Saturday, February 3, 2007

Omega-3 Fats: The Right Ratio

There has been some interest of late in omega-3 fatty acids or, as some people know them by, fish oils. This is due to the interesting things that science has found about these oils.

First and foremost as almost anyone who has grown-up in the last 40 years knows, fat is bad for you and should be avoided at all cost. WRONG!

Not only are some fats good for you but some are essential. That's right, like some vitamins, minerals, and amino acids (proteins) some fats are needed by our body yet cannot be produced by our body thus they must come from our diet making them "essential". This fact alone should radically alter the view most people have of fats.

Some Fats Are Essential

Fat is used by the body in many ways. The way that most people think of is as a means to store energy. This is why you gain fat when you eat more calories than you burn. Your body converts those extra calories into fat because fat is a highly efficient means of storage (more calories stored per gram).

But fat is also used in the construction of cells, their walls and interiors. The brain itself is largely constructed with fat. Fat is also used as a means to communicate between cells where the types of fat exchanged can play a role in how those cells behave. This point, though seemingly innocuous, can have serious health consequences. If your cells, say pancreas cells, get the wrong information on how to behave (due to exchange of the wrong kind of fat, maybe due to dietary restriction of essential fats) this could eventually lead to health problems.

The essential fats, omega-3 and omega-6 fatty acids, are also known as omega fats. There are also omega-9 fatty acids but they are not essential in that our bodies have the enzymes to produce these as needed. The term omega is used to distinguish the naming system (nomenclature) used to identify the carbon at which the first double-bond (unsaturation) is encountered (see figure). The need for the term is an artifact of the different carbon counting systems used by chemists and physiologists. With regards to diet and the body the physiological nomenclature makes sense since the body interacts with these molecules from the omega end of the molecule.

Chemical structure of alpha-linolenic acid (ALA), an essential omega-3 fatty acid, (18:3Δ9c,12c,15c). Although chemists count from the carbonyl carbon (blue numbering), physiologists count from the omega (ω) carbon (red numbering). Note that from the omega end (diagram right), the first double bond appears as the third carbon-carbon bond (line segment), hence the name "omega-3"
Chemical structure of alpha-linolenic acid (ALA), an essential omega-3 fatty acid, (18:3Δ9c,12c,15c).
Although chemists count from the carbonyl carbon (blue numbering), physiologists count from the omega (ω) carbon

Get the Right Ratio
In recent decades research on the two essential fats has begun to focus not only on the absolute quantity (how much) of the two fats consumed but also on the relative ratio (amounts of one relative to the other) of the two fats consumed. Using modern hunter-gatherer diets as aguide researchers have come to the conclusion that our ancestral diet, our paleo-diet, had a ratio of omega-3 to omega-6 fatty acids of about 1:1 or one omega-3 for each omega-6 consumed. Iin our modern diet this ratio has changed drastically. We now consume ratios of 1:10 with one study giving a 1:20 ratio between the two fats. The higher ratio of omega-6 to omega-3 is implicated in increased risk to heart disease as well as other inflammation diseases (Crohn's disease, insulin resistance and diabetes, as well as others) though the exact mechanism by which this ratio difference can impact the body is not yet fully realized. The impact that the ratio of the two fats has on the body is basically at the cutting edge of research. The take home message from that last sentence is, with regard to our understanding of diet, health, and the body, ideas derived from "cutting edge research" often change dramatically, as most anyone who follows such research is painfully aware.

In addition to the ratio of omega-3s to omega-6s there is also research looking into the impact of the three different types of omega-3 fatty acids, alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). You can read more about the three different types in a previous post.

Avoid the Bad Fats
Now there is a lot of information here to keep track of. To add to that it should be remembered that saturated fats (solids at room temperature) such as butter and animal fats are still to be minimized and avoided as should hydrogenated fats found in margarine, many prepared foods, and most off the shelf snack foods. The hydrogenation process destroys the double bonds (adds hydrogens) which preferentially destroy the omega-3 bonds over the omega-6 bonds thus increasing the ratio. Though I am skeptical of the "worst fat" moniker that trans-fats have been given they are at best as bad as saturated fats and thus should be eliminated.

Before changing your diet consult a physician and if you change your diet, consult your body. Listen to what it is telling you and adjust your diet to your body's needs. These needs will likely change over the course of a dietary change (and as you age) so make sure to keep listening.
  • Eat more vegetables (higher in omega-3s) the fresher the better.
  • Increase your consumption of good fats by replacing corn oil with canola oil or flax oil (don't fry with flax oil but baking is OK). You can also replace oil in recipes with flax meal in a 3:1 flax meal:oil ratio (you might need to adjust fluids but I have yet to do so.)
  • Do not get all your omega-3s from flax or other vegetable sources since this omega-3 (ALA) is not converted into "brain" omega-3 (DHA) by the body.
  • Eat more cold water fish, the lower on the food chain the better (due to bio-magnification process where heavy metals and PCBs are increasingly concentrated as you move up the food chain) this means more sardines but since eating sardines everyday really isn't tenable include salmon and other upper food chain fish in limited amounts (~ 1 or 2 servings a week).
  • Use fish oil supplements. Make sure they are purified to remove heavy metals and that they are third party certified.
  • Fish stocks globally are being harvested unsustainably. Please consider that you can now get DHA derived from algae from this site (note: I am not invested nor do I receive proceeds from this company. Full disclosure is that I plan to invest in this company in the future.)
  • Avoid saturated fats, processed foods (they contain hydrogenated fats to increase shelf life), and other hydrogenated fats.
  • Replace conventional dariy products with organics, there is some suggestion that organics have a higher ratio omega-3 to omega-6.
  • Eat grass fed meat products if you eat meat since these are higher in omega-3s.

