Should we be consuming low-fat or high-fat foods? What are omegas, are they important and where do you get them? Ian Craig answers your questions.
People form their opinions from what they read or what they are told. Indeed, we were told 20 years ago that food should always be low in fat. This theme ran concurrently with the revolution of aerobics and the exercise craze and we're still having to put up with low-fat, flavourless dairy products and meat substitutes in the supermarkets.
Despite a huge reduction in fat intake over the last two decades in some countries, obesity is now the most important nutritional disease in developed countries, with rapidly increasing prevalence.¹ The Atkins movement around 16 years ago did a lot to change our relationship with fat, to the extent that many people have now embraced a high-fat diet.
EFA DEFICIENCY
Nonetheless, whether you lie in the low- or high-fat consumption camp, or have ignored these dominant dietary trends in pursuit of culinary content, you are almost certainly deficient in fats – GOOD FATS‚ that is. A group of nutrients called essential fatty acids (EFAs), known as omega-3 and omega-6, are critical to our health and well-being. EFAs are the main structural component of every cell membrane, meaning that their presence contributes to the function of every system in the body. The average person today will consume only one sixth of the omega-3 fats that were consumed in 1850, a fact that results in more than 90% of the British public being deficient in these vital fats,² and no doubt also the South African public, which has followed similar dietary habits. When EFAs were first discovered, they were thought to be a vitamin and named vitamin F, a fact that clearly reflects their importance in the body.
Deficiency in EFAs will compromise our outward appearance. Problems may include dry, flaky skin, weak nails and dull, brittle hair.³ These deficiencies quite possibly fuel the current boom of the cosmetics industry. Have you ever stopped to consider, as you reach for a bottle of body lotion from the supermarket shelf, why we need to improve our skin quality through the application of external creams? Complexion is simply a reflection of our nutritional health and cosmetics alone will not resolve the deeper imbalance in health.
SYMPTOMS OF EFA DEFICIENCIES
Common indications of EFA deficiency include: water retention, lack of energy, lowered immunity, pre-menstrual tension, impaired brain function (e.g. attention deficit), depression, skin conditions (e.g. eczema or acne), food cravings and allergies.
On a more serious note, deficiencies in EFAs have been linked to hypertension, high cholesterol, heart and circulatory disease, mental deterioration, arthritis, male sterility, miscarriage, auto-immune diseases (e.g. multiple sclerosis), cancer plus many other potentially life-threatening illnesses.²
EAT MORE FAT AND LOSE WEIGHT
Another sign of EFA deficiency is a sluggish metabolism, which may result in weight gain and obesity. According to Fat Guru, Udo Erasmus,² essential fatty acids (especially omega-3) help us to lose weight in a number of ways:
- Increase activity of the enzymes that control fat breakdown and decrease enzyme activity for fat storage.
- Decrease reliance on carbohydrates for fuel and boost fat metabolism.
- Stabilise blood sugar and insulin levels, decreasing carbohydrate storage in adipose tissue.
- All fats suppress appetite by increasing feelings of fullness.
- A diet of empty calories will increase food cravings as the body looks for the nutrients that it lacks. A diet high in micronutrients (including EFAs) will reduce these cravings.
- Omega-3 oils decrease inflammation and the resulting water retention in the body, removing excess water via the kidneys.
- Improve thyroid function, helping to normalise metabolic rate and energy levels. This in turn makes it more likely that the individual will increase their activity levels.
- Advance mood and decrease depression, factors that often lead to over-eating and under-activity.
- It is important to remember that essential fats influence every cell, organ and system in our body. Taken as a whole, these nutrients enhance the efficiency of the body and consequently every health attribute of an individual can effectively be improved by increasing EFAs in the diet.
A CLOSER LOOK AT THE GOOD FATS
Omega-3
The parent omega-3 fatty acid is called alphalinolenic acid (ALA), which can be converted in the body to longer-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Among other protective mechanisms, EPA and omega-3 are responsible for keeping our arteries free of plaque and holding blood lipid levels, blood pressure and other cardiovascular risk factors in check.² In addition, omega-3 is an important structural component of the grey matter in the brain, so your mother was actually correct when she told you that fish will give you brains. In a healthy person, 5% to 10% of ALA will be converted to EPA and omega-3, but this process can be inhibited in certain individuals.4 The conversion enzymes may be compromised in people with diabetes and atopic allergies. Additionally, excess consumption of sugar, cholesterol, saturated fats, alcohol, processed oils and trans-fats (from margarine and other processed foods) can tune down these enzymes. In this case, it is therefore recommended that individuals consume direct dietary sources of EPA and omega-3 such as fish or fish oil.
Omega-6
The parent omega-6 fatty acid is called linoleic acid (LA), which can be converted to the longer-chain gamma-linoleic acid (GLA) and arachidonic acid (AA). GLA has been associated with the same health benefits of omega-3 oils such as: cardiovascular protection, increase in metabolic rate, and improved hair and skin quality. It is perhaps best known for its ability to relieve pre-menstrual syndrome in up to 90% of sufferers,² usually via supplementation of evening primrose or borage oil. In a healthy person, conversion of LA to GLA and AA is much more efficient than the omega-3 process, although the enzymes can also be affected by the same health factors mentioned above.
BALANCE IS KEY
The balance between omega-3 and omega-6 oil intake is crucial, because too much of one will lead to a reduced conversion of the other into its longer-chain fats. For example, a diet low in omega-3 and high in omega-6 (through consumption of vegetable oils) is a very common scenario, which will mean that more LA will be converted to AA. AA is known to increase inflammation in the body, with resulting conditions such as eczema and arthritis and increased fluid retention from the kidneys, with a resultant rise in body-weight. The National Institute of Health (NIH) in America recommends that we consume omega-6 and omega-3 oils in the ratio 2:1 to 3:1.5
WHERE CAN I GET GOOD FATS?
Omega-3
Rich sources of ALA include: flax seed, hemp seed, walnuts and algae. Rich sources of EPA and omega-3 are from deep-water oily fish such as snoek, sardines, herring and, to a lesser extent, salmon. White fish also contain EPA and omega-3, but to a lesser extent.
Omega-6
Rich sources of LA include: sunflower, sesame, pumpkin and hemp seeds, and walnuts. Rich sources of GLA include: evening primrose (generally recommended for pre-menstrual syndrome), borage and blackcurrant oils. It is essential that these oils come from a cold-pressed source. Heat-pressed sources, such as commercial sunflower and canola oils (in a clear plastic bottle) and margarines, can be extremely disruptive to these vital biochemical reactions and your long-term health.
CONCLUSION
Since the majority of the population does not eat fish or flaxseed on a regular basis, omega-3 oils are the main source of deficiency. Good sources of ALA are flax and hemp seed oils – be careful with long-term use of flax oil because it can cause a relative deficiency in omega-6. Hemp oil is a more balanced source of omega-3 and -6, although I generally recommend rotating these oils.
References
- Garrow JS. Obesity. Human nutrition and dietetics (Ch. 34). UK: Churchill Livingston; 2000.
- Erasmus U. Fats that heal fats that kill. Canada: Alive books; Burnaby; 1993.
- Earle L. New vital oils. UK: Vermilion; 2002.
- Davis BC, Kris-Etherton PM. Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications. Am J Clin Nutr. 2003; 78(suppl):640S-6S.
- Simopopulos AP, Leaf A, et al. Workshop on the essentiality of and recommended dietary intakes for n-6 and n-3 fatty acids. Bethesda, MD: National Institutes of Health; 1999.
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