Guest guest Posted July 3, 2002 Report Share Posted July 3, 2002 In a message dated 7/2/02 7:09:09 PM, Gettingwell writes: << Re: CLA info wanted Here are some notes from various sources that I collected a while back on CLA: Liz Health Benefits of CLA Many people are taking CLA as an expensive supplement for the benefits described below. But wouldn't it make much more sense to get it for free in your food? There is a new reason why it may be beneficial to allow cows to graze on pasture. That reason involves a compound called conjugated linoleic acid (CLA). CLA is a fatty acid found in beef and dairy fats. Scientific interest in CLA was stimulated in 1988 when a University of Wisconsin researcher discovered its cancer-fighting properties in a study of rats fed fried hamburger. CLA cannot be produced by the human body, but it can be obtained through foods such as whole milk, butter, beef, and lamb. " The interesting thing is that dairy cattle that graze produce higher amounts of CLA in their milk than those which receive conserved feed, such as grain, hay, and silage, " says Agricultural Research dairy scientist Larry Satter. This is true even when the nongrazers eat pasture grass conserved as hay. Satter, who is based at the Dairy Forage Research Center in Madison, Wisconsin, conducted a study comparing the amount of CLA in milk from cows grazing on pasture to the amount from cows fed hay or silage. His findings: Pasture-grazed cows had 500% more CLA in their milk than those fed silage. Larry Satter is at the USDA-ARS U.S. Dairy Forage Research Center, 1950 Linden Lane, University of Wisconsin, Madison, WI 53706; phone (608) 264-5353, fax (608) 264-5147. ------ CLA may be one of the most potent cancer-fighting substances in our diet. In animal studies, as little as one half of one percent CLA in the diet has reduced tumor burden by more than 50 percent. ------ CLA has also been shown to reduce body fat in people who are overweight. by Mary Shomon A double-blind, randomized, placebo-controlled study, published in the December 2000 issue of the Journal of Nutrition found that CLA reduces fat and preserves muscle tissue. According to the research project manager, an average reduction of six pounds of body fat was found in the group that took CLA, compared to a placebo group. The study found that approximately 3.4 grams of CLA per day is the level needed to obtain the beneficial effects of CLA on body fat. Dr. Michael Pariza, who conducted research on CLA with the University of Wisconsin-Madison, reported in August 2000 to the American Chemical Society that " It doesn't make a big fat cell get little. What it rather does is keep a little fat cell from getting big. " Pariza's research did not find weight loss in his group of 71 overweight people, but what he did find was that when the dieters stopped dieting, and gained back weight, those taking CLA " were more likely to gain muscle and not fat.'' In a separate study conducted at Purdue University in Indiana, CLA was found to improve insulin levels in about two-thirds of diabetic patients, and moderately reduced the blood glucose level and triglyceride levels. CLA has been the subject of a variety of research in the past several years, and findings also suggest that some of the other benefits of CLA include the following: * Increases metabolic rate -- * Decreases abdominal fat -- * Enhances muscle growth -- * Lowers cholesterol and triglycerides -- * Lowers insulin resistance -- * Reduces food-induced allergic reactions -- * Enhances immune system -- Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid, which is found preferentially in dairy products and meat. Preliminary studies indicate that CLA is a powerful anticancer in the rat breast tumor model with an effective range of 0.1-1% in the diet. Conjugated linoleic acid is unique because it is present in food from animal sources, and its anticancer efficacy is expressed at concentrations close to human consumption levels. Conjugated linoleic acid and atherosclerosis in rabbits Lee K.N.; Kritchevsky D.; Pariza M.W. Food Research Institute, Dept. Food Microbiology/Toxicology, University of Wisconsin-Madison, 1925 Willow Drive, Madison, WI 53706 USA Atherosclerosis (Ireland), 1994, 108/1 (19-25) Could a widespread deficiency of a specific nutrient be a major factor in causing the excess body fat in many people? One hypothesis Conjugated Linoleic Acid and the Weight Connection Conjugated linoleic acid (CLA) is a component of beef and milk that has been shown to reduce body fat in both animals and humans. CLA is essential for the transport of dietary fat into cells, where it is used to build