In my first article, (What) To Eat or not to Eat, it was argued that low-carb diets are becoming more and more popular. There is yet more evidence than ever before suggesting the advantages of these diets. Recent research, published in The Endocrine Society's 92nd Annual Meeting and Expo (2010) held in San Diego, shows that low-carb diets are more effective than low-fat diets when weight loss is needed. In the study, insulin-resistant women lost more weight on a low carbohydrate diet than on a low fat diet over a three-month period. One must, however, keep in mind that this study focused on a three-month period and one might argue that over a longer time frame, results could be different.
In another study published in the same meeting, the consumption of foods containing a high level of fructose (a type of sugar found in most processed foods and beverages) by pre-teen children was linked to obesity and was shown to have an effect on insulin sensitivity.
Once it has been shown that low-carb diets are advisable, the question remains as to which are the best fats to be eating. This article will focus on “good fat” which is one of the main elements in a low carbohydrate diet. More precisely it will focus on the balance between Omega-3 and Omega-6 fatty acids, which are both considered to be essential fatty acids or EFAs (no political connotations involved!). These are required for good health but the human body is not able to build them up itself, hence it is essential to take them in the diet and so their name, "essential".
Definition of the term Low-Carb Diet
Before moving on to fats it’s important that a good definition of the term low-carb Diet is given. According to weight loss company Jenny Craig, a diet low in fat is one where 60% of the calories come from carbohydrates, 20% from fat and 20% from protein. A so-called low-carbohydrate diet, on the other hand, comprises 45% carbohydrates, 35% unsaturated fats and 20% protein. There again, those carbohydrates in the diet have to be carefully chosen, with carbohydrates eaten preferably coming from fruit and vegetables, cereals, and pulses - hence carbohydrates with as low a GI (glycaemic index) as possible.
Considering that the amount of protein in both types of diet remains the same (20%), the difference in the two diets is replacing carbohydrates with fats, which might be surprising. Moreover food high in protein - like nuts, meat and fish - generally contain a substantial amount of fat/ oils. But which types of fats should one go for?
The Right types of Fat
When choosing which kind of protein to choose, people should opt for high-protein food that contains the most beneficial types of fat. As mentioned earlier on, the right balance between Omega-3 and Omega-6 fatty acids is very important for a good diet.
Omega-6 fatty acids are found in eggs, poultry, cereals, vegetable oils, baked goods, and margarine and they can promote healthy skin and lower cholesterol. However when not balanced with Omega-3 fatty acids, they can make our blood too sticky and this may increase the risk of heart attacks and/ or strokes. Increasing Omega-3 fatty acids in the diet will make platelets in our blood clump less (it regularises blood clotting) whereas also decrease the amount of atherosclerosis in the blood vessel, even causing regression of said atherosclerosis. Atherosclerosis is what causes the narrowing of arteries which eventually leads to events like heart attacks and some strokes.
The ideal ratio between the two is four parts Omega-3 to one part Omega-6 which is very far from the actual, existing average ratio in the average diet.
It seems that the typical American tends to consume 14 - 25 times Omega-6 than they consume Omega-3 fatty acids. On the other hand, the so-called Mediterranean diet (not the pastizzi and pizza diet) is more balanced. This diet contains an abundance of vegetables, fruits, nuts, pulses, fish, olive oil etc. In order to achieve a better balance, consumption of foods with a higher content of Omega-3 fatty acids is therefore being encouraged.
Omega-3 Fatty Acids and their Sources
These include:
1. Cold-water high fat fish, especially wild salmon, sardines, anchovies, mackerel, shad, herring and trout.
2. Flaxseed oil (flaxseed oil has the highest linolenic content of any food), flaxseeds, flaxseed meal, hempseed oil, Krill oil, hempseeds, walnuts, pumpkin seeds, Brazil nuts, sesame seeds.
