Consumption of spicy foods and total and cause specific mortality: population based cohort study
BMJ 2015; 351 doi: https://doi.org/10.1136/bmj.h3942 (Published 04 August 2015) Cite this as: BMJ 2015;351:h3942All rapid responses
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To the editor,
Lv et al. observed that habitual consumption of spicy foods was inversely associated with total and certain cause specific mortality in a population based study of over 0.5 million Chinese adults from 10 geographically diverse areas across China.1 Although there are potential mechanisms supporting their findings, the observed associations may be explained, at least in part, by the geographical variations in diet, lifestyle, socioeconomic status, and environmental factors.
In China, there are very clear geographical disparities in diet habituation. The Chinese cuisine shows regional similarity due to geographical proximity and varies substantially across the country.2 Regional cuisines differ markedly in food variety, recipes, and ingredients, and cooking methods. For example, residents in Jiangsu province habitually add sugar during cooking, but never or seldom consume spicy foods. In contrast, people in Sichuan province are well known in consuming spicy foods frequently. Thus, the comparison based on the frequency of spicy food consumption is likely to reflect the geographical variation in diet and/or other factors. For instance, individuals from Jiangsu province are more likely to be classified into the reference group (less frequent spicy food consumption). Of note, participants in Lv et al. were enrolled from residents in 10 provinces in China between 2004 and 2008 and were followed-up for an average of 7 years. According to China National Health Statistics, the mortality in Jiangsu province was higher than that of any other provinces included in Lv et al. in both years 20043 and 20094, which was consistent with the observed inverse threshold association between spicy food consumption and total mortality.
As the authors mentioned, consumption of spicy foods may be correlated with other dietary habits, lifestyle behaviors, and socioeconomic status. To test the robustness of their findings, we think Lv et al. should consider potential “center effect” by adjusting for study areas. Ideally, given the large, geographically diverse study population, it may be important that the investigators should examine the association within each major geographical area (study center) and then pool the results with a meta-analysis.
Ka He, MD, ScD
Department of Epidemiology and Biostatistics
School of Public Health – Bloomington
Indiana University
Yiqing Song, MD, ScD
Department of Epidemiology
Richard M. Fairbanks School of Public Health
Indiana University
Pengcheng Xun, MD, PhD
Department of Epidemiology and Biostatistics
School of Public Health – Bloomington
Indiana University
References
1. Lv J, Qi L, Yu C, Yang L, Guo Y, Chen Y, et al. Consumption of spicy foods and total and cause specific mortality: population based cohort study. BMJ 2015;351:h3942.
2. Zhu YX, Huang J, Zhang ZK, Zhang QM, Zhou T, Ahn YY. Geography and similarity of regional cuisines in China. PloS one 2013;8(11):e79161.
3. Total Population and Birth Rate, Death Rate and NaturalGrowth Rate by Region (2004). http://www.allcountries.org/china_statistics/4_3_total_population_and_bi... (accessed 6 August 2015).
4. Veeck G, Pannell CW, Smith CJ, Huang Y. China's Geography: Globalization and the Dynamics of Political, Economic, and Social Change. 2nd ed: Rowman & Littlefield Publishers, Inc., 2011.
Competing interests: No competing interests
Re: Consumption of spicy foods and total and cause specific mortality: population based cohort study
I would like to congratulate the authors on the publication of a new study about the health benefit of regular spice intake in The BMJ:
I would like to point out that in the results section, the article mentioned: a 14% relative risk reduction in total mortality which really means 14% risk reduction in total mortality during the course of the study. Alternatively, a relative risk of 86% with 95% CI can be reported to imply risk reduction to total mortality.
I would also like to know why the study didn't leverage the power of a cohort study design by collecting more exposure factors and generate more hypotheses and findings at the same time like Framingham heart study did? It would be more interesting to see what other exposure factors that can be easily collected along with this study can contribute to total mortality in China
I can think of a potential confounder, water intake which has been approved health beneficial and is positively associated with spice intake. Has this potential confounder been adjusted? There might be many other baseline covariates such as geographical, cultural, habitual and ethnic factors etc. that are worth adjusting for. I think with such a large sample size the study should have the power to adjust for more covariates if they don't conflict with the rational of causal pathway in this study setting.
It is an interesting study after all and I would love to hear more about further developments.
