The major food sources for LA are sunflower, safflower, corn, and soybean oils. LA can also be converted to another fatty acid called omega 6 arachidonic acid (AA) found in meats and animal products. LNA is found in walnuts, dark, leafy green vegetables, flaxseed, canola and soybean oils.
LNA can be converted at various rates to other omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). You may have seen these on fish oil supplement labels. We can get EPA and DHA directly by eating fish and fish oils or by taking supplements.
So far the major lipid players consist of LA and AA that are omega-6 fats and LNA, EPA and DHA that are omega-3 fats. For those of you who are still with me, that’s the hard part. For keeping this simple, this post will mainly concentrate on the functions of the three and six families, with little to none of the nine family.
Is Fish a Brain Food?
The fact remains that nutrition science is becoming more aware of the impact of lifestyle factors in the prevention of chronic diseases. The overall number of Americans afflicted with dementia is expected to triple by the year 2050. Whether you become a victim has a lot to do with your health behavior patterns.
Recently there was a major study in 2019 that looked at the effects of certain foods and food components on cognitive function. A group of 116 elderly Americans with an average age of 69 underwent cognitive testing, MRI scans to assess brain function and structure, and blood tests to assess nutrient status.
The Results: The results identified six categories of nutrients found in the blood associated with enhanced cognitive performance that measured general intelligence, executive function, and memory. The nutrients associated with improved cognitive performance included carotenoids (antioxidants), folate, B6, B12, Vitamin D, and a healthy balance or ratio of omega-3 to omega-6 fatty acids.
MRI imaging revealed enhanced brain network connectivity in those with healthy balances of omega-6/omega-3 fatty acids which will be the focus of this post. For those who had more vascular risk factors (smoking, high blood pressure, diabetes, and obesity) the MRI imaging showed greater brain shrinkage and less gray and white matter in brain tissues.
What is a balanced ratio of omega 6 to omega 3 fats in the diet?
Most modern diets contain excessive amounts of omega-6s and insufficient amounts of omega-3s. Americans regularly eat processed food and vegetable oils but eat fish infrequently so we end up with many more omega-6s and fewer omega-3s.
The recommended ratio of omega-6 to omega-3 fatty acids in the diet is 4:1 or less, ideally 1:1. On average in the U.S., the omega-6 to omega-3 ratio is a disastrous 16:1.
Therefore, although omega-6 fats are essential in the right quantities, most people in the developed world should aim to reduce their omega-6 intake. Refined vegetable fats such as soybean oil are used in cookies, crackers, sweets, salad dressings and most fried foods. For example, a meal from a fast food restaurant consisting of a fried chicken sandwich and salad can result in over 17000 mg of omega-6 fats being eaten. And it gets worse. One serving of crunchy onion rings contain 30, 989 mg. of omega-6 (from Applebee’s). If you have a salad with soybean or safflower oil dressing, you’d consume about 7,200 mg of additional omega-6 fats. In contrast, a typical serving of wild salmon may provide 2,000 mg of omega-3.
Top 9 Foods with the Highest Omega 3 to Omega 6 Ratio (Try to get close to a 4:1 ratio)
|Food||Ratio of Three to Six|
|Snow crab (3 oz)||61:1|
|Atlantic cod (6 oz)||29:1|
|Tuna (6 oz)||25 :1|
|Mussels (3 oz)||25:1|
|Broccoli Rabe (1 cup)||7:1|
|Spinach (1 cup)||5:1|
|Flax seeds (1 oz)||4:1|
|Mangos (1 cup)||3;1|
|Lettuce (1 cup)||2:1|
The authors of this 2019 study advocate for drastic reductions in ingested omega 6 and increases in omega 3. They advise that for each milligram of omega 6 that you eat, consume about an equal amount of omega-3 fats. That may prove difficult in our current U.S. food environment. This is especially true if you are not a fish lover. Although not a fan of dietary supplements, in this case, a good quality supplement of fish oils (EPA and DHA) may be prudent. Look for brands with the USP label or the Consumer Lab (CL) label for purity, safety and efficacy. A major supplement provider recommends 2400 mg a day of fish oils (EPA/DHA. (Life Extension)
But wait, there’s more! What in the Heck are Eicosanoids and How Do they Function in the Body?
Omega-6 fatty acids produce compounds called eicosanoids from arachidonic acid (AA) that tend to favor higher blood pressure, more blood clotting, and inflammatory compounds in the body. These events are associated with a higher risk for heart disease. They are often referred to as “bad” eicosanoids.
Omega-3 fatty acids produce eicosanoids from EPA with opposing effects, i.e., lower blood pressure, less blood clotting, and anti-inflammatory effects. They are often referred to a “good” eicosanoids.
How do you help block excess arachidonic acid formation? By making sure your body has an adequate amount of EPA and LNA that compete with AA for an enzyme that acts as an inhibitor of the “bad” eicosanoids. The higher the EPA and LNA in the diet, the more the enzyme is inhibited and the less “bad” eicosanoids are produced
The Bottom Line:
What to do? Using olive oil in salad dressings and coconut oil for cooking is recommended. Olive oil contains monounsaturated fat and coconut oil is more stable since it has more saturated fat content. Neither of these participate in the production of eicosanoids as well as olive oil contains neutral fats from the nine family of fatty acids.
Eating less processed foods and/or fast foods goes a long way to bring that ratio from 16:1 closer to a healthier 4:1. Your heart and your brain may thank you.
Judith E. Brown. Nutrition Now Seventh Edition, 2013.
Life Extension, October 2019
Linus Pauling Institute, Oregon State University
Zwilling, CE, Talukdar T., Zamroziewicz, MK, et al. Nutrient biomarker patterns, cognitive function, and fMRI measures of network efficiency in the aging brain. Neuroimage. 2019, Mar;188:239-51.