compare and contrast dr ornish and dr atkins

The fractional catabolic rate (FCR) of apo A-I increased 11%, whereas its absolute transport rate decreased 14%. 1997;337:562-563. The relative risk of developing type 2 diabetes was 58% lower when comparing the highest with the lowest quintile of whole grain intake (14). In addition, patients on an Atkins diet are counseled to take n-3 fatty acids in the form of fish oil (something else we agreed on), which is known to reduce triglycerides significantly. (All groups consumed about the same amount of protein.). Join the hundreds of thousands in my email community for the latest news, insight, and more, Gardner CD, Kiazand A, Alhassan S, Kim S, Stafford RS, Balise RR, Kraemer HC, King AC. The point is, its possible to cherry-pick observational studies to support almost any nutritional argument. WebDean Ornish, in full Dean Michael Ornish, (born July 16, 1953, Dallas, Texas, U.S.), American physician and author whose approach to treating heart disease through radical Available at: http://hin.nhlbi.nih.gov/atpiii/calculator.asp?usertype=prof . Whats more relevant to the discussion is this fact: During the time in which the prevalence of obesity in the U.S. nearly tripled, the percentage of calories Americans consumed from protein and fat actually dropped whereas the percentage of calories Americans ingested from carbohydratesone of the nutrient groups Ornish says we should eat more ofincreased. National Institutes of Health. 2003;348:2074-2081. Over and over, Ive seen patients with coronary heart disease so severe that they cant walk across the street or work or play with their kids or make love or do much of anything without getting severe chest pain become pain-free after only a few weeks of making these diet and lifestyle changes. So theres little evidence to suggest that we need to avoid protein and fat. Am J Physiol. Meat has virtually no dietary fiber. The percentage of calories from fat has decreased, but the amount of fat consumed has increased (6). Pres. The other way people get too many calories is by consuming too many simple carbohydrates. Esselstyn CB Jr. Updating a 12-year experience with arrest and reversal therapy for coronary heart disease (an overdue requiem for palliative cardiology). I have presented these research findings on several occasions at the annual scientific meetings of the American Heart Association, American College of Cardiology, American Dietetic Association (now the Academy of Nutrition and Dietetics), the Institute of Medicine of the National Academies and many others. 1968;2:702-703. Bill Clinton is one of the more public examples of this, having lost and kept off more than 20 pounds since following the whole foods, plant-based diet I recommended for him five years ago (including salmon once a week). In contrast, differences in HDL-C levels between people on a given diet correlate with and may result from differences in apo A-I FCR. Effect of 6-month adherence to a very low carbohydrate diet program. Anitschkow N. Experimental arteriosclerosis in animals. Earlier this year a panel of experts from U.S. News & World Report rated the Ornish Diet as the number-one diet for heart health for the fifth year in a row (that is, all five years they have been doing rankings). I wrote: For example, in the OmniHeart trial she cited, the group that was asked to consume 10 percent more protein emphasized plant proteins, not animal protein. Taubes G. What if its all been a big fat lie? Campbell TC, Parpia B, Chen J. For 37 years he has been touting the benefits of very low-fat, high-carbohydrate, vegetarian diets for preventing and reversing heart disease. WebDr, Atkins vs. Dean Ornish and John McDougall - USDA Debate from 2000. Thanks for reading Scientific American. High-protein diets may cause loss of calcium and decreased levels of urinary citrate, leading to osteoporosis and kidney stones (52). HDL-C decreased 9% from 40.0 to 36.3 mg/dL after 1 year, yet these patients showed clear improvement in coronary atherosclerosis, myocardial perfusion, and cardiac events. It concluded that low-carbohydrate/high-protein diets are associated with increased risk of cardiovascular diseases.. Again, we dont know because his studies have not been designed in a way that can tell us anything about the effect of his diet alone. WebIn this study, premenopausal overweight and obese women assigned to follow the Atkins diet, which had the lowest carbohydrate intake, lost more weight and experienced more Thus, we need to move beyond simplistic notions that anything that raises HDL-C is beneficial and anything that lowers HDL-C is harmful. 