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From the Townsend Letter for Doctors & Patients
June 2002

The Skinny on Fats & Breast Cancer
by Stephen Byrnes, PhD, RNCP
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In today's nutritional world, fat has become a dirty word. Women in particular are encouraged to eat a low-fat diet to help prevent breast cancer, as well as other ailments, including other cancers. Animal fats such as butter have taken a terrible beating in the media over the past few decades and have been blamed for horrific crimes, including obesity, heart disease and cancer. Accordingly, Western peoples have been virtually brainwashed into thinking that butter and other predominantly saturated fats like coconut oil and tallow are unhealthy. So-called safe substitutes like margarine and various vegetable oils have been heavily promoted and advertised with the result being that the public associates these things with health and well-being.


Unfortunately for us, all of these contentions and claims are false. When it comes to breast cancer prevention, and in some cases treatment, the so-called "bad fats” are actually the good guys, and the "safe substitutes” are increasingly being shown up for what they really are: fabricated foods that cause disease, including breast cancer.

All Fats Are Not the Same
A common misconception the general public and some food writers hold is that all fats are essentially the same. This is not true. There are, to be sure, certain fats and oils that we need to avoid, but one must always be very specific as to what those are. Let's define our terms to end the confusion once and for all.

Fatty acids are chains of carbon and hydrogen atoms linked together in certain ways with an acid, or carboxyl group, attached to their end. When three fatty acids are bonded together with a glycerol molecule, the result is a triglyceride. In lipid biochemistry, all fatty acids are classified according to the number of carbon atoms present in their structure, as well as the degree of saturation, or how many hydrogen atoms are bonded to the carbons. A fatty acid that has two hydrogen atoms linked up to each carbon atom is saturated; a fatty acid with two hydrogens missing is monounsaturated; and a fatty acid with four or more hydrogens missing is polyunsaturated. All fats and oils, whether of animal or vegetable origin, are blends of these three types, but with one usually predominating, depending on the food in question.

Saturated fats predominate principally in animal fats, though palm and coconut oils are noted plant sources. Monounsaturated fats abound in nuts, avocadoes, olive oil, and some animal fats (especially lard). Polyunsaturated fats mostly make up vegetable oils, but significant amounts are found in fish oils and chicken skin.

It should be noted here that the more a fat is saturated, the more stable it is chemically. Saturated and monounsaturated fats do not go rancid easily if stored properly. Likewise, these fats are more stable under heat, making them ideal for cooking. Polyunsaturated fats, however, especially those of vegetable origin, are not as stable and go rancid more quickly, even in the body. Rancid oils breed one thing: cancer-causing and tissue damaging free radicals. While some polyunsaturated fats are needed by the body, the so-called essential fatty acids (EFAs), they should not exceed about 5% of your total caloric intake due to this problem.1

The two EFAs are linolenic (an omega 3 fatty acid) and linoleic (an omega 6 fatty acid). The "3" and "6" indicates where the first double bond occurs in the fatty acid molecule. For example, in an omega-3 fatty acid, the first double bond occurs at the third carbon atom. The body takes the EFAs and creates other omega-3 and 6 fatty acids and hormone-like substances called prostaglandins to carry out a host of metabolic functions. Like vitamins and minerals, EFAs must be derived from our food. In times past, humans consumed a balance of linolenic and other omega 3 fatty acids (found principally in cold water fish, walnuts, eggs, flax oil, dark green leafy vegetables, cod liver oil, and some whole grains) and linoleic and other omega 6 fatty acids (found principally in vegetables), and this is as it should be as both are equally important. When there is an overabundance of linoleic acid in the diet, however, our body's ability to absorb and utilize linolenic acid is inhibited.2 This causes a host of undesirable reactions including sexual and immune dysfunction, and increased cancer risk.3 The Western world has greatly increased its linoleic acid intake due to its higher use of vegetable oils over the past 60 years.4 Not surprisingly, cancer (and heart disease) rates have skyrocketed.

There is another type of "fatty acid” that is produced during chemical processing called a trans-fatty acid (TFA). These are unnatural fats that our bodies cannot utilize properly due to their bizarre chemical structure. In a TFA, a liquid vegetable oil has been made solid by forcing hydrogen atoms into it with the help of a nickel catalyst. In terms of visual appearance, a hydrogenated fat looks like a saturated one since both are solid at room temperature. On a molecular level, however, the TFA is quite different, making it unusable by the body. These fake fats are found in margarine, "vegetable oil spreads,” vegetable shortening, and refined canola oil. It is trans-fatty acid, as opposed to saturated fatty acid, consumption that is strongly correlated with cancer, cardiovascular disease, and other diseases.5

