Introduction

Ischemic heart disease (IHD) means that the heart muscle does not receive enough blood and oxygen1 which includes acute myocardial infarction, chronic stable angina, chronic IHD, heart failure, and the highest disease burden among all cardiovascular diseases (CVDs)2,3. IHD is pathologically caused by fat deposition in the arteries, which is called atherosclerosis4. Indeed, IHD is one of the most common causes of heart failure, in which the contractile strength of the myocardial muscle tissue is lost3. The clinical implications of IHD are the high prevalence of mortality and morbidity, and the increased financial burden, which are still high despite the improvement of treatment strategies and preventive measures5. Currently, among non-communicable diseases (NCDs?), CVDs, especially those related to IHD, remain the leading cause of mortality and morbidity worldwide2,6. According to the Global burden of ischemic heart disease report in 2019, 9.14 million (95% uncertainty interval (UI): 8.40–9.74 million) deaths and 182 million (95% UI: 170–194 million) disability-adjusted life years (DALYs) were attributed to IHD7. Evidence shows that more than 70% of the world's population has several IHD risk factors, and only a small percentage has no risk factors4.

The formation of an atherosclerotic plaque due to increased consumption of unhealthy fats as well as the presence of risk factors such as smoking, hypertension, diabetes, male gender, and inflammation leads to narrowing of the coronary arteries6,8. This narrowing causes a decrease in blood flow in the coronary arteries and, subsequently, an imbalance of oxygen supply and demand4,8. In high-income and middle-income countries, respectively, 46% and 55% of deaths from CVDs are attributable to dietary risks9. The effects of dietary risks on CVDs continue to be considered important, and there is no doubt about the importance of dietary risks as a cause of global disease burden10. The results from a meta-analysis and systematic review of 13 prospective studies showed higher adherence to red and processed meat was significantly associated with a higher risk for IHD, while did not observe any association between poultry intake and risk of IHD11. Nevertheless, the results of another meta-analysis and systematic review of 10 studies demonstrated that a plant-based diet is associated with a reduced risk of CVDs12. An umbrella review found no association between a low-salt and low-fat diet and CVDs, while other study findings supported a preventive association of legumes, nuts, and a vegetarian diet with reduced CVDs risk13.

Understanding dietary risk factors for IHD is critical to designing effective dietary interventions and promoting better cardiovascular health outcomes. Recently, many studies have been conducted on the relationship between dietary factors and CVDs. Although this information is useful, so far no study has comprehensively examined the distribution of dietary data related to IHD in terms of population distribution and socio-demographic status. Therefore, his study was done to find out how dietary risks affect the epidemiology of IHD in order to lower the number of deaths, DALYs, and Years Lived with Disability (YLDs) using the Global Burden of Disease model.

Methods

This study was conducted using data collected in the Global Burden of Disease (GBD) study. GBD has reported information on incidence, prevalence, death, and 369 disability-adjusted life years (DALYs) of diseases and 84 risk factors related to diseases according to age and gender from 204 countries and from 1990 to 2019 annually per hundred thousand populations (https://vizhub.healthdata.org/). Indeed, DALYs represent the measure of overall disease burden, expressed as the number of years lost due to ill health, disability, or early death. The Global Burden of Disease (GBD) study employs a rigorous and standardized methodology to collect and analyze data, ensuring the comparability of findings across countries and over time. Specifically, the researchers utilized age-standardized direct rates (ASR) for all metrics related to ischemic heart disease (IHD), enabling meaningful comparisons between populations with different age structures. The GBD study used a wide range of data sources and advanced analytical methods, along with this thorough and standardized approach. This approach significantly improves the reliability and validity of the IHD global burden analysis. In this study, we extracted information on death, years lived with disability (YLD), and DALYs of IHD affected by dietary risks in one hundred thousand people, with a 95% confidence level, based on the direct ASR. We also categorized the data according to age and gender groups in 1990 and 2019. ASR is related to a summary measure of the rate that would have been observed if the population had a standard age structure. DALYs index is a combination of YLL (years of lost life) or years lost due to early death and YLD.

GBD divides countries based on an index called the Socio-demographic Index (SDI), which is a combination of economic information, education, and fertility rate of countries as a report of the social status and economic progress of countries into five categories as follows: high SDI, high-middle SDI, middle SDI, low middle SDI, and low SDI (https://ghdx.healthdata.org). This study compares countries based on their DALYs as measured by the Socio-demographic index (SDI).

Ethics approval

This study was approved by the Ethics Committee of Kermanshah University of Medical Sciences (ethics approval number: IR.KUMS.REC.1403.507).