1990;85:144-151. Angiology. N Engl J Med. 2002;40:265-274. What happens to changes in blood pressure, cholesterol and weight are important only to the extent that they affect the underlying disease process (for example, degree of atherosclerosis, blood flow to the heart, cardiac events, changes in prostate cancer), which is what we documented. So even when we look at the data Ornish likes, we still dont see reason to blame Americas ill health on unprocessed red meat and saturated fats. Telling people what they want to believe is part of the reason that the Atkins diet has become so popular. J Lipid Res. These are rich in fiber, which enhances satiety without adding significant calories. Dean Ornish, MD Whole grain consumption improves insulin sensitivity in overweight and obese adults (15). Ornish D. The case for low fat. For example, an important article, published in The New England Journal of Medicine, reviewed data showing that high-protein, low-carbohydrate diets promote coronary artery disease independent of their effects on traditional risk factors such as blood pressure and cholesterol levels. Wing RR, Vazquez JA, Ryan CM. This is some-what akin to the story of Dr Johnsons dog walking on its hind legs: it does not do it very well, but it is amazing that it can do it at all. Am J Clin Nutr. The decrease in the percentage of calories from fat during the period 1971 to 1991 is attributed to an increase in total calories consumed; absolute fat intake in grams actually increased. Dietary cholesterol and saturated fats increase plasma LDL-C in part by down-regulating LDL receptors in the liver (28). 1998;318:549-557. 1995;19:811-816. . Int J Obes Relat Metab Disord. Some scientists think so. But Ornish is conflating hot dogs and pepperoni with fresh, unprocessed meats, says Lydia Bazzano, professor of nutrition and epidemiology at Tulane University School of Public Health and Tropical Medicine, and theres a big difference between them. A 2010 systematic review and meta-analysis of 20 studies found consumption of processed meat was associated with an increased risk of diabetes and heart disease but eating unprocessed red meat was not. This is why I use the USDA data (which tracks consumption of the entire food supply, not just a tiny sample). Fleming RM. The Lifestyle Heart Trial. Clinical Nutrition and Dietetics. 2003;138:460-467. The other problem with Ornishs antiprotein stance is that he lumps all animal proteins together. First, I cited several large-scale studies from many different investigators, all of which showed that a diet high in red meat increases the risk of premature death from virtually all causes, even when adjusting for confounding variables. The mechanism of the effects on HDL-C levels of changing from a high- to low-fat diet differs substantially from the mechanism explaining the differences in HDL-C levels between individuals who are eating a high-fat diet. Other high-protein diets such as the Zone and the South Beach diets are somewhat better but still emphasize consumption of meat, eggs, and butter. Am J Cardiol. Potential benefits and risks have not been tested adequately. A person is likely to lose more weight by reducing intake of both simple carbohydrates and fat than from simple carbohydrates alone. Whole foodssuch as whole grain products and fruits and veggiesare healthy, but I think that dairy products, fish and lean cuts of meat or poultry can also be part of a healthy diet, Steffen says. In this study, premenopausal overweight and obese women assigned to follow the Atkins diet, which had the lowest carbohydrate intake, lost more weight at 12 months than women assigned to follow the Zone diet, and had experienced comparable or more favorable metabolic effects than those assigned to the Zone, Ornish, or LEARN diets [corrected] While questions remain about long-term effects and mechanisms, a low-carbohydrate, high-protein, high-fat diet may be considered a feasible alternative recommendation for weight loss. Fiber also slows the absorption of food, thereby preventing blood glucose from rising too rapidly and reducing insulin surges. Ketone bodies formed on a high-protein diet undergo urinary excretion with a cation to maintain electrical neutrality, resulting in the loss of cations such as calcium, magnesium, and potassium (55,56). J Clin Invest. Twelve-month randomized trial conducted in the United States from February 2003 to October 2005 among 311 free-living, overweight/obese (body mass index, 27-40) nondiabetic, premenopausal women. While every effort has been made to follow citation style rules, there may be some discrepancies. Question 9 options: her bones and muscles her heart and lungs her flexibility her physical Harrisons Advances in Cardiology. Below is my letter to the editor of The New England Journal of Medicine that they published about this study: Protein, too, doesnt look so evil when one considers the 2010 trial published in The New England Journal of Medicine that found individuals who had recently lost weight were more likely to keep it off if they ate more protein, along with the 2005 OmniHeart trial that reported individuals who substituted either protein or monounsaturated fat