WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
Dietary fats are essential to good health. Although it's harmful to eat too many of some or not enough of others, without healthy fats your body won't work properly.1 Fat is used to keep your skin and hair healthy, absorb certain vitamins and insulate your body to keep you warm. Certain types of fats are called "essential" since your body can't make them.
There are two major categories of polyunsaturated fatty acids (PUFAs). These are omega-3 (n-3) and omega-6 (n-6), which are essential fatty acids your body needs for a wide variety of cellular functions, including cell division, cognition, heart health and normal growth and development. Much of your dietary N-6 comes from vegetable oils like linoleic acid (LA), which converts to gamma linoleic acid during metabolism.2
Most related research has been focused on three important types of n-3: alpha-linolenic acid (ALA); docosahexaenoic acid (DHA); and eicosapentaenoic acid (EPA).3 ALA is commonly found in plants and plant-based oils, while EPA and DHA are produced by microalgae, which are then eaten by fish.
Thus, fatty fish, such as mackerel, wild-caught Alaskan salmon, herring and krill oils are rich sources. N-6 is associated with higher rates of inflammation in the body, while n-3 has an anti-inflammatory effect. However, neither n-6 nor LA is the underlying issue in the proliferation of disease but, rather, the oxidized form of the fatty acid found in processed vegetable oils.
Consequences of the Dramatic Shift From Omega-3 to Omega-6
The ratio of n-6 to n-3 in the diet began changing in the U.S. during the industrial revolution nearly 150 years ago.4 The onset of vegetable oil production and an increase in feeding cereal grains to livestock increased the ratio from what had been close to 1-to-1 to 10.3-to-1 and higher. Some estimate the current average ratio in the U.S. is 25-to-1.5
Where sources of n-6 used to come from whole foods, such as nuts and seeds, the modern intake of processed foods and oxidized vegetable oils has unbalanced the ratio for those eating a Western diet. This fatty acid imbalance is one root of inflammatory diseases including heart disease, diabetes and cancer.
A primary source of n-6 in the American diet is soybean oil, which accounts for 60% of all vegetable oils found in processed foods, salad dressings, snacks and margarine.6 Researchers link diets high in soybean oil with obesity and Type 2 diabetes; both of those are associated with heart disease, neuropathy, impaired cognition7 and early death.
One of the challenges in finding the balance is that n-3 and n-6 compete for the same enzymes. With so much n-6 in the body, the conversion of n-3 ALA (found in plants) to EPA and DHA is significantly impacted. This is something we have to be mindful of because EPA and DHA are both responsible for protecting the body against disease.8 The good news is that with a greater intake of n-3 there is a reduction in the buildup of n-6, effectively reducing inflammation.
Favoring Vegetable Oil Over Saturated Fat Harms Heart Health
Balancing your n-3 to n-6 ratio helps protect your body against chronic degenerative diseases such as metabolic syndrome, arthritis, irritable bowel syndrome and autoimmunity. This is a point I have stressed for many years, as it also reduces your risk for heart disease.
As I've written in past articles, consuming oxidized LA in vegetable oils leads to a cascade of events promoting inflammation and creating atherosclerotic plaques; all of this leads to a higher risk of heart attack and stroke.
Unfortunately, health authorities have insisted that vegetable oils are healthier than saturated animal fats such as those found in butter and lard, despite research evidence to the contrary.
A study published in the BMJ in 20139 demonstrated that men with a history of coronary events, such as heart attack or angina, had a higher risk of dying from heart disease when advised to reduce saturated fats and increase their intake of LA from safflower oil and safflower oil polyunsaturated margarine.
It is important to remember that LA is also found in nuts, seeds and eggs. But the sheer volume of intake from processed foods creates a severe imbalance in the ratio. The combination of increased intake with the oxidized fats in vegetable oils is a significant factor in the rising number of those who develop heart disease.
