In order to remain robust, energetic and healthy, we need a variety of nutrients. These include amino acids, proteins, carbohydrates, vitamins, minerals, lipids and fatty acids.
In some cases, living organisms are able to synthesize some of these nutrients in each of these classifications. Other nutrients, called “essential,” cannot be synthesized by an organism, but must be obtained through the diet. In addition, there are nutrients that a living organism can synthesize but are still required in the diet because the organism may not synthesize enough of the nutrient. In order to obtain sufficient amounts of essential nutrients, then, sometimes we need to take an appropriate supplement.
In this installment, we will deal with a few of the nutrients in the lipid classification, specifically phospholipids and the class of fatty acids known as omega-3s. We will discuss the chemistry of these molecules, their benefits to human health, and review some sources, with a focus on krill oil, a supplement rich in both phospholipids and fatty acids.
What are fatty acids?
Fatty acids are molecules with a long hydrocarbon chain with a carboxlate group on one end of the chain. There are many different types of fatty acids, which are identified by the length of the hydrocarbon chain and the degree of saturation of that chain. Most typically, fatty-acid chain lengths in humans are between 14 and 24 carbons, generally an even number. The degree of saturation refers to the extent of double bonds between carbon atoms in the hydrocarbon chain. If all the carbon-carbon bonds are single bonds, such a fatty acid is saturated. If there are one or more carbon-carbon double bonds, then such a fatty acid is considered unsaturated.
Some fatty acids are essential in the diet. Key essential omega-3 fatty acids include α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).
Fatty acids are components of two classes of lipid molecules – glycolipids and phospholipids (we will not deal with glycolipids here). Phospholipids are composed of a backbone molecule of either glycerol or spingosine. Fatty acids are then attached to the backbone molecule, along with a phosphoric acid molecule, hence the term phospholipid. Another molecule is attached to the phosphoric acid such as serine, ethanolamine, choline, inositol, as well as others. A phospholipid with a glycerol backbone and a serine attached to the phosphoric acid would be known as phosphotidyl serine, or PS, for short. If spingosine is the backbone of the phospholipid, then the phospholipid is known as spingomyelin.
Phospholipids are important components of all cell membranes. They are also involved in some cellular signaling pathways, the molecular method cells use to telegraph information about physiological changes in their environments. Fatty acids, in addition to being components of phospholipids, are also involved in the storage of excess energy in fats known as tricylglycerols (a topic for future discussion).
Phospholipids are, as we said, are an excellent source of fatty acids, and it is now clear that dietary intake of fatty acids, especially the omega-3 fatty acids, promotes good human health.
The many benefits of omega-3 fatty acids
There is much evidence in biomedical literature to show that the omega-3 fatty acids play a role in cardiovascular health,1 and that supplements containing omega-3 fatty acids have beneficial effects on cardiovascular health. These include lowering triglyceride levels,2,3preventing arrhythmias,4,5decreasing inflammation,4 decreasing platelet aggregation (clotting),6 and stabilizing plaques.7
There is also a report that omega-3 fatty acids may lower blood pressure,8 although that observation has not been clearly replicated. The effect of omega-3 fatty acids on lowering triglyceride levels appears to be most pronounced in people with the highest levels of triglycerides, those with the greatest risk.2
Omega-3 supplements also appear to be helpful to people undergoing treatment for cardiovascular disorders. They appear to enhance the effect of statin drugs, which are used to lower cholesterol.2,9,10 Published evidence also indicates that omega-3s may be helpful to people with implanted defibrillators, although the results of this work are not yet definitive.11,12,13 At least one study indicated that omega-3s improve results for patients who have undergone bypass surgery.14
The benefits of omega-3 fatty acids for cardiovascular health are so convincing that the American Heart Association recommends that healthy people eat fatty fish twice a week. This cardiovascular benefit outweighs any risks that may arise from eating fish that may be contaminated with pollutants, such as mercury.15
Preliminary evidence indicates that omega-3 fatty acids may have beneficial effects with respect to tumors. Such studies include observational data for some types of colon cancer16,17 and prostate cancer.18 Studies in animal models suggest a positive role for omega-3s in breast cancer.19,20
Research has indicated that omega-3 fatty acids are associated with benefits to the central nervous system. Increased omega-3 fatty acids in plasma were associated with a lower rate of decline in sensor-motor speed over a three-year period.21 They were also associated with increases in well being,22 improved cognitive-test results, 23 and a decrease in dementia.24 Using a gerbil model, omega-3s were associated with improvements in memory and learning.25 In all these cases, additional work in the form of fully randomized clinical trials are still required.
Omega-3s may be useful for patients with depressive disorders,26,27 first because these patients suffer from a greater number of cardiovascular incidents.26,27 Second, initial experiments have indicated that omega-3s were more effective than placebo for dealing with depression in both adults and children, as well as in bipolar depression.28 And although omega-3 fatty acids are not yet a recommended method of treating mental illness, there have been proposals to use omega-3s for depressive patients, as well as for control of mood changes.26,27 Again, randomized clinical trials are required before exact treatment protocols can be proposed.
Additional benefits of omega-3 fatty acids appear to be related to their anti-inflammatory properties,4 including positive effects on rheumatoid arthritis,29,30 asthma,31infection,32 and autoimmunity.33 These observations still require more study in the form of well executed clinical trials.
Keep in mind that if you are taking any pharmaceutical, or if you are undergoing treatment for any condition, it is critical to speak with your health-care provider before taking any supplement.
The best sources of omega-3s
Foods rich in fatty acids include walnuts, fatty fish (like salmon, sardines and mackerel) and krill. Krill oil is especially rich in omega-3 fatty acids and phospholipids. It has been shown to control serum (blood) lipids in rats.34,35 In humans, krill oil has been shown to be better than fish oil at increasing omega-3 levels in obese patients.36 In a rat model, krill-oil supplements fared better than fish oil supplements in controlling triglyceride levels in various tissues.37 Krill oil also was able to inhibit growth of a colon-cancer cell line.34
Such observations indicate that krill oil is a good supplement choice, and perhaps even better than fish oil. It is an excellent source both of phospholipids and omega-3 fatty acids, both of which have important properties for human health.
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