In the past, dietary fat was considered the most expendable of macronutrients. No one would seriously argue about the necessity to consume enough carbohydrates and protein, but fats were another thing entirely. Fat earned its negative reputation because of associations with the onset of cardiovascular disease and also obesity.At about 9 calories per gram, fat contains considerably more energy content when compared to the 4 calories that comprise both protein and carbs. In addition, while both protein and carbs use energy just to be metabolized, fats pale in this regard, too. In recent years, the concept of "good" and "bad" fats has emerged. Examples of good fats are the omega-3 fats found in fish and fish oils, and the omega-9 fats represented by monounsaturated fats, such as that found in olive oil. In the bad fat category are saturated fat and trans fats. The question of whether saturated fat actually does promote cardiovascular disease, as is frequently mentioned, is still open to debate. A heavy intake of saturated fat does increase the level of low density lipoprotein cholesterol (LDL), which when oxidized, is linked to the onset of CVD. Often overlooked in the discussions on saturated fat is that it serves as a substrate for the synthesis of testosterone in the body. The only other type of dietary fat capable of doing this are the monounsaturated fats.Indeed, several studies show that if the dietary intake of these fats decreases to less than 20% of daily caloric intake, testosterone production significantly declines.
Only two types of fat are considered essential. These are omega-3, represented by alpha-linoleic acid (ALA) , and omega-6, represented by linoleic acid (LA). In actuality, ALA is a precursor to the true essential omega-3 fatty acids, namely EPA and DHA, both of which are found pre-formed in fatty fish. The human body has only a small capacity to convert ALA into EPA, and almost no ability to do the same for DHA. Omega-6 fatty acids, found mainly in vegetable oils, used to be highly touted by nutrition experts and scientists. This related not only to the essential nature of the omega-6 fatty acids, but also because of their health benefits. Such health benefits included raising levels of protective high density lipoprotein cholesterol (HDL), which in turn offered potent protective effects against the onset of CVD. But in recent years, the omega-6 fats have been demonized. This relates to the fact that there is an imbalance in the ratio of omega 6 to omega-3 fatty acids in the usual American diet.Most people consume a ratio of 20:1 in favor of the omega-6 fats over omega-3 due to the ubiquity of omega-6 fats in the food supply. In contrast, unless you eat plentiful amounts of fatty fish, you are likely deficient in omega-3. The human body evolved to prefer a ratio of 1:1 between omega 6 and omega 3 fats. Most scientists suggest that the ratio should not exceed 4:1 in favor of omega 6 fats.
The problem with omega 6 fats is that they compete with omega-3 fats in the production of a group of substances known collectively as eicosanoids. These eicosanoids affect everything from blood pressure control to hormone release, to either prevention or promotion of cancer and CVD. Omega-3 fats are protective in this regard, while the omega-6 fats have been implicated in promoting these leading killer diseases. Much of the criticism directed at omega-6 fats is because they are associated with increased body inflammation. Increased inflammation is now known to be the cornerstone of most degenerative disease, including both cancer and CVD. As a result, numerous authors have suggested that the dietary emphasis be on omega-3 fats in favor of omega-6, which they say is much more prevalent in the diet anyway. In short, you don't have to worry about getting sufficient omega-6 fats, while you have to go out of your way to ensure an adaquate intake of omega-3 to balance the usual higher intake of omega-6. Many people who eschew natural omega-3 rich foods, mainly fatty fish, are encouraged to consume fish oil supplements.
Omega-6 fats are considered pro-inflammatory because they serve as substrates to the conversion of another fatty acid called arachidonic acid (AA). In fact, it's AA that is really essential in human nutrition, not the omega-6 fat, linoleic acid. But since LA does serve as a substrate or raw material for the production of AA in the body, it's considered essential because the body cannot synthesize LA. And it's true that AA does serve as the substrate for a host of various inflammatory mediators in the body, including a class of eicosanoids. Indeed, many analgesic drugs, such as aspirin and non-steroidal anti-inflammatory drugs, such as ibuprofen, work by interfering with the synthesis of AA by inhibiting the primary enzyme (COX-1 and COX-2) that converts LA into AA. Doing so significantly decreases inflammation. But AA does a number of benefical things in the body, too. One example of this is that it serves as the precursor for prostaglandin F2A, which plays an important role in promoting muscle hypertrophy or growth. Indeed, studies show that if drugs that block AA synthesis, such as ibuprofen, are ingested within proximity of a workout, gains in muscular size and strength are blunted.
The notion that omega-6 fats cause inflammation has been challenged in several studies. These studies show that normal intakes of omega-6 fats, which is suggested to comprise about 5-10% of daily caloric intake, do not promote inflammation. In fact, AA has been shown to lower several markers of inflammation, such as interleukin-6 in the body.While the danger of producing a full-blown omega-6 deficiency is rare because of its ubiquitous presence in the typical diet, the current emphasis on ingesting large doses of omega-3 fats, such as fish oil, can in rare instances produce an imbalance of omega-3 to omega-6. If all omega-6 food sources are curtailed, there is even the possibility of producing an outright deficiency of omega-6 fats.In a recent rat study, rodents were bred to not have the gene that regulates the production of AA. These rats suffered severe dermatitis,or skin inflammation, marked by extreme itchiness and scratching in the animals.They developed a severe skin condition called ulcerative dermatitis.When AA was added to the animal's diets, the condition was relieved.This study suggests that AA is essential for normal skin function.What does this mean in a practical sense? It's still a good idea to focus on omega-3 fats, since they are comparatively scarce in the typical diet. But if you either consume huge amounts of omega-3 fats, such as over 10 grams a day or more, while avoiding consuming foods rich in omega-6 fats, you might want to consider adding a supplement such as borage oil in small amounts to ensure an
optimized balance of omega-3 to omega-6 fats.
