As the amount of omega-6 in our diets has skyrocketed, so, as expected, has the amount of omega-6 that we carry in our tissues. Dr Stephan Guyenet, author of The Hungry Brain, published this graph to demonstrate the phenomenon. Levels have gone from 8 per cent – matching other primates (chimps) in 1961 – in a slow progressive rise as more and more vegetable oils and grains have been consumed, to 23 per cent in 2008.
Omega-3 and the Western Diet
If omega-6 levels, in our post-1980s diet, look plentiful, how did the changes affect omega-3? The dietary guidelines recommended a decrease in saturated-fat intake. If a population cuts down on grass-fed meats and dairy products in order to decrease their cholesterol intake, they will also cut out an important source of omega-3. We know that any animal that feeds on grass has good levels of omega-3 in their tissues, as well as in their milk. In this respect, decreasing the amount of red meat and dairy products consumed also decreased total amounts of omega-3 taken in.
Livestock are Fed Cheaper Grains
But it’s not only the decreasing amount of meat that affects omega-3 intake, it is also the quality of the meat. More intensive farming methods mean that most cattle are now fed grains to make them grow faster (as we saw in chapter 2). Seeds (grains) also contain a lot more energy compared to the same weight of grasses and can be stored for longer (because they don’t contain much omega-3), making them more convenient and cost-effective for large farms to feed their cattle.
Grain-Fed Cattle Have High Levels of Omega-6 and Low Levels of Omega-3
Grain-fed cattle take in the large doses of omega-6 from the grains and miss out on the omega-3 that they would normally obtain from grass. This change in their diet is reflected in the nutritional quality of their meat (less omega-3 and more omega-6). Fish are not immune to this change in their nutritional quality either. Most of the fish now available in supermarkets originate from fish farms, and just like cattle (and humans) fish get bigger if they are fed grains rather than their natural food (plankton). At the pinnacle of the food chain are humans, consuming affordable grain-fed meat or fish – and switching the levels of key omega fatty acids in our own tissues from omega-3 to omega-6.
If It Has a Shelf Life, It Doesn’t Contain Omega-3
How about the increasing amounts of vegetable oil and processed food that we consume – how does this affect our omega-3 intake? Remember the food left unattended, the food going brown? The oxidized food, which contained omega-3?
Processed foods, the food made in factories (and not farms), need to have a long shelf life. But, remember, any type of food that has a reasonable shelf life will have had most of its omega-3 removed. Fresh foods contain omega-3, that’s why they go off rapidly when left out of the fridge. The same rule applies to vegetable oils (but not olive oil): they need to be rid of their omega-3, otherwise they become rancid quite quickly. Therefore they are chemically and heat treated to eliminate it. As mentioned previously, the hydrogenation process to remove the oxidizing potential of unsaturated fats causes the production of cardio-toxic trans-fats – all in the interest of making the food taste fresher for longer, and ultimately with the aim of making the food company a larger profit.
So the changes in our food that were supposed to help us to decrease the level of saturated fats in our diet actually resulted in a big divergence in the proportions of the two essential fatty acids consumed. The amount of omega-6 increased dramatically and the amount of omega-3 decreased rapidly.
Omega-3 to Omega-6 Ratio Changes
Ideally, and throughout our history, the ratio of omega-3 to omega-6 within our bodies would have been between 1:1 and 1:4 (i.e. four times more omega-6 compared to omega-3). If we go back to hunter-gatherer times, when all foods were fresh and the diet was not based on grains or vegetable oils, we would see this range. People living in remote areas of the world today, who consume natural home-grown foods, will have these levels as well. But if you consume a Western diet, as we have seen, many omega-3s have been removed and large amounts of omega-6 have been added to foods that have been processed or commercially produced. So, the omega-3 to omega-6 ratio rises to a staggering 1:50 in some Westernized cities.
Table 9.2 summarizes the changes in the omega-3 to omega-6 ratio over time, and the differences between geographical regions, from a 2004 study from the Center for Genetics, Nutrition and Health in Washington, DC.