3. Avocado
4. Certain dark green leafy vegetables, including kale, spinach, purslane, mustard greens, collards, oregano and more.
Meat and eggs can also be a source of Omega-3 fatty acids, but much depends on the way the animal or poultry are fed. Meat contains more Omega-6 than Omega-3 fatty acids, but in grass-fed beef the Omega-6: Omega-3 ratio is much lower than grain-fed beef.
All in all, it seems that nutritionists tend to favour fish, plant oil, nut oil and other seafood as a source of Omega-3 acids. Also fish caught in the wild tend to have lower amounts of Omega-3 fatty acids - but this piece of data must be viewed taking into consideration also the higher level of dioxin found in farmed fish.
More research also suggests that Omega-3 fatty acids may be better absorbed when eating food rather than from supplements. However, the risk of also absorbing certain “heavy metals” which may be found in fish, is considerably lower when Omega-3 acids are taken in supplement form. Still, the advantages of eating fish are considered to outweigh any potential risks according to the Journal of the American Medical Association (JAMA) in 2006.
But what are the Benefits of Increasing Omega-3 Fatty Acid Consumption?
Various health benefits have been cited in studies and the strongest indications relate to benefits which are linked to heart disease. These include the increasing of plasma levels of "good" cholesterol, a lower rate of cardiovascular accidents (MIs and strokes) and a lowering of blood pressure. Persons suffering from the following conditions may also benefit: Diabetes Melitus, Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus (SLE), Osteoporosis, Depression, Bipolar Disorder, Schizophrenia, Attention Deficit/Hyperactivity Disorder (ADD/ ADHD), Skin Disorders, Inflammatory Bowel Disease (IBD), Asthma, Macular Degeneration, Dysmenorroea (menstrual and pre-menstrual pain). A higher level of dietary Omega-3s also contributes to a decreased incidence of cancers of the breast, colon and prostate. (More info: http://www.umm.edu/altmed/articles/omega-3-000316.htm)
Another recent study published in the JAMA, in 2010, implies that Omega-3 oils may slow aging in heart patients. However it seems that much more evidence is needed to confirm such a theory.
Conclusion
So to recap it all: both Omega-3 and Omega-6 fatty acids can be beneficial to a healthy life-style in the right quantity. It seems that modern diets have altered the desired balance between these two leading to undesireable effects. As Omega-6 fats tend to outweigh Omega-3 fats in our diets, we need to increase the consumption of the latter and reduce that of the former to establish a desired ratio. This can be done by eating foods which have a high Omega-3 content, like oily fish (salmon – preferably wild and not farmed) mackerel, sardines etc. Other foods high in Omega-3s are walnuts, oils like canola oil and vegetables and fruits like broccoli, Cantaloupe melons, kidney beans, spinach, grape leaves, Chinese cabbage, and cauliflower.
For those who are not very good at remembering lists of foods, just stick to the traditional Mediterranean diet - simpler than that it cannot be.
Caution: Most of these studies described above are conducted on a restricted number of subjects, so before taking any supplements one should always consult his/her doctor because they might interact with other medications. Remember, never take medicines without consulting your doctor first.
Disclaimer: The author of this article is not a qualified nutritionist.
References:
The Endocrine Society, June 19-22, 2010
http://www.doctorslounge.com/index.php/news/pb/11931
Omega-3 fatty acids University of Maryland
http://www.umm.edu/altmed/articles/omega-3-000316.htm
Eating High Levels Of Fructose Impairs Memory In Rats
http://www.sciencedaily.com/releases/2009/07/090716113247.htm
Good Fat, Bad Fat: The Facts About Omega-3
http://www.webmd.com/diet/guide/good-fat-bad-fat-facts-about-omega-3
Association of Marine Omega-3 Fatty Acid Levels with Telomeric Aging in Patients with Coronary Heart Disease - JAMA 2010;303(3):250-257.
http://jama.ama-assn.org/cgi/content/abstract/303/3/250
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