muscle and produce energy. Fat that is not used for anabolic energy production is converted into newly stored fat cells. There are published research findings about how dietary CLA reduces body fat, but first let's take a look at why many Americans are now deficient in CLA compared with their parents. The primary dietary sources of CLA are beef and milk, and Americans are eating less beef and drinking less whole milk in order to reduce their dietary intake of saturated fat. People often drink nonfat milk, but it's the fat content of the milk that contains CLA. Since skim milk contains virtually no CLA, those seeking to lose weight, those who use skim milk, are depriving themselves of a potential source of this fat-reducing nutrient. Now, here's where the real problem occurs. In 1963, the CLA percentage in milk was as high as 2.81%. By 1992, the percentage of CLA in dairy products seldom exceeded 1%. The reason for the sharp reduction in milk CLA was because of changing feeding patterns. Cows that eat natural grass produce lots of CLA. Today's " efficient " feeding methods rely far less on natural grass. For example, grass-fed Australian cows have 3 to 4 times as much CLA in their meat as do American cows. Researchers reported in June of 1999 in Biosciences, Biotechnology, Biochemistry Journal that animal studies demonstrated that " CLA has an obesity-preventing action. " Another study reported that CLA effects on glucose tolerance and glucose homeostasis indicate that dietary CLA may prove to be an important therapy for the prevention and treatment of obesity (Biochem. Biophys. Res. Commun., 1998 [March]). So health-conscious Americans are avoiding beef and whole milk because these foods are high in fat, and, when people do consume beef or milk, they are consuming very little CLA because of CLA-deficiency in today's cows. Thus, most Americans have inadequate amounts of CLA in their diet, and this CLA deficit may be at least partially responsible for the epidemic of overweight people of all ages that now exists. Encouraging Results with CLA How significant is CLA in preventing excess accumulation of body fat? The results to date are preliminary, but extremely encouraging. Athletes are taking CLA to push glucose into their muscle cells and connective tissues instead of letting it turn into fat. CLA has been shown to reduce protein degradation in both humans and animals. CLA is required to maintain optimal function of the phospholipid membranes of cells. Healthy cell membranes will allow fat, protein, and carbohydrates to flow into active cells such as muscle, connective tissue, and organ cells, instead of being stored passively in fat cells. A deficiency of CLA can inhibit fat from entering muscle cells, which can result in excessive accumulation of body fat. CLA has been studied in different species of animals, and the results consistently show that CLA reduces the percentage of body fat. An abstract from the 1996 Environmental Biology Conference showed that rats, after 28 days of being supplemented with CLA, showed a 58% reduction in body fat, compared with the control animals which did not receive CLA. In addition, the percentage of muscle was greater in the CLA group; CLA did not induce weight loss, since muscle weighs more than fat. In July 1997, the results of the first human study on CLA were released by the Medstat Research Ltd. group of Lillesterom, Norway. This 3-month preliminary study involved 20 healthy volunteers. Half the group was given six 500-mg CLA capsules a day, and the other half received identical-looking placebo capsules. The subjects were asked not to alter their diet or lifestyle; 18 of the 20 subjects completed the study protocol. The results showed that the people in the CLA group experienced a 15 to 20% reduction of average body fat, compared with the placebo group. In the CLA group, the initial body fat percentage was 21.3% at the beginning of the study, and only 17% body fat after 3 months on CLA capsules. In contrast, the placebo group started with an average of 22% body fat, and 3 months later recorded an averag e of 22.4% body fat. CLA received widespread media attention in the early 1990s when it was identified as a component of red meat that helps prevent cancer. Further research showed that CLA is a potent anticancer agent, an anticatabolic agent and, through a unique mechanism, a fat metabolizing agent. CLA is one of the substances the FDA is investigating for disease prevention. New studies are appearing about the ability of CLA to prevent cancer, and possibly function as an adjuvant (assisting) cancer therapy. CLA appears to be especially effective in