How Does the Change Affect Our Bodies?
So, we have unearthed a new, modern deficiency, one that until recently had not been known about. This deficiency of an essential fatty acid is made worse by food processing, and by a lack of fresh foods. The parallels with vitamin B1 and vitamin C deficiency are starting to appear. But, just as these vitamin deficiencies were revealed as the true causes of beriberi and scurvy, will the new deficiency we have identified help us understand the modern disease of obesity?
Population ω6:ω3
Palaeolithic 0.79
Greece prior to 1960 1.00–2.00
Current Japan 4.00
Current India, rural 5–6.1
Current United Kingdom and northern Europe 15.00
Current United States 16.74
Current India, urban 38–54
Table 9.2 Omega-6 to omega-3 ratios in various populations Source: A. P. Simopoulos (2004). Omega-6/omega-3 essential fatty acid ratio and chronic diseases. Food Reviews International, 20 (1), 77–90.
The Story of the Omega Brothers
We learned that the omegas originate from different parts of the plants: omega-3 from their green leaves, and omega-6 from their seeds. When we look at the function of the omegas within our bodies we can also see that they have many opposing effects. They are like two brothers, originating from the same mother, but having opposite personalities. The omega-3 brother is quick and fast and flexible, with a personality that is healing, but a constitution that is brittle. The stiffer omega-6 brother is much more solid and stable, but is slow and tends to cause trouble wherever he is. As with many brothers, the omega boys have major rivalries. They are constantly competing and fighting with each other for their favourite place: they want to sit on the same wall. That wall is our cell wall, a critical area for our health.
Imagine the small, friendly, quick and flexible (omega-3) brother wearing green (from the leaves he originated from) and the bigger, more stable and more angry brother (omega-6) wearing brown (from the seeds he came from). Now imagine that there are many pairs of omega brothers sitting on your garden wall, guarding it. In normal circumstances, there would be an even number of green- and brown-shirted brothers (a 1:1 ratio). If you wanted something passed over the wall to the next garden there would be plenty of friendly, flexible greens to help pass things backwards and forwards. If, one day, scores of brown shirts turned up and there were hardly any – only two or three – green-shirted brothers, the wall would be guarded predominantly by the stiff and sulky brown shirts. It would be difficult to get them to agree to pass things over the wall to the neighbour and, in addition, when you ventured too close to them you might get kicked, or, even worse, ambushed and injured, by them.
Now imagine those omega brothers miniaturized and guarding your cell walls, helping to control what comes into and out of the cell and also defending the cell against danger. This is the function of the omega brothers: they play a critical role in the functioning of our cell walls and hold the keys to entry into our cells and the weapons to defend them.
As we mentioned, the omega brothers are in a constant fight with each other to sit on our cell walls: there is limited space and some will be unable to find room. If there is more omega-3 circulating, there will be more in the wall, and the same goes for omega-6. The proportion of the omegas – 3 or 6 – within our cell walls mirrors the proportion of omega-3s to omega-6s that we eat in our diets.
The Food We Eat Literally Imprints Itself into Our Cell Walls
We know that the amount of omega-3 in our diet has fallen dramatically in the last forty years and the amount of
omega-6 in our diet has increased even more dramatically. This change in the ratio of omegas in our diets is reflected in a similar change to the ratio of omega brothers within each and every one of our cell walls – all 30 trillion of them. Suddenly our cell walls have a ratio of around 20 stiff, unfriendly omega-6 brothers to every 1 quick, friendly, flexible omega-3 brother. Let’s guess what this may be doing to our health.
The Functions of the Omega Fatty Acids
The (opposing) functions of the omega brothers span three main areas:
Defence (inflammation)
Cell wall permeability (insulin sensitivity)
Messaging (mood and appetite).
Defence
Omega-3 and omega-6 have opposing actions in their inflammatory response to infection or injury.
