Elsevier

Nutrition

Volume 33, January 2017, Pages 216-224
Nutrition

Applied nutritional investigation
Urbanized South Asians' susceptibility to coronary heart disease: The high-heat food preparation hypothesis

https://doi.org/10.1016/j.nut.2016.07.006Get rights and content

Highlights

  • Known risk factors do not fully explain the high prevalence of coronary heart disease (CHD) among South Asians.

  • High-heat cooking, common in South Asian cuisine, leads to an increased production of neo-formed contaminants including advanced glycation-end products and trans-fatty acids.

  • NFCs produce biochemical and microanatomic alterations enhancing the effects of traditional CHD risk factors.

  • This phenomenon (high-heat food preparation hypothesis) is responsible for the increased risk for CHD in South Asians compared with other populations that use low-heat cooking.

Abstract

Objective

Known risk factors do not fully explain the comparatively high susceptibility to coronary heart disease (CHD) in South Asians (Indian, Pakistani, Bangladeshi, and Sri Lankan populations in South Asia and overseas). The search for explanatory hypotheses and cofactors that raise susceptibility of South Asians to CHD continues. The aim of this study was to propose “the high-heat food preparation hypothesis,” where neo-formed contaminants (NFCs) such as trans-fatty acids (TFAs) and advanced glycation end-products (AGEs) are the cofactors.

Methods

We reviewed the actions of AGEs and TFAs, the burden of these products in tissues and blood in South Asians, the relationship between these products and CHD, the effects of preparing food and reheating oils at high temperatures on NFCs, and the foods and mode of preparation in South Asian and Chinese cuisines.

Results

Animal and human studies show NFCs increase the risk for CHD. Evidence on the consumption and body burden of these products across ethnic groups is not available, and comparable data on the NFC content of the cuisine of South Asians and potential comparison populations (e.g., the Chinese with lower CHD rates) are limited. South Asians' cuisine is dominated by frying and roasting techniques that use high temperatures. South Asian foods have high TFA content primarily through the use of partially hydrogenated fats, reheated oils, and high-heat cooking. Reheating oils greatly increases the TFA content. In comparison, Chinese cuisine involves mostly braising, steaming, and boiling rather than frying.

Conclusion

We hypothesize that South Asians' susceptibility to CHD is partly attributable to high-heat treated foods producing high NFCs. Research to accrue direct evidence is proposed.

Introduction

The susceptibility to coronary heart disease (CHD) of urbanized South Asians remains incompletely explained [1], [2] (South Asians refers to people from the Indian Subcontinent especially India, Pakistan, Bangladesh, Sri Lanka, including those living overseas). For example, there was 62% increased mortality from ischemic heart disease among Pakistani-born men compared with the population of England and Wales [3]. Such high mortality reflects high incidence, not high case fatality [4]. The susceptibility of urbanized South Asians to CHD is international [3], [5], [6], [7], [8], [9], [10], [11].

This susceptibility has been linked to diabetes and metabolic syndrome. The insulin resistance hypothesis [11], however, does not explain the higher CHD risk in South Asians compared with white Europeans [2]. New ideas include the adipose tissue compartment hypothesis [12], the mitochondrial efficiency hypothesis [13], and the variable disease selection hypothesis [14], [15]. These augment the longstanding thrifty genotype and thrifty phenotype hypotheses [16], [17]. (A short account of these hypotheses can be found in online Supplementary Data.) Collectively, these evolutionary and developmental hypotheses have not yet explained the problem.

Unhealthy diets are important in CHD [18], [19], [20] and the type of food and its preparation might matter. We have, therefore, formulated the high-heat food preparation hypothesis. This is a cultural, rather than evolutionary, hypothesis and moves in a new direction. High-heat cooking promotes neo-formed contaminants (NFCs) such as trans-fatty acids (TFAs) and advanced glycation end-products (AGEs) [21], [22], [23], [24]. The present study compares the potential for producing NFCs in South Asian cuisine with Chinese cuisine, as the Chinese do not have special susceptibility to CHD, whether in China or overseas [25]. The search strategy used for this study is presented in Box 1.

