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Fat: Friend and/or Foe

by Esther Trepal MS RDN on August 26, 2015

It’s time to revisit an old acquaintance, one that’s been the subject of a lot of negative press. I’m talking about fat.

Along with carbohydrates and proteins, fat is one of the major nutrients in our food.  It plays several roles in cancer promotion and prevention.  Too much of the wrong kind and/or too little of the right kind are cancer promoting.  You want to strike the right balance between the good fats and the bad fats.


First, The Good News

Tops on the good fat list are omega 3 fats.  Many studies have confirmed their beneficial role in preventing death from heart disease, but they are also known to decrease inflammation. This is important because cancer is associated with inflammation – either as an initiator or something that fuels cancer’s “unfriendly fire.” Reducing inflammation helps to reduce tumor growth and the spread of cancer. Some studies have shown that inflammation promotes blood supply to the tumor, increases permeability of the outside tumor wall, releases factors that support tumor growth and weakens the immune system.  Reducing inflammation also may help you tolerate conventional treatments such as radiation.  Also, recent studies have demonstrated a connection between inflammation and cancer-related cachexia, a severe loss of weight.

Omega 3 fats are referred to as an essential nutrient because they are not made in the body, so we need to obtain them from our food. There are many types of omega 3 fats, and they are found in both animal and plant sources. The most effective forms are docosahexaenoic acid and eicosapentaenoic acid, more familiarly known as DHA and EPA. They are found in cold-water fish, specifically wild salmon (fresh or in the can), tuna, sardines, and mackerel.

The form in most plant sources is alpha-linolenic acid, or ALA. To be effective, however, it must convert to DHA or EPA, a process that isn’t very efficient. Plants that are high in ALA include flax seeds, chia seeds, and walnuts. An alternative plant source is hemp, which is more readily converted to DHA and EPA. Note, however, that men with prostate cancer should avoid large amounts of ALA, as it may promote that form of cancer. Like life, cancer is complicated.

A Little Rocket Science

Omega 3s are most effective when balanced with omega 6 fats.  These two fats run counter to each other, but in a good way. While the omega 3s reduce inflammation and blood clotting, the omega 6s do the opposite.  Both activities are needed.  However, our diets tend to overdo the omega 6s; according to some research estimates by a factor of about 11-1.   A recommended ratio is 2-4 to 1, omega 6s to omega 3s. Omega 6 fats are widely found in the diet in vegetable oils, including corn, soybean, safflower and sunflower. Look for them in many commercial products, like mayonnaise, salad dressing, crackers and baked goods.

The overall recommendation is to eat at least two 4-ounce servings of cold-water fish per week and decrease consumption of omega 6 oils. The best cooking oil is canola oil, which has one of the best omega 6/omega 3 ratios. A close runner up is olive oil because it is low in omega 6 fats.

Now the Bad News

On the negative side is the saturated fat found in animal products, especially red meat and full-fat dairy. Note that red meat includes beef, pork, and lamb – either fresh or processed, as in cold cuts. According to some sources, saturated fat promotes cancer because it interferes with detoxification, suppresses the immune system, and causes oxidative damage. There is a possible link between saturated fat and prostate and postmenopausal breast cancers. Several studies have shown a likely relationship between colorectal cancer and the animal fat found in lard and butter.

How Much Fat?

Diets high in fat have been shown to increase risk of lung, colorectal and postmenopausal breast cancers.  For general health, the recommendation is to keep fat to less than 30% of total calories for the day. But for those fighting cancer, the goal is closer to less than 25%.

For someone consuming 1600 calories a day, that comes to roughly 400 calories, or 45 grams of fat. At 1800 calories, there are 450 calories from fat, or about 50 grams.  To put that into perspective, 3 ounces of skinless chicken breast, baked, has 4 grams of fat, whereas 3 ounces of lean hamburger has roughly 7. One teaspoon of oil has 4.5 grams.  Yes, that’s teaspoon. On the other hand, for the most part, fruits and vegetables have extremely small amounts of fat.

Tipping the Scales

While fat by itself doesn’t cause weight gain, a diet high in fat, by definition high in calories, can contribute to overweight and obesity. Since obesity promotes inflammation, it creates an environment that encourages tumor development and growth. Studies link obesity to various cancers, such as esophageal, pancreatic, colorectal, kidney, endometrial, gall bladder, and postmenopausal breast cancers.

Fat City: Putting It All Together

So, while some fats can make it tough to fight off cancers, other fats are either helpful or at least neutral. Here’s the bottom line on making some healthful food choices:

Boost the omega 3s

  1. Eat cold-water fish two times per week. Portion sizes should be 4 ounces. Try wild salmon (fresh or canned), tuna, mackerel, sardines, halibut, or wild rainbow trout.
  2. Include flax seeds, hemp seeds, chia seeds, and walnuts in your diet (see exception for prostate cancer, above).

 

Cut the omega 6s

  1. Cook with canola or olive oil.
  2. Check all food labels for corn, soybean, safflower and sunflower oil. Minimize use of these oils. 

 

Eat lean animal meat only

  1. Poultry and fish are the best bets.
  2. If eating red meat, use lean cuts and keep portion sizes to 3 ounces (cooked). That’s about the size of the palm of your hand.
  3. Opt out of animal protein altogether and try beans and tofu.

Keep your body lean

  1. Keep body fat in a healthy range through exercise and diet. 
  2. See www.myplate.gov for evaluation tools and suggested lifestyle changes. 

Having trouble doing it alone? Registered Dietitians can help you plan your diet around your taste preferences, health issues and lifestyle.  Some visits may be covered by your insurance. Check with your carrier. 

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