Results from a 2017 study reveal important links between carbohydrates, fat and mortality. Researchers examined food frequency questionnaires from 135,335 subjects from 18 countries across five continents enrolled in the Prospective Urban Rural Epidemiology (PURE) study, an epidemiological cohort study. Findings revealed that higher intake of carbohydrates was associated with an increased risk of mortality, while total fat and individual types of fat were linked to lower total mortality. Subjects with the highest carb intake (77% of calories) had a 28% increased mortality risk than those who ate the least (45% of calories). Alternately, those with the highest fat intake (35% of calories) had a 23% lower risk of mortality compared with those who consumed the least (10% of calories). More specifically, polyunsaturated fat was linked to a 20% reduced risk of death, monounsaturated fat 19% and saturated fat 14%. Total carbohydrates and total fat and types of fat were not associated with cardiovascular disease, myocardial infarction or cardiovascular disease mortality.
Specific types of dietary fat have different associations with total and cause-specific mortality, according to a 2016 study.
Subjects were women and men from the Nurses’ Health Study (n = 83,349) and Health Professionals Follow-up Study (n = 42,884) who were free of cardiovascular disease (CVD), cancer, and types 1 and 2 diabetes at study entry. Dietary intake was measured every two to four years using food frequency questionnaires. Study analyses provide strong evidence that using polyunsaturated (PUFA) and monounsaturated fat (MUFA) as the replacement nutrients for saturated fats (SFAs) can confer substantial health benefits, while replacing SFAs with carbohydrates has little impact on CVD mortality (but may depend partly on the quality of the carbohydrates). When looking at different types of fat, analyses showed that replacement of 5% of calories from SFAs with PUFAs and MUFAs would result in an estimated reduced total mortality by 27% and 13%, respectively.
A 30-year study conducted at Harvard University and published in JAMA Internal Medicine found people who frequently consume unsaturated fats have a lower risk of dying early.
More than 126,000 people who were free of major disease at the beginning of the study submitted a dietary questionnaire every two to four years throughout the study. Researchers looked specifically at the effect of replacing 5% of calories from saturated fat with calories from carbohydrates, monounsaturated fat and polyunsaturated fat. Results showed a reduced risk of death by 13% and 27%, with the substitution of monounsaturated fat or polyunsaturated fat, respectively.
A large meta-analysis, which included more than 1.5 million participants, looked at the relationship between adhering to the Mediterranean diet (vegetables, fruits, legume, grains, fish and moderate intake of red wine with meals) and mortality (death) as well as the incidence of cardiovascular disease and chronic neurological diseases. The results show that participants who closely followed the Mediterranean diet was associated with a 9% decrease in overall mortality, a 9% decrease in death related to cardiovascular disease, a 6% decrease in the incidence of or death from cancer and a 13% decrease in the incidence of Parkinson’s disease and Alzheimer’s disease.
New research published in The Journal of the American Medical Association Internal Medicine indicates that men with non-metastatic prostate cancer who replace 10% of daily energy from carbohydrates and animal fats with healthy fats may have a reduced risk of all-cause mortality. In a prospective study of more than 4,500 men, those who replaced animal fats and carbohydrates with vegetable oils, nuts, seeds and avocados were 29% less likely to die from the spreading of prostate cancer and 26% less likely to die from other diseases.
Furthermore, those who added just one tablespoon of an oil-based salad dressing to their diet each day saw a 29% decreased risk of dying from prostate cancer and a 13% decrease risk of dying from all other causes. In contrast, a 5% and 1% replacement of carbohydrate intake with saturated and trans fats, respectively, was associated with higher all-cause mortality. Although the findings cannot be labeled as conclusive, researchers indicate that the results are promising and merit a randomized controlled trial to see just how healthy fats affect the prostate.
Results from a study in Diabetes Technology and Therapeutics found that consumption of canola and olive oil, which are higher in monounsaturated fat, improved grading of fatty liver, liver span, measures of insulin resistance and lipids in Asian Indians with nonalcoholic fatty liver disease (NAFLD).
The study included 93 males with NAFLD. Each was randomized into three groups — olive oil, canola oil and commonly used soybean/safflower oil (control group) as a cooking medium —plus each received counseling for therapeutic lifestyle changes. Researchers measured BMI, fasting blood glucose, fasting insulin levels and lipids. The results showed that olive oil led to a significant decrease in weight and BMI compared with the control group. Meanwhile, the canola oil group experienced a significant decrease in fasting blood glucose and triglycerides. This study shows that a diet which includes canola and olive oil may improve NAFLD.