If you follow the 2015 Dietary Guidelines for Americans or the equivalent Eatwell Guide in the UK, you are consuming ample amounts of vegetable oils, like soybean, corn, safflower and sunflower oils, to lower your cholesterol levels and reduce your risk of heart disease.
While these recommendations emphasize consuming vegetable oils, another extremely important type of fat—omega-3—is overlooked entirely. Omega-3 fats have long been considered 'heart healthy,' but not only are they not included in these guidelines, they're now being attacked in the press.
Many cardiologists no longer consider omega-3s heart healthy, and even Dr Eric Topol, editor-in-chief of Medscape, a respected clearinghouse for medical news, said, "I have an awful lot of patients that come to me on fish oil, and I implore them to stop taking it."
In fact, authorities would have us believe that fish oil isn't just useless—it's actually detrimental to health. It's even been accused by the American Cancer Society of increasing the risk of prostate cancer.
So-called 'vegetable oils' actually come from grains, beans and seeds such as corn, soybeans, sunflower kernels, and cotton and safflower seeds, and are often called industrial seed oils.
In order to extract large amounts of oil from things like soybeans and corn kernels—which aren't all that fatty in the first place—stunning amounts of heat and pressure are applied. These oils may be heated again in order to clarify, bleach and deodorize them before they're bottled.
Then, they sit on store shelves in clear plastic bottles, where they're exposed to bright lights almost around the clock. These fragile oils are exposed to the damaging trio of heat, light and air multiple times before they even get to the store, let alone when you use them in your home cooking.
Industrial seed oils are high in a particular type of polyunsaturated fatty acid called linoleic acid, which is considered an "essential" fat.
Since 1961, when the American Heart Association and then health agencies and government organizations around the world began advising people to swap out animal fats for vegetable oils, we've experienced a dramatic increase in our consumption of omega-6 linoleic acid.
Between 1909 and 1999, the estimated amount of linoleic acid consumed in the United States increased from approximately 2.8 percent to 7.2 percent of total calories—more than a 2.5-fold increase.1
This represents one of the single greatest changes that has occurred in the American diet during the 20th century.
The dramatic rise in linoleic acid consumption is due primarily to the use of soybean oil. Soybean oil is high in linoleic acid, and consumption of soybean oil increased over 1,000 percent from 1909 to 1999.2
In the early 1900s, our diet contained approximately equal amounts of omega-6 and omega-3 fats. Now, however, we eat almost 30 times as much omega-6 fat as we do omega-3.3
Fats are the building blocks for vital signaling molecules in your body—signals that can either help promote or help resolve inflammation. Omega-3 and omega-6 fats can both serve as building blocks for pro- and anti-inflammatory compounds, but generally speaking, omega-3s produce more anti-inflammatory compounds, while omega-6s produce more pro-inflammatory compounds.
Why are omega-6s so harmful?
There are four main factors that can damage a fat: heat, light, air and pressure. And the form this damage takes is oxidation.
Oxidation is responsible for causing chemical changes to fats—the fats in your foods as well as the fats in your body.
What we end up with when linoleic acid is oxidized is something called oxidized linoleic acid metabolites, or OXLAMs for short.
OXLAMs have been implicated in causing or worsening many health problems, including chronic pain, cardiovascular disease, and liver and neurodegenerative diseases.4
Since the Western diet is so heavily skewed toward omega-6, many people live in a constant state of inflammation, as if their body is constantly awash in damage and injury, but all that's really going on is excessive omega-6 and insufficient omega-3.
Chronic inflammation has been linked to rheumatoid arthritis, psoriasis, inflammatory bowel disease, hypertension, atherosclerosis, allergies, cancer and more.5
Fatty acids—all kinds, including saturated, monounsaturated and polyunsaturated (see box, right)—are the primary elements in all your cell membranes. Your cell membranes are like security guards defending the perimeter of every cell: they let in good things like vitamins and minerals, and keep out bad things like toxins and waste products.
If your cell membranes are going to do their job correctly, they must be built correctly. This means they have to have a healthy makeup of fats, and these fats have to be intact and undamaged.
When the fats in your cells become oxidized, it can set off a chain reaction that causes other biological molecules to become damaged as well, including DNA and proteins.6
Alzheimer's disease, Parkinson's disease and other neurological and neurodegenerative disorders have among their hallmarks the buildup of abnormal and malfunctioning proteins in the brain. These dysfunctional proteins might not be the primary causes of these conditions, but as they accumulate and reach toxic levels inside and outside cells, they certainly worsen the process.
