and sealed roads prevent dust being produced. In economically advanced countries, special filters on car and truck exhausts plus strict controls on industry emissions from combustion and dust-producing activities improve air quality.
However, unusual as it may seem, a healthy diet may also protect us as individuals from the effects of air pollution. Many of the negative health consequences of air pollution are linked to an exacerbated inflammatory response, which can be modulated through the diet. Péter and co-workers have summarized evidence linking micronutrients with protection from air pollution, and bring to attention the following studies:
Omega-3 supplements, particularly fish oil, modulated negative effects of air pollution on oxidative stress markers (Romieu et al.)
Omega-3 supplements prevented negative air pollution-related changes to cardiovascular disease markers (Tong et al.)
PM2.5 increased heart rate variability only in people with low intakes of vitamins B6, B12 and the related amino acid methionine (Baccarelli et al.), and this relationship was modified by genetic polymorphisms.
Levels of antioxidants were low in coal electric-power plant workers compared to people living in the community. A vitamin C and E intervention for six months normalized antioxidant levels (Possamai et al.).
Supplementation with sulforaphane from broccoli increased the expression of antioxidant enzymes in airway cells (Riedl et al.) and reduced the allergic response to particles from a diesel exhaust (Heber et al.).
The research in this field is evolving rapidly, especially in the field of nutrigenomics. And the reduction of particulate matter in the air is a global health concern. But some advice for reducing the effects of air pollution is common sense. Eat your vegetables, and make sure that you get enough vitamins, minerals and omega-3, for general health and the health of your lungs.
Szabolcs Péter, Fernando Holguin, Lisa G. Wood, Jane E. Clougherty, Daniel Raederstorff, Magda Antal, Peter Weber and Manfred Eggersdorfer. Nutritional Solutions to Reduce Risks of Negative Health Impacts of Air Pollution. Nutrients 2015, 7(12), 10398-10416; doi:10.3390/nu7125539
Baccarelli A, Cassano PA, Litonjua A, Park SK, Suh H, Sparrow D, Vokonas P, Schwartz J. Cardiac autonomic dysfunction: effects from particulate air pollution and protection by dietary methyl nutrients and metabolic polymorphisms. Circulation. 2008 Apr 8;117(14):1802-9. doi: 10.1161/CIRCULATIONAHA.107.726067. Epub 2008 Mar 31. http://www.ncbi.nlm.nih.gov/pubmed/18378616
Sulforaphane-rich broccoli sprout extract attenuates nasal allergic response to diesel exhaust particles. Heber D, Li Z, Garcia-Lloret M, Wong AM, Lee TY, Thames G, Krak M, Zhang Y, Nel A. Food Funct. 2014 Jan;5(1):35-41. doi: 10.1039/c3fo60277j. http://www.ncbi.nlm.nih.gov/pubmed/24287881
Possamai FP, Júnior SÁ, Parisotto EB, Moratelli AM, Inácio DB, Garlet TR, Dal-Pizzol F, Filho DW. Antioxidant intervention compensates oxidative stress in blood of subjects exposed to emissions from a coal electric-power plant in South Brazil. Environ Toxicol Pharmacol. 2010 Sep;30(2):175-80. doi: 10.1016/j.etap.2010.05.006. Epub 2010 May 20. http://www.ncbi.nlm.nih.gov/pubmed/21787649
Riedl MA, Saxon A, Diaz-Sanchez D. Oral sulforaphane increases Phase II antioxidant enzymes in the human upper airway. Clin Immunol. 2009 Mar;130(3):244-51. doi: 10.1016/j.clim.2008.10.007. Epub 2008 Nov 22. http://www.ncbi.nlm.nih.gov/pubmed/19028145
Romieu I, Garcia-Esteban R, Sunyer J, Rios C, Alcaraz-Zubeldia M, Velasco SR, Holguin F. The effect of supplementation with omega-3 polyunsaturated fatty acids on markers of oxidative stress in elderly exposed to PM(2.5). Environ Health Perspect. 2008 Sep;116(9):1237-42. doi: 10.1289/ehp.10578. http://www.ncbi.nlm.nih.gov/pubmed/18795169
Tong H, Rappold AG, Diaz-Sanchez D, Steck SE, Berntsen J, Cascio WE, Devlin RB, Samet JM. Omega-3 fatty acid supplementation appears to attenuate particulate air pollution-induced cardiac effects and lipid changes in healthy middle-aged adults. Environ Health Perspect. 2012 Jul;120(7):952-7. doi: 10.1289/ehp.1104472. Epub 2012 Apr 19. http://www.ncbi.nlm.nih.gov/pubmed/22514211