You really are what you eat: A tale of two eggs

Have you heard the expression, "You are what you eat"? This might call to mind images of heads sprouting into fast food cheeseburgers. Seriously though, have you ever wondered what the food you ate might have eaten, or was fed? If we are what we eat, and the food we eat is what it ate, than aren't we what they ate also. Huh? Perhaps an illustration might help better explain the thought I'm trying to communicate. 

Food chain -

Image from the Victoria Dept. of Education

You've probably heard of the food chain, or web. Princeton's Wordnetweb defines the food chain as basically "a community of organisms where each member is eaten in turn by another member" (1). This is depicted by the image at left which shows a very simple marine community food chain. So, this brings me to my tale.

The tale of two eggs -

It all began when I was making a recipe which required two eggs. One egg, the last in a carton I bought from the grocery store, came from a "cage free/grain fed" hen. The other was in a dozen I purchased from my local food co-op. This egg came from a foraging pastured hen raised on a north Texas family farm. As I attempted to crack the food co-op egg into the bowl, I noticed that the shell seemed thicker than the grocery store egg (a result of a diet providing the hen with more available calcium for egg shell formation) (10). However, what surprised me most was the difference in appearance between these two eggs. As you can see from the photo, the egg on the top is larger, has a much deeper yolk color and a cloudier egg white compared to the egg on the bottom.

Having been raised in the suburbs of Chicago and a suburbanite ever since, what I know about farming or livestock could fill a thimble.  What I did know was that both of these eggs came from chickens, and I expected them to be rather similar. So, this got me to wondering: 

1. why are these two eggs different from each other? 
2. what might these differences mean from a nutritional standpoint? 
3. which egg represents the healthier option? 

Prior to buying eggs from the local food co-op, I assumed I was making a wise purchase by choosing eggs from the grocery store that were marked as coming from "cage-free, grain fed" hens, and I felt the increased cost was justified because of this label. But all was not as it seemed in the land of eggs. As they say in the literary world, "the plot thickens". This tale of two eggs has reminded me, yet again, of the importance of being an informed consumer and it also underscores the need for "buyer beware".

Cage free vs. free range vs. pastured -

The carton my store bought eggs came in clearly states the eggs inside are from "cage-free/grain fed" hens. Okay, I'm sheepishly disclosing that the egg carton's labeling brought images to my mind of chickens happily roaming freely out in the sun and fresh air in a pleasant, green pasture, pecking away to their heart's content. The reality is that "cage free" simply means that the chickens don't live in cages. Admittedly, this is an improvement over the living conditions of caged chickens. However, according to the Humane Society of the United States, "hens laying eggs labeled as 'cage-free' [live] uncaged inside barns or warehouses, but they generally do not have access to the outdoors." Unlike caged birds, "they can engage in many of their natural behaviors such as walking, nesting and spreading their wings", although the cutting of their beaks is permitted (2).  Ouch. This type of existence is a far cry from my naive and idyllic view of how I thought cage free chickens lived.

Free range -

Free range chickens sound even better than cage free, right? Not necessarily. The University of California Division of Agriculture and Natural Resources states that free range eggs actually come from chickens that are generally allowed to "graze or roam outdoors" (3). This sounds great in theory, but is this what is actually happening? Evidently, not very often (4). My understanding is that there are no certifications in the US that pertain to "free range" eggs, only to free-range chickens sold for their meat. As a result, the words "free range" can be loosely interpreted and even more loosely applied. For example, in many cases "free ranging" chickens may have access to a tiny doorway in the building where they are confined. The door may be opened for only five minutes, and perhaps only 2 chickens exit through it, but this still qualifies a farm to state its chickens are free-ranging. "No other criteria such as environmental quality, number of birds, or space per bird, are included in the term free-range" (4).

Now, some of you might be saying that this kind of cruelty to animals is a logical reason why we should not eat animal products. However, the purpose of this post isn't to discuss the issues pertaining to a vegan vs. non-vegan lifestyle.  So, I am not going to delve into the very real problems inherent in the large scale production of eggs that result from our consumption and desire for an inexpensive product. A primary concern for us as food consumers is that we should be able to make informed decisions and choices about what we eat. This tale of two eggs highlights that the product labeling on egg cartons can be misleading and the eggs inside the carton, forgive the pun, might not be what they're cracked up to be. So, back to the tale and the pastured eggs I purchased from the food co-op.