Adding insult to cellular injury, the destructive chain reaction of oxidation and damage doesn't stay localized to just one cell. Most cells are close enough to each other that the molecules that cause oxidation—free radicals—can jump from one cell to another, and another, on and on, spreading like dominoes, until they reach an area that has enough antioxidants to neutralize them.7
Since cell membranes—especially the ones in your brain and central nervous system—are so rich with polyunsaturated fats, your body seems to interpret the oxidation of these fats as a signal that damage is occurring, and then tries to mount a response to repair that cellular damage.8
Damaged fats are like the alarm going off at a fire station, telling the firefighters to put on their gear and run to the truck. DHA (docosahexaenoic acid), the major omega-3 fat found in the brain, seems to be the canary in the coal mine in terms of sounding the oxidation alarm.
If a cell has been so highly damaged that it's safer for it to sacrifice itself rather than 'infect' nearby cells, it commits cellular suicide, a process called apoptosis. But if a cell membrane doesn't have enough DHA in it, the warning bells might never go off, leaving this damaged cell to leak more toxic molecules into its environment, harming its neighbors.
Many of the studies that concluded omega-3 fats have no impact on disease processes ignored the role of excessive omega-6 in the subjects' diets. It's not that omega-3s 'do nothing,' it's that it's almost impossible for them to make a difference against the surfeit of omega-6 they have to work against. It would be like firemen trying to put out an enormous blaze using coffee cups.
In order to offset the amount of omega-6 in most people's diets today, the studies would have had to give people about 4 grams of omega-3. But most studies used about 1 gram or even less.
The conversion process of omega-6 and omega-3 fats into other fats in the same families (see box, right) requires multiple steps, each one controlled by an enzyme. Various health conditions affect the activity of these enzymes.
The incidence of insulin resistance and type 2 diabetes has skyrocketed in recent years, with over half of American adults diagnosed with prediabetes or full-blown type 2 diabetes, and these conditions result in a reduction in the activity of one of these key conversion enzymes.9
On the other hand, insulin increases the actions of other enzymes involved in the conversion pathway. When the activity of the different enzymes is upregulated or downregulated—they're either working overtime or slacking on the job—the compounds produced along the way either accumulate or dwindle.
In the case of ALA (alpha-linoleic acid), the 'parent' omega-3 fatty acid, those downstream metabolites are the crucial factors that contribute to the synthesis of DHA and another critical omega-3 in the body, EPA (eicosapentaenoic acid), which are so lacking in our modern food supply.
People with chronic low-grade inflammation can be thought of as being in a state of EPA and DHA deficiency. Neurons in your brain are especially rich in DHA, so an inadequate DHA supply could also potentially contribute to cognitive problems.
Cognitive decline and Alzheimer's disease
DHA is believed to make up 30 to 50 percent of all the fats in the mammalian brain.10 DHA and EPA are also necessary for insulin signaling in your brain and central nervous system, which may be disrupted in Alzheimer's disease. Long-chain omega-3s are especially important for memory, cognitive function and brain plasticity.11
Patients with Alzheimer's disease have been found to have lower amounts of brain DHA compared to healthy individuals.12 Ten to 15 percent of patients with mild cognitive impairment will develop full-blown dementia within a year of being diagnosed, and these individuals were found to have low blood levels of EPA and DHA.13
In the Framingham Heart Study, which followed 899 men and women, all free of dementia at the start of the study, over nine years , the subjects whose DHA levels were the highest had a nearly 50 percent lower risk of developing dementia compared to subjects with the lowest levels.14
With DHA playing such a crucial role in the physical structure of neurons, it's not an exaggeration to say you cannot have healthy cognitive function without adequate DHA.
Studies show that eating a diet high in omega-3 results in higher concentrations of neurotransmitters, more receptors for these neurotransmitters (neurotransmitters don't do much good if they can't get into their target cells), increased neuron growth in the hippocampus (a brain region involved in learning and memory), higher concentrations of antioxidant enzymes, reduced concentrations of damaged brain-cell fats, better blood flow to the brain and better memory.15
A high intake of fish, which of course is rich in omega-3 fatty acids, is also associated with a lower risk of dementia and Alzheimer's disease.16 One study found that individuals who consume fish once a week or more had a 60 percent lower risk of being diagnosed with Alzheimer's compared to those who rarely or never eat fish.17
The role of insulin resistance
Alzheimer's disease and other forms of cognitive decline are also associated with a reduction in your brain's uptake and metabolism of glucose.
Glucose typically serves as your brain's primary fuel source, and PET scans show that Alzheimer's patients have substantial reductions in the brain's consumption of glucose (up to 20 percent in some areas).18
What this means is, some forms of dementia may simply be a result of the brain 'starving' for energy because of impaired insulin sensitivity.
Animal studies, which of course may not apply to humans, have shown that deficiency of long-chain DHA and EPA can reduce brain glucose uptake by as much as 30 to 40 percent.19
It's not that the glucose isn't there; it's that the brain isn't taking it in. Having enough DHA helps the brain accept that glucose. Getting plenty of this fat in your diet might be a good tool in your arsenal to potentially prevent cognitive impairment.
These fatty acids can even help patients with mild cognitive decline. A review of a number of double-blind placebo-controlled trials found that in people with cognitive impairment but without dementia, DHA and EPA supplementation led to improvements in immediate recall, attention and processing speed.
