Diet and the Immune Response
We are what we eat! Dietary fats are used to construct every cell in the body. Cell membranes are made from fatty acids and serve as a protective barrier for eachand every cell. They protect the cell from its surroundings while facilitating cell-to-cell communication. Cell membranes also serve as a reservoir for fatty acids. This reservoir of fatty acids provides precursors to powerful hormone-like moleculesthat drive the body’s immune response and can promote anti-inflammatory activity.
The Standard American Diet
High in Omega-6
The Standard American Diet is rich in saturated fats, trans fatty acids, and arachidonic acid. Saturated fats and trans fatty acids result instiffer, non-permeable cell membranes, which reduce cellcommunication and limit adequate transport of nutrients into acell. Arachidonic acid is an Omega-6 fatty acid found primarilyin meat and dairy. Arachidonic acid is the precursor toimmune molecules that create inflammation and cancontribute to chronic inflammatory diseases such as heart disease.
Diet high in Essential Fatty Acids
Rich in Omega-3 and GLA
Omega-3 fatty acids are considered Essential Fatty Acids (EFAs) becausethey cannot be produced in the human body and therefore they mustbe obtained from the diet. Omega-3 fatty acids from fish are a directsource of EPA and DHA, two fatty acids vital for proper cellularfunction. EPA and GLA are precursors to immune molecules thatpromote a positive immune response and are the body’s strongestinflammation-reducing compounds. The American HeartAssociation recommends the consumption of Omega-3fatty acids to reduce risk factors associated withheart disease including hypertension, hightriglycerides, and atherosclerosis. Omega-3 fatty acids also reduce therisk of sudden cardiac death.
The immune system reacts differently, depending on the amount of Omega-3 in the cell membranes.
Inflammation is part of the healing process but it can get out of control. An immune response consists of acascade of events that is triggered when the body is subjected to trauma, allergens, toxic chemicals, ordisease. During the immune response, fatty acids are released from cell membranes within thetissue being protected. The fatty acids are quickly converted into hormone-like moleculesknown as Eicosanoids. There are different types of Eicosanoids, some of whichpromote aggressive inflammation, while others promote healing and decreaseinflammation. If the reservoir of fatty acids in the cell membrane has toomuch Omega-6 fatty acids, then a pro-inflammatory immune responsewill occur. If the reservoir has a healthy amount of Omega-3fattyacids, then an anti-inflammatory immune response will occur.
Trans fatty acids are new-to-nature molecules produced in thehydrogenation of vegetable oil. Trans fatty acids allow forincreased shelf life and crispness of processed foods suchas chips, cookies, fried foods, margarine and bakedgoods. Trans fatty acids are incorporated into the cellmembrane; however, the body does not know whatto do with them. They will disrupt the vitalfunctions of essential fatty acids, promoteatherosclerosis, raise cholesterol and trigly-cerides levels, and are strongly associatedwith an increased risk for heart disease.
The Standard American Diet, which consists of excess Omega-6fatty acids, trans fatty acids, and saturated fats, results in cellmembranes with a high proportion of these unhealthy fats. Whenthe immune system is triggered, these fats are released from thecell membrane and converted into pro-inflammatory Eicosanoidsincluding leukotriene-B4, thromboxane A2, and prostaglandin E2. These pro-inflammatory Eicosanoids initiate a cascade of negativeimmune responses and excessive inflammation. Chronic inflam-mation is directly related to most degenerative diseases.
A healthy whole foods diet rich in Omega-3 fatty acids from fish and fishoil results in a cell membrane with a high proportion of healthy fattyacids. When the immune system is triggered, EPA and DHA are releasedfrom the cell membrane and converted into anti-inflammatory Eicosanoidsincluding leukotriene-B5 and prostaglandin E3. These anti-inflammatory Eicosanoids initiate a cascade of beneficial immune effects and reduce the overall inflammatory response. Daily consumption of Omega-3 fattyacids is associated with a reduced risk for many chronic diseases and isrecommended in the current Dietary Guidelines for Americans publishedby the Department of Health and Human Services and the USDA.