Pastured -

The food co-op egg carton's label said their eggs came from pastured hens.  Wondering what the term "pastured" really meant, I took my question straight to the source. According to Mrs. Connie Hale, who runs Windy Meadows Family Farm with her husband Mike and their children, the term "pastured" on their farm means that their "hens spend almost their entire life spans on grassy turf, most often protected [from predators] in large, movable bottomless pens, or electric netting enclosures." In this way, the chickens "have direct access to the forage and insects that make up their natural diet. The chickens are usually 'locked up' at night for added protection from predators, but at the first light of day are released to begin another day in the fresh outdoors."

Big differences between cage free, free range and pastured hens -

If you'd like a better appreciation of the differences between the way factory farm eggs are produced vs. the sustainable, family scale agricultural way of producing eggs check out the video below:

You can find the Cornucopia Institute's Organic Egg Scorecard here.

Chickens are what they eat too -

Eating eggs that come from hens raised on pasture have benefits beyond the more humane and sustainable aspects of this type of farming. Connie Hale from Windy Meadows Family Farm, also mentioned that because chickens are omnivores there are definite positive effects to the health of the hens and their eggs when they spend most of their lives outdoors foraging on the pasture in the fresh air and sunlight. This is because the natural diet of chickens consists of insects, worms, green plants, and seeds, among other things.  This type of diet includes more diversity than the feed grain mix that most caged, cage-free, or free range chickens are fed (7). So, this answers my first question: Why are the two eggs in my tale different? They are different because of the hen's diet.

Nutrition benefits from pastured eggs -

As Connie so aptly put it, "Everyone is healthier when he eats his greens, even our animals." Science is finding that animals allowed free access to pasture are generally healthier. Researchers have found that pastured foraging hens receive more beta carotene, magnesium and other vitamins and minerals than do animals who are not able to forage. When animals eat this type of diet this also translates into a healthier diet for those of us who eat the products that come from these animals (5).

One study by Penn State's College of Agricultural Science showed that "compared to eggs of commercial hens, eggs from pastured hens had twice as much vitamin E and long-chain omega-3 fats, more than double the total omega-3 fatty acids and less than half the ratio of omega-6 to omega-3 fatty acids" (5).  Western diets tend to be higher in omega-6's than omega-3's, but scientific evidence suggests that "higher dietary omega-3 intakes are associated with reductions in heart disease" (6). You can read more about the health benefits of these fats here. Researchers also found that the Vitamin A concentration was "38 percent higher in the pastured hens' eggs than in the commerical hens' eggs. Their research shows that nutrient levels present in the eggs are responsive to dietary changes in the hens.

Another study found that as compared to US Department of Agriculture (USDA) data for commercial "factory-farm" eggs, the eggs from hens raised on pasture contain:

• one third less cholesterol 
• one quarter less saturated fat 
• two thirds more vitamin A
• two times more omega-3 fatty acides
• three times more vitamin E
• seven times more beta carotene (this explains the bright orange color of the yolk)!
• three to six times as much vitamin D (it's good to get a little sun)! An example of what this translates to in our diet is "two scrambled eggs from pastured hens may give you 63 to 126 percent of the recommended daily intake of 200 International Units of vitamin D" (6). You can read more about Vitamin D here.

Well, that answers my other two questions. Eggs from pastured hens are more nutritious than conventionally produced "factory farm" eggs. So, considering the nutritional benefits, along with the more humane and sustainable farming practiced in raising pastured hens, for my dollar, the food co-op egg is the better choice. I would much rather support a small, local, family farm that raises their eggs in a humane, responsible and sustainable way. Best selling author Michael Pollan says it best - We can become responsible consumers. Consumers and farmers have shown with the organic movement "how they can work together as co-creators of an alternative food system.  We need to join together now, to recruit a larger and larger army of co-creators, to rewrite the rules of the game and create a different kind of food system" (9). 

