History of CLA People used to receive healthy doses of CLA in their diets through regular consumption of beef and dairy fats. However, changes over the past 30 years in the way cattle are raised and in the foods people eat have lowered the amount of CLA people get from their diet. Cattle are no longer pasture grazed, resulting in a decrease in their internal production of conjugated linoleic acid. Most individuals are concerned with cholesterol and fat so they eat less red meat and dairy products. This eliminates even more CLA from the average diet. Fortunately, Natural scientists developed a proprietary process to convert the linoleic acid of pure safflower oil, into conjugated linoleic acid. Because it is difficult to obtain an optimal level of CLA through one's diet without over-consuming foods that are high in fat and cholesterol, Natural Inc. distributes Tonalin® CLA to dietary supplement and functional foods manufacturers. CLA was first identified in 1987 by researchers at the University of Wisconsin-Madison. The identification of CLA resulted in nine years of experiments by Michael Pariza, PhD. at the University of Wisconsin-Madison. In 1978, Dr. Pariza first noted an extract in beef that appeared to be an anitcarcinogenic. In 1987, he identified this extract as CLA. With this identification, came a surge of scientific studies and research on how CLA affects body mass and other beneficial effects on human health. Extensive research is now showing CLA to play an important role as a multi-beneficial health promoter. More than 200 studies worldwide are indicating that CLA may help reduce the incidence of breast cancer, improve asthma, allergy control, and blood sugar control (diabetes), and limit the extent of atherosclerosis which can lead to heart disease. Studies show that CLA (the active ingredient in Tonalin® CLA) works three ways to help you achieve your diet goals. CLA interferes with a substance in your body called lipoprotein lipase that helps store fat in your body. CLA helps your body use its existing fat for energy. CLA increases lean muscle tissue, which naturally slims your body (and makes you feel strong and healthy). And the more muscle you have, the more calories your body uses in order to function, thereby speeding up the fat burning process. As a result, you get smaller in all the right places. You drop clothes sizes. You look great. You feel great. And no yo-yo dieting effect. Dietary CLA has been shown to effect body composition by creating a reduction in body fat and an enhancement of lean tissue or muscle. According to Michael Pariza at the University of Wisconsin, this area of CLA research is the most supported. Recently, the research has focused on clinical studies with much success; showing statistically significant reduction in body fat as measured by BMI (Body Mass Index). A significant decrease measured in waistline measured in inches, a positive result for weight loss in mildly overweight subjects and an increase in strength. Human clinical studies to substantiate improved body composition have been conducted worldwide. Positive results of CLA supplementation have been seen at research centers worldwide. Kent State University, University of Memphis, University of Wisconsin, USDA Western Human Research Center, Medstat Research Ltd. in Norway, Uppsala University in Sweden, University of Kumanoto in Japan and University of Tours in France. CLA appears to exert direct effects on adipocytes, which are the principle sites of fat storage and skeletal muscle cells and are the primary sites of fat combustion. It has been proposed that the physiologic mechanism of body fat reduction by CLA involves inhibition of fat storage in adipocytes coupled with elevated b-oxidation in skeletal muscle. An overall increase in skeletal muscle tissue may be mediated at least in part via the inhibition of immune-induced catabolism. CLA is a metabolically active compound that has been demonstrated to dramatically reduce body fat and increase lean body tissue. The mechanisms of action are not completely understood, but because CLA has been shown to affect a wide variety of enzymes and hormones in the body, multiple mechanisms may come into play. Numerous human studies are in progress, which will make a stronger case for efficacy and dose response. Expectations are high that research will additionally show no regain of body fat lost, suggesting that Tonalin™ CLA should be included with every diet regimen. Not only does Tonalin® have no harmful side effects, but it's actually good for your body. As a matter of fact, scientists worldwide are just begining to understand CLA's wide range of potential health benefits. Here are quick summaries of CLA's current four principal health benefit areas. In the early 1980s, a noted doctor, Michael Pariza, working at the University of Wisconsin and his colleagues discovered that CLA interfered with the growth of cancer tumors. Since then, a number of other studies have further shown CLA's cancer-fighting potential. Some of these studies have shown that CLA can suppress cancer development in animals, and in human cancer cell lines in vitro. Dietary CLA also seems to protective against breast cancer in humans, as demonstrated in a large French study by Lavillonniere et. al. at the University Francois-Rabelais. When breast adipose tissue was collected at the time of surgery, higher levels of CLA in the control group suggested CLA's protective effect against breast cancer. A different study in Finland confirmed the reverse correlation between milkfat intake, which contains CLA and breast cancer. Over the next few years, additional studies are planned to help further understand the role CLA may play in the fight against cancer. Over time, cholesterol and other substances can form plaque in your arteries, narrowing them, reducing your heart's