Omega-6 fatty acids are broken down in the cell membrane and release factors that encourage:
Increased inflammatory response
Increased blood coagulability (clotting).
Omega-3 fatty acids have an opposing response when released from cell membranes. They are much less inflammatory and decrease blood coagulability. So an upsurge in the cell wall of omega-6 compared to omega-3 will increase the amount of inflammation to any given stimulus: it will make our immune systems more sensitive. If the omega-6 to omega-3 ratio goes up dramatically, it could make our immune systems hypersensitive.
A hypersensitive immune system can lead to the development of autoimmune diseases (where the immune system gets confused and attacks its own cells). These include: arthritis, allergies, asthma and inflammatory bowel conditions. A low-grade inflammation in the body, in response to an overly primed immune system, can increase the risk of cancer. When combined with an increase in the clotting tendency of the blood, our low-grade inflammation also increases the risk of heart disease.
So changing the ratio of omega-6 to omega-3 in the blood increases the risk of all these modern types of diseases – which were rare before processed food and vegetable oils literally became part of our bodies.
Finally, low-grade inflammation in the body increases TNF-alpha (the inflammatory molecule discussed in chapter 5). We know that TNF-alpha acts to block the action of leptin. Leptin resistance causes a higher weight set-point and – you guessed it: obesity.
Figure 9.9 The inflammatory chemicals of omega-6 and omega-3 Key: LA – linoleic acid; GLA – gamma-linolenic acid; DGLA – dihomo-gamma-linolenic acid; AA – arachidonic acid; ALA – alpha-linolenic acid; EPA – eicosapentaenoic acid; DHA – docosahexaenoic acid.
Source: Adapted from W. E. Lands (1992). Biochemistry and physiology of n-3 fatty acids. FASEB J. 6 (8), May, 2530–36.
Cell Wall Permeability
The flexible, dynamic and fast-moving tail of the omega-3 fatty acid increases the flexibility of the cell wall. This makes the cell wall more fluid and adaptable. Transmission of elements, such as calcium, through the cell wall is faster when there is more omega-3 present. Metabolic adaptation and adaptability are increased. The wall is also more sensitive to hormonal messages from the outside. The opposite occurs when there is a high proportion of the stiffer omega-6 in the cell wall. Adaptability and permeability are decreased. Metabolism is blunted. The cell membrane is less sensitive to hormonal messaging.
An important change in cellular walls with high omega-6 to omega-3 ratios is a decrease in the sensitivity of the cell wall to insulin in muscles and leptin in the brain. Higher insulin levels and leptin resistance raise the weight set-point, increasing the risk of obesity.7
Messaging (Mood and Appetite)
The omega-6 fatty acids act as precursors to endocannabinoids, which are signalling molecules that stimulate the cannabinoid receptors located in the brain. Yes, you may have guessed, these are the same receptors that are triggered when cannabis, or weed, is smoked! The effect of stimulating the cannabinoid receptor when you smoke weed is an elevated, happy mood. If the dose is high enough, you are likely to experience feelings of euphoria as well. We also know what happens about an hour after the weed has stimulated those cannabinoid receptors: a sudden appetite combined with food-seeking behaviour. When food is eventually eaten, it gives a more pleasurable feeling and also enhances any sweet taste.
What happens to our endocannabinoid system when our omega-6 to omega-3 ratios are massively elevated by exposure to the modern Western diet? The excess of omega-6 produces an excess of endocannabinoid messengers and the system is chronically over-stimulated.8 This is not to say that everyone with a high omega-6 to omega-3 ratio will walk around cheerfully looking stoned – but that the same system, the endocannabinoid system, is stimulated to a low level over long periods of time.
Let’s look at the proven effects of high omega-6 to omega-3 ratios on the function of the endocannabinoid system and therefore on our behaviour and health.9
Activation of CB1 (cannabis) receptors leads to increased appetite and calorie intake.fn1
The endocannabinoid system is involved in energy balance and over-stimulation of this system leads to obesity.10
Activation of the system enhances sweet taste and also an increase in the release of pleasure and reward (dopamine) chemicals in the brain. Food tastes better and gives you more pleasure.
