Dr. Kumar’s Take:
What I am reviewing here is not the PURE trial report itself but a commentary by Andrea Poli, published in European Heart Journal Supplements in 2020, that re-examines the PURE findings alongside other cohort data and meta-analyses. That distinction matters, because PURE is an observational epidemiologic study, not an experiment, and the commentary’s job is interpretation. Read that way, the message I take from it is that the case against dietary fat, and against saturated fat in particular, is weaker than the guidelines assume, and that a diet dominated by carbohydrate of poor nutritional quality carries its own risk. I would not read any of this as licence to eat without limit. I read it as a reason to stop treating fat percentage as the main lever in a heart-healthy diet.
Brief Summary:
The Prospective Urban Rural Epidemiology (PURE) study was designed to collect data on lifestyle, nutrition, and cardiovascular risk in countries with low or intermediate per capita income, enrolling people in both rural and urban areas. It was coordinated by Salim Yusuf’s group at McMaster University in Canada. Between January 2003 and March 2013 it enrolled approximately 140,000 men and women aged 35 to 70, living in over 600 communities, most of them in the Far East and in rural areas. Rural China alone contributed around 40% of the cohort.
The findings the commentary summarises:
✔ Total mortality falls as the share of calories from total fat rises. The lowest all-cause mortality was seen at about 45% of calories from total fat, which was the highest intake measured.
✔ Mortality was not substantially influenced by saturated fat intake, even when that intake was very high. Total mortality tended to fall as saturated fat consumption rose, to at least around 15% of calories, then stayed substantially unchanged at higher intakes.
✔ Major cardiovascular events were stable across saturated fat intakes of 10% to 18% of total calories, 18% being the highest level detected.
✔ Above about 60% of calories from carbohydrate, total mortality begins to rise, and it moves in parallel with mortality from cardiovascular events.
✔ As mono- and polyunsaturated fat intake rose, mortality tended to fall.
Key Takeaways:
✔ The harm signal in PURE sits with a carbohydrate-dominated diet, not with fat.
✔ Dietary fats, including saturated fat, are not as harmful as decades of advice assumed.
✔ The carbohydrate signal probably reflects diet quality. People eating 70% or more of calories as carbohydrate in the rural East were likely eating mostly boiled rice, with a high glycaemic index and few of the protective nutrients a varied diet supplies.
✔ Geography changes the answer. In many, though not all, US studies saturated fat is associated with a small increase in cardiovascular events or total mortality, on the order of 5 to 10%. European studies do not show this.
Study Design:
PURE is a large prospective observational cohort study. It recruited adults aged 35 to 70 from over 600 communities, mostly in the Far East and in rural settings, and it followed both urban and rural residents. Enrolment ran from January 2003 to March 2013.
The analyses discussed here assessed:
✔ Total mortality (death from all causes)
✔ Major cardiovascular events
✔ The relationship of both to the share of calories from total fat, saturated fat, mono- and polyunsaturated fat, and carbohydrate
Because the design is observational, it can show associations between eating patterns and outcomes. It cannot establish that changing one macronutrient causes the change in outcome.
Results:
✔ Total and cardiovascular mortality decreased as the share of calories from total fat increased, with the minimum all-cause mortality at about 45% of calories from fat, the highest intake recorded.
✔ Saturated fat intake did not substantially influence mortality, even at very high intake. Major cardiovascular events were flat across intakes of 10% to 18% of total calories.
✔ Rising mono- and polyunsaturated intake was associated with falling mortality.
✔ Total mortality rose once carbohydrate exceeded about 60% of calories, tracking cardiovascular event mortality in parallel.
✔ The two recent meta-analyses that addressed saturated fat and cardiovascular and total mortality found no increase in risk moving from low-consumption groups to high-consumption groups. In de Souza’s meta-analysis, high intake did not correlate with fatal or non-fatal stroke, or with new cases of diabetes.
✔ In the EPIC cohort, the pattern ran the other way: subjects with the highest saturated intake had significantly lower total mortality, by 16%, in multivariate analysis, compared with those with the lowest intake.
Implications for Diet & Health:
These results run against the recommendations of most global dietary guidelines, and the commentary makes the case that the guidelines, not the data, are what should move. There is a real limitation to acknowledge first: PURE was conducted largely in rural Eastern communities where the diet is often insufficient or inadequate, so its extremes do not automatically define an optimal Western or Mediterranean eating pattern. But the recent epidemiological literature that does not share that geographic limitation points the same way.
The commentary’s conclusion is that, assuming adequate calories and weight control, the evidence does not support limiting total dietary fat, and saturated fat in particular. It also warns that pushing saturated fat down too far in Europe would mean an unnecessary restriction of foods such as cheese, whose overall effect on health is favourable.
So, what should you eat?
✔ Watch the quality of your carbohydrate, not just the quantity. The mortality signal in PURE sat with monotonous, low-nutrient, high-glycaemic-index staples.
✔ Incorporate healthy fats (olive oil, nuts, seeds, fatty fish). Mono- and polyunsaturated intake tracked with lower mortality.
✔ Do not fear saturated fats in a varied diet. Cheese and similar foods are the specific example the commentary defends.
✔ Aim for a balanced diet rather than extreme macronutrient restriction.
Related Studies and Research
Coconut Oil and Cholesterol: Analyzes the effects of coconut oil consumption on cholesterol levels and cardiovascular risk.
Linoleic Acid and Heart Disease: Examines the role of linoleic acid in cardiovascular health and its impact on heart disease risk.
LDL-C and Mortality: A Review: Investigates the relationship between LDL cholesterol levels and overall mortality, questioning conventional wisdom.
Saturated and Trans Fats: Risk Analysis: Reviews the impact of saturated and trans fats on cardiovascular health and disease risk.
Frequently Asked Questions:
Does this mean I can eat as much fat as I want?
No. The conclusion that dietary fat need not be limited comes with an explicit condition attached: adequate calories and weight control. Excess calories from any source remain a problem.
Should I avoid all carbohydrates?
No. The risk in PURE appeared at very high carbohydrate shares of the diet, and the likely explanation is a monotonous, nutrient-poor pattern built on a high-glycaemic-index staple rather than carbohydrate itself. A varied diet supplying the nutrients and protective compounds that pattern lacks is a different situation.
How much fat should I eat?
This work does not set a target for you, and I would not invent one. What it shows is that no excess of unfavourable events appeared above 30% of calories from fat, and that the lowest all-cause mortality was seen at about 45% of calories from total fat, the highest intake measured. On that basis the commentary argues against limiting total dietary fat, and saturated fat in particular, provided calories and weight are controlled.
Does this study prove that fat is healthy?
No. PURE is observational, so it shows associations, not causation. Its size and the breadth of the populations studied make the findings worth taking seriously, and the fact that recent meta-analyses without PURE’s geographic limitations point the same way strengthens the case. Proof would require something PURE was not designed to provide.
Conclusion:
PURE, read alongside the recent meta-analyses and the European cohort data, undercuts the assumption that lower fat means lower risk. Saturated fat intake was not associated with higher mortality or with more cardiovascular events across the range studied, while a diet built mostly on low-quality carbohydrate was associated with higher mortality. My practical reading: pay attention to the quality of what fills your plate, control calories and weight, and stop treating the fat percentage as the number that decides whether a diet is heart-healthy.
