Human Evolution- Diet and Health
Genetic factors determine susceptibility to many diseases, while environmental factors such as nutrition and physical activity greatly influence which genetically susceptible individuals that may be affected. The spontaneous mutation rate for nuclear DNA is estimated to be 0.5 % per million years. Thus, our genetic profile today is very similar to the one of our ancestors which was formed 40-50,000 years ago and shaped around their diet [1, 2]. An essential part of their diet was the fatty acids, including saturated-, monounsaturated- (omega-9) and polyunsaturated fatty acids (omega-6 and omega-3).
Rapid dietary changes over short period of time that have occurred over the past 100-150 years are a totally new phenomenon in the history of human evolution. This is especially true in regard to the intake of omega-6 and omega-3 essential fatty acids and antioxidants from vegetarian sources . Ready meals and processed food have turned our calorie consumption towards vegetable oils, meat, sugar and starch, and away from complex carbohydrates and fibre and fresh vegetables [4, 5]. These unhealthy trends have been exacerbated by a 50 % decrease in physical activity. In brief, our diet during the last 100-150 years has turned from balanced and anti-inflammatory to unbalanced and pro-inflammatory. Such dietary changes and reduction in physical activity have had a profound impact on our health.
Fatty acids carry out many functions that are necessary for normal physiological health. The contribution of fat to our energy supply is both qualitatively and quantitatively important. In addition to being mere storehouse of energy they are critical for cell membrane structure and function and for local“ hormonal” signaling. Imbalances in fatty acid level are known to affect the clinical course of several life-style related disorders, [6, 7, 8, 9, 10].
Omega-6 and Omega 3 Fatty Acids
The increased consumption of soya oil in the US has increased the intake of the essential omega-6 linoleic acid (LA) from an average of 0.01 kg/year in 1909 to the present level of 12 kg/year . The dietary omega-6 linoleic acid (LA) gets converted to omega-6 arachidonic acid (AA) in the body, which is stored in our cell membranes. Bioactive components made from omega-6 arachidonic acid (AA) are responsible for both initiating acute inflammation and continuation of chronic inflammation in the body, which may lead to several life-style related health problems [6, 12].
Compared to the diet on which humans evolved, todays western diets are generally deficient in omega-3. The alternative to the marine essential omega-3 fatty acids EPA and DHA that the body need as building blocks, is the vegetarian omega-3 fatty acid alpha-linolenic acid (ALA). However, vegetable ALA is not sufficiently converted to EPA and DHA in the body to be able to act as a substitute to the marine omega-3 sources. Hence, they must be supplied by direct intake of EPA and DHA from marine sources. From isotope-labelled ALA, the range of conversion of ALA to EPA has been estimated to be up to 8 % in men and up to 21 % in women of reproductive stage [13, 14]. The overall efficiency of conversion from ALA is 0.2 % to EPA, 0.13 % to DPA and 0.05 % to DHA . An ALA rich vegetarian diet is generally providing less than 4 % Omega-3 (EPA+DHA) level in the fatty acids profile in whole blood (BioActive Foods, in house results).
The key message is that a balanced omega-6 and omega-3 fatty acids ratio is an essential part of a balanced diet aimed to promote good health.
Polyunsaturated Essential Fatty Acids
Omega-3 and omega-6 are polyunsaturated fatty acids (PUFA), which means that the fatty acid have more than one double bond. In the omega-3 fatty acids the first bond is located between the third and fourth carbon from the methyl end (CH3) on the carbon chain. Omega-6 fatty acids have the first double bound between the sixth and the seventh carbon from the methyl end. In the human body saturated and unsaturated fats can be synthesized from carbon groups in carbohydrates and proteins, but we lack necessary enzymes to produce the essential polyunsaturated fatty acids such as omega-3 and omega-6. Essential fatty acids (EFA) are fatty acids that the body cannot produce itself and therefore must be provided through the diet. The most important of these fatty acids are linoleic acid (LA, C 18:2, omega-6) and α-linolenic acid (ALA, C 18:3, omega-3). From LA and ALA the body can synthesize, under optimal conditions, arachidonic acid (AA, C 20:4,n-6), gamma-linoleic acid (GLA, C18:3, omega-6), dihomogamma- linoleic acid (DGLA, C20:3, omega-6), eicosapentaenoic acid (EPA, C20:5, omega-3) and docosahexaenoic acid (DHA, C22:6, omega-3), as shown in the figure.
The synthesis is performed through a number of desaturation (addition of double bonds) and elongation (addition of two carbon atoms) steps. LA and ALA compete about the same desaturation and elongation enzymes in the synthesis of the long chained fatty acids AA, EPA and DHA, meaning that even though ALA is a preferred substrate in the process, a higher production of AA will occur due to our high dietary intake of omega-6 fatty acids compared to omega-3 fatty acids.
