Sunday, February 28, 2010

The link between air pollution and atherosclerosis: What is the right biological explanation?

Studies around the world have consistently shown that both short and long term exposures to Particulate Matter (PM) air pollution are associated with a host of cardiovascular diseases, including myocardial ischemia and infarctions, heart failure, arrhythmias, strokes and increased cardiovascular mortality.
Very recently it was published a study in humans confirming the association of the exposure to ambient air pollution and atherosclerosis through the progression of carotid artery intima-media thickness (1).
In an interesting recent paper by Robert Brook (2) he states that there are three putative ‘general’ pathways to explain the biological mechanisms whereby PM exposure may be capable of mediating cardiovascular events: 1) autonomic mechanisms: parasympathetic nervous system withdraw and/or sympathetic nervous system activation; 2) the release of circulating pro-oxidative and/or pro-inflammatory mediators from the lungs (e. g. cytokines and activated immune cells) into the systemic circulation following PM inhalation that, in turn, indirectly mediate CV responses; and; 3) nano-scale particles and/or soluble PM constituents translocating into the systemic circulation after inhalation that then directly interact with the CV system. According to Robert Brook, chronic actions of PM and the enhancement of atherosclerosis, are most likely to be induced by the generation of a chronic pro-inflammatory state (pathway 2).
Taking in view the results of studies in humans showing that particulate air pollutants continuous exposition decreases the heart rate variability (3,4) and may lead to an impaired autonomic control with potential acceleration in the progression of atherosclerosis (5,6,7), with the due respect, I feel obliged to differ from Brook’s opinion regarding the biological mechanism related to chronic PM exposure and atherosclerosis.
In our view the sympathetic over activity may start the whole process of atherosclerosis which ends in the inflammatory state as hypothesized in the acidity theory of atherosclerosis (8) and discussed in our last article in this blog (9)
Carlos Monteiro
1. Nino Kunzli, Michael Jerrett, Raquel Garcia-Esteban, Xavier Basagana, Bernardo Beckermann, Frank Gilliland, Merce Medina, John Peters, Howard N. Hodis, Wendy J. Mack. "Ambient Air Pollution and the Progression of Atherosclerosis in Adults." PloS ONE 5(2): e9096. doi:10.1371/journal.pone.0009096, February 8, 2010. Full free text at Brook RD, Cardiovascular effects of air pollution. Clinical Science (2008) 115, (175–187) Full free text at
3. Duanping Liao, Yinkang Duan, Eric A. Whitsel, Zhi-jie Zheng, Gerardo Heiss, Vernon M. Chinchilli, and Hung-Mo Lin. Association of Higher Levels of Ambient Criteria Pollutants with Impaired Cardiac Autonomic Control: A Population-based Study, Am J Epidemiol 2004;159:768–777
4. C. Arden Pope III, Matthew L. Hansen, Russell W. Long, Karen R. Nielsen, Norman L. Eatough, William E. Wilson, and Delbert J. Eatough. Ambient Particulate Air Pollution, Heart Rate Variability, and Blood Markers of Inflammation in a Panel of Elderly Subjects. Environmental Health Perspectives, V 112; N 3: March 2004
5. Heikki V. Huikuri; Vesa Jokinen; Mikko Syvänne; Markku S. Nieminen; K. E. Juhani et al, Heart Rate Variability and Progression of Coronary Atherosclerosis. Arteriosclerosis, Thrombosis, and Vascular Biology. 1999;19:1979-1985.
6. Anders Gottsäter , Åsa Rydén Ahlgren, Soumia Taimour and Göran Sundkvist, Decreased heart rate variability may predict the progression of carotid atherosclerosis in type 2 diabetes Clinical Autonomic Research Volume 16, Number 3 / June, 2006
7. J. C. Longenecker, M. Zubaid, K.V. Johny, A.I. Attia, J. Ali, W. Rashed, C.G. Suresh, M. Omar. Association of low heart rate variability with atherosclerotic cardiovascular disease in hemodialysis patients. Med Princ Pract 2009;18:85-92
8. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at
9. Sympathetic predominance: a primary factor in the cascade of events leading to the atherogenic spiraling, Carlos Monteiro, Monday, February 22, 2010 at

Monday, February 22, 2010

Sympathetic predominance: a primary factor in the cascade of events leading to the atherogenic spiraling.