blood supply. This is artherosclerosis, and it can kill you. In a collaborative study where a diet high in cholesterol was fed along with CLA to animals, the data suggested that CLA could help prevent artherosclerosis. By week 12, the LDL and total cholesterol and triglyceride counts were markedly lower in the blood of the animals fed CLA. Other studies have indicated that CLA reduces plasma lipoproteins and early aortic atherosclerosis in the animal model. According to Dr. David Kritchevsky at the Wistar Institute, another significant finding is the apparent ability of CLA to reduce the severity of preinduced atherosclerosis lesions in the animal model. Overall, CLA has considerable potential for the prevention and treatment of artherosclerosis, and studies continue to reveal it's potential health benefits. One of the most important health benefits of CLA could possibly be its ability to affect and treat some types of diabetes. According to Dr. Martha Belury at Purdue University and Dr. John Vandel Heuvel at Penn State University, CLA normalizes impaired glucose tolerance in non insulin-dependent diabetes. In earlier experiments by Houseknecht et. al., it was observed that CLA and troglitazone reversed the symptoms of diabetes in a specific diabetic animal model. Effects included decreased triglycerides, insulin and leptin, and improved glucose utilization. Belury and Vanden Heuvel conclude that CLA may represent an important agent for the treatment of Type II diabetes. Because CLA isomers share many of the attributes of the clinical thiazolidinedione drug, troglitazone, without exhibiting as many side effects, CLA may represent a new insulin-sensitizing agent for treatment of Type II diabetes. Additional clinical studies are scheduled at many universities worldwide in order to further explore the possibilities of using CLA for diabetes treatment. In 1991, evidence obtained through the collaborative efforts of Dr. Mark Cook and Dr. Michael Pariza at the University of Wisconsin revealed the immune boosting potential of CLA. Feeding CLA to chicks provided partial protection against the catabolic effects of exposure to endotoxin. This research expanded to include rodents and supported the fact that CLA-fed animals exhibit enhanced immune functions. CLA is the only known nutrient that enhances the immune system and protects against the harmful "cellular backlash" that occurs when the immune system is stimulated. As published in sperate issues of Cancer Research, CLA has been shown to be an effective antioxidant in vitro according to Dr. Yeong Ha and in vivo according to Dr. Clement Ip. Because numerous studies indicate that oxidative reactions are associated with the development of cancer and atherosclerosis, CLA's ability to reduce the harmful effects of these oxidative reactions could be its most important health benefit In addition, research suggests that CLA may ease the inflammation that occurs when the immune system is challenged. CLA: Does Fat Have a Silver Lining? by Selanna Reiner The role of diet in the development of cancer has been the focus of much scientific research during the past decade. Researchers now know that high intakes of certain naturally occurring dietary chemicals increase our risk of cancer. Such chemicals include benzo(a)pyrene (found in charcoal-broiled meat), aflatoxin (found in peanuts), and certain hydrazines (found in edible mushrooms). But scientists studying the chemical makeup of the human diet have also identified some naturally occurring anticancer chemicals. One looks especially promising. Conjugate Bliss? Among the more potent naturally occurring anticarcinogens is conjugated linoleic acid (CLA), a fatty acid found mainly in milk fat. The compound was first isolated in 1983 (from ground beef), by a research team led by Michael W. Pariza, Ph.D., of the University of Wisconsin. During the past few years, researchers have not only confirmed CLA's anticarcinogenicity in experimental animals — it is the only fatty acid that has been shown unequivocally to inhibit cancer growth in such animals — but have also explored ways of increasing the amount of CLA in our diet. However — and here's the rub — while CLA's anticarcinogenicity has been demonstrated in rats and mice and in in vitro ("test-tube") studies of human cancer cells, whether it can significantly protect humans is wide-open to question. Exactly how CLA inhibits cancer is the subject of ongoing scientific investigation. Whence CLA? The term "conjugated linoleic acid" refers to a group of several variants of linoleic acid (also called octadecadienoic acid), an essential fatty acid. Variants of linoleic acid differ from one another in the type and arrangement of their chemical bonds. The specific structure of CLA's chemical bonds is crucial to the compound's ability to fight cancer; at high levels, linoleic acid, whose chemical structure is slightly different, increases cancer growth in lab animals. Researchers are excited about CLA because it is anticarcinogenic at much lower dosages than are many other naturally occurring anticarcinogens. It is effective in animals at dietary levels as low as .05 percent. According to researchers at the October 1996 Cornell Nutrition Conference, the normal human intake of CLA from dairy products provides about one third of the level of CLA shown to afford cancer protection in experimental animal models. Most dietary substances protective against cancer originate in plants, but CLA is found almost exclusively in animal products. Dairy products are the main source of CLA for humans. Meat, particularly beef, is another major source. The meat of ruminants — cows, sheep, and other animals that chew the cud — contains more CLA than nonruminant meats, such as turkey, chicken, and pork. Because CLA is a fatty acid, its concentrations in food are generally measured