Talking with a Fat Expert
Dr. Mary Enig, PhD, is president of the Maryland Nutritionists Association, a former research associate of nutritional biochemistry at the University of Maryland, and a recognized international expert in lipid biochemistry. In 1978, Enig and two colleagues, published a ground-breaking paper that analyzed the claims made for cancer and fat intake.6 Then, as now, the widely accepted notion was that a higher intake of saturated fatty acids increased one's risk of cancer, while increased consumption of polyunsaturated fatty acids, the kind found in vegetable oils, offered a protective effect. Enig contended the actual data showed the exact opposite. In the ensuing years, Enig turned her attention to trans-fatty acids, their ever-increasing presence in Western diets, and their roles as disease promoters.7

"What is wrong with the current dietary advice to prevent breast and other cancers,” she stated, "is that the evidence against ‘fat' is not defined correctly. There is no solid evidence against the natural fats, whether they are animal or vegetable fats. Research has always shown, however, that the high linoleic acid-containing oils promote experimentally induced cancer, and high lauric acid-containing oils (such as coconut and palm kernel oils) prevent experimentally induced cancer. There is also some published evidence that the TFAs promote breast cancer. As for the claim that either animal fats or saturated fats promote breast or other cancers, this is not true; there is just the opposite evidence.

"The TFAs have been shown to correlate with the incidence of breast cancer,” she continued. "There has been at least one research report from the NIH [National Institutes of Health] that showed linoleic acid to be a promoter; this research has not been continued for some reason.

"Furthermore, research from Europe showed that the TFAs were higher in tissues of women who had breast cancer. Research from Denmark and Greece identified the partially hydrogenated vegetable fats and/or margarine with breast cancer.

"When it comes to other diseases, there is evidence of adverse effects of the TFAs as factors in heart disease, diabetes, poor infant growth and development, and hormonal and immune system dysfunction.TFAs also inhibit prostaglandin synthesis.”8

It would appear, then, that the "bad” fats are the very ones that women have been told to eat more of in the last few decades: margarine, vegetable shortening, and vegetable oils (including corn, soy, safflower, and cottonseed oils). Furthermore, the evidence implicating TFAs as causative factors in breast cancer is growing stronger. For the woman interested in breast cancer prevention vegetable oils, margarine and all partially-hydrogenated oils have got to go! Due to their wide presence in processed foods, women should check food labels and be on the lookout for these biochemical marauders.

Are Saturated Fats Really Bad?
No they are not. Despite current beliefs that saturated fats cause an increased risk for cancer, a long term study of 60,000 women recently completed in Scandinavia showed no such connection.9 There was, however, a high rate of cancer associated with vegetable oil consumption. This is in keeping with what is being increasingly revealed about vegetable oils: they are bad news.

There are many vital nutrients and substances found in saturated fats. Butter, for example, is rich in several trace minerals, including selenium, a key antioxidant and cancer preventer. Several studies have linked low selenium levels with higher cancer and heart disease rates.10 Butter also contains all the fat-soluble vitamins, especially vitamins A and D, both antioxidants and protective against cancer. Butter also contains fair amounts of two fatty acids: butyric and lauric. Both of these are antifungal, antibacterial, and anticarcinogenic substances.11 (Coconut and palm kernel oils, and Roquefort cheese are other significant sources of lauric acid.) Butter is also the best source of a particular fatty acid getting a lot of attention lately: conjugated linoleic acid (see below).12

Coconut oil is another good example. Formerly used widely in baked goods, this oil is very rich in lauric acid. This fatty acid converts in the intestines into monolaurin, a powerful antifungal, antiviral, and antibacterial substance. Coconut oil also contains caprylic acid, also a powerful antifungal. Recent research shows coconut oil to be stimulatory to the immune system and to offer substantial benefits to HIV+ individuals.13 Yet these properties are lost amidst a plethora of unwarranted warnings about "the dangers of saturated fat.”

Dr. Enig added that, "The fats that humans have consumed for millennia were almost always more saturated than they were unsaturated. It was the easily extractable fat or oil, such as the fat that came from the animal or, in tropical areas, the oil that came from the coconut or palm fruit, that was used in cooking. People really didn't have the ability to extract oil from vegetables like corn as they do today. However, people got their EFAs from many of these plants when they were included in the foods the people were eating. This was the way the EFAs were historically consumed.” In other words, like our ancestors, it's best to have more saturated fats in your diet and to get your EFAs from whole foods rather than from processed vegetable oils.