Sympathetic overactivity has been found to be associated with blood pressure and lipid abnormalities (1,2,3). In this respect a recent study has demonstrated that sympathetic overactivity may favour the development of sustained hypertension and hypercholesterolemia early in life, and lead to increased susceptibility of vascular complications. (4).
In fact accumulating data collected in animals and humans suggest that metabolic syndrome is associated with markers of adrenergic overdrive. Several markers of adrenergic drive, such as plasma norepinephrine, norepinephrine spillover from adrenergic nerve terminals, heart rate and others, have all show an increase in the different conditions clustering in metabolic syndrome like obesity, hypertension and insulin resistance state (5,6). Evidence also has shown that the sympathetic activation participates in the development of hypertension-related target organ damage, such as left ventricular diastolic dysfunction (7).
It is well established that the sympathetic nervous system (SNS) activity is also influenced by food ingestion, and that diet composition plays an important role. What is interesting to note is that, among dietary types, carbohydrates (starch and sugars) ingestion significantly increases SNS activity, especially in high-glycemic load, with deleterious effects to human health (8). On the other side protein or fat ingestion have no significant sympathoexcitatory effect (9,10,11).
The evidences above mentioned strengthen our views regarding to the acidity theory of atherosclerosis where continuous stress is placed as the most important risk factor (12). However, this do not undermine the value of other key factors as expressed in our monography:
“The acidity theory of atherosclerosis does not underestimate the importance of other key factors for atherosclerosis like ageing, improper diet, environmental pollution, lifestyle, physical inactivity, tobacco smoking and genetic predisposition. However, most of these risk factors might result in altered autonomic nervous system, sympathetic bias, increased lactic acid and acidic environment thus propitiating atherogenesis. Our proposal may extend to any respiratory or metabolic disturbances resulting in acidosis.“
Carlos Monteiro
1. Masuo K, Mikami H, Ogihara T, Tuck ML. Sympathetic nerve hyperactivity precedes hyperinsulinemia and blood pressure elevation in a young, nonobese Japanese population. Am J Hypertens 1997; 10:77–83.
2. Nakao M, Nomura K, Karita K, Nishikitani M, Yano E. Relationship between brachial-ankle pulse wave velocity and heart rate variability in young Japanese men. Hypertens Res 2004; 27:925–931.
3. Arner P, Wahrenberg H, Lonnqvist F, Angelin B. Adipocyte betaadrenoceptor sensitivity influences plasma lipid levels. Arterioscler Thromb Vasc Biol 1993; 13:967–972.
4. Palatini P, Longo D, Zaetta V, Perkovic D, Garbelotto R and Pessina AC. Evolution of blood pressure and cholesterol in stage 1 hypertension: role of autonomic nervous system activity. Journal of Hypertension 2006, 24:1375-1381
5. Mancia G, Bousquet P et al. The sympathetic nervous system and the metabolic syndrome. Journal of Hypertension 2007, 25 (5):909-920
6.Grassi G, Quarti-Trevano F et al. Cariovascular risk and adrenergic overdrive in metabolic syndrome. Nutr Metab Cardiovasc Dis 2007, 17(6): 473-81
7. Grassi G, Seravalle G et al. Sympathetic and baroreflex cardiovascular control in hypertension-related left ventricular dysfunction. Hypertension 2009;53:205-209. Full free paper at
8. Koop W. Chronically increased activity of the sympathetic nervous system: our diet-related “evolutionary” inheritance. The Journal of Nutrition, Health & Aging Volume 13, Number 1, 2009
9. Welle S, Ulavivat U, Campell G. Thermic effect of feeding in men: Increased plasma
norepinephrine levels following glucose but not protein or fat consumption. Metabolism 1981; 30: 953-958
10. Welle SL, Lilavivathana U,Campell RG. Increased plasma nor epinephrine concentrations and metabolic rates following glucose ingestion in man. Metabolism 1980; 29: 806-09
11. Tentolouris N, Tsigos D, Perea E et al. Differential effect of high-fat and high carbohydrate isoenergetic meals on cardiac autonomic nervous system activity in
lean and obese women. Metabolism 2003; 52: 1426-32
12. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at

Friday, February 5, 2010

What causes the elevation of cholesterol levels in blood?