preventing breast cancer. Using CLA to reduce body fat may reduce your risk of getting cancer. Compare this to FDA-approved diet drugs that were removed from the market after being linked to heart-valve degeneration. A deficiency of CLA in our diet may be a major factor in causing Americans to gain so many fat pounds. CLA is a potent antioxidant, but appears to prevent cancer via other mechanisms of action. A dose of three 1000-mg capsules of 70% CLA, taken in the morning on an empty stomach, may be an effective part of an overall weight-loss program. The studies indicate that it usually takes about 3 weeks before body fat loss occurs in response to CLA supplementation. CLA inhibits fat storage by enhancing the ability of cell membranes (other than fat cells) to open up and allow the absorption of fats and other nutrients. CLA promotes the growth of muscles by letting nutrients into active muscle cells. That's why CLA has become such a popular supplement among body builders. The fat-reducing mechanism of CLA involves the rejuvenation of cell membranes in the muscles and connective tissues to allow fats to enter freely in order to generate energy and growth. This anabolic effect could provide anti-aging benefits in the elderly, but there have been no studies to date to investigate this. Recent Findings on CLA Several years ago, the discovery of conjugated linoleic acid (CLA) caused a scientific sensation. Here was a fatty acid found in red meat and cheese that showed strong anticancer properties, being particularly effective in inhibiting breast and prostate tumors, as well as colorectal, stomach, and skin cancer, including melanoma. On the whole, scientists found CLA to be more strongly anticarcinogenic than other fatty acids. What made CLA especially unique is that even low concentrations significantly inhibited cancer cell growth. CLA supplementation was also shown to improve the ratio of lean mass to body fat, decreasing fat deposition, especially on the abdomen, and enhancing muscle growth. One way in which CLA reduces body fat is to enhance insulin sensitivity so that fatty acids and glucose can pass through muscle cell membranes and away from fat tissue. This results in an improved muscle-to-fat ratio. CLA was also shown to have antioxidant properties and to prevent muscle wasting (an anticatabolic effect). It became popular with muscle builders because of its ability to improve the transport of glucose, fatty acids, and protein to the muscle tissue. It is interesting that while it is chemically related to linolenic acid, conjugated linoleic acid (CLA) appears to have opposite effects in certain important areas. For instance, linolenic acid stimulates fat formation (lipogenesis) in adipose tissue, while CLA inhibits fat formation; linolenic acid tends to promote tumor growth, while CLA is an excellent inhibitor of tumor growth; linolenic acid makes cholesterol more susceptible to oxidation, while CLA makes cholesterol more stable. One of the greatest problems with the Western diet during the last 50 years has been excessive consumption of linoleic acid, due to the introduction of margarine, seed oils, such as corn oil and safflower oil, and the modern artificial livestock feeding methods that have raised the linoleic-acid content of meat. At the same time, the consumption of beneficial fatty acids such as omega-3 fats (fish, flax, and perilla) and CLA has gone down. Because of the enormous impact that fatty acids have on our physiology, an excess of linoleic acid combined with a deficiency of CLA could have far-reaching effects on health and longevity. Let us now take a closer look at the current research findings about CLA. CLA Reduces Body Fat in Mice by up to 88% A study at Louisiana State University confirmed that feeding male mice a CLA-enriched diet (at 1% of the diet by weight, or 10 g/kg) for 6 weeks resulted in 43 to 88% lower body fat, especially in regard to abdominal fat. This occurred even if the mice were fed a high-fat diet. The effect was partly due to reduced calorie intake by CLA-supplemented mice, and partly to a shift in their metabolism, including a higher metabolic rate. In another study, performed at the University of Wisconsin-Madison, mice supplemented with only 0.5% of CLA showed up to 60% lower body fat and up to 14% increased lean body mass compared to controls. The researchers discovered that CLA-fed animals showed greater activity of enzymes involved in the delivery of fatty acids to the muscle cells and the utilization of fat for energy, while the enzymes facilitating fat deposition were inhibited. CLA Improves Insulin Sensitivity A study using diabetic