Won't increasing your saturated fat intake increase your chances for heart disease? Dr. Enig says, "No. The idea that dietary saturated fats and cholesterol cause heart disease or "clogged arteries” is completely wrong. Studies have actually revealed that arterial plaque is mostly made up of unsaturated fats, particularly polyunsaturates.”14

In fact, the body needs saturated fats in order to properly utilize EFAs.15 Saturated fats also lower the blood levels of the artery-damaging lipoprotein a (Lpa levels are elevated by TFAs);16 are needed for proper calcium utilization in the bones;17 stimulate the immune system;18 are the preferred food for the heart and other vital organs;19 and, along with cholesterol, add structural stability to the cell wall.20 Dr. Enig further comments that, "Increasing one's intake of saturates spares the body's supply of antioxidants which get rapidly used up with a high polyunsaturated fat diet. This is another way that saturates protect against cancer.”

One caveat: it's important to try to obtain organic sources of your fats as environmental toxins are lipophilic, or "fat loving.” It's worth a few more dollars to look for organic butter, milk, cheese, and other animal foods. If your budget just won't permit you to buy organic all of the time, then purchase organic sources of the food items that you use the most to minimize your exposure to possible toxins.

Conjugated Linoleic Acid
CLA is a fatty acid produced by ruminating animals such as cows. Dr. Enig states that, "CLA is an isomer of linoleic acid; the natural forms are found in milk fat (especially high fat cheeses) and meat fat. CLA has been shown to inhibit the development of cancer, including breast cancer.” Indeed, the October 2000 issue of the Journal of the American College of Nutrition contained a research abstract describing how CLA inhibited breast cancer cell growth.21 As a side benefit, several studies have shown CLA to promote muscle growth and fat burning by the body.22 In other words, CLA is a fatty acid that helps you lose unwanted fat and build a leaner body.

Where do you find CLA? Some supplement companies now manufacture CLA in capsule form, but the best source is fat from grass-fed cows. It's important that you look for full fat dairy products (milk, cheese, butter) and meats from grass-fed animals. Why? Because cows manufacture CLA from grass in their stomachs.23 Commercially-raised cows which only eat soybeans or corn meal produce little, if any, CLA. New Zealand's butter and meat products are from grass-fed livestock, as are those from smaller farms (see sources). It should be pointed out here that non or low fat dairy foods will obviously contain little or no CLA (or the fat soluble vitamins A and D). Consuming skim or low fat milk, cheese, and yogurt will automatically deprive the health-minded woman of several important nutrients.

How sad that modern farming methods, with the loss of grass feeding, deprive us of such a healthful fat! It is also unfortunate that establishment nutritionists have urged women and the public away from full fat dairy products and butter: the best sources of CLA.

The Right Fat Diet
Avoiding phony fats like margarine and vegetable shortening, as well as processed vegetable oils that are high in polyunsaturates is a must for any woman wanting to prevent breast cancer and ill health. Taking extra care to include organic sources of healthy fats like olive oil, butter, and coconut oil, as well as CLA-rich foods from grass-fed cattle, will help prevent breast cancer and other diseases. Dr. Enig agrees, "The best dietary advice is to avoid partially hydrogenated vegetable oils and high levels of omega-6 oils. Use a broad balance of natural fats and oils and consume as many whole foods and whole food mixtures as possible.”


Mary Enig's book Know Your Fats is available from or from www.Bethesda Dr, Enig can be contacted at Enig Associates, Inc., 301-680-8600. Papers by Dr. Enig on coconut oil and other fats can be found at

For sources of organic, grass-fed butter and other animal foods, check your local health food market, or the Weston A. Price Foundation which maintains a list of nationwide farms and cooperatives. See above for web address or call 202-333-HEAL.

Stephen Byrnes' new book, Diet and Heart Disease: Its NOT What You Think (Whitman Books; 2001) is available from or your local book store. Visit his website to receive his free ezine:


1. Lasserre M, et al. Lipids, 1985, 20:4:227; Fallon S and Enig M. Nourishing Traditions, 2nd ed., New Trends Publishing, Washington DC, 1999, 10.

2. Kinsella JE. Food Technology, October 1988, 134; Lasserre M, et al. Lipids, 1985, 20:4:227.

3. Horrobin DF. Reviews in Pure and Pharmacological Sciences, vol. 4, 1983, Freund Publishing House, 339-383; Devlin TM, ed., Textbook of Biochemistry, 2nd ed., 1982, Wiley Medical, 429-430; Fallon S and Enig MG. Tripping Lightly Down the Prostaglandin Pathways. Jnl of Price-Pottenger Nutr Fnd, 1996, 20:3:5-8, posted at

4. Rizek RL, et al. Fat in Today's Food Supply, Jnl Amer. Oil Chem. Soc., 1974, 51:244.

5. Mann G, "Metabolic Consequences of Dietary Trans-fatty Acids", Lancet 343:1268-71 (1994); Enig MG, et al., Fed. Proc. July 1978, 37:2215; Kummerow F, "Nutritional Effects of Isomeric Fats,” Dietary Fats and Health, Horisberger and Bracco, eds. (Amer Oil Chem Soc; IL), 1983, pp. 391-402; Schantz EJ, et al. Jnl Dairy Sci, 1940, 23:181-89; Watkins BA, et al., Br Poul Sci, Dec 1991, 32(5):1109-19.