I wish I could say this this tale ends happily ever after, but I can't. The underlying issues still remain. As Michael Pollan points out, we consumers have the ability to force a change in food labeling and production processes. However, until this occurs the tale continues.  Change is difficult and often requires concessions. As is evidenced by the price of the pastured eggs I purchased, one concession for consumers will come in the form of paying higher food prices. For many, this economy has brought a time of uncertainty where just getting any food on the table is difficult enough. Never the less, I encourage you to consider that cheap food is really more expensive in the long run.  This is because it's generally lacking in nutrients. As a result, it leads to more disease and higher medical costs (8). There really is no escaping the fact that we are what we eat.

PS - In case you were wondering...which egg in the photo was from the foraging pastured hen? The top egg.
What does a cloudy egg white mean? "Cloudy egg whites usually indicate very fresh eggs" (3).


Sources
(1) Princeton Wordnetweb -  http://wordnetweb.princeton.edu/perl/webwn?s=food%20chain
(2) Humane Society http://www.humanesociety.org/issues/confinement_farm/facts/guide_egg_labels.html 
(3) University of California Dept. Natural Resources - http://ucanr.org/freepubs/docs/8154.pdf
(4) United Poultry Concerns - http://www.upc-online.org/freerange.html 
(5) Penn State University - http://live.psu.edu/story/47514
(6) Linus Pauling Institute - http://lpi.oregonstate.edu/infocenter/othernuts/omega3fa/
(7) Mother Earth News - http://www.motherearthnews.com/natural-health/health-benefits-free-range-eggs.aspx
(8) Dr. Mark Hyman  - http://www.huffingtonpost.com/dr-mark-hyman/why-quick-cheap-food-is-a_b_681539.html
(9) Ecoliteracy Michael Pollan - http://www.ecoliteracy.org/essays/we-are-what-we-eat 
(10) Skyline College - http://www.skylinecollege.edu/case/biol215/docs/eggshell.pdf 

Understanding the omegas

Are you finding it challenging to understand precisely what it is you’re supposed to eat and why it’s good for you? Unfortunately, part of the difficulty in making determinations about our food can result from misinformation we may receive about nutrition. Compounding the problem of a better understanding of healthy nutrition are the intricacies of the subject matter itself.

At first glance, nutrition seemed fairly straightforward to me. In the world of fitness training, it can be as simple as: calories in equal calories out for weight maintenance.  That understanding is definitely important, but there’s a whole lot more going on between the calories in and the calories out. You might find, as I have, that an awareness of the finer details aids in a better understanding of the bigger picture. So, in order to make more educated choices about eating for our health, I've found it helpful to take a closer look at the foods I eat and how they affect me. This educational journey through fat nutrients was a veritable alphabet soup of acronyms and a few of the concepts required some critical thinking. Yet, in the end I found it was worth it. However, if you're less interested in the fascinating workings of fatty acids, just skip down to the bottom line section of the post.

Well, it's good to know that I'm not alone in my quest for nutritional knowledge. Let's journey on and get back to the topic of discussion in the last 2 posts: fats and specifically the polyunsaturated fatty acids (PUFA’s) known as omega-3 and 6.

Omega-3 and 6: Why are they important?
In case you missed the previous posts on fats, omega-3 and 6 are also known as essential fatty acids (EFA’s).  This is because our bodies can’t make enough of them, so they must come from the foods we eat. EFA’s are extremely important in, among other things, cell membrane structure and function, cardiovascular health, vision, the regulation of gene expression and the proper working of our nervous system (Linus Pauling Institute).

Omega-3 and 6: What are they?
Omega-3 and omega-6 are terms which actually represent 2 families of fatty acids.  In the omega-3 family the nutritionally important fatty acids include: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA can be made from ALA. However, the body doesn’t do this very efficiently (around 5% in men and slightly higher in women) (Wikipedia). The body can also convert EPA into hormone like substances called eicosanoids. Omega-3 eicosanoids are thought of as being less prone to cause inflammation. Unfortunately, since the body doesn’t convert EPA very efficiently, the rate at which these omega-3 eicosanoids are produced is much slower than that of omega-6.

In the omega-6 family there is linoleic acid (LA), gama-linoleic acid (GLA) and arachidonic acid (AA). Through a cascade of chemical reactions the body can make AA from LA. However, because of the excess of LA compared to ALA in the Western diet, the result is usually a greater formation of AA than that of the EPA that is made from omega-3. The body also converts AA into eicosanoids and because of the greater amounts of available AA more of the omega-6 eicosanoids are formed as a result.