Results

Comparison of the burden of IHD affected by dietary risks in different SDI conditions by ASR

In 2019, the number of IHD deaths, YLDs, and DALYs attributable to dietary risks were 62.43 (95% UI [50.97–73.63] per 100,000 population), 36.88 (95% UI [23.87–53.32] per 100,000 population), and 1271.32 (95% UI [1061.29–1473.75] per 100,000 population), respectively. Based on SDI, in 2019 low-middle SDI areas had the highest burden of deaths 73.92 (95% UI [60.93–87.32] per 100,000 population) and DALYs 1642.23 (95% UI [1367.85–1919.24] per 100,000 population). High-middle SDI with 44.31 (95% UI [28.39–64.13] per 100,000 population) had the highest ASR of diet-related YLDs (Table 1).

Table 1 Comparison of the burden of ischemic heart disease affected by dietary risks in different socio-demographic index (SDI) conditions from 1990 to 2019 by ASR (per 100,000 population).
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Comparison of the DALY of IHD affected by dietary risks to ASR between the sexes in 2019

As seen in Fig. 1, the highest DALYs of IHD affected by dietary risks to ASR are seen in areas with low middle SDI in both sexes.

Figure 1
figure 1

Comparison of the DALY of ischemic heart disease affected by dietary risks to ASR between the sexes in 2019 in DALY rate per 100,000 population.

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The age trends the DALY rate of IHD affected by dietary risks in both sexes in the SDI in 2019

When we reported the DALYs by age group, we found that the lowest DALYs of IHD affected by dietary risks by ASR are for high SDI countries (Fig. 2).

Figure 2
figure 2

The age trends The DALY rate ischemic heart disease affected by dietary risks in both sexes in the SDI in 2019.

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The DALY rate of ischemic heart disease affected by dietary risks from ASR in the SDI from 1990 to 2019

It can also be seen in Fig. 3 that the DALYs trend has decreased more steeply in high SDI countries from 1990 to 2019.

Figure 3
figure 3

The DALYs of ischemic heart disease affected by dietary risks by ASR in the SDI from 1990 to 2019.

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A percentage of total DALY related to IHD by ASR in both sexes was attributed to the dietary risks in the SDI in 2019

A percentage of total DALYs related to IHD attributed to a diet high in red and processed meat in the high middle and high SDI were higher than other SDI categories in both sexes. In addition, the percentage of total DALYs related to IHD attributed to a diet high in sodium was highly prevalent in high middle and high SDI (12.4% and 13% in men, 8% and 7.7% in women, respectively). More than 3% and 9% of DALYs related to IHD were associated with diets high in sugar-sweetened beverages and trans fatty acids in high SDI. Moreover, the highest percentage of DALYs related to IHD attributed to a diet low in legumes was in high SDI (14.7% in men and 13.9% in women). About 6% of DALYs related to IHD were associated with a diet low in fiber in low middle SDI. In low and low middle SDI was observed high percentage of DALYs related to IHDs in both sexes by attributed to the diet low in fruits. Furthermore, we also observed the most percentage of DALYs related to IHDs in both sexes by attributed to the diet low in nuts and seeds in low middle SDI (9.7% in men and 8.9% in women). Additionally, a diet low in PUFA, seafood W3 fatty acids, vegetables, and whole grains was attributed to the highest percentage of DALYs related to IHDs in low SDI (Fig. 4).

Figure 4
figure 4

A percentage of total DALYs related to of ischemic heart disease by ASR in both sexes attributed to the dietary risks in the SDI in 2019.

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Discussion

Overall, we found that the number of YLDs, deaths, and DALYs in 2019 reduced compared to 1990 and the most deaths and DALYs of IHD attributable to dietary risks were in low-middle SDI in 2019. Meanwhile, the countries with high SDI had the lowest death and DALYs in which its trend is decreasing with a sharp slope compared to 1990. As seen, the most dietary risk factors related to IHD in countries with high and high middle SDI were related to a diet high in red and processed meat, sodium, and low in legumes, but in countries with low and low middle SDI, it was related to a diet low in fiber, fruit, nuts and seeds, PUFA, seafood W3 fatty acids, vegetable and whole grain. Although the number of YLDs, deaths, and DALYs has decreased compared to 1990, it is still the main cause of premature mortality in the world4. Despite the overall improvement in CVDs incidence, IHD accounts for half of global CVDs deaths14. Lifestyle and especially dietary factors play a significant role in the development of IHD. Hence, to learn more, this study looked into the epidemiological aspects of dietary risks to lower the number of deaths, DALYs, and YLDs caused by IHD. In this study, we found that the lowest deaths and DALYs due to IHD are related to countries with high SDA and its trend is decreasing more steeply. According to a study in the United States, the incidence of myocardial infarction in areas with low socioeconomic status is two times higher than in areas with high socioeconomic status. In general, low socioeconomic status was associated with an increase in coronary artery disease15. Results from the China Kadoorie Biobank (CKB) prospective cohort study showed that lower socioeconomic status was associated with an increase in visits to hospitals due to IHD16. It seems that in low socioeconomic status, economic poverty is associated with increased stress and the production of atherogenic factors17,18. Also, the lack of access to a safe environment for physical activity and the appropriate diet due to economic poverty is not ineffective15. In addition, low social status, which is characterized by a low level of awareness, also has an adverse effect in this situation19.