6. Enig MG, et al., Fed. Proc. July 1978, 37:2215.

7. Enig MG. Trans Fatty Acids in the Food Supply: A Comprehensive Report Covering 60 Years of Research, 2nd ed., Enig Associates, Inc., Silver Spring, MD, 1995.

8. Enig MG, personal interview, January 4, 2001.

9. Wolk A, et al., Arch of Inter Med, 158:41 (1998)

10. Studies summarized by Lieberman S and Bruning N. The Real Vitamin and Mineral Book, 2nd ed., Avery Publishing Group, Garden City, NY, 1997, 299-302.

11. Shanks L, et al., Symposium on the Pharmacological Effects of Lipids, J. Kabara, ed., American Oil Chemists Society, Champaign, IL, 1978, 51-62.

12. Fallon S and Enig MG. "Why Butter is Better”, posted at, accessed on Jan. 4, 2001.

13. Enig MG. Lauric oils as antimicrobial agents: theory of effect, scientific rationale, and dietary application as adjunct nutritional support for HIV-infected individuals. Food and Nutrients in AIDS, R. Watson, ed., CRC Press, Boca Raton, Florida, 1999, 81-97; Isaacs CE, Kim KS, Thormar H. Inactivation of enveloped viruses in human bodily fluids by purified lipds, Annal NY Acad Sci., 724:457, 1994; Sadeghi S, et al., Dietary lipids modify the cytokine response to bacterial lipopolysaccharide in mice. Immunology, 1999, 96(3):404-10.

14. Felton CV, et al. Dietary polyunsaturated fatty acids and composition of human aortic plaques, Lancet, 1994, 344:1195.

15. Garg ML, et al. FASEB Jnl, 1988, 2:4:A852; Oliart Ros RM, et al. "Meeting Abstracts,” AOCS Proceedings, May 1998, 7, Chicago, IL.

16. Dahlen GH, et al. J Intern Med, Nov 1998, 244(5):417-24; Khosla P and Hayes KC. J Am Coll Nutr, 1996, 15:325-339; Clevidence BA, et al. Arterioscler Thromb Vasc Biol, 1997, 17:1657-61; Enig MG. Fat Facts: Trans Fats and Saturated Fats are Not the Same, Jnl of Price-Pottenger Nutr Fnd, Winter 1998.

17. Watkins BA, et al. "Importance of Vitamin E in Bone Formation and in Chondrocyte Function,” Purdue University, Lafayette, IN, ACOS Proceedings, 1996; Watkins BA and Seifert MF. "Food Lipids and Bone Health,” Food Lipids and Health, RE McDonald and DB Min, eds, p 101, Marcel Dekker, Inc., New York, NY, 1996.

18. Kabara JJ. The Pharacological Effects of Lipids, The American Oil Chemists Society, Champaign, IL., 1978, 1-14; Cohen LA, et al. FASEB Jnl, Meeting Abstracts, Mar 1999, 204.1, p. A222.

19. Lawson LD and Kummerow F. Lipids, 1979, 14:501-503; Garg ML. Lipids, 1989, 24(4):334-9.

20. Fallon S and Enig M. Nourishing Traditions, 2nd ed., New Trends Publishing, Washington DC, 1999, 11.

21. See also Ip C, Banni, S, Angioni, E, Carta G, McGinley J, Thompson HJ, Barbano D, Baumann D. Conjugated Linoleic Aicd-Enriched Butter Fat Alters Mammary Gland Morphogenesis and Reduces Cancer Risk in Rats. Jnl of Nutr, 129:2135-2142; Hubbard NE, Lim D, Summers L, Erickson KL. Reduction of murine mammary tumor metastasis by conjugated linoleic acid. Cancer Lett 2000 Mar 13;150(1):93-100.

22. Gavino VC, Gavino G, Leblanc MJ, Tuchweber B. An isomeric mixture of conjugated linoleic acids but not pur cis-9, trans-11-octadecadienoic acid affects body weight gain and plasma lipids in hamsters. Jnl of Nutr 2000 Jan;130(1):27-9; Ostrowska E, Muralithraran M, Cross RF, Bauman DE, Dunshea FR. Dietary conjugated linoleic acids increase lean tissue and decrease fat deposition in growing pigs. Jnl of Nutr 1999 Nov;129(11):2037-42.

23. Belury MA, Nutr Rev, April 1995, 53:(4)83-89; Kelly ML, et. al. Jnl Dairy Sci, Jun 1998, 81(6):1630-6.

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