The eicosanoids formed from the omega-6 AA are thought to be more "pro inflammatory" than the eicosanoids converted from ALA (AHRQ Evidence Report). If you're looking for more information on inflammation, this topic is discussed in another post.  The important point here is that anything that promotes an inflammatory state in the body for long periods of time isn't good (Linus Pauling Institute).

Now we’re getting to the heart of the matter.  Some experts believe that the current Western diet contains as much as anywhere from 10-25 times more omega-6 than omega-3. Compounding the situation is that omega-3 and omega-6 eicosinoids compete to use the same chemicals in order to be transformed. So the ratio of omega-3:omega-6 directly affects the type of eicosanoids formed and our Western diet encourages more production of omega-6. Remember that eicosanoids produced from the AA derived from omega-6 are considered to be pro-inflammatory.

Omega-3 and 6: Are their ratios important?
If you’ve been following the previous posts in this blog you know that studies have shown that there are definitely health benefits associated with including more omega-3’s in our diet. Table 2 below shows some of the benefits of omega-3's DHA and EPA (Lavie, et al).

Research suggests that an imbalance between omega-3 and omega-6 is an underlying cause in many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases (Simopoulos, A.P.). It's thought that omega-3 eicosanoids have regulating effect over omega-6 eicosanoids.  When the two are totally out of balance, this regulating effect is removed and the eicosanoids from omega-6 exert a more "pro-inflammatory" state. It seems experts aren't in agreement yet on a specific ratio of omegas, however they do seem to recognize that more eicosanoids from omega-6 than from omega-3 contributes to inflammation, blood vessel constriction (which causes increases in blood pressure) and blood clotting (Linus Pauling). 

Omega-3 and 6: How much to eat and from what foods?
So, aside from the ratios, how much of each omega is necessary for optimal health and what foods do we eat to get them? Well, as far as I can tell, at this point in time the US hasn’t assigned a Recommended Daily Allowance (RDA) for omegas.  However, the Food and Nutrition Board of the U.S. Institute of Medicine has established adequate intake (AI) levels for both omega-6 and omega-3 fatty acids. You can view the AI’s here at the Linus Pauling Institute. An example  of the AI's for adult males 19-50 years old is 17 grams per day and for females it's 12 grams per day. For males 51 years and older the AI for LA decreases to 14 grams per day and 11 grams per day for females.  The Linus Pauling Institute also has a list of the best food sources for omega-3 and 6 and you can check that out here.

Image from www.extension.org

There has been some research on omega supplementation in the case of individuals with cardiovascular disease. The American Heart Association recommends a combined EPA and DHA intake of approximately 1,000 mg/day for people with this disease. However, for people who don’t have cardiovascular disease their suggested RDA is based on fish consumption. They advise eating two oily fish meals per week. This amount of fish would provide about 400-500 mg/day of EPA + DHA (Linus Pauling Institute). Remember to be careful to avoid fish containing higher levels of mercury and other contaminants.

According to a report on EFA's by the Agency for Healthcare Research and Quality Evidence, Acceptable Macronutrient Distribution Ranges (AMDR’s) have been established for the essential fatty acids. You can view their table of sources and proportions of omega-3 foods and supplements here. 

Bottom Line
As you can see from the above information, knowing how much and what ratio of omegas to consume is a rather confusing and complicated subject. When it comes to the question of what to eat, I like how simply the Harvard School of Public Health puts it: “out with the bad and in with the good.”  Here are their suggestions for how to eat better and also get more of the healthy fats:

•  Try to eliminate trans fats from partially hydrogenated oils. Check food labels for trans fats; avoid fried fast foods.
•  Limit your intake of saturated fats by cutting back on red meat and full-fat dairy foods. Try replacing red meat with beans, nuts, poultry, and fish whenever possible, and switching from whole milk and other full-fat dairy foods to lower fat versions.
• In place of butter, use liquid vegetable oils rich in polyunsaturated and monounsaturated fats in cooking and at the table.
•  Eat one or more good sources of omega-3 fats every day—fish, walnuts, canola or soybean oil, ground flax seeds or flaxseed oil.

