Your Personal Paleo Code: The 3-Step Plan to Lose Weight, Reverse Disease, and Stay Fit and Healthy for Life (12 page)
Authors: Chris Kresser
Tags: #Health & Fitness / Diet & Nutrition / Diets, #Health & Fitness / Diet & Nutrition / Weight Loss
Research over the last two decades suggests that CLA may protect against several different diseases. For example:
•
CLA is inversely associated with heart disease. In other words, those who eat higher amounts of CLA have a lower risk of heart disease, and vice versa.
•
CLA may help prevent and manage type 2 diabetes by improving glucose tolerance and insulin sensitivity, and observational studies show an inverse association between CLA levels in fat tissue and diabetes risk.
•
CLA has been shown to reduce the risk of cancer, primarily by blocking the growth and metastatic spread of tumors, controlling the cell cycle, and by reducing inflammation.
•
Some research suggests that CLA can help reduce body fat and promote weight loss in those who are overweight or obese.
Artificial trans fats have slightly different chemical structures than the natural trans fats found in beef and butter. But these minor differences in structure lead to dramatically different effects in the body. While natural trans fats may reduce the risk of cancer, heart disease, obesity, and inflammatory conditions, artificial trans fats have been shown to
increase
the risk of those diseases—even at relatively low doses.
Their effects on cardiovascular health are particularly harmful. They promote inflammation, damage the fragile linings of the blood vessels, increase the number of LDL particles, reduce HDL cholesterol, and reduce the conversion of shorter-chain omega-3 fats into DHA. Artificial trans fats are the quintessential junk food because they provide no benefit, have no role in human physiology, and cause significant harm.
•
Natural trans fats:
Dairy and meat from pastured animals are the best sources of CLA and other natural trans fats. In fact, products from 100 percent grass-fed animals contain three to five times more CLA than products from grain-fed animals. And since CLA is in the fat, the best sources will be fattier cuts of meat, bone marrow, high-fat dairy products like butter and whole milk, and full-fat cheeses.
•
Artificial trans fats:
These are found in highly processed, refined, and fried foods (doughnuts, margarine, fast food, frozen food, chips, cookies, crackers, candy, and so on); packaged foods (for example, instant soups, cake mixes, microwave popcorn, and flavored rice and pasta mixes).
Food
: Cow’s milk
Cla, Mg/G Fat
*
: 3.4–23.6
Food
: Beef
Cla, Mg/G Fat
*
: 3.7–17
Food
: Lamb
Cla, Mg/G Fat
*
: 5.6–14.9
Food
: Butter
Cla, Mg/G Fat
*
: 4.7–14.1
Food
: Goat’s milk
Cla, Mg/G Fat
*
: 5.8–10.5
Food
: Yogurt (cow’s milk)
Cla, Mg/G Fat
*
: 2.8–10.5
Food
: Cheese (cow’s milk)
Cla, Mg/G Fat
*
: 2.9–9.8
Food
: Cheese (goat’s milk)
Cla, Mg/G Fat
*
: 2.7–6.3
*
Food
: White Castle Haas chocolate frosted doughnuts
Trans Fat, G/Serving
: 9
Food
: Long John Silver’s breaded clam strips
Trans Fat, G/Serving
: 7
Food
: Celeste Pizza for 1
Trans Fat, G/Serving
: 5
Food
: Marie Callender’s lattice apple pie
Trans Fat, G/Serving
: 5
Food
: Pop Secret popcorn (butter flavor)
Trans Fat, G/Serving
: 5
Food
: Pillsbury Grands! biscuits
Trans Fat, G/Serving
: 3.5
Food
: Safeway Creme Wafer Cookies (vanilla)
Trans Fat, G/Serving
: 3.5
Food
: Jimmy Dean croissant sandwiches
Trans Fat, G/Serving
: 3
Food
: Sara Lee Chocolate Mint Creme Pie
Trans Fat, G/Serving
: 3
Food
: Land O’Lakes margarine
Trans Fat, G/Serving
: 2.5
Food
: Betty Crocker pie-crust mix
Trans Fat, G/Serving
: 2.5
•
Conjugated linoleic acid (CLA): Eat pastured-animal meat and dairy products (if you tolerate them) to obtain CLA.
Note that CLA supplements do not have the same benefits as naturally occurring CLA. Most CLA supplements are derived from linoleic acid in safflower oil, and some studies have shown that CLA supplementation in humans can cause fatty liver disease, inflammation, unfavorable changes in lipid profiles (high LDL cholesterol and triglycerides and low HDL cholesterol), and insulin resistance. Furthermore, CLA supplements have not demonstrated the beneficial effects seen from dietary intake of CLA in human trials.
•
Artificial trans fats: Avoid like the plague.
Polyunsaturated fats can be divided into two categories:
omega-6
and
omega-3
. Omega-3 fats are present in green leaves and algae (and the animals that eat them), and omega-6 fats are found primarily in seeds (as well as in the animals that eat them).
Polyunsaturated fats play both a structural and regulatory role in the body. They help form cell membranes, regulate gene expression, and aid in cell function. Omega-3 and omega-6 fatty acids have specific effects on the cells close to where they are formed, including both pro-inflammatory and anti-inflammatory effects. In general, both too much omega-6 and too little omega-3 cause inflammation, while restricting omega-6 and getting adequate omega-3 will prevent inflammation.
Polyunsaturated fats are a complex subject involving a lot of biochemistry. I’m going to spare you the unnecessary details, but there are a few basic concepts you’ll need to understand about them before we proceed.
•
Like all fats, polyunsaturated fats are chains of carbon, hydrogen, and oxygen atoms.
•
There are
six different omega-6 fats
and
six different omega-3 fats.