No benefit was found in those who had full-blown Alzheimer's disease, which suggests that there might be a threshold after which interventions that are promising in people with milder impairment are no longer effective.20
The bottom line? Start supplementing with omega-3s earlier rather than later to protect cognitive function. Having adequate omega-3 fats to balance your omega-6 fats helps keep inflammation in check, helps spur the growth of neurons in your brain to support memory and cognitive function, allows for healthy communication between your brain and your muscles, and supports healthy blood vessel function (for proper blood pressure regulation) and proper overall heart function.
Your brain depends on it.
The words saturated, monounsaturated and polyunsaturated have to do with the chemical structure of fatty acids. Fats are long strings of carbon atoms joined together. But these carbon atoms have extra spaces for other atoms to attach to them too, and these other atoms are hydrogen. When all the extra spaces that can be filled are filled, the fat is said to be saturated—that is, it's saturated with hydrogen atoms.
When two or more of the carbon atoms in a fat double up their attraction to each other (a double bond), it crowds out room for hydrogen.
Because of this, the fat is said to be unsaturated, because it does not contain the full amount of hydrogen it would if there was no double bond. When there is just one double bond in the fat molecule, it's a monounsaturated fat (mono meaning one). When there are two or more double bonds, that's a polyunsaturated fat (poly meaning many).
In a nutshell, saturated fats are more stable than unsaturated fats. Double bonds make unsaturated fats susceptible to detrimental chemical changes upon exposure to heat, air and light: the more double bonds a fat has, the more susceptible it is.
What this means is that some fats and oils are better suited for cooking, while others are best eaten cold—or not eaten at all.
Good for cooking
•All rendered animal fats (beef, duck, chicken, lard), plus coconut and palm oils (these are all saturated fats)
•Olive oil (the number of double bonds determines how "fragile" and easily damaged a fatty acid is, and monounsaturated fats like olive oil have just one double bond)
Bad for cooking
•All so-called vegetable oils (industrial seed oils—these are polyunsaturated and easily degraded)
Types of omega-3 fats
Linoleic acid is a subtype of omega-6 fatty acid.
Similarly, the category of omega-3 fats includes several different subtypes of fatty acids.
Alpha-linolenic acid (ALA) is a subtype of omega-3 fat that, like linoleic acid, is also an 'essential' fat, meaning that your body cannot make it, so you need to get it from your diet. ALA is found mostly in green vegetables, nuts and seeds (such as flax and chia seeds).
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is often referred to as the 'parent' omega-3 because your body can convert ALA into EPA and DHA. Primarily found in fatty fish, shellfish and krill, EPA and DHA are also present at lower levels in the fat of grass-fed ruminant animals (cattle, sheep, goats, deer) and in egg yolks, especially if the hens' feed includes fishmeal, flax or chia seeds. However, with the exception of women of reproductive age, humans are able to convert only about 5 percent of ALA to EPA and just 0.5 percent to DHA.1
During Paleolithic times, total linoleic acid intake (omega-6) was around 7.5 to 14 grams per day. Currently we consume twice this amount.2
Paleolithic people consumed as much as 15 grams a day of omega-3s, compared to an almost negligible 1.4 grams today—10 times less.
Our diet also contains as much as 143 times less EPA and DHA (100 to 200 mg) than Paleolithic humans consumed (660 to 14,250 mg).3
Currently, we consume as much as 15 to 20 times more omega-6 than omega-3.
Dietary omega-6 and omega-3: past vs present
The modern diet has double the omega-6 but only one-tenth the omega-3 levels consumed in Paleolithic times
How a deficiency of omega-3s hurts your brain
DHA and EPA deficiency can cause the following1:
• Impaired cell membrane function
• Decreased energy generation in neurons
• Increased levels of inflammatory compounds
• Decreased phosphatidylserine content—a major component of cell membranes
• Decreased dopamine levels and dopamine receptor activity
• Decreased blood flow to your brain
• Reduced availability of growth factors to support healthy neurons
• Decreased amino acid delivery across your blood-brain barrier (amino acids are the building blocks for serotonin, dopamine and other neurotransmitters).
Healthy ways to supplement your omega-3 oils
Take one of the following:
• Fish or algal oil (derived from algae): 3 to 4 grams per day (combined EPA and DHA) for maintenance of good health; more may be warranted for those suffering from inflammatory, cardiovascular or metabolic disease.
• Krill oil: 500 mg daily as a maintenance dose; 1 to 3 grams daily for those dealing with a condition that may respond to increased levels of omega-3s.
• Alpha-linolenic acid: 2.5 to 5 grams per day to maintain good health; 5 to 10 grams daily from flaxseed or ALA-enriched foods in order to reduce inflammation.
Excerpted from Superfuel by Dr James DiNicolantonio and Dr Joseph Mercola (Hay House, 2019)