So, I’m no longer stuck in the old thinking that generic, low-fat eating is the way to go. From now on when it comes to fats it’s out with the bad and in with the good. Making educated choices about the foods we eat may seem complex at first, but with practice it becomes easier. Don't you think it's worth the effort to understand which food is healthier than another? When you consider how profoundly what we put into our bodies affects our health, we really owe it to ourselves and those we love to practice healthy nutrition habits! 

Sources
Simopoulos, A.P., Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases. Retrieved from  http://www.ncbi.nlm.nih.gov/pubmed/17045449
Carl J. Lavie, MD, Richard V. Milani, MD, Mandeep R. Mehra, MD and Hector O. Ventura, MD, Omega-3 Polyunsaturated Fatty Acids and Cardiovascular Diseases,  J Am Coll Cardiol, 2009; 54:585-594, doi:10.1016/j.jacc.2009.02.084, Retrieved from http://www.natap.org/2009/HIV/080509_04.htm
Linus Pauling Institute: http://lpi.oregonstate.edu/infocenter/othernuts/omega3fa/#intro
http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-full-story/index.html
http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=erta89&part=A131672#A131673
Edwards,T., Inflammation, pain, and chronic disease: an integrative approach to treatment and prevention.Retrieved fromhttp://www.ncbi.nlm.nih.gov/pubmed/16320856

More skinny on fats - the good, the bad, the ugly

While we're on the topic of fat...Yesterday the U.S. Centers for Disease Control (CDC) released statistics on obesity. First, what defines obesity?  In determining overweight or obesity for adults, a tool called the Body Mass Index (BMI) is used.  According to the CDC:

• an adult that has a BMI between 25 and 29.9 is considered overweight
• an adult that has a BMI of 30 or more is considered obese

Check out the CDC's BMI tool in the right hand column of this blog. As you can see, it uses height and weight, and for most people this correlates with their amount of body fat. If the tool isn't working for you (it requires Flash Player 9) you can go directly to the CDC's website here and use their interactive BMI calculator. Children and teens have their own BMI calculator that also uses height and weight, but this data is then plotted on a BMI-for-age growth chart in order to obtain a BMI percentile. You can find that tool here.

So, back to the obesity statistics.  This may not be all that surprising to some, but it's a sad fact that recent data released by the Weight Control Information Network (WIN) shows that over one third (33.8%) of American adults (age > 20) are obese and over two thirds (68%) are overweight. After checking your BMI, you might even be realizing that you're among these statistics.

Okay, enough of the depressing news. Let's talk about what can be done to make a positive change in these obesity trends.   The last post mentioned the 1990's low-fat/no-fat diet craze. Then the pendulum swung the other way and low carbohydrate eating became the next fad. Regardless of how or what you're eating, the most important information to keep in mind when you're trying to lose weight is calorie consumption. If the calories being consumed are greater than the calories being burned, weight gain occurs. It's as simple as that.

Most experts agree that 20-35% of our daily calories should come from fat  This amounts to about 44 to 78 grams of total fat a day, based on a 2,000 calorie a day diet (Mayo Clinic). Even though all fats contain the same number of calories (9 calories per gram), it's the foods we eat and the types of fat they provide that is vitally important. In addition, the ratio of certain fats in our diet is being recognized as significant for good health as well.

Plant Oils

Perhaps you've seen the classic spaghetti western starring Clint Eastwood called The Good, the Bad and the Ugly. The title of this film might be a helpful way to remember the reputation, so to speak, of the different dietary fats. They are:

Unsaturated fats - the good
These fats are called unsaturated because of their chemical structure, where most of the fatty acids are not saturated with hydrogens. You may recall that unsaturated fats can be mono- or polyunsaturated fatty acids (also known as MUFA's and PUFA's respectively).  Major sources of MUFA's are:

• plants oils ( olive oil, peanut oil, canola oil)
• avocados, nuts and seeds 

Major sources of PUFA's are:

• plant oils (safflower, sesame, soy, corn and sunflower) 
• nuts and seeds
• high in omega 3 - Fatty, cold-water fish (such as salmon, mackerel and herring), flax seeds, flax oil and walnuts