for some of their carbohydrates reduced their cardiovascular risk factors compared with individuals who did not. These foods are low in cholesterol, saturated fat, oxidants, and other disease-promoting substancesa double benefit (12). A low-fat diet decreases high density lipoprotein (HDL) cholesterol levels by decreasing HDL apolipoprotein transport rates. But heres the thing: The patients who followed his diet also quit smoking, started exercising and attended stress management training. Dean Ornish, in full Dean Michael Ornish, (born July 16, 1953, Dallas, Texas, U.S.), American physician and author whose approach to treating heart disease through radical diet modification and exercise generated significant debate in the medical community and attracted a popular following. They lost 24 pounds during the first year and kept off more than half of that weight 5 years later and had 2.5 times fewer cardiac events than the control group. Am J Med. CA Cancer J Clin. Dean Ornish, MD, is founder and president of the non-profit Preventive Medicine Research Institute and is Clinical Professor of Medicine at the University of California, San Francisco. Second, there was no statistically significant difference in either systolic blood pressure or diastolic blood pressure after one year in comparing the groups. Outcomes were assessed at months 0, 2, 6, and 12. An AHA/NCEP 30% fat diet reduces LDL-C by only about 5% to 7% in most patients (22-24). 1998;339:12-20. Am J Clin Nutr. Even better would be to reduce the intake of simple carbohydrates and most fats, which results in losing even more weight while enhancing health rather than potentially harming it. This site is using cookies under cookie policy . This case report is not proof, but it is worrisome, especially in that these disorders of electrolytes and free fatty acids that increase the risk of sudden cardiac death may be seen in high-protein diets. The editor of JAMA Internal Medicine invited me to write an accompanying editorial for this study. Diet, obesity, and cardiovascular risk. Bonow RO, Eckel RH. Also, C-reactive protein and creatinine clearance were significantly lowered only on the Ornish and Weight Watchers diets. Since the U.S. population last year was 322 million people, this represents only 0.000044% of the population, and different people are surveyed each year. HDL-C is predictive of relative heart disease risk only in populations in which everyone is eating a similar high-fat diet, such as the Framingham population. The March 2014 study that Ornish cites as finding a 75 percent increase in premature deaths from all causes and a 400 percent increase in deaths from cancer and type 2 diabetes among heavy consumers of animal protein under the age of 65, also did not distinguish between types of animal protein. The Ornish and Zone books suggest some stimulus-control strategies but on the whole do not emphasize behavior modification, whereas both the Atkins and LEARN Westman EC, Yancy WS, Edman JS, et al. Fiber from whole grains, but not refined grains, was inversely associated with all-cause mortality in 11,040 postmenopausal women followed for 11 years (16). Question 12 options: his core , muscle memory, his progression , specificity training, Kim is conditioning. Second, another big fat lie that has been repeated so often its becoming a meme is that there is not enough good science to inform us about an optimal way of eating. Prev Cardiol. In his lengthy reply to my article Dean Ornish says I distort his beliefs, cite questionable studies and dont have the clinical experience to assess nutritional evidence. Was Dr. Atkins Right? WHAT EVIDENCE SUPPORTS THAT HIGH-PROTEIN DIETS MAY BE HARMFUL? Copyright [c] 2004 by the American Dietetic Association. Goldstein JL, Brown MS. Cholesterol and cardiovascular disease. American Dietetic Association. There are so many other factors. Dietary cholesterol and the pathogenesis of atherosclerosis. Hunninghake DB, Stein EA, Dujovne CA, et al. I feel passionately about doing this work because it helps transform peoples lives for the better. Also, as I wrote in my oped in The New York Times, my colleagues and I have conducted randomized controlled trials that these same diet and lifestyle changes reverse the progression of other common chronic diseases. CLAIMS THAT AN ATKINS DIET IS BETTER THAN A LOW-FAT DIET. Prev Cardiol. New York: MacMillan; 1933:271-322. Explain the scientific basis of each author's position. Most Americans consume a diet high in saturated fat and cholesterol, so those who are able to increase HDL-C in response to this diet are at lower risk than those who cannot, since they will be more efficient at metabolizing excessive dietary fat and cholesterol. It was found that a diet containing 10% of calories from fat with little saturated fat and dietary cholesterol (30,31) decreased LDL-C by an average of 40% after 1 year in ambulatory patients not