against the fat in the food: milligrams (mg) of CLA per gram (g) of fat. According to one study that used this measure, lamb, beef, and veal — in descending order of concentration — contain more CLA than other meats. The study also showed that seafood is very low in CLA and that plant oils contain much less CLA than animal fats. Grazin' in the Grass Microorganisms that live in the rumen (the first stomach compartment) of cows help create the CLA found in dairy products by secreting enzymes that contribute to the breakdown of food. CLA forms during the digestion of dietary linoleic acid. CLA is absorbed from the rumen and ends up in the cow's milk. The concentration of CLA in milk fat varies substantially. Dr. Dale Bauman of Cornell University examined milk from various herds of New York cows and found that CLA levels ranged from 2.4 to 18 mg CLA/g fat — more than a sevenfold variation. A survey of milk from Canadian creameries uncovered a similar range of CLA levels. This wide variation in cows' CLA levels results partly from differences in diet and dairy-farm management. Evidence indicates that when cows are allowed to graze in pastures, their milk contains more CLA than when they are fed grain concentrates. This probably explains the finding of one study that in summer cow's milk contained double the CLA it contained in winter. (Researchers found no seasonal variation when they measured CLA from dairy cows given the same diet throughout the year.) CLA levels in milk also increase when cows are fed supplements (corn oil, for example) that contain high levels of unsaturated fatty acids. CLA seems to be a stable component of milk fat. Some investigators have found that neither processing (heating, canning, etc.) nor storage has much effect on the CLA levels of dairy products. In contrast, studies of CLA levels in meat suggest that cooking and processing meat can increase its concentration of CLA. One study showed a nearly fivefold increase in the CLA content of ground beef after grilling. The Downside Even if researchers demonstrate that CLA is anticarcinogenic in humans, the compound would have limited public-health utility, since it is abundant only in fatty foods. It is the fat in milk that contains CLA. The making of "fat free," low-fat, and "reduced fat" dairy products entails losses of the compound. For example, "fat free" cottage cheese and "fat free" ice cream contain very little CLA. Increasing consumption of fatty foods to increase CLA intake is ill-advised — not only because researchers have not demonstrated CLA's effectiveness against cancer in humans, but also because high fat intakes may have adverse health effects, such as increasing one's risk of heart disease and certain types of cancer. One approach to increasing CLA's availability would be to boost the proportion of CLA in milk fat, which would increase the CLA content of products made from the milk. As mentioned above, changing cow's diets — as by increasing their intake of unsaturated fatty acids — might increase the CLA content of their milk. Another possibility for increasing the CLA content of milk involves genetic engineering: Potentially, DNA technology could enhance the production of enzymes by ruminal bacteria. For example, in a lab, scientists could insert a gene that would boost bacterial production of the CLA-synthesizing enzyme into the DNA of bacteria native to the bovine rumen. They could then feed the altered bacteria to a cow. In the cow's rumen, the bacteria might become a stable colony, producing offspring that continue the production of CLA-synthesizing enzymes at high levels. For the rest of its lifetime, the cow might produce milk with a high CLA content. However, many questions about CLA remain unanswered. The short- and long-term human health consequences of ingesting CLA are unknown. "The application of CLA as an anticarcinogen in humans is intriguing but far from proven," says Dr. Pariza. Other Possible Uses CLA may have various physiological effects. Researchers have found that CLA can suppress atherosclerosis in rabbits. Dr. Pariza and others have suggested that CLA has antioxidative effects. Antioxidants may help prevent chronic diseases such as heart disease by inhibiting free radicals (disruptive atoms, and groups of atoms, that arise from normal metabolism). CLA research may interest not only health professionals but also meat producers. According to the February 1996 issue of Inform, a publication of the American Oil Chemists Society, mice, rats, chickens, and rabbits on diets that included CLA ate less overall and showed an increase in body protein and a drop in body fat. Thus, supplementing animals' diets with CLA might result in leaner meat and lower feed costs. The Bottom Line Conjugated linoleic acid (CLA) ranks among the most potent natural anticarcinogens for animals ever identified, and researchers are investigating ways of increasing its concentration in dairy products. But the carcinogenicity or anticarcinogenicity of a given substance in laboratory animals does not necessarily indicate either in humans. How — indeed, whether — CLA can improve human health remains uncertain. Selanna Reiner holds a B.A. degree in biology from Oberlin College. Molecular Structure of CLA Like all other fatty acids, conjugated linoleic acid is basically a chain of carbon atoms. The position and types of bonds distinguish CLA from other fatty acids. C carbon atom -C-C- single bond (-) -C=C—C—C=C- Detail of Linoleic Acid In part of the molecule, a double bond is followed by two single bonds and then another double bond. -C=C- double bond (=) -C=C—C=C- Detail of Conjugated Linoleic Acid In part of the molecule, a double bond is followed by one single bond and then another double bond. This alternation of double and single bonds is called "conjugation," hence the term "conjugated linoleic acid."