Zucker rats indicates that part of CLA's effectiveness in preventing obesity may lie in its ability to act as a potent insulin sensitizer, thus lowering insulin resistance and consequently insulin levels. Since elevated insulin is the chief pro-obesity agent, it is enormously important to keep insulin within the normal range. By activating certain enzymes and enhancing glucose transport into the cells, CLA acts to lower blood sugar levels and normalize insulin levels. Thus, besides being antiatherogenic and anti-carcinogenic, CLA is also antidiabetogenic: it helps prevent adult-onset diabetes, characterized by insulin resistance. If the current animal results are corroborated, CLA may prove to be important not only in the prevention of diabetes, but also as a new therapy for adult-onset diabetics, aimed at lowering insulin resistance. CLA Inhibits the Growth of Prostate Cancer, While Linoleic Acid Promotes It Immunodeficient mice inoculated with human prostate cancer cells were fed either a standard diet, a diet supplemented with 1% linolenic acid, or a diet supplemented with 1% CLA. Mice receiving linolenic acid showed significantly higher body weight and increased tumor load compared with the two other groups. CLA-supplemented mice, on the other hand, showed the lowest tumor load and a dramatic reduction in lung metastasis. CLA Supplementation Helps Prevent the Initiation, Promotion, and Metastasis of Breast Cancer In a study performed at Roswell Park Cancer Institute in Buffalo, 50-day-old rats were treated with a potent carcinogen and then supplemented with 1% CLA for 4, 8, or 20 weeks. Only rats receiving CLA for the full 20 weeks showed tumor inhibition. CLA lowered the total number of carcinomas by 70%. Interestingly, there was a much higher incorporation of CLA into the neutral lipids of the mammary tissue rather than into the phospholipids (cell membranes). While the physiological significance of this phenomenon is not understood, it seems that the presence of CLA in mammary tissue plays a highly protective role against the initiation of breast cancer. In another study, immunodeficient mice were fed 1% CLA-enriched diet for 2 weeks prior to inoculation with human breast adenocarcinoma cells. Besides inhibiting tumor growth, CLA totally prevented the metastasis of breast cancer to lungs and bone marrow. The preventive effect of CLA against breast cancer is independent of the amount of fat in the diet. Even when the tumor-promoting excess levels of linoleic acid reach 12% in the diet, CLA was still incorporated into the lipids of the mammary tissue and still provided protection against carcinogenesis. Anticarcinogenic effects of CLA did not increase with doses beyond 1% of CLA in the diet. A recent in vitro study of breast cancer cells showed that CLA worked synergistically with nordihydroguaiaretic acid (NDGA), a potent antioxidant and lipoxygenase inhibitor found in the desert herb chaparral. This suggests that one mechanism of CLA's suppression of tumor growth is its ability to inhibit the production of leukotrienes, inflammatory compounds that may be even more harmful and difficult to control than series II prostaglandins. (Both series II prostaglandins and leukotrienes fuel tumor growth; both are metabolites of arachidonic fatty acid, itself a metabolite of linoleic acid.) Yet another mechanism of CLA's anticancer action may be its interference with tumor-growth factors such as thymidine. CLA is especially effective in inhibiting the proliferation of estrogen-receptor-positive breast cancer cells, arresting estrogen-dependent cell division. Besides the oncostatic properties of CLA, it is also likely that CLA inhibits the enzymes that activate various carcinogens. Thus, CLA appears to protect against all three stages of cancer: initiation, promotion, and metastasis. Early CLA Supplementation Lowers the Glandular Density in Mammary Tissue Previous research showed that supplementation with CLA during the formative period in mammary-gland development confers a lasting protection against carcinogen-induced breast cancer. A new and more detailed study showed that female rats fed 1% CLA diet after weaning showed a 20% reduction in the density of the ductal-lobular tree, meaning that the glandular density of the mammaries was lower. High glandular density is a very significant breast cancer risk factor. This study implies that supplementing the diet of young girls with CLA might reduce the glandular density of their breast tissue, conferring a significant degree of life-long protection against breast cancer. Immune-Enhancing Effects of CLA CLA has been found to stimulate the