taking lipid-lowering drugs (32). To understand better the mechanism of this phenomenon, Breslow and colleagues studied the turnover of HDL apolipoproteins (apo) A-I and A-II in 13 subjects on two contrasting metabolic diets. If anything, our attempts to eat less fat in recent decades have made things worse. Despite being told to eat less fat, he says, Americans have been doing the opposite: They have actually consumed 67 percent more added fat, 39 percent more sugar and 41 percent more meat in 2000 than they had in 1950 and 24.5 percent more calories than they had in 1970. Yes, Americans have been eating more fat, sugar and meat, but we have also been eating more vegetables and fruits (pdf)because we have been eating more of everything. 2023 Scientific American, a Division of Springer Nature America, Inc. Functional foods: Position of the American Dietetic Association. Another meta-analysis of 21 studies found no association between saturated fat intake and heart disease. An Atkins diet may increase postprandial lipemia and increase free fatty acids, which may have harmful effects on platelet aggregation and may promote ventricular arrhythmias (57,58). Boston: W.B. (This lack of association is notable because this analysis probably overestimates risks associated with red meat consumption; all but two of the studies it assessed lumped processed meats into the red meat category.) RESULTS: Ornish was raised in Dallas by his father, a dentist, and his mother, a childrens book author and filmmaker. Ornish eventually received a bachelors degree in humanities (1975) from the University of Texas at Austin, graduating first in his class. Zeman FJ, Hansen RJ. Circ Res. In contrast, control group patients following a 30% fat diet showed more progression of atherosclerosis after 5 years than after 1 year. These include a whole foods, plant-based diet low in refined carbohydrates, moderate exercise, stress management techniques and social support. The title is confusing and potentially harmful to many readers. In August 1993 the insurance company Mutual of Omaha announced that it would reimburse policyholders for the cost of participation in Ornishs program, marking the first time a major insurer had agreed to cover an alternative treatment for heart disease. In contrast, there was a statistically significant reduction in LDL-cholesterol in the Ornish group but not in the Atkins group after one year. However, CHD patients who followed a 10% fat, whole foods diet demonstrated significant regression of coronary atherosclerosis after 1 year as measured by quantitative coronary arteriography (37) and even more regression after 5 years (the amount of exercise was not significantly different between groups, but the experimental group was also practicing yoga and meditation) (32). The effect of high-protein diets on coronary blood flow. Taubes G. The soft science of dietary fat. Sample sizes ranged from 1,730 men and 2,003 women in NHANES 1999 to 2000 to 6,630 men and 7,537 women in NHANES III. On one side was Atkins, who had two strips of bacon and three eggs for breakfast. It found that individuals assigned to eat high-fat (41 percent calories from fat), Mediterranean-style diets for nearly five years were about 30 percent less likely to experience serious heart-related problems compared with individuals who were told to avoid fat. There are no data showing that the physiologic reduction of HDL-C levels with a low-fat diet is detrimental, especially in that LDL-C usually decreases more than HDL-C (42). Although Dr Atkins and I agreed on the diagnosisthat many Americans eat too many simple carbohydrateswe disagreed about the prescription. The arterial damage was caused by animal-protein induced elevations in free fatty acids and insulin levels and decreased production of endothelial progenitor cells (which help keep arteries clean). Dr. David Perlmutter is on the cutting edge of innovative medicine that looks at all lifestyle influences on health and illness. You used to find a lot more people interested in I would love to be able to tell you that these are health foods, but they are not. Thus, neither an Atkins diet nor a 30% fat diet is very effective in lowering LDL-C or in maintaining long-term weight loss (25). But his claims about the dangers of saturated fat and red meat go beyond the science and in some cases contradict it. But Ornish is conflating hot dogs and pepperoni with fresh, unprocessed meats, says Lydia Bazzano, professor of nutrition and epidemiology at Tulane University School of Public Health and Tropical Medicine, and theres a big difference between them. A 2010 systematic review and meta-analysis of 20 studies found consumption of processed meat was associated with an increased risk of diabetes and heart disease but eating unprocessed red meat was not. Also, in a randomized controlled trial, ketogenic diets such as the Atkins impaired cognitive performance