The human diet has been constantly changing over the centuries and so have our dietary sources of fatty acids. Research indicates that the diet of our ‘hunter-gatherer’ ancestors was relatively low in saturated fat but contained special kinds of polyunsaturated fats (omega-3 and omega-6) that are crucial to brain development and immune function. The ratio of omega-6 to omega-3 in the diet at that time is thought to have been between 1:1 and 4:1, and our physiology has changed relatively little since then.
With the increased consumption of saturated fat and trans fats (artificially saturated fats found in many processed foods) and lower consumption of foods high in omega-3 fatty acids, this omega-6 to omega-3 ratio currently ranges from 14:1 to approximately 20:1 in the modern western diet.
Why does this matter for people with allergies?
This relative deficiency of omega-3 fatty acids (and the high level of saturated and trans fats) has been linked with many physical health problems, including heart disease and stroke, cancer, inflammatory conditions, auto-immune diseases and the increased risk of allergic diseases.
During pregnancy and infancy, a good supply of long-chain omega-3 fatty acids (known as EPA and DHA) are needed for healthy brain development and function. Higher intakes of fish and seafood by mothers during pregnancy are also associated with a lower risk of asthma and allergic diseases in their children. Although research is ongoing, the current evidence suggests that maternal dietary omega-3 intake may have a positive allergy protective effect on the mother’s child.
Omega-3 fatty acids have also been associated with a decrease in allergic diseases, specifically asthma, rhinitis and aeroallergen sensitisation in adolescents. A recent cohort study published in the Journal of Allergy and Clinical Immunology and conducted in Sweden by Magnusson et al, (2018) found a positive association between omega-3 levels and allergic diseases after blood samples were taken at age 8 and again at age 16. Read the abstract and full article here .
Getting the balance right.
Achieving a desirable ratio of omega-6 to omega-3 in one’s diet need not be difficult, expensive or complicated.
Increasing dietary intake of fish to twice per week, one of which should be an oily fish and decreasing saturated fat intake, mainly from meat and dairy products, would go a long way. Eliminating products that contain trans fatty acids, mainly from processed foods, would be optimal.