Balancing Ratio May Help Protect Against Air Pollution
Exposure to air pollution also increases the risk of inflammation. In one study,10 researchers found that children who had a higher intake of n-3 had a lower response to particulate matter and appeared to be more resilient.
This study has added to the growing body of evidence that suggests dietary intake has an influence on the body's response to air pollution, a known cause of inflammation. The authors of another study11 conducted in Mexico City found that for children with asthma, supplementation with antioxidants helps with the impact of air pollution on their small airways.
Problems Converting Omega-3 from Plants Increases Risk
N-3 fats are present in plant and marine animals like fish and krill. However, the types of n-3 are different and they are not interchangeable. Plant-based n-3 contains alpha linoleic acid (ALA), which is a short chain and must be converted to long chain EPA and DHA for use in the body.
Since the enzyme needed for conversion is not highly active in most people, the conversion rate is low. This information is particularly relevant for strict vegans and vegetarians who may believe their body converts plant-based ALA to EPA and DHA in sufficient amounts. It is nearly impossible to get enough this way, and the minor amount theoretically taking place is hindered when the diet contains excessive amounts of n-6 from vegetable oils and processed foods.
Importance of Getting Tested
As I've written before, omega-3 fatty acid testing is needed to determine if you're deficient. The n-3 index test provides the most accurate measurement in the body and should ideally be above 8%. The index measures the amount of n-3 in the red blood cells as a reflection of how much is found in the rest of the body.
Since the test measures the average of your intake based on the lifespan of a red blood cell over 120 days, it is not influenced by recent meals and is expressed as a percent of all fatty acids found in the red blood cell membrane. Researchers find the index to be accurate and they use it analyze data, including that of the Framingham Study and the Women's Health Initiative.
Maintaining the level in a range associated with low risk reduces your chance of heart disease. Those with an index below 4% have a high risk; those with an index from 4% to 8% have an intermediate risk and those with an index greater than 8% have a lower risk for coronary heart disease.12
In a follow-up study13 using a randomized control trial to assess the effects of supplementation on telomere length and oxidative stress, researchers found telomere length increased with a decreasing ratio of n-6 to n-3. They suggest that even over a short time, the ratio has an impact on cell aging and may influence asthma symptoms, the risk of Parkinson's disease, multiple sclerosis symptoms and depression.
Safely Raise Your Omega-3 Intake
After being tested, if it turns out you need more n-3, consider ways to raise it without adding toxins to the mix. These are great sources of omega-3:
• Fish — Small, cold-water fatty fish such as anchovies and sardines are excellent sources of n-3 that have a low risk of hazardous contamination. Wild Alaskan salmon is also low in mercury and other environmental toxins.
Since much of the fish supply is heavily polluted with industrial waste, including heavy metals such as arsenic, cadmium, lead, mercury and radioactive poisons, it is extremely important to be selective, choosing fish high in healthy fats and low in contaminants, such as wild-caught Alaskan salmon, mackerel, herring and anchovies.
• Krill oil — Krill oil is my preferred choice as an n-3 supplement because it has the indispensable animal-based DHA and EPA n-3s your body needs, and in a form that's less prone to oxidation.
With the help of phospholipids, the nutrients in krill oil are carried directly to your cell membranes where they are more readily absorbed. Additionally, they may cross your blood-brain barrier to reach important brain structures.
While the following sources may be tempting because they are readily available and less costly than the ones mentioned above, I strongly advise avoiding:
• Farmed salmon — It contains about half the n-3 levels of wild salmon, is often fed a genetically engineered diet of corn and soy products and may contain antibiotics, pesticides and other chemical toxins.
• Large carnivorous fish — Marlin, swordfish and tuna (including canned tuna), for example, tend to contain some of the highest concentrations of mercury, a known neurotoxin.
• Fish oil — While fish oil may appear to be a convenient and relatively inexpensive way to increase your intake of n-3 fats, it typically delivers insufficient antioxidant support. It is also highly prone to oxidation, leading to the formation of harmful free radicals.