New research indicates the benefits of eating omega-3 fatty acids, but also that pollution particles can penetrate the lungs into many organs, including testicles
Supplements of healthy fats could be an immediate way of cutting the harm caused to billions around the world by air pollution, according to emerging research.
However, the research also shows air pollution particles can penetrate through the lungs of lab animals into many major organs, including the brain and testicles. This raises the possibility that the health damage caused by toxic air is even greater than currently known.
The new research on mice showed that omega-3 fatty acids (OFAs), found in flax, hemp and fish oils, can both prevent and treat the inflammation and oxidative stress caused by air pollution, with the OFAs delivering a 30-50% reduction in harm.
Air pollution around the world is rising at an alarming rate, according to the World Health Organization, with virtually all cities in poorer nations blighted by unhealthy air and more than half of those in richer countries also suffering.
Low air quality has long been linked to lung and heart disease and strokes, but scientists are now uncovering links to brain problems such as dementia, mental illness and reduced intelligence, as well as diabetes, kidney disease and premature births.
Dr Jing Kang, at Massachusetts General Hospital, part of Harvard Medical School in the US, who led the research said: “These pathological changes are very important because they are the fundamental mechanisms for the common chronic diseases we have today.
“I can anticipate the same things [that happen in mice] would happen in humans, because many other inflammatory diseases in humans can be treated with OFAs. We feel very confident OFAs can do something very good.”
“I would definitely recommend taking OFAs to counter air pollution problems,” he said. “OFAs are well known to have many other healthy benefits and the key thing is they are not like a drug, but a nutrient with so many benefits.”
Kang said two to four grammes per day would be the equivalent dose in humans to that given to the mice. A small human trial in 2012 also indicated OFAs offered protection against the adverse effects of air pollution and the US Environmental Protection Agency has now begun a larger trial. There is also supporting evidence from work on human cells in the lab.
Two to four grammes of OFAs would be roughly equivalent to two 85g portions a day of salmon or herring, but the NHS recommends no more than one such portion a day and significantly less for children and pregnant women due to the risks of mercury and other pollutants in fish. Flax oil is about 50% OFA and OFA capsules are also widely available but the NHS says people should get medical advice before taking them.
Dr Richard Russell, a consultant respiratory physician in the NHS and medical adviser to the British Lung Foundation (BLF), said the new research from Kang’s team is “a thorough piece of work and the science is good”. But he added: “The findings need to be interpreted with some caution, given that responses in mice are quite different to humans.” He also noted the level of air pollution the mice were exposed to was high.
Nonetheless, Russell said: “There is an increasing amount of evidence showing that these fatty acids do have significant anti-inflammatory effects. Can they be recommended as a healthy thing to be supplementing the diet of us all? Yes, probably. They do not do harm and may well do good.”
Cutting air pollution at source is the ultimate solution to the problem, said Kang: “Pollution is a very critical issue for human health, but we cannot change the environment right away.” His team concluded that OFAs present “an immediate, practical solution for reducing the disease burden of air pollution”.
In September, a new inhaler that could protect the lungs was revealed, and the BLF recommends avoiding hotspots such as busy road junctions when pollution levels are high and reducing strenuous outdoor exercise.
In the experiments, Kang’s team exposed the mice to fluorescent particles of similar size to the tiny specks that form dangerous PM2.5 air pollution. This made it easier to track the progress of the particles through the bodies of the mice.
“Fine fluorescent particles were observed not only in the lungs but also in other organs, including the brain, liver, kidneys, spleen, and testes,” the researchers reported. “These results demonstrate that fine particles can penetrate the [lung] barrier and travel to other organs, potentially inducing systemic illnesses.”
The discovery of particles in the testes “is a concern for fertility and reproduction”, said Kang. Further research is needed to investigate whether this also occurs in men and the risk posed, but he said: “At least we know the particles can harbour in that type of tissue.”
Previous work in rats has found that nanoparticles are able to pass through the lungs into internal organs, but the particles used in Kang’s work are about 200 times larger. The discovery of “abundant” toxic nanoparticles from air pollution in human brains was revealed in September.
How much omega-3 fatty acids could protect against air pollution?
The research is at an early stage but the doctor leading the latest study, conducted in mice, said 2-4g of omega-3 fatty acids (O3FAs) would be the equivalent human dose. A small human trial found benefits from 3g of fish oil per day, though only some of which will be O3FAs.
Does this mean we should eat fish every day?
Two portions (85g) a day of salmon or herring would give roughly 3g of O3FAs a day, but the NHS recommends not more than one such portion a day and just three a week for pregnant women due to the risks of mercury and other pollutants in fish.
How else can you consume these fats?
Both flax and hemp seed oils are rich in O3FAs, with the former containing about 50%. Supplement capsules of O3FAs are also available and, while the fats are widely thought to the beneficial to health, the NHS says people should get medical advice before taking supplements.
Is food a better way to consume O3FAs than supplements?
A balanced and healthy diet is the best way to get the nutrients the body needs and there is some evidence that supplements do not provide the same benefits as O3FAs obtained from food.
What other measures can you take to protect against air pollution?
When air pollution is high, the British Lung Foundation advises avoiding hotspots such as main roads and strenuous outdoor exercise. If in a vehicle, the BLF says keep the windows closed and recycle the air. It says there is little evidence to recommend the use of face masks.
Can planting more trees and plants help cut air pollution?
Trees do reduce pollution, by 7-24% according to one recent study. But poorly planned trees could actually make things worse. If they are too close together along a street they can form a tunnel that traps traffic pollution and prevents the wind from dispersing it. Hedges and plants can help form physical barriers that protect gardens and playgrounds.