They are classified by the length of their chains (that is, the number of carbon atoms each chain has) and the number of carbon-carbon double bonds.
•
Essential fatty acids are the shortest-chain polyunsaturated fats. They are called essential fatty acids because they’re required for the body’s proper function but can’t be produced by the body and thus must be obtained from the diet. There is
one essential omega-6 fat (linoleic acid)
and
one essential omega-3 fat (alpha-linoleic acid).
•
Linoleic acid (LA) and alpha-linoleic acid (ALA) are converted into longer-chain derivatives in our bodies.
The most important long-chain omega-6 fat is arachidonic acid (ARA), and the most important long-chain omega-3 fats are EPA and DHA.
•
Though linoleic acid and alpha-linoleic acid are considered essential because they can’t be manufactured in the body, the
longer-chain derivatives (ARA, EPA, and DHA) are primarily responsible for the health benefits
we get from polyunsaturated fats.
With that in mind, let’s take a closer look at omega-6 and omega-3 fats.
Linoleic acid (LA)
is the essential omega-6 fatty acid. It is found in small or moderate amounts in a wide variety of foods, including fruits, vegetables, cereal grains, and meat. But it is present in large amounts in industrial processed and refined oils, like soybean, cottonseed, corn, safflower, and sunflower. These oils are ubiquitous in the modern diet, present in everything from salad dressing to chips and crackers to restaurant food. LA is also relatively high in most nuts and in all poultry, especially in dark meat with skin.
The evidence suggests that a moderate intake of linoleic acid from whole foods like poultry, vegetables, and nuts and seeds is unlikely to cause problems in the context of a diet containing sufficient amounts of long-chain omega-3 fats like EPA and DHA. But when linoleic acid is consumed in excess amounts—especially in the form of industrial seed oils (which have a tendency to oxidize)—and when intake of EPA and DHA is low, LA has a pro-inflammatory effect and may contribute to modern chronic diseases.
Arachidonic acid (ARA)
is a longer-chain omega-6 fat that can be produced in our bodies using linoleic acid. It is also found in animal foods like chicken, eggs, beef, and pork, because animals are also capable of making this conversion. ARA is present in cell membranes, involved in cellular signaling (aiding cells in exchanging information), and can also act as a vasodilator (relaxing the blood vessels). It is necessary for the growth and repair of skeletal muscle tissue, and, along with DHA, it is
one of the most abundant fatty acids in the brain. You may have seen stories in the media claiming that eating meat and other animal products causes inflammation in the body. This is based on the idea that ARA leads to the production of inflammatory compounds. Animal products are high in ARA, so it stands to reason that eating animal products would increase inflammation. Right?
Not so fast. While it’s true that the compounds derived from ARA can be pro-inflammatory, recent evidence suggests that they may have important anti-inflammatory actions as well. Moreover, it’s now clear that ARA serves as a precursor for a potent group of compounds that help reduce and resolve inflammation. (A precursor is a substance—in this case, ARA—from which another substance can be formed.) ARA is needed to make a class of molecules called lipoxins, which trigger the release of anti-inflammatory compounds synthesized from EPA and DHA. In epidemiological studies, higher plasma levels of ARA, EPA, and DHA were associated with the lowest levels of inflammatory markers. And clinical studies have found that adding up to 1,700 milligrams of ARA per day to the diet (an amount far greater than the average U.S. intake of 100 to 500 milligrams per day) does not promote inflammation.
•
Omega-6 linoleic acid:
Found in whole foods like nuts, seeds, poultry, and avocados; also present (in large amounts) in industrial seed oils like corn, soybean, cottonseed, safflower, and sunflower. These oils are ubiquitous in processed and refined foods, and most restaurant kitchens cook with them (because they’re so cheap).
•
Omega-6 arachidonic acid:
Found primarily in animal foods such as meat, poultry, and eggs.
Oil
: Safflower oil
Omega-6, %
: 72
Oil
: Sunflower oil
Omega-6, %
: 63
Oil
: Corn oil
Omega-6, %
: 52
Oil
: Wheat germ oil
Omega-6, %
: 53
Oil
: Soybean oil
Omega-6, %
: 49
Oil
: Cottonseed oil
Omega-6, %
: 50
Oil
: Peanut oil
Omega-6, %
: 31
Oil
: Canola oil
Omega-6, %
: 18
Oil
: Chicken leg
Omega-6, %
: 19
Oil
: Chicken breast w/skin
Omega-6, %
: 18
Oil
: Chicken breast w/o skin
Omega-6, %
: 17
Oil
: Ham
Omega-6, %
: 13
Oil
: Duck, roasted
Omega-6, %
: 12
Oil
: Tilapia
Omega-6, %
: 11
Oil
: Eggs
*
Omega-6, %
: 11
Oil
: Bacon
Omega-6, %
: 10
•
Omega-6 linoleic acid (LA): Limit
LA intake to moderate consumption of whole foods like nuts, avocados, and poultry. Avoid industrial seed oils as much as possible.
•
Omega-6 arachidonic acid (ARA): Eat liberally
in animal foods such as meat, poultry, and eggs. Intake of more than five times the average has been shown to be safe.
Alpha-linoleic acid (ALA), the essential omega-3 fat, is found in plant foods such as walnut and flax. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the most important long-chain omega-3 fats (and now you know why it’s easier to refer to them as EPA and DHA!). They are found in seafood and, to a lesser extent, in the meat and fat of ruminant animals.
While ALA is considered essential, it’s really EPA and DHA that are responsible for the benefits we get from eating omega-3 fats. (Some researchers have even proposed that DHA be considered an essential fatty acid, because, like ALA and LA, it’s essential for human health and must be obtained from the diet to ensure adequate levels.)