production of lymphocytes and of interleukin-2, and to increase the levels of certain immunoglobulins, while lowering the release of immunoglobulin E, associated with allergies. Improved immune function resulting from CLA supplementation can also be postulated on the basis of its ability to lower the production of immunosuppressive compounds such as leukotrienes and series II prostaglandins, and to improve insulin sensitivity (elevated insulin leads to immunosuppression). The anti-obesity benefits of CLA do not necessarily manifest themselves as weight loss. Rather, CLA works through the process of " repartitioning, " which results in improved muscle-to-fat ratio. Since CLA causes a loss of body fat, especially abdominal fat, while simultaneously stimulating muscle growth, the effect is a leaner, more muscular physique. This is much more beneficial than starvation diets, which cause a greater loss of muscle mass than of body fat, setting the stage for sluggish metabolism and even greater future obesity. Anti-Atherogenic Effects of CLA We have already mentioned that CLA improves insulin sensitivity. Since elevated insulin promotes atherosclerosis, any agent that lowers insulin levels by improving insulin sensitivity can be classified as anti-atherogenic. However, CLA has also been shown to have further anti-atherogenic benefits thanks to its ability to improve serum lipids and to its tocopherol (vitamin E)-sparing effect. CLA Lowers Cholesterol and Triglycerides, Helps Keep Arteries Clean A study at the University of Wisconsin-Madison found that rabbits supplemented with 0.5 g CLA per day showed markedly lower total and LDL cholesterol, lower LDL-to-HDL ratio, lower total cholesterol-to-HDL ratio, and lower serum triglycerides. On autopsy, the aortas of CLA-supplemented rabbits showed less atherosclerotic plaque. A more recent study done at the University of Massachusetts confirmed that hamsters whose diets were supplemented with CLA showed significantly lower total cholesterol, LDL cholesterol, and triglycerides compared to controls. The serum of CLA-fed hamsters also showed higher tocopherol/ cholesterol ratios, indicating that CLA has a tocopherol-sparing effect (that is, being less oxidizable than linoleic acid, it does not require as much vitamin E for antioxidant protection). It is not cholesterol per se, but oxidized cholesterol that is harmful to the blood vessels. The oxidizability of cholesterol varies mainly in propor-tion to the percentage of linoleic acid that it contains; thus the more stable fatty acids, such as CLA, that can be incorporated into cholesterol serve to make it less vulnerable. CLA's antioxidant properties may also play a role in its ability to help keep the blood vessels clean. As a side note, CLA tends to be incorporated more abundantly into the cell and mitochondrial membranes of the heart muscle. Since the heart relies on fatty acids rather than glucose as its energy source, greater abundance of CLA in the heart muscle may improve the efficiency of fat transport and fat metabolism in the cardiac mitochondria. Possible Anti-Osteoporotic Effects of CLA An in vitro study done at Purdue University showed that in various rat tissue cultures, including bone tissue, supplemental CLA (at 1% of diet) decreased the levels of omega-6 fatty acids and total monosaturated fatty acids, while increasing the concentrations of omega-3 fatty acids and saturated acids. The levels of inflammatory series II prostaglandins were also decreased by CLA feeding. Since inflammatory compounds lead to bone loss, CLA might potentially be of use in preventing osteoporosis. We are gaining more and more understanding of the importance of beneficial fatty acids for bone health. Unfortunately, women aren't being told about the need to consume adequate amounts of healthy fats in order to prevent bone loss. Recognizing the Importance of Essential Oils Not long ago the low-fat diet gurus were trying to terrorize us into paring down all fat consumption. Now that we have witnessed the epidemic of obesity that followed, we know better. Healthy fats help keep us slender! They also help protect against atherosclerosis, cancer, diabetes, autoimmune diseases, and various other degenerative disorders. Through their impact on important metabolic enzymes, healthy fats increase the synthesis of beneficial prostaglandins while decreasing the levels of inflammatory prostaglandins; they also modify cell membrane composition and fluidity. Hence, improved blood flow and tissue oxygenation, higher metabolic rate, improved insulin sensitivity, immune enhancement, more muscle and bone formation, better brain function