Fats, Part 3--Unsaturated Fats

For many years, I didn't eat nuts.  Not because I didn't like them, but because they contained fat.  And everyone knew fat was "bad".  Thank goodness, we have now come out of nutritional darkness and into the light!  Nuts are a great source of unsaturated fats.  And now a moderate amount of nuts are part of my daily diet.

In the first Fats post, I covered Fat basics and trans fats.  And in Fats, Part 2, I covered saturated fats.  Now it is time for unsaturated fats to shine!

A little more about unsaturated fats

Unsaturated fats are important to good health.  Replacing saturated fats with unsaturated fats reduces heart disease risk and LDL (bad) cholesterol levels. 

In unsaturated fats, some carbons are joined by double bonds, making the fats "bendy" and usually liquid at room temperature.  This also means unsaturated fats are more likely to spoil.  A single double bond means that the fat is monounsaturated.  Two or more double bonds is described as polyunsaturated.  To save my typing fingers, I will use MUFA for monounsaturated fatty acids and PUFA for polyunsaturated fatty acids.

Unless you live under a rock, you probably have not missed packages touting food products as great sources of omega-3 (not a great thing if you have a fish allergy as many products have fish oil added).  Omega-3 and omega-6 are both PUFA.  The number just indicates the location of the first double bond.  Most MUFA are in the omega-9 group.

One key point to remember is that oils and solid fats are a mixture of saturated, MUFA, and PUFA.  For a quick comparison of three common cooking fats: 

Amt per Tablespoon in grams	Saturated Fat	MUFA	Linoleic Acid (a kind of omega-6 PUFA)	Alpha-linolenic Acid (a kind of omega-3 PUFA)
Canola Oil	1.0	8.2	2.8	1.3
Olive Oil	1.8	10.0	1.1	0.1
Butter	7.2	3.3	0.3	0.2

(data taken from this 2007 PDF)

As the table above notes, linoleic acid is part of the omega-6 family (and is its primary member).  Alpha-linolenic acid (or ALA) is the primary member of the omega-3 family.  Both of these fatty acids are essential, meaning the body cannot create them.  They must be consumed via diet. 

Using ALA, the body can make small amounts of DHA (docosahexaaenoic acid) and EPA (eicosapentaenoic acid), two important omega-3 fatty acids.  However, the conversion is not very efficient.  While ALA is found in plant sources, DHA and EPA are found in animal (fish) sources.  This difference has led to the recommendation that we consume fatty fish as a means to increase our omega-3 intake.

Omega-3 fatty acids get a lot of attention as they have been implicated in lowering blood pressure, reducing inflammation and other health benefits.  However, before you start taking big doses of fish oil, remember that these supplements are not regulated by the FDA (buy only a trusted brand).  Additionally, there are possible side effects of too much omega-3:  interference with wound healing, suppressed immune function, and increased prostate cancer risk.  Omega-6 fatty acids are essential, but have also been implicated in some negative impacts like promoting clot formation and blood vessel constriction.  But, as we see from omega-3's pluses and minuses, balance is key.

Balance--the omega-6 to omega-3 ratio

Both omega-3 and omega-6 fatty acids used the same enzymes in the body.  As a result, they compete for those enzymes and sometimes oppose each other's actions.  Given this competition, there has been much interest in the "ideal" ratio between omega-6 and omega-3.  Suggestions for good ratios to maximize health range from 4:1 (omega-6 to omega-3) to 10:1.  Typical Western diets are 15:1, but like more because of our high intake of animal fats and corn oil.  Generally, it is thought we should try to increase our omega-3 intake to get our ratio in balance. 

How Much?

There is no recommended daily amount (RDA) for omega-3.  The current suggested Adequate Intake for ALA is 1.6 grams for adults males and 1.1 grams for adult women.  Canola oil has 1.3 grams per tablespoon and walnuts are at 0.7 grams per tablespoon.  Pretty easy to meet this suggested amount.  More study will be needed to come up with an RDA for ALA, DHA, and EPA.

A Few Food Sources (this is by no means a comprehensive list)


Monounsaturated Fats 

Great post-run snack of toast and
fresh ground peanut butter

• Peanuts and peanut butter (consider natural peanut butter without added sugar or fat)
• Avocados
• Nuts: raw or dry roasted (great table of fat amounts on the Mayo Clinic's website)
• Olive Oil
• Canola Oil

Polyunsaturated Fats

Omega-3

• ALA--flaxseed and canola oils, flaxseeds, eggs (from hens raised in pastures or fed flaxseed meal), walnuts, green leafy vegetables (check out this link for an extensive list)
• EPA and DHA--Fatty fish like sardines and salmon (consider opting for wild salmon which has less saturated fat than farmed)

Omega-6
Corn and soybean oils, whole grain bread, animal fats

Additional thought--As I noted in my previous post on saturated fats, pastured animals have a better omega-6 to omega-3 ratio and contain more unsaturated fatty acids.

What to cook with?

For a great overview of cooking oils, Eating Well covered the options in their September/October 2014 issue.  In short, canola makes a great choice for cooking because of its high smoke point.  The smoke point is the temperature at which the oil breaks down and harmful chemicals are created.  If you are using low heat, consider olive oil for sautéing (extra virgin olive oil has a low smoke point).  And extra-virgin is always a good choice for salad dressings and for finishing a dish.  Butter also has a low smoke point, so it is best for low heat sautéing or baking.

What to eat?

If I have taken away any lesson from these posts on fats, it is the need to eat real food and all foods in moderation.  Marion Nestle writes in What to Eat that she doesn't worry about the omega-6 to omega-3 ratio because she gets these PUFA from foods, not oils.  She notes, "...you are better paying attention to your overall dietary pattern than worrying about whether any one single food is better for you than another."  As Dr. Frank Hu notes in a New York Times article, "The single macronutrient approach is outdated.  I think future dietary guidelines will put more and more emphasis on real food rather than giving an absolute upper limit or cutoff point for certain macronutrients."

Perhaps we would do well to take a page from Brazil's new dietary guidelines.  The second point is:
Use oils, fats, salt, and sugar in small amounts when seasoning and cooking natural or minimally processed foods and to create culinary preparations

But Brazil's overall focus is on cooking, eating real food, and community.  As it should be.

References

All quotes and sources are linked in the above text.  General nutrition information came from Whitney and Rolfes' Understanding Nutrition, 13th ed., from Nutrition for Sport and Exercise, 2nd ed. by Dunford and Doyle, and from Marion Nestlé's What to Eat.