in higher order mental processing after only 1 week (61). Whereas simple carbohydrates tend to have a high glycemic index/glycemic load and may be harmful for reasons discussed earlier, complex carbohydrates usually have a low glycemic index/glycemic load and are beneficial. You may lose weight and start to attract people to you, but, when they get too close, it may be counterproductive. Intensive risk factor modification. Second, as I made clear in the oped as well as in my books and journal articles, the diet I recommend is low in refined carbohydrates and high in good carbs such as fruits, vegetables, whole grains, legumes and soy products in their natural, unrefined forms (which tend to have low glycemic loads). (Also: the heavy protein consumers in the study were consuming nearly 30 percent more protein than the average American does.) Chanmugam P, Guthrie JF, Cecilio S, Morton JF, Basiotis PP, Anand R. Did fat intake in the United States really decline between 1989-1991 and 1994-1996? A receptor-mediate pathway for cholesterol homeostasis. Dr. Atkins believed that cutting off carbohydrates and sugar will also do the same. , e gradually, what is Alonso thinking about? It's the type of protein, fat and carbohydrates that matters. Ornish D, Brown SE, Scherwitz LW, et al. Paradoxically, it may sometimes be easier for people to make more comprehensive changes in diet and lifestyle because they experience the benefits so quickly and to a much greater degree (25,64). (In contrast, the recommendations of the American Heart Association allowed up to 30 percent of total calories from fat and 300 mg of cholesterol daily.) David Perlmutter, MD, FACN is a board-certified neurologist, Fellow of the American College of Nutrition, and five-time New York Times bestselling author. The March 2014 study in Cell Metabolism did distinguish between animal protein and plant-based proteins. Was Dr. Atkins Right? In contrast, there was a statistically significant reduction in LDL-cholesterol in the Ornish group but not in the Atkins group after one year. Dr. Atkins' Diet Revolution, first published in 1972 Dr. Robert C. Atkins, cardiologist Achieve a "metabolic advantage" with a four-phase diet low in carbohydrates Pereira MA, Jacobs DR Jr, Pins JJ, et al. Plus, discouraging the intake of entire macronutrient groups can backfire. On one side was Atkins, who had two strips of bacon and three eggs for breakfast. First, in this study, JAMA published a retraction of one of the main conclusions of this study by led by Christopher Gardner, which initially claimed that people lost more weight on the Atkins diet than on the diet I recommend, which turned out to be false (JAMA. 1970;27:59-67. For those simply trying to lose weight or lower their risk factors moderately, less extensive changes may be required. 1990;336:129-133. 1994;1:283-286. This becomes a way of eating rather than a diet with rigid eat this and dont eat that guidelines. As I mentioned above, we found significant improvements in virtually all risk factors in almost 3,000 patients who went through my lifestyle program in 24 hospitals and clinics in West Virginia, Nebraska, and Pennsylvania. Dansinger ML, Gleason JL, Griffith JL, Li W, Selker HP, Schaefer EJ. Its hard to move the science forward when there are so many stakeholders who say this is the right diet and no other one could possibly be right, Bazzano says. Fleming R, Boyd LB. But the real issue is what happens to actual measures of heart disease, not just risk factors, which I will describe further on. But Ornishs arguments against protein and fat are weak, simplistic and, in a way, irrelevant. Leaf A, Weber PC. Journal of the American Medical Association 104(2004):537. Fourth, the patients in our randomized controlled trial (JAMA. A wide body of scientific evidence links the consumption of animal protein, saturated fat, and cholesterol with CVD, cancer, and other chronic illnesses (47-51). This reduction in LDL-C is much greater than on an Atkins diet and is comparable with the effects of statin drugs. (An adult who consumes two tablespoons of olive oil in, say, a portion of salad dressing has already exceeded getting 10 percent of his days calories from fat if hes eating 2,000 calories daily.). J Am Diet Assoc. In summary, decreases in HDL-C due to a low-fat diet have a very different prognostic significance than someone who cannot raise HDL-C as much on a high-fat diet. These surges may cause a reactive hypoglycemia, increasing hunger and a desire to eat more simple carbohydrates in a vicious cycle, sometimes called carbohydrate cravings. In addition, excessive insulin enhances the growth and proliferation of arterial smooth muscle cells, promoting atherosclerosis (9). For example, someone may indulge himself or herself one day and eat more healthfully the next. N Engl J Med. Mean apo A-II levels did not change. You can burn more calories by exercising. 