An uncontrolled observational study that measures saturated fat consumption and heart disease mortality can be very misleading. Even a diet experiment that reduces saturated fat but doesn't tell people what to eat more of when they reduce saturated fat has the same problem. Replacing it with stick margarine should increase heart attacks. Replacing it with sugar and white flour (which is just as bad) shouldn't make any difference. Replacing it with canola oil based margarine should reduce heart attacks like it did in the Lyon Diet-Heart Study. Replacing it with fruits, vegetables, beans and whole grains should also reduce heart attacks like it did for the rural Chinese during the 80's and like it did for Dr. Ornish and Dr. Esselstyn's clinical trials.
There's also the problem that different kinds of saturated fat have different effects. Wild game has a higher percentage of stearic acid which lowers LDL, lauric acid from coconuts improves the LDL/HDL ratio and palmitic acid from feedlot meat raises LDL and and makes the LDL/HDL ratio worse. Also meat can have vastly different palmitic acid content depending on whether it is wild game, grass-fed or produced in a feedlot. Also there are confounding variables like smoking, exercise, alcohol, pre-existing health conditions etc. etc.
So there are several observational studies that show an association with heart disease mortality and several that don't. And there are several experimental studies that show an association and others that don't. This isn't surprising. However, in experiments when saturated fat is replaced by polyunsaturated fat with a good balance of omega-3 to omega-6, heart disease is consistently reduced. (1) And in experiments when saturated fat is replaced with fruits, vegetables, whole grains and beans, heart disease is consistently reduced in about 80% of the people.
Is animal fat ever the best replacement for refined carbs? In spite of the claims of non-scientists modern HGs did not eat a diet high in palmitic acid (because wild game is low in palmitic acid). And high palmitic acid diets like the traditional Atkins don't produce the same low LDL levels or the same low rate of heart disease. See myth #1.
REFERENCES
1. Ramsden CE, Hibbeln JR, Majchrzak SF, Davis JM. n-6 fatty acid-specific and mixed polyunsaturate dietary interventions have different effects on CHD risk: a meta-analysis of randomised controlled trials. Br J Nutr. 2010 Dec;104(11):1586-600.
Tuesday, August 30, 2011
Thursday, August 25, 2011
Myth #1. Modern hunter gatherers prove we are all adapted to eat a lot of animal fat
HGs ate wild game, not feedlot meat. If you look up wild elk, moose or whale meat in the USDA National Nutrient Database, you will find that their palmitic acid content (represented as 16:0 under saturated fat in the database) is so low they could be part of an Ornish diet. (1) Even though HGs ate the whole carcass, the average palmitic acid consumption was only about 1/2 that of Americans according to Professor Loren Cordain in his book The Paleo Diet. In fact whale meat contains about 1/75 the amount of palmitic acid found in a comparable portion of T-bone from a feedlot steer. It's also an objective fact that their serum cholesterol is in the 100 to 150 range and their LDL is in the 50 to 70mg/dL range. (2)
In metabolic ward studies when the AVERAGE American eats a high animal fat diet, their serum cholesterol goes up a lot. Dr. Stephen Phinney conducted a metabolic ward trial with nine healthy lean men during weight maintenance, not weight loss. These men consumed nothing but meat, fish, eggs, cheese and cream (no hydrogenated vegetable oil) for 35 days. Their carbohydrate intake was less than 20 grams a day. Their blood cholesterol went up from 159 to 208 on average in 35 days. (3) That is a 31% increase. The average adult in this country has a cholesterol level of 199. A 31% increase would give 261. The high risk category is anything over 240.
A meta-analysis of 395 metabolic ward experiments concluded that in typical British diets replacing 60% of saturated fats by other fats and avoiding 60% of dietary cholesterol would reduce blood total cholesterol by about 0.8 mmol/l (that is, by 10-15%), with four fifths of this reduction being in low density lipoprotein cholesterol. (4)
The Masai (they are not hunter gatherers and they eat a lot of dairy) seem to contradict this, but 82% of their food additives contain potentially cholesterol lowering saponins or phenolics. (5) If their food wasn't full of statin-like chemicals their serum cholesterol would be high also.
Like the Masai, Pacific Islanders actually did eat a lot of saturated fat, but it was from coconuts. These are high in lauric acid and polyphenols instead of palmitic acid and don't raise serum cholesterol as much. They also improve the LDL/HDL ratio while feedlot meat makes it worse. (6,7)
Finally the very low LDL levels of modern HGs have not been duplicated in clinical trials of Paleo diets even when people eat only lean meat. However various parasitic infections which are common among HGs can lower LDL. In fact the parasitic infection, schistosomiasis, has been shown to lower LDL and reverse atherosclerosis in mice. (8)
REFERENCES
1. The USDA National Nutrient Database: http://www.nal.usda.gov/fnic/foodcomp/search
2. O'Keefe JH Jr, Cordain L, Harris WH, Moe RM, Vogel R. Optimal low-density lipoprotein is 50 to 70 mg/dl: lower is better and physiologically normal. J Am Coll Cardiol. 2004 Jun 2;43(11):2142-6.