Saturated fats - the bad
In addition to fats that are unsaturated, there are also fats that are saturated.  They are called saturated fatty acids because their chemical structure has all the hydrogens it can hold, so it is said to be saturated. Later in the post the significance of the hydrogen saturation/unsaturation will become clearer, but for now it's important to note that saturated fats should be limited in the diet.  Consuming saturated fat is one of the main dietary factors linked to increased blood (serum) cholesterol levels.  Major sources of saturated fats are:

• whole milk, cream, butter, cheese,
• fatty cuts of beef and pork, sausage
• coconut, palm and palm kernel oils and products containing them like prepackaged cakes, cookies, pies, doughnuts and pastries

Trans fats - the ugly
The fact that a fat is saturated, or mono/polyunsaturated influences its firmness at room temperature and also its stability. Generally speaking, an example would be that polyunsaturated vegetable oils are liquid, whereas saturated fats like that found in beef or butter are more solid. All fats eventually become spoiled (rancid) when exposed to oxygen (oxidation), but polyunsaturated fats are the most unstable, so they're the most susceptible.

Back in the early 1900's a chemist figured out a way to alter the chemical structure of fats through a process called hydrogenation. This is the chemical process of taking a mono- or polyunsaturated fat and partially saturating it with more hydrogen atoms. Why bother? Well, one reason behind hydrogenation is that it makes a liquid fat more solid.  It also increases the stability of the fat. This helps to prevent spoilage and extends the shelf life of prepackaged foods containing partially hydrogenated oils. Unfortunately, the downside of this process results in what are called trans-fatty acids, which are also known as trans-fats. Major sources of trans-fats are:

• Commercial baked goods — such as crackers, cookies and cakes 
• Fried foods, such as doughnuts and french fries
• Shortenings and some margarine can be high in trans fat (Mayo Clinic)

What's so "ugly" about trans-fats? Well, it turns out that when it comes to cholesterol, these fats pack a deadly one, two punch. Not only does consuming trans-fat lower the "good" cholesterol called high density lipoprotein (HDL), it raises the bad cholesterol called low density lipoprotein (LDL). In brief, lipoproteins are clusters of lipids and proteins and they transport fat through the bloodstream. LDL is loaded with cholesterol whereas HDL has the job of carrying cholesterol to the liver for recycling or disposal. A high HDL level represents better elimination of cholesterol.  As a result it is considered the good cholesterol. This is why high LDL and low HDL levels are risk factors for heart disease and stroke. You can find much more detailed information on cholesterol levels at the American Heart Association's website here.

So, now that we're familiar with the types of fat, and a few of the food sources, how can we apply this knowledge? How can we consume more of the good fats and in the proper ratios? The next and final post on fats will cover these questions. In the meantime, one suggestion is to avoid or eliminate processed, prepackaged (short for prepared and packaged) and fast foods which contain the bad and ugly fats. Replace these with whole foods, which are in their natural state, or have been processed or refined as little as possible. Start by trying to make small dietary changes, like substituting a serving of omega 3 rich fish for meat once a week. Taking small steps does make a difference and can eventually lead to lifestyle changes and healthier nutrition. 

Sources
http://www.ncbi.nlm.nih.gov/pubmed/16287956?dopt=Citation
http://www.aafp.org/afp/980315ap/masley.html
http://lpi.oregonstate.edu/infocenter/othernuts/omega3fa/#intro
http://books.google.com/books?hl=en&lr=&id=RhW3v6x9n44C&oi=fnd&pg=PA9&dq=can+eating+the+right+kind+of+fat+make+you+skinny%3F&ots=EmrvqR_voX&sig=gpTV4AAhMwT3bMcsqwt5I6in7u0#v=onepage&q&f=false
http://www.cdc.gov/obesity/defining.html
http://win.niddk.nih.gov/statistics/
http://www.nhlbi.nih.gov/health/dci/Diseases/Hbc/HBC_WhatIs.html
http://en.wikipedia.org/wiki/Trans_fat
http://www.americanheart.org/presenter.jhtml?identifier=4582
Image source: Merriam Webster

The skinny on fat

What comes to mind when you think of dietary fat? More than likely you're not thinking of the word skinny. Most often eating fat is thought of as being bad for us. Fat became the villain nutrient in the 90's, and was responsible for the low-fat diet craze which spawned countless low fat and fat free food products.

