Dr. Paul's Research Perspectives
From fat to fit

Research on the benefits of conjugated linoleic acid is stacking up

By Paul Hepperly

December 9, 2004: You probably already know about omega 3 fatty acids. These essential components of the human diet are much touted these days for their ability to fight everything from circulatory problems to depression. Iron Magazine, a leading online bodybuilding and fitness magazine (www.ironmagazine.com/review9.html), digs deeper into the benefits of conjugated linoleic acid (CLA), another essential and physiologically active fatty acid. Although less widely understood than omega 3s, this essential fatty acid is thought to:
  • fight cancer
  • increase metabolism
  • reduce cholesterol, triglycerides, and fat accumulation
  • decrease internal oxidation
  • increase muscle mass

Although CLA was virtually unknown just a couple of decades ago, there are a number of excellent animal studies that convincingly support these claims. As Iron Magazine quips, “The cattle, pigs and chickens are all low-fat, high-muscle machines - sort of like a barnyard version of Muscle Beach.” Data from human CLA trials are also starting to accumulate, and point to similar human health benefits.

All joking aside, the most important health problem afflicting our nation right now is obesity, according to the National Institute of Health. USDA nutritionist C. Welt, in his study "Benefits from human nutrition research" of 1992, estimated that 500,000 lives would be saved annually if minimum daily recommended allowances of vitamins and nutrients were met in the national diet. Moreover, he estimates that 80 percent of the obesity epidemic can be attributed to poor diets.

So if CLA proves to be an effective protector against cancer, heart disease, diabetes and obesity, its impact will be a block buster. In a recent article in Professional Animal Scientist, M.F. Weis and colleagues postulate that the diverse health benefits of CLA are the result of its potential ability to reduce inflammation, a common physical reaction linked to degenerative diseases and aging.

CLA is an unusual fatty acid that occurs naturally as a byproduct of bacterial metabolism occurring in the complex stomachs of cows, sheep, and goats. Dr. Mir from Ag Canada suggests that CLA has decreased in the North American diet by at least by two thirds in the last fifty years, due to reduction in animal fats in human diets and to the change of ruminant management from pasture to feedlot. According Dr. Dhiman of Utah State University, CLA in pastured cows is 5 times higher than in commodity milk. Drs. Olson and Dhiman have shown that modifying feed rations can help reduce the negative impacts of feed concentrates on levels of CLA in meat and milk.

Scientists who study CLA have found the following effects:

  1. Pigs produce leaner and firmer bacon due to CLA induced fat metabolism (Allan Schinckel, Purdue University)
  2. CLA-supplemented dairy cows produce milk that has higher protein and less fat than conventional milk (Dale Bauman, Cornell University)
  3. Rabbits supplemented with CLA have less arterial plaque (Kritchevsky, Wistar Institute).
  4. Rats fed CLA-enriched butter had reduced mammary cancer rates and risks (Clement Ip, Roswell Park Cancer Research Institute, Buffalo)
  5. CLA inhibited the growth of human cancer cells in laboratory cultures (T.D. Schultz, Anticancer Research)
  6. Women fed a diet of grass-fed meat and dairy products showed significantly lowered breast cancer development than women eating foods from grain-fed animals in Finland (Aro et al., Cancer).

To compare differences between pasture and feedlot beef, www.farmprofitability.org/research/beef/linoleic.htm summarizes the CLA levels in beef produced by these two approaches to animal husbandry. Normal feedlot beef had one-third to one-sixth of the CLA concentration found in pastured beef. What’s more, new research shows that consumers are growing increasingly willing to support these types of changes in animal production. Recent reports suggest that consumers, as they learn of the potential health benefits of particular foods, are willing to pay premiums for these foods because they see health values in their use (www.leopold.iastate.edu/pubs/staff/ecolabels/index.htm).

Paying a premium for higher quality food that provides a more solid foundation for human health is a good national investment. The percentage of Gross National Product devoted to medicine now exceeds 20 percent, a figure that is considered “out of control” by experts in the field. Much of this national expenditure is the result of poor diet and lifestyle choices.

Medical approaches that focus on symptomatic treatments of these diseases do not address the root causes of our health care crisis. Instead, we need to focus on controlling our forks, and improving the quality of the foods we put on them.

By changing and improving our focus as consumers, we can begin to transition away from a faltering food system to provide an alternative food future for ourselves, demanding more optimized nutrition and healthier lifestyles for ourselves and others.

Weis, M. F., F. Martz, and C. Lorenz. 2004. Conjugated linoleic acid: Implicated mechanisms related to cancer, atherosclerosis, and obesity. Professional Animal Scientist 20:127-135.

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