The message here is that the omega-6 brothers, those stiff and unfriendly wall guards, have a secret cannabis affinity. The more omega-6 in the cell wall, the more the appetite and weight-regulating system will be ratcheted towards weight gain. And gaining weight will be a pleasurable experience because the omega-6 stimulates a more pleasant taste and more rewarding food feelings. That familiar KFC family bucket craving doesn’t come from nowhere: it comes from the previous experience of KFC, whose omega-6 is still clogging up your cells and turning out cannabinoids.
Another important health implication of altering our omega fatty-acid ratios is in the effect on their function within the brain. This book does not have the scope to go into detail about this but we should bear in mind that:
High levels of omega-3 (25 per cent) are normally present within the brain cell membrane
Changes in our dietary omega-6 to omega-3 intake alter the ratio within the brain
Severe omega-3 deficiency can cause numbness, weakness and blurred vision
Low omega-3 levels in the brain are found in multiple sclerosis, macular degeneration and Huntington’s disease11
An increase in the omega-6 to omega-3 ratio has been implicated in: Alzheimer’s disease, dementia, anxiety mood disorders, suicide.
All these disorders are increasingly common in the Western world.
John Stein, Emeritus Professor of Physiology at the University of Oxford, commented on the increasing ratio of omega-6 to omega-3 fatty acids, saying: ‘The human brain is changing in a way that is as serious as climate change threatens to be.’
Omega-6 Blocks Omega-3
Finally, as if the news was not bad enough already, high levels of omega-6 can prevent the body from converting the omega-3 that we get from plants to the more active omega-3 that we get from fish and animals. In other words, if the diet is already very high in omega-6 it doesn’t matter how many green vegetables you eat – their conversion into useful omega-3 will be blocked. So we have a compelling argument that, yes, a deficiency of an essential dietary nutrient – omega-3 – is a cause of obesity. This fits in with:
Epidemiological evidence – populations with a low omega-6 to omega-3 ratio do not suffer with obesity (e.g. the Japanese and any non-Western rural communities), whereas those with a high omega-6 to omega-3 ratio always have high rates of obesity.
Lipid (fat) cell membrane research – multiple effects of high omega-6 to omega-3 ratios on metabolism have been found, leading to a raised weight set-point.
What patients say – the omega-6 to omega-3 ratio takes months to change, and dieting will not have an impact on this. This explains weight regain after dieting. When patients move to another country, their weight set-point will readjust to the new food environment. (We will discuss how
exactly you can do this, without moving country, in Part Three.)
Our New Deficiency Disease
Just as a lack of vitamin C in the diet causes scurvy and leads to symptoms of extreme tiredness, personality changes and cravings for food, so the altered omega fatty-acid ratio in the Western diet causes a raised weight set-point. Hunger and tiredness are then the symptoms of the condition and result in weight gain and, ultimately, the disease of obesity.
Figure 9.10 Link between the intake of vegetable oils and obesity rates in the USA, 1970–2010 Sources: For calories consumed, see USDA Economic Research Service, loss-adjusted food disappearance; for obesity rates, see C. L. Ogden and M. D. Carroll (2008). Prevalence of Overweight, Obesity, and Extreme Obesity among Adults: United States, Trends 1960–1962 through 2007–2008. National Health and Nutrition Examination Survey (NHANES), June. National Center for Health Statistics; for added fats, see data from the USDA Economic Research Service.
Winter is Coming – Evolutionary Adaptation
Our weight set-point is a programmed response to information from our genes and epigenes, and to our past and present environments. This data is used by our bodies to select an appropriate size of ‘fuel tank’ (or stored-energy reserve) that will help us survive in a future environmental disaster such as famine. When we think of it this way, then the omega fatty acids are acting as messengers, like a proxy from nature, informing us about our future environment.
Why We Eat (Too Much) Page 21