Section snippets

Neo-formed contaminants and CHD: Human and animal evidence

We prioritized human studies [26], [27] despite their limitations, given our focus on the South Asian ethnic group, and NFCs in human foods. Limitations included that food intake data, usually based on a 3-day record or memory based-recall [28], do not equate to long-term exposure. Also, AGE levels from a food database may not always be the same as the food actually consumed by those surveyed. Nonetheless, evidence that NFCs influence human CHD is strong enough to underpin our hypothesis.

Animal

Evidence for the high-heat food preparation hypothesis: Indian and Chinese cuisines

If NFCs in food produced during cooking increase South Asians' susceptibility to CHD, they should be both comparatively high in diets and body tissues and associated with CHD in South Asians. Our literature searches yielded no data on this. Therefore, we have supported our hypothesis on indirect observations we compiled on cuisine and cooking methods (Table 1, Table 2, Table 3) and recently published empirical data on oils and TFAs (Table 4) [73]. The data on Indian and Chinese cuisines in

Testing the high-heat food preparation hypothesis

Our hypothesis, outlined in Figure 3, proposes that high-heat food preparation is a potentially important risk factor for South Asians. Despite searching for evidence carefully (Box 1), at this point, our hypothesis can only be supported indirectly, as no direct, comparative studies of either NFCs in South Asian cuisine, body or plasma NFC burdens, or on the relationship between NFCs and the relevant disease outcomes in South Asians were found. We recommend ways of testing the hypothesis,

Acknowledgments

The authors acknowledge Antonis Vlassopoulos for providing helpful guidance and suggestions to improve the quality of this study; Fu-Shing Lee for providing insight into Chinese cuisine; and Anne Houghton for providing secretarial support.

References (96)

  • W. Cai et al.

    Reduced oxidant stress and extended lifespan in mice exposed to a low glycotoxin diet: association with increased AGER1 expression

    Am J Pathol

    (2007)
  • R. Petrova et al.

    Advanced glycation endproduct-induced calcium handling impairment in mouse cardiac myocytes

    J Mol Cell Cardiol

    (2002)
  • I. Birlouez-Aragon et al.

    The health and technological implications of a better control of neoformed contaminants by the food industry

    Pathol Biol (Paris)

    (2010)
  • S. Panagiotopoulos et al.

    Aminoguanidine has an anti-atherogenic effect in the cholesterol-fed rabbit

    Atherosclerosis

    (1998)
  • T. Goldberg et al.

    Advanced glycoxidation end products in commonly consumed foods

    J Am Diet Assoc

    (2004)
  • S. Stender et al.

    A trans world journey

    Atheroscler Suppl

    (2006)
  • E. Lopez-Garcia et al.

    Consumption of trans fatty acids is related to plasma biomarkers of inflammation and endothelial dysfunction

    J Nutr

    (2005)
  • D. Mozaffarian et al.

    Dietary intake of trans fatty acids and systemic inflammation in women

    Am J Clin Nutr

    (2004)
  • S. Bhardwaj et al.

    Overview of trans fatty acids: biochemistry and health effects

    Diabetes Metab Syndr

    (2011)
  • A. Ibrahim et al.

    Dietary trans-fatty acids alter adipocyte plasma membrane fatty acid composition and insulin sensitivity in rats

    Metabolism

    (2005)
  • S. Bhardwaj et al.

    Effect of heating/reheating of fats/oils, as used by Asian Indians, on trans fatty acid formation

    Food Chem

    (2016)
  • G. Hull et al.

    N(carboxymethyl) lysine content of foods commonly consumed in a Western style diet

    Food Chem

    (2012)
  • P. Chao et al.

    Analysis of glycative products in sauces and sauce-treated foods

    Food Chem

    (2009)
  • M.J. Williams et al.

    Impaired endothelial function following a meal rich in used cooking fat

    J Am Coll Cardiol

    (1999)
  • J.A. Satia et al.

    Use of qualitative methods to study diet, acculturation, and health in Chinese-American women

    J Am Diet Assoc

    (2000)
  • I.C. Arts et al.

    Catechin intake might explain the inverse relation between tea consumption and ischemic heart disease: the Zutphen Elderly study

    Am J Clin Nutr

    (2001)
  • N.G. Forouhi et al.