Further on in the process, locally functioning hormones and signaling molecules (eicosanoids) will be produced from AA and EPA in a process called prostaglandin synthesis. The eicosanoids are formed after an enzyme, cyclooxygenase are released, and the prostaglandin synthesis are initiated by oxidation of the fatty acids AA and EPA. When these fatty acids are oxidized, the initial structure changes into the type of prostaglandin which is needed in the body at that certain time. COX1 is the enzyme responsible to maintain the body’s normal levels of prostaglandins, while COX2 are initiated when a tissue damage or infection occurs. The prostaglandin synthesis take place in almost all of the cells in the body. They belong to the group "eicosanoids" because they consist of 20 carbon atoms. The prostaglandins have from 1 to 5 double bonds, given by the number behind the PG E: PG E1 have one double bond, PG E2 have two, and so on.
PG E2 is produced from the omega-6 fatty acids AA, via LA, or directly from AA which we find for instance in grain fed animal meat. PG E2 is prothrombotic, meaning that it is responsible for stopping bleeding and for wound healing, but in the same time PG E2 can cause thrombosis, affects blood pressure and contraction of involuntary muscles. PG E2 is involved in all inflammatory and pain processes in the body, hence it is important that PG E2 is balanced by among other PG E3, to avoid chronic inflammatory situations in the body as a result of a high LA and AA intake.
PG E3 is produced from the omega-3 fatty acids EPA, via ALA, or directly from EPA through a diet rich in fatty fish. PG E3 has an anti-coagulation effect on the blood and anti-inflammatory function in the body .
Omega-6/omega-3 Fatty Acid Balance and the Prostaglandin Balance in the Body
The production of some prostaglandins is strongly affected by our diet, but also by the body's hormone balance, health status, medication and so on. Many people have, due to a high intake of vegetable oils and meats, too much of the omega-6 fatty acid AA in their body, resulting in high PG E2 production. If the diet is not balanced with an adequate intake of the omega-3 fatty acids EPA and DHA, an unbalance between PG E2 and PG E3 can occur, resulting in the increased risk of having a chronic inflammatory status in the body. The prostaglandin synthesis may be balanced by a diet rich in omega-3 fatty acids, promoting the production of more of the health beneficial prostaglandin PG E3.
Oxidative Stress and Health
All cells produce free radicals and reactive oxygen that can turn polyunsaturated fatty acids such as omega-3 and omega-6 in cell membranes rancid. The body has therefore developed its own defence against rancidity. Oxidative stress is a condition that arises when there is an imbalance between the production of rancidity products in the body and the body’s defence against rancidity. This often occurs after prolonged physical activity and is exacerbated by a diet that is unbalanced and pro-inflammatory. The imbalances that create oxidative stress in the body can be corrected by changing diet. Good protection requires an intake of 5 - 9 portions of fruit, green vegetables or olives every day [17, 18]. However, most people’s intake of the recommended amount is less than half of what it should be. People who exercise regularly, and do not have a balanced diet, may have a level of oxidative stress that is too high. This suggests that active individuals with genetic susceptibility to disease are especially vulnerable if their daily diet is unbalanced and pro-inflammatory.
Commercially Available Oils
Before modern technology was introduced to food processing organically sourced and unprocessed oils for dietary consumption were the only options available. Nowadays most of the commercially available oils have been processed or refined. The refining process eliminates all flavours, odours and contaminating agents that might be harmful or spoil the smell, taste or look of the product. However, the process also removes natural antioxidants, vitamins and other minor components such as polyphenols that have beneficial anti-inflammatory properties. The removal of nutrients and important anti-inflammatory components is only partly compensated by the addition of antioxidants for stabilization purposes. The removal of these important nutritional components from the oil we consume enhances the pro-inflammatory profile of our present diet. A very recent example is olive oil. During the refining process of olive oil, the polyphenols are removed. In October 2011 the European Food Safety Authority (EFSA) approved a heart health claim for olive oil polyphenol: “Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress”. Thus, removal of minor components during refining can affect the bioactivity of oils. A similar example is the removal of vitamin A and vitamin D during the refining of fish oil.
BioActive Foods Products
To compensate the loss of important nutritional components during refining of fish oil, the unique BioActive Foods products contains a combination of biologically active antioxidants from cold pressed olives (polyphenols), vitamin D and an adequate dose of marine omega-3 EPA and DHA from fish.
These components work together in a synergetic good way. Omega-3 EPA and DHA from fish that circulate in the blood are activated rapidly when inflammation occurs locally. They are converted into biologically active substances (resolvins and protectins) that ensure a balanced immune response. Polyphenols are also powerful anti-inflammatory agents blocking inflammatory and tissue-damaging enzymes [19, 20]. Polyphenols such as those from olives (tyrosol, hydroxytyrosol and more) also possess antioxidant properties protecting the cells and the blood lipids from oxidative stress proportionally to intake [21, 22]. Vitamin D contributes to the normal function of the immune system.