Follows some suggestions from medical literature about factors, beyond the famous but wronged and simplistic idea that foods based on saturated fats cause the development of atherosclerosis (1, 22, 23), suggesting that stress, high carbohydrate diets and smoke may raise total cholesterol and low density lipoproteins levels:
1. Stress
a) Anxiety and cholesterol elevation (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
b) Hostility and cholesterol elevation (12, 13, 14)
c) Extreme physical exertion and cholesterol elevation (15)
2) High carbohydrate diets and cholesterol elevation (16, 17, 18).
3) Smoke and cholesterol elevation (19, 20).
It is interesting to notice that specially in stress conditions and in high carbohydrate diets there is a significant elevation in blood lactic acid, with paralleling elevation of cholesterol levels in blood which represents in our view, a healing response of the body to the vascular endothelial lesion (21).
As Dr. Malcolm Kendrick, a colleague from the International Network of Cholesterol Skeptics (THINCS), use to say: "Do cigarettes contain fat? No, not at all. So, how can smoking a cigarette, containing no fat or cholesterol, end up depositing fat and cholesterol in the artery walls. What is the mechanism for that?"
By the way, in a recent paper the authors have assessed all dietary interventions using Dietary Cholesterol (DC) or eggs and presented their own conclusions. They point out that short-term effects where there is a rise in plasma cholesterol with DC should be interpreted with caution because they differ from long-term effects where there is no relationship between DC and plasma cholesterol (22).
Carlos Monteiro
A recent meta-analysis of prospective epidemiologic studies during 5–23 years of follow-up of 347,747 subjects showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD. Consideration of age, sex, and study quality did not changed the results (23)
1. Uffe Ravnskov, Cholesterol Myths at
2) Changes in plasma lipids with psychosocial stress are related to hypertension status and the norepinephrine stress response. Wirtz PH, Ehlert U, Bärtschi C, Redwine LS, von Känel R. Metabolism. 2009 Jan;58(1):30-7.
3. Effects of hemoconcentration and sympathetic activation on serum lipid responses to brief mental stress, Elizabeth A. Bachen, Matthew F Muldoon et al, Psychosomatic Medicine 64:587-594 (2002)
4. Serum lipids, neuroendocrine and cardiovascular responses to stress in healthy Type A men, Fredrikson M, Blumenthal JA, Biol Psychol. 1992 Oct;34(1):45-58
5. Factors associated with the development of panic attack and panic disorder: survey in the Japanese population Kaiya H et al. Psychiatry Clin Neurosci. 2005 Apr;59(2):177-82a
6. Changes in mental well-being, blood pressure and total cholesterol levels during workplace reorganization: the impact of uncertainty, Taylor & Francis V15, N1 January 1, 2001: 14-18
7. Examination stress: changes in serum cholesterol, triglycerides and total lipids. Agarwal V, Gupta B, Singhal U, Bajpai SK. Indian J Physiol Pharmacol. 1997 Oct;41(4):404-8.
8. Wives of patients with acute myocardial infarction are at an increased risk of developing coronary artery disease, Papamichael Ch et al, J Cardiovasc Risk. 2002 Feb;9(1):49-52
9. Lipid reactivity to stress: I. Comparison of chronic and acute stress responses in middle-aged pilots, Stoney CM et al, Health Psychol. 1999 May;18(3):241-250
10. Associations between acute lipid stress responses and fasting lipid levels 3 years later, Andrew Steptoe and Lena Brydon, Health Psychology 2005, Vol. 24, No. 6, 601-607
11. Effect of preoperative stress on serum cholesterol level in humans. Sane AS, Kukreti SC, Experientia. 1978 Feb 15; 34(2): 213-4
12. Prevalence of hostility in young coronary artery disease patients and effects of cardiac rehabilitation and exercise training, Lavie CJ, Milani RV, Mayo Clin Proc. 2005 Mar;80(3):335-42
13.Richards JC, Hof A, Alvarenga M. Serum lipids and their relationships with hostility and angry affect and behaviors in men.Health Psychol. 2000 Jul;19(4):393-8.
14. Hostility-related differences in the associations between stress-induced physiological reactivity and lipid concentrations in young healthy women.Suarez EC, Harralson TL. Int J Behav Med. 1999;6(2):190-203.
15. Changes in lipoprotein profiles during intense military training. B. L. Smoak, J. P. Norton, E. W. Ferguson and P. A. Deuster. Journal of the American College of Nutrition, Vol 9, Issue 6 567-572
16. Metabolic effects of dietary fructose in healthy subjects.Swanson JE, Laine DC, Thomas W, Bantle JP. Am J Clin Nutrition 1992;55:851-6
17. Blood lipids, lipoproteins, apoproteins, and uric acid in men fed diets containing fructose or high-amylose cornstarch. Reiser S. Powell AS, Scholfield DI. Panda P. Ellwood KC. Canary II. Am J Clin Nutr 1989:49:832-9.
18. Hallfrisch J, Reiser 5, Prather ES. Blood lipid distribution of hyperinsulinemic men consuming three levels of fructose. Am J Clin Nutr 1983:37:740-8.
19. The Relationship Between Smoking, Cholesterol, and HDL-C Levels in Adult Women
Bert H. Jacobson; Steven G. Aldana; Troy B. Adams; Michael Quirk; Haworth, Women & Health, Volume 23, Issue 4 July 1996 , pages 27 - 38
20. Smoking and smoking cessation -- the relationship between cardiovascular disease and lipoprotein metabolism: a review. Chelland Campbell S, Moffatt RJ, Stamford BA. Atherosclerosis. 2008 Dec;201(2):225-35
21. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at
22. Fernandez ML and Calle M. Revisiting Dietary Cholesterol Recommendations: Does the Evidence Support a Limit of 300 mg/d?, August 4, 2010
23. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease, Patty W Siri-Tarino, Qi Sun, Frank B Hu, and Ronald M Krauss. Am J Clin Nutr doi: 10.3945/ajcn.2009.27725. First published ahead of print January 13, 2010