    Do known risk factors explain the higher coronary heart disease mortality in South Asian compared with European men? Prospective follow-up of the Southall and Brent studies, UK

    Diabetologia

    (2006)
  • S.H. Wild et al.

    Mortality from all causes and circulatory disease by country of birth in England and Wales 2001-2003

    J Public Health (Oxf)

    (2007)
  • N. Bansal et al.

    Myocardial infarction incidence and survival by ethnic group: Scottish Health and Ethnicity Linkage retrospective cohort study

    BMJ Open

    (2013)
  • T. Sheth et al.

    Cardiovascular and cancer mortality among Canadians of European, south Asian and Chinese origin from 1979 to 1993: an analysis of 1.2 million deaths

    CMAJ

    (1999)
  • S. Yusuf et al.

    Global burden of cardiovascular diseases part i: general considerations, the epidemiologic transition, risk factors, and impact of urbanization

    Circulation

    (2001)
  • E.A. Enas et al.

    Coronary heart disease and its risk factors in first-generation immigrant Asian Indians to the United States of America

    Indian Heart J

    (1996)
  • S.L. Chadha et al.

    Epidemiological study of coronary heart disease in urban population of Delhi

    Indian J Med Res

    (1990)
  • S. Wild et al.

    Cross sectional analysis of mortality by country of birth in England and Wales, 1970-92

    BMJ

    (1997)
  • A.D. Sniderman et al.

    Why might South Asians be so susceptible to central obesity and its atherogenic consequences? The adipose tissue overflow hypothesis

    Int J Epidemiol

    (2007)
  • R.S. Bhopal et al.

    Could mitochondrial efficiency explain the susceptibility to adiposity, metabolic syndrome, diabetes and cardiovascular diseases in South Asian populations?

    Int J Epidemiol

    (2009)
  • R.S. Bhopal

    A four-stage model explaining the higher risk of type 2 diabetes mellitus in South Asians compared with European populations

    Diabet Med

    (2013)
  • J.C. Wells

    Ethnic variability in adiposity and cardiovascular risk: the variable disease selection hypothesis

    Int J Epidemiol

    (2009)
  • J.V. Neel

    Diabetes mellitus: a ‘thrifty’ genotype rendered detrimental by ‘progress’?

    Am J Hum Genet

    (1962)
  • C.N. Hales et al.

    The thrifty phenotype hypothesis

    Br Med Bull

    (2001)
  • R. Iqbal et al.

    Dietary patterns and the risk of acute myocardial infarction in 52 countries: results of the INTERHEART study

    Circulation

    (2008)
  • D. Mozaffarian

    Dietary and policy priorities for cardiovascular disease, diabetes, and obesity: a comprehensive review

    Circulation

    (2016)
  • A.O. Odegaard et al.

    Western-style fast food intake and cardiometabolic risk in an Eastern country

    Circulation

    (2012)
  • F.B. Hu et al.

    Dietary fat and coronary heart disease: a comparison of approaches for adjusting for total energy intake and modeling repeated dietary measurements

    Am J Epidemiol

    (1999)
  • R.S. Bhopal et al.

    Mortality from circulatory diseases by specific country of birth across six European countries: test of concept

    Eur J Public Health

    (2012)
  • S.M. Hofmann et al.

    Improved insulin sensitivity is associated with restricted intake of dietary glycoxidation products in the db/db mouse

    Diabetes

    (2002)
  • O. Sandu et al.

    Insulin resistance and type 2 diabetes in high-fat-fed mice are linked to high glycotoxin intake

    Diabetes

    (2005)
  • F. Zheng et al.

    Prevention of diabetic nephropathy in mice by a diet low in glycoxidation products

    Diabetes Metab Res Rev

    (2002)
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    Funding for this study was largely from authors' employing organizations; however, SK was funded by the charitable Cardiovascular Disease Research Fund at the University of Edinburgh (administered by RSB). RSB conceived the high-heat food preparation hypothesis. RSB and SK led on AGEs, and SB and AM on TFAs. SK led on successive drafts with intellectual contributions from all others. All authors have read and approved the final manuscript. The authors have no conflicts of interest to declare.

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