For a number of reasons, the accepted wisdom at that time was if you cut the amount of fat in your diet you'd lose weight, lower cholesterol and reduce the risk for heart disease, among other things. The thinking about weight loss isn't totally out of line, considering there are a little over twice as many calories in one gram of fat as there are in one gram of carbohydrate. Ironically though, the backlash of the no fat/low fat campaign resulted in even greater numbers of overweight Americans, with elevated cholesterol levels and at risk for or diagnosed with heart disease.

Fast forward to a new millennium. We're older, wiser and still a country with an obesity problem. In addition, heart disease is now the number one cause of death (CDC). Fortunately, some interesting information about fat has been learned over the last twenty years. Dr. Walter Willett, of the Harvard School of Public Health, states that he and his colleagues began examining data from studies which shows that "the percentage of calories from fat in a diet has not been related to any important health outcome." Really? How can that be? Well, they realized what is especially significant is the type of fat in the diet. This was the critical factor impacting our health.

So, what type of fat and how much of it should we eat for positive health effects? First, perhaps a little background on fat will aid in understanding. Fat actually refers to a class of nutrients called lipids. Lipids include triglycerides, which are fats (solid form) and oils (liquid form), phospholipids (like lecithin) and sterols (the most well known of these is cholesterol). For now, let's look a little more closely at the triglycerides, in particular.

Just a tiny bit of chemistry is helpful here and, although it may seem a bit tedious, it will become clear why it's important once you've finished reading. Triglycerides are made up of one molecule of glycerol and a chain of fatty acids.  Fatty acids may be saturated or unsaturated. For now I'm focusing on the unsaturated fatty acids. Depending on how many points of unsaturation the fatty acid contains, they can be monounsaturated (mono meaning one) or polyunsaturated (poly meaning many).

Are you still with me? Good because this next part is key. The location of the first point of unsaturation on a polyunsaturated fatty acid's (PUFA's) chain determines whether that PUFA is an omega 3 or an omega 6 fatty acid. We're all relatively familiar with the omega terminology. It's important to note, however, that the terms omega 3 and omega 6 are actually a classification for a group of PUFA's and include, among others, alphalinoleic acid (ALA), EPA and DHA, which are all omega 3's, and linolenic acid (LA), eicosadienoic acid (EA), and GLA, which are all omega 6's. There's also an omega 9 group. The human body can make sufficient amounts of all fatty acids except for the omegas. As a result, omega 3 and omega 6 are considered essential fatty acids (EFA's) because they must be supplied by the foods we eat. The body can manufacture modest amounts of the omega 9's.

Now that you  have  slugged through all of that science, why is it important?  Well, research has clearly shown that omega 3 and 6 fats have health benefits when consumed in the right amounts and ratios. Interestingly, a large body of scientific research suggests that adding more dietary omega-3 fatty acids may have an even greater benefit. This is because, according to the Linus Pauling Institute, "it has been estimated that the ratio of omega-6 to omega-3 fatty acids in the diet of early humans was 1:1, but the ratio in the typical Western diet is now almost 10:1 due to increased use of vegetable oils rich in LA as well as reduced fish consumption."Other experts believe we get as much as 25 times more omega 6 than omega 3 (Black).

So, what do you think? Can we eat fat and at the same time not gain weight or have our cholesterol levels increase? The research suggests it's possible IF we eat the right kinds and amounts of fat. I don't know about you, but all this has made me hungry.  I'm going to go grab a healthy omega 3 snack of a few walnuts. Next post will look at the other types of fats, as well as the recommended intakes, which fats to avoid, what foods will provide the fats we need and the many health benefits of eating good fats. Stay tuned for more skinny on fat.


Sources
http://www.pbs.org/wgbh/pages/frontline/shows/diet/themes/lowfat.html
Whitney, E. and Rolfes, Sharon, Understanding Nutrition, 11th edition,  Thomson 2008.
http://www.cdc.gov/features/heartmonth/
http://lpi.oregonstate.edu/infocenter/othernuts/omega3fa/#intro
Black, Jessica, ND, The Anti-inflammation book, Berkeley 2006.