As mentioned in this study, the most common dietary risk factors related to IHD were diets high in red and processed meat and sodium, and low in legumes in countries with high SDI. The results from a meta-analysis and systematic review showed that a higher intake of red meat and processed meat can increase the risk of IHD by 9% and 18%, respectively11. The Health Professionals Follow-up Study in the US reported that a diet rich in plant products such as legumes, whole grains, etc., instead of red and processed meat, was associated with a reduction in the risk of coronary artery disease20. The mechanisms involved in the development of IHD and red and processed meat consumption are caused by its high content of saturated fats, which can increase the risk of IHD by increasing LDL21. On the other hand, processed meats contain high amounts of nitrosamine, trimethylamine-N-oxide (TMAO), and sodium, which are effective in causing arteriosclerosis and hypertension22,23,24. Furthermore, the high content of heme in red and processed meat contributes to an increase in inflammatory factors and reactive oxidative species25,26.

We found that a diet low in legumes was another dietary risk for developing IHD. A meta-analysis and systematic review of 15 intervention studies showed that legume intake can reduce the risk of CVDs27. The mechanism by which legume consumption reduces IHD appears to be due to the high content of fiber, B vitamins, unsaturated fat, and carbohydrates with a low glycemic index28. Evidence shows that legumes are a rich source of ACE-inhibitory peptides that play a significant role in improving systemic blood pressure by affecting this pathway29. On the other hand, they have compounds that compete with 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase, which is the main enzyme in the process of making cholesterol. This is important for lowering cholesterol and preventing CVDs as a result30.

This study found that in countries with low and low middle SDI, IHD was associated with diets low in fiber, fruit, nuts and seeds, PUFA, seafood W3 fatty acids, vegetables, and whole grains. The EPIC prospective study reported that a higher intake of fruits and vegetables was associated with a lower risk of IHD (HR 0.94; CI 95% 0.90–0.99). Moreover, the risk of IHD was decreased with a higher intake of nuts and seeds (HR 0.9; CI 95% 0.82–0.98), total fiber (HR 0.91; CI 95% 0.85–0.98), fiber from fruits and vegetables (HR 0.95; CI 95% 0.91–0.99)31. A meta-analysis of 14 randomized controlled clinical trials showed that W3 fatty acids supplementation had beneficial effects on coronary heart diseases32. According to a prospective study in China, weekly seafood intake can reduce the risk of CVDs and death33. A diet rich in plants will reduce blood cholesterol due to fiber and its binding to saturated fats and bile acids in the intestinal lumen and therefore beneficial in reducing the incidence of IHD31. Nuts and seeds are also part of a plant-based diet. They contain polyunsaturated fatty acids (PUFA), vitamin E, dietary fiber, polyphenols, flavonoids, and phytosterols, all of which may help lower the risk of cardiovascular diseases34. Omega-3 fatty acids, having anti-inflammatory and anti-oxidative stress properties, improve vascular function and serum lipoprotein levels, and are important in reducing the risk of CVDs35.

Policymakers in the food industry can identify nutritional problems related to IHD in society by understanding the dietary risk factors and investing in their improvement. Therefore, this approach contributes to enhancing the overall health of society. Also, bolding these dietary risk factors at the community level based on SDI can open a window for future nutritional research and interventions.

Limitations

This study faced several limitations. Its reliance on secondary data from the Global Burden of Disease (GBD) study introduces inherent challenges. Although the GBD data is comprehensive and standardized, it depends on the quality and completeness of the underlying primary data sources, which can vary across countries and periods, potentially affecting the reliability of the findings. It's hard to figure out how much ischemic heart disease is caused by certain dietary risk factors because self-reported data on dietary intake isn't always accurate (recall bias). Furthermore, the complexity of dietary patterns and their interactions with other risk factors makes it difficult to isolate the independent effects of individual dietary components. Using aggregate-level GBD data rather than individual-level data may not capture the nuances and heterogeneity of the relationship between dietary risks and ischemic heart disease. This limitation restricts the granularity of the insights that can be drawn from the study's findings.

Conclusion

In conclusion, this present study indicated the number of YLDs, deaths, and DALYs in 2019 reduced compared to 1990. In addition, the countries with high SDI had the lowest death and DALYs in which its trend is decreasing with a sharp slope compared to 1990. We found that most deaths and DALYs of IHD attributable to dietary risks occurred in the low-middle SDI in 2019. Furthermore, most dietary risk factors related to IHD in countries with high and high middle SDI were related to a diet high in red and processed meat, sodium, and low in legumes, but in countries with low and low middle SDI, it was related to a diet low in fiber, fruit, nuts and seeds, PUFA, seafood W3 fatty acids, vegetable, and whole grain.