Remember, a healthy diet includes fat, within limits, and that getting the ratio of omega-3s to omega-6s right as well as the right mix of the three types of omega-3s is important. Once again, a balanced diet is called for. For more information of the food sources of omega-3 follow this link.

Lastly, this isn't a lecture, this is a co-operative joint venture. I am very willing to tap into the collective knowledge-base that is the readership. The human body is a super complex mechanism so please, if you've read conflicting information or know of the latest research email me or add a comment.

DISCLAIMER: The information and advice contained in this article are intended as a general guide to healthy eating and are not specific to individuals or their particular circumstances. All content within this article is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional.

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Thursday, February 1, 2007

Good Fat: Omega-3s and Your Health


The three different types

ALA (sometimes LNA): alpha-linolenic acid
EPA:                         eicosapentaenoic acid
DHA:                        docosahexaenoic acid
Omega-3 fatty acids which are important in human nutrition are: alpha-linolenic acid (18:3, ALA), eicosapentaenoic acid (20:5, EPA), and docosahexaenoic acid (22:6, DHA). These three polyunsaturates have either 3, 5 or 6 double bonds in a carbon chain of 18, 20 or 22 carbon atoms, respectively. All double bonds are in the cis-configuration, i.e. the two hydrogen atoms are on the same side of the double bond.

What are the general findings?

  • Natural (human evolution) diet ratio of omega-3 to omega-6 fatty acids (omega3:omega6) was about 1:1 but present American diet is around 1:20 [4,5]

A diet rich in omega 3 fatty acids (such as the LNA from flax oil or the EPA and DHA from fish oils) not only provides the body with healthy fats, but it also lowers the blood level of potentially harmful ones, such as cholesterol and, possibly, even reversing the effects of excess trans fatty acids.

DHA is the primary structural component of brain tissue, so it stands to reason that a deficiency of DHA in the diet could translate into a deficiency in brain function. In fact, research is increasingly recognizing the possibility that DHA has a crucial influence on neurotransmitters in the brain, helping brain cells better communicate with each other. Asian cultures have long appreciated the brain-building effects of DHA. In Japan, DHA is considered such an important "health food" that it is used as a nutritional supplement to enrich some foods, and students frequently take DHA pills before examinations.

Journal article

  • Men are more efficient at converting ingested fat to energy than women [2,3].  For men ALA conversion was 33% versus 22% for women.
  • The conversion of ALA to EPA is strongly linear (what percent?) Thus increased consumption of ALA should lead to an equally large increase in the amount of EPA in the blood.
  • There is no relationship to the consumption of ALA and the blood levels of DHA.  Thus ALA consumption should not substitute for the consumption of DHA.  Unfortunately DHA is found widely in resources that are being harvested unsustainably.

Conversion percent
  • Role of gender in conversion
The article Compartmental modeling to quantify alpha-linolenic acid conversion after longer term intake of multiple tracer boluses says that the body incorporates about 7% of the ALA consumed and converts about 1% of that into DHA (eventually).  (That's 0.07% of ALA consumed becomes DHA - 1000mg ALA = 70mg of DHA for the body. Compare that to the amount (minimum ~150mg) in one DHA enriched egg.)  This conflicts with the previously mentioned study which found no conversion.  This study uses isotopic methods of investigation that the previous study mentioned as having some problems.  None-the-less neither study shows substantial conversion of ALA into DHA.

Health benefits of ala, epa, and dha
Omega-3s and
Colon cancer

CiteULike link

[1] G.C. Burd, Metabolism of α-linolenic acid in humans  Prostaglandins, Leukotrienes and Essential Fatty Acids Volume 75, Issue 3 , September 2006, Pages 161-168
[2] A.E. Jones, J.L. Murphy, M. Stolinski and S.A. Wootton, The effect of age and gender on the metabolic disposal of 1-13C palmitic acid, Eur. J. Clin. Nutr. 52 (1998), pp. 22–28. Abstract-EMBASE | Abstract-MEDLINE   | Abstract + References in Scopus | Cited By in Scopus

[3] A.E. Jones, M. Stolinski, R.D. Smith, R.J.L. Murphy and S.A. Wootton, Effect of fatty acid chain length and saturation on the gastrointestinal handling and metabolic disposal of dietary fatty acids in women, Br. J. Nutr. 81 (1999), pp. 37–43. Abstract-MEDLINE | Abstract-EMBASE   | Abstract + References in Scopus | Cited By in Scopus

[4] Omega-3 fatty acids in health and disease and in growth and development

Am J Clin Nutr, Vol. 54, No. 3. (1 September 1991), pp. 438-463.
by Simopoulos A
[5] Human requirement for N-3 polyunsaturated fatty acids.
Poult Sci, Vol. 79, No. 7. (July 2000), pp. 961-970.
by Simopoulos AP


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