3. Phinney SD, Bistrian BR, Wolfe RR, Blackburn GL. The human metabolic response to chronic ketosis without caloric restriction: physical and biochemical adaptation. Metabolism. 1983 Aug;32(8):757-68.4. Clarke R, Frost C, Collins R, Appleby P, Peto R. Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies. BMJ. 1997 Jan 11;314(7074):112-7.
5. Johns T, Mahunnah RL, Sanaya P, Chapman L, Ticktin T. Saponins and phenolic content in plant dietary additives of a traditional subsistence community, the Batemi of Ngorongoro District, Tanzania. J Ethnopharmacol. 1999 Jul;66(1):1-10.
6. Assunção ML, Ferreira HS, dos Santos AF, Cabral CR Jr, Florêncio TM. Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity. Lipids. 2009 Jul;44(7):593-601.
7. Beauchesne-Rondeau E, Gascon A, Bergeron J, Jacques H. Plasma lipids and lipoproteins in hypercholesterolemic men fed a lipid-lowering diet containing lean beef, lean fish, or poultry. Am J Clin Nutr. 2003 Mar;77(3):587-93.
8. Doenhoff MJ, Stanley RG, Griffiths K, Jackson CL. An anti-atherogenic effect of Schistosoma mansoni infections in mice associated with a parasite-induced lowering of blood total cholesterol. Parasitology. 2002 Nov;125(Pt 5):415-21. http://www.ncbi.nlm.nih.gov/pubmed/12458825
In metabolic ward studies when the AVERAGE American eats a high animal fat diet, their serum cholesterol goes up a lot. Dr. Stephen Phinney conducted a metabolic ward trial with nine healthy lean men during weight maintenance, not weight loss. These men consumed nothing but meat, fish, eggs, cheese and cream (no hydrogenated vegetable oil) for 35 days. Their carbohydrate intake was less than 20 grams a day. Their blood cholesterol went up from 159 to 208 on average in 35 days. (3) That is a 31% increase. The average adult in this country has a cholesterol level of 199. A 31% increase would give 261. The high risk category is anything over 240.
A meta-analysis of 395 metabolic ward experiments concluded that in typical British diets replacing 60% of saturated fats by other fats and avoiding 60% of dietary cholesterol would reduce blood total cholesterol by about 0.8 mmol/l (that is, by 10-15%), with four fifths of this reduction being in low density lipoprotein cholesterol. (4)
The Masai (they are not hunter gatherers and they eat a lot of dairy) seem to contradict this, but 82% of their food additives contain potentially cholesterol lowering saponins or phenolics. (5) If their food wasn't full of statin-like chemicals their serum cholesterol would be high also.
Like the Masai, Pacific Islanders actually did eat a lot of saturated fat, but it was from coconuts. These are high in lauric acid and polyphenols instead of palmitic acid and don't raise serum cholesterol as much. They also improve the LDL/HDL ratio while feedlot meat makes it worse. (6,7)
Finally the very low LDL levels of modern HGs have not been duplicated in clinical trials of Paleo diets even when people eat only lean meat. However various parasitic infections which are common among HGs can lower LDL. In fact the parasitic infection, schistosomiasis, has been shown to lower LDL and reverse atherosclerosis in mice. (8)
REFERENCES
1. The USDA National Nutrient Database: http://www.nal.usda.gov/fnic/foodcomp/search
2. O'Keefe JH Jr, Cordain L, Harris WH, Moe RM, Vogel R. Optimal low-density lipoprotein is 50 to 70 mg/dl: lower is better and physiologically normal. J Am Coll Cardiol. 2004 Jun 2;43(11):2142-6.
3. Phinney SD, Bistrian BR, Wolfe RR, Blackburn GL. The human metabolic response to chronic ketosis without caloric restriction: physical and biochemical adaptation. Metabolism. 1983 Aug;32(8):757-68.4. Clarke R, Frost C, Collins R, Appleby P, Peto R. Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies. BMJ. 1997 Jan 11;314(7074):112-7.
5. Johns T, Mahunnah RL, Sanaya P, Chapman L, Ticktin T. Saponins and phenolic content in plant dietary additives of a traditional subsistence community, the Batemi of Ngorongoro District, Tanzania. J Ethnopharmacol. 1999 Jul;66(1):1-10.
6. Assunção ML, Ferreira HS, dos Santos AF, Cabral CR Jr, Florêncio TM. Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity. Lipids. 2009 Jul;44(7):593-601.
7. Beauchesne-Rondeau E, Gascon A, Bergeron J, Jacques H. Plasma lipids and lipoproteins in hypercholesterolemic men fed a lipid-lowering diet containing lean beef, lean fish, or poultry. Am J Clin Nutr. 2003 Mar;77(3):587-93.
8. Doenhoff MJ, Stanley RG, Griffiths K, Jackson CL. An anti-atherogenic effect of Schistosoma mansoni infections in mice associated with a parasite-induced lowering of blood total cholesterol. Parasitology. 2002 Nov;125(Pt 5):415-21. http://www.ncbi.nlm.nih.gov/pubmed/12458825
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