The world’s poorest suffer disproportionately from cardiovascular diseases (CVD), and there are few easy or cheap solutions—but a simple change in cooking oil could make a big difference.
3 out of 4 CVD deaths occur in low- and middle-income countries, where the poor bear a greater burden. For example, in a survey across 4 LMICs, more than 50% of hospitalized CVD patients reported that out-of-pocket costs of treatment were pushing their families toward poverty.
Governments in these countries have limited options to address this challenge. For instance, medications can address risk factors such as hypertension and high levels of blood cholesterol. However, low levels of literacy, inadequate supply chains along with limited budgets and limited access to certified clinicians make it extremely challenging to use medications as a population-level strategy. Behavioral interventions such as tobacco cessation, reducing salt intake, increasing fruits and vegetables intake, regular physical activity and avoiding harmful alcohol use can all reduce CVD risk. Yet, getting a large number of individuals to change their behavior is neither easy nor cheap.
Reducing the saturated fat content of cooking oil, on the other hand, can be a promising strategy for reduction of overall cardiovascular risk in a population. Research has clearly established the beneficial effects on CVD risk of replacing saturated fat with mono- and poly-unsaturated fats (PUFA). A reduction of only 5% of energy intake from saturated fat with equivalent energy from PUFA is associated with a 27% reduction in total mortality.
Cooking oil is an important source of fatty acids, and more so in poorer households that choose the type of cooking oil based on cost. Palm oil is the most common edible oil used across the world, accounting for almost a third of the global vegetable oil consumption. Evidence from several clinical trials, observational studies and policy interventions suggests that reducing consumption of palm oil reduces the cardiovascular disease burden. A rigorously conducted meta-analysis of 32 clinical trials concluded that palm oil consumption, when compared to vegetable oils low in saturated fat, is associated with 9-24mg/dL higher LDL-cholesterol, depending on the dose of palm oil administered. This translates to an estimated 8-20% higher hazard of death from heart disease. In 1987, the government of Mauritius initiated a program to change the primary cooking oil from palm oil to soy bean oil, and serum cholesterol levels fell by 30 mg/dL. Another epidemiological investigation in Costa Rica found that palm oil users had, on average, a 33% higher risk of non-fatal acute myocardial infarction. A country-level analysis using 17 years of data from 10 developing countries found that ischemic heart disease (IHD) mortality rates increased by 68 deaths per 100,000 for every additional kilogram of palm oil consumed per-capita annually.
Despite the mounting evidence summarized above, more than 90 countries import palm oil, with Malaysia and Indonesia accounting for 90% of the exports. An analysis of views of stakeholders from policy circles in Thailand revealed that most of them doubted the evidence of negative health effects of palm oil, and several believed there is a global conspiracy to demonize tropical oils such as palm while promoting soybean oil to the benefit of Western countries. Evidence suggests that the palm oil industry may have played at least some role in propagating these conspiracy theories. A meta-analysis conducted by a team of researchers from the National University of Singapore demonstrated that industry-funded feeding trials of palm oil appeared to report weaker effects on blood lipids, compared to trials funded by governments. These views are not restricted to Thailand.
Sub-Saharan Africa is also facing a burgeoning epidemic of noncommunicable diseases. In a community-based study conducted among middle-aged and older adults in peri-urban Tanzania, we found high levels of serum total cholesterol in half of the participants. Of these, only 2% of men and 7% of women reported taking cholesterol-lowering medications. After evaluating their diet and accounting for bias, we found that those who used palm oil had 15 mg/dL higher serum total cholesterol compared to those who used sunflower oil. Interestingly, we also found that 94% of the poorest participants used palm oil that cost about 2,500 Tanzanian Shillings ($1.10) per litre at the time of the study. Even among the wealthiest, only 34% used sunflower oil that cost 4,000 Tanzanian Shillings($1.80) per litre. These socioeconomic differences may affect disparities in CVD in the coming years with burden shifting more swiftly to poorer households.
Reducing the saturated fatty acid content of cooking oil should be explored more deeply as a potential target for population-level interventions to address the burden on cardiovascular disease in LMICs. Potential interventions include creating incentives for consumption of unsaturated cooking oils through reduced taxation or providing subsidies, or reducing the proportion of saturated fat content of palm oil by mixing it with other unsaturated oils. Benefits of these, or other such interventions will have to be balanced against concerns about employment loss and food security. Greater attention from the global health community will go a long way in finding definitive solutions.
Sujay S. Kakarmath, MBBS MS is a physician-scientist with joint appointments at Harvard Medical School and the Massachusetts General Hospital in Boston.
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