Competing interests: No competing interests
Thank you for the interesting comments. If herbal tea consumption and/or medication use are related to spicy food consumption and also related to death; they may add noise to the protective effect observed for spicy foods. However, the influence may be minor considering consuming herbal tea and medication only affects a small proportion of the study population.
Competing interests: No competing interests
We read an interesting research article [BMJ 2015;351:h3855] .
The relationship between eating spicy food and a lower death rate was in people who didn’t drink alcohol. Researchers mentioned the limitations of their study, and truly said that prospective studies in other populations are required to demonstrate these findings in general [1].
Facts about spicy food:
Chili Peppers- capsaicin in hot peppers helpful in relieving all kinds of pain including migraines and other headaches (but also trigger in some migraine sufferers), and ginger a remedy for nausea and vomiting, common symptoms of migraine [2].
Spices in small or average amounts play a role in lowering blood glucose by increasing insulin sensitivity in patients with type 2 diabetes. Spices may also improve blood circulation, decrease platelet aggregation, lower blood pressure, and act as blood vessel protectants, a beneficial role in patients with cardiovascular disease associated with type 2 diabetes [3].
Spices taste good because they are good for us: spices exhibit antibacterial and antifungal activity, use should be greatest in hot climates (unrefrigerated foods spoil quickly), a greater proportion of bacteria should be inhibited by recipes from hot climates than from cool climates. Spices are defensive compounds from plants and these phytochemicals have antioxidant, antimicrobial, and antiviral properties [4].
Herbs and spices are beneficial in cancer prevention[5].
Preference for spicy food among men is related to endogenous testosterone levels [6].
Eating spicy, hot food causes the same physical reactions as does physical heat like burning and sweating [7].
People love the pain of spicy food, eating hot chili peppers reduces danger without risk, activating areas of the brain related to both pleasure and pain [8].
Some people have a preference for spicy foods: people with the thrill-seeking personality, cultural influences play role, and it’s in their genes [9].
Spicy food lovers are more loyal customers [10].
1. BMJ 2015;351:h3855
2.http://www.epicurious.com/archive/blogs/editor/2014/03/migraine-food-cur...
3.http://www.emeraldinsight.com/doi/abs/10.1108/00346650510585868
4.http://bioscience.oxfordjournals.org/content/49/6/453.full
5.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2771684/
6.http://www.sciencedirect.com/science/article/pii/S0031938414005940
7.http://www.scientificamerican.com/article/why-is-it-that-eating-spi/
8. http://www.wsj.com/articles/why-we-love-the-pain-of-spicy-food-1420053009
9. http://www.mindthesciencegap.org/2013/03/20/some-like-it-hot-part-1-why-...
10.http://www.wsj.com/articles/SB10001424052702304893404579530290585919688
Competing interests: No competing interests
It is so good to hear this news that eating spicy foods habitually may reduce the risk of mortality, because I and my family enjoy spicy foods several times per month. However, the habit also troubles me, since I often suffer from excessive internal heat (we call it “shanghuo” in Chinese), and sometimes get constipation after eating such foods. For this reason, I often drink herbal tea, and sometimes seek treatments including taking laxatives and some other medications to make myself feel comfortable. So I have one question--namely, whether the reductions in mortality are due to such treatments rather than spicy foods per se.
Competing interests: No competing interests
Spices are seeds, leaves, stems, bark, and berries of plants that have a strong smell or taste. Common spices are ginger, cayenne, cinnamon, pepper, curry, basil, thyme, rosemary, and fennel. We use these spices to enhance the taste of our food. But spices are not food and must be used with restraint. Too much spice can ruin our food and our health.
Competing interests: No competing interests
Re: Re: Consumption of spicy foods and total and cause specific mortality: population based cohort study
Thank you for the comments. We have collected as much information as possible about lifestyle behaviors, diet, and environmental factors potentially related to the risk of major chronic diseases. However, considerations for the feasbility and maintaining respondent motivation precluded us from using a quite long questionnaire to learn details of more exposure factors. For example, we didn’t collect detailed information on water intake with spicy food consumption. However, the influence may be minor considering drinking water after eating spicy foods only accounts for a small proportion of daily total water intake. We acknowledge that residual confounding by other unmeasured or unknown biological and social factors was still possible although we have carefully adjusted for several established and potential risk factors for death. We will try to collect information of more variables in future follow-up.
Competing interests: No competing interests