2002;75:848-855. For the past 37 years my colleagues and I at the nonprofit Preventive Medicine Research Institute, in collaboration with leading scientists and medical institutions, have published a series of randomized controlled trials and demonstration projects showing that comprehensive lifestyle changes may slow, stop and often reverse the progression of many chronic diseases. Get a Britannica Premium subscription and gain access to exclusive content. But looking more closely at the report (pdf) he discussesas others already haveone finds that it, too, shows that in the decades from 1970 to 2000, when obesity and chronic disease rates skyrocketed, U.S. consumption of red meat and eggs dropped 12 percent. She wrote about the reasons that autoimmune diseases overwhelmingly affect women in the September 2021 issue. Body weight is inversely associated with dietary fiber and carbohydrates and positively associated with protein intake (11). which types of nerves carries stimuli away from the brain?, In planning his fitness goals, Alonso wants to make sure that he improves his fitness without pushing himself too hard too fast. Second, if subjects in dietary clinical trialswho are attending dietician-led classes and being monitored regularlyare unable to reduce their fat intake to anywhere close to Ornishs recommendations, then how could his approach possibly be a sustainable solution for the entire country? In a study from Harvard School of Public Health they prospectively observed 37,698 men from the Health Professionals Follow-Up Study (19862008) and 83,644 women from the Nurses' Health Study (19802008) who were free of cardiovascular disease (CVD) and cancer at baseline. Ornish goes to argue that protein and saturated fat increase the risk of mortality and chronic disease. The abstract clearly states, Respondents aged 5065 reporting high protein intake had a 75 percent increase in overall mortality and a fourfold increase in cancer death risk during the following 18 years. Westman EC, Yancy WS, Edman JS. 4) Dr. Induction of ventricular arrhythmias by elevation of arterial free fatty acids in experimental myocardial infarction. Diabetes Care. As I wrote: I agree that replacing fat with sugar is not healthful, as Ive written about for decades. Ornish first takes issue with the data I cite on food consumption patterns from the National Health and Nutrition Examination Survey (NHANES). He is recognized internationally as a leader in the field of nutritional influences in neurological disorders. Am J Clin Nutr. In locations such as Asia, where a low-fat diet has been the norm, HDL-C levels are low, yet the incidence of CVD is among the lowest in the world (43). But the research he cites to back up his oped claims is tenuous at best. Weight loss was 1 lb/week on the 10% fat diet and 0.6 lb/week on the Atkins diet. As evidence for these causal claims, he cites a handful of observational studies. Corrections? 1996;46:325-341. All evidence is to the contrary. First, shes again perpetuating the myth that when we cut out fat, we began eating foods that were worse for us. As the USDA data show, were eating more fat, not less. After 1 year, there was a 52% decrease in LDL-C on the 10% fat diet compared with a 6% increase in LDL-C on the Atkins diet (33). If you know or suspect that you have a health problem, consult a health professional. DISTINGUISHING BETWEEN RISK FACTORS AND ACTUAL MEASURES OF DISEASE. They wrote: In any event, I wasnt wrong about this; in my oped I was clear that these benefits were seen in those under age 65. Could it be that our attempts to reduce fat have in fact been part of the problem? Ornish D. A diet rich in partial truths. J Am Coll Nutr. Circulation. Total fat and animal fat intake were higher and carbohydrate intake was lower in those with recently diagnosed diabetes or previously undiagnosed diabetes in the multinational, multicenter study of the Mediterranean Group for the Study of Diabetes (17). J Am Diet Assoc. Changes in myocardial perfusion abnormalities by positron emission tomography after long-term, intense risk factor modification. Weight loss was greater for women in the Atkins diet group compared with the other diet groups at 12 months, and mean 12-month weight loss was significantly different between the Atkins and Zone diets (P less than .05). In contrast, someone who increases the amount of fat and cholesterol in their diet (eg, an Atkins diet) may increase their HDL-C because their body is trying to get rid of the extra garbage (fat and cholesterol) by increasing the number of available garbage trucks (HDL). The primary drive was volume not calories (7). In one of these studies, low-density lipoprotein cholesterol (LDL-C) increased from 118 to 121 mg/dL on an AHA/NCEP low-fat diet and increased from 114 to 118 mg/dL on a high-protein/low-carbohydrate diet (19).

Jannell Najera Anaheim, Largest Championship Parade, Articles C