and faster nerve impulse conductance result, to mention just a few of the major benefits. Thus, while in the 70s and 80s dietary fat was demonized and presented as the problem, in the 90s we are beginning to see various kinds of healthy fat as part of the solution. CLA is the collective name for a group of linoleic acid derivatives found chiefly in beef, lamb, and dairy fat. When ruminants such as cattle and sheep consume linoleic acid (an essential polyunsaturated fatty acid) in grass or feed, the bacteria in their stomachs convert some of that linoleic acid to its variant forms, or isomers (two isomers-cis-9, trans-11 and cis-12, trans-10-predominate; the 9,11 isomer is thought to be the most biologically active). Adding certain strains of starter culture bacteria to dairy products can also increase the content of conjugated linoleic acids-generally spoken of in the singular, much as we use the word " estrogen " to denote the whole family of various estrogens. It turns out that the intestinal bacteria of rats are also capable of producing CLA out of linoleic acid. At this point, however, it is not known whether human intestinal flora can produce CLA. The most studied and best understood mechanisms of CLA's benefits involve its modulation of eicosanoid (prostaglandin and leukotriene) synthesis and its cell-membrane effects. A study of liver fatty acids in CLA-supplemented mice showed that CLA has powerful effects on the fatty-acid composition of neutral lipids and phospholipids (phospholipids are the building materials of cell membranes and membranes surrounding cellular organelles such as mitochondria). CLA lowers the levels of linoleic acid in phospholids; in neutral lipids, CLA lowers the levels of linoleic and arachidonic fatty acid, while increasing the more stable oleic acid. Other studies have found that CLA lowers the production of the inflammatory metabolites of arachidonic acid: leukotrienes and PGE2 (series II) prostaglandins. CLA's ability to inhibit the production of leukotrienes is of particular interest. While various hormones and many other biochemical modulators inhibit the release of inflammatory prostaglandins, it is difficult to lower leukotriene levels-except by using cortisone and cortisone-like drugs, with their harmful side effects. CLA is a promising, nontoxic alternative. Insofar as CLA is incorporated into phospholipids, it affects the transport properties of cell membranes and mitochondrial membranes. Apparently CLA facilitates the transport of glucose and fatty acids for energy, and of protein for muscle-building. There is still much about CLA that needs further investigation. Part of its metabolism involves being desaturated into an as-yet unnamed fatty acid that may be analogous to gamma-linolenic acid (GLA). CLA and its metabolites seem to affect many important metabolic enzymes. A more detailed understanding of the mechanisms of CLA's action should help us develop ways of using it for maximum benefits. The common assumption is that we need to obtain CLA from diet or supplements. Commercial CLA supplements are manufactured by a special treatment (isomerization) of sunflower oil. The Safety of CLA In a study conducted by the Nutrition Department of Kraft Foods, male rats were fed a diet of 1.5% CLA, which is 50 times higher than the estimated upper-range human intake. The animals were examined weekly for any signs of toxicity; no toxicity was found. After the end of the 36-week study, the animals were sacrificed and autopsied. Again, no pathology was found. The study confirmed that CLA supplementation is safe even at high doses. Nevertheless, high doses are not necessary for obtaining the benefits of CLA. Most people obtain their essential omega-3 fatty acids from flax, fish, or perilla oils. CLA appears to be in a class by itself as far as its unique mechanism of disease prevention and bodyfat reduction. A deficiency of CLA in the diet may be a major factor in causing Americans to gain so many fat pounds. CLA is a potent antioxidant, but appears to prevent cancer via other mechanisms of action. A particularly rich source of CLA is melted cheddar cheese, yet most consumers prefer to obtain this fatty acid from low-cost CLA supplements that provide the exact isomers that have shown the greatest levels of protection against disease and obesity. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted July 6, 2002 Report Share Posted July 6, 2002 Wow, that was quite the group ofsaved notes. Thank you for taking the time to post them. Vache Quote Link to comment Share on other sites More sharing options...
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