In this interview, News-Medical talks to Dr. Mahshid Dehghan about her latest research on diet, and how a diet high in carbohydrates may increase your risk for heart disease.
What inspired your research on diet?
Diet is one of the most important variable risk factors for cardiovascular disease and other non-communicable diseases. In 2017, we published the results of the PURE study in the Lancet and described the link between the number of carbohydrates and health outcomes. We found that those who ate more than 60% of their energy from carbohydrates had a higher risk of death and CVD.
A month ago, we published the results of another study in BMJ. In that study, we evaluated the association between carbohydrate quality as refined, whole grains, and rice and health products. We reported that grains were highly reconstituted, compared with low intake (<50 g / day v > 350 g / day) was significantly associated with a 27% higher risk of overall death, 31% non-cardiovascular mortality, 33% major cardiovascular disease events, and 47% higher risk for stroke.
In the current study, we were interested in highlighting the extent to which the glycemic index has no value as an indicator of carbohydrate quality associated with chronic disease in general and cardiovascular disease in particular.
By better understanding the harmful effects of poor quality carbohydrates on health outcomes, we will be able to prevent premature death and CVD.
Bad carbohydrates. Image credit: Oleksandra Naumenko / Shutterstock.com
Why is a healthy balanced diet so important for our health?
Diet is one of the most important variable risk factors for chronic illness and premature death. Cardiovascular disease is the leading cause of mortality worldwide, with 80% of the burden in low- and middle-income countries.
Thus, the impact of poor quality diet may be deeper in these sectors and among low-income families worldwide.
Please give examples of poor quality carbohydrates?
Poor quality carbohydrate foods include those with a little fiber, a higher percentage of reconstituted grains than whole grains. Poor quality carbohydrates are usually processed grains such as cereals (eg white bread) with a high glycemic index.
In contrast, low glycemic index foods are a rich source of fiber such as fruits, vegetables, legume, and whole grains. Low glycemic index foods gradually increase blood glucose and this is one of the reasons they are healthier than regenerated grains.
Can you cite your latest research on carbohydrates and heart disease?
Using data from a large prospective cohort study that included 137,851 individuals in the Prospective Urban and Rural Epidemiology (PURE) study, we evaluated the association between glycemic index and health outcomes. During a median follow-up of 9.5 years, approximately 9000 deaths and over 8000 cardiovascular diseases were recorded.
Diet information was obtained using a country-specific food frequency questionnaire at the beginning of the study. Our study population is unique in that it includes people from 20 low, middle and high income countries across North America, Europe, South America, Africa and Asia.
What did you find?
After extensive adjustments, we found that a diet with a high glycemic index was associated with 28%, 25%, 14%, higher risk of stroke, major CV events, and death due to individual cardiovascular disease. in all participants.
Associations were even stronger among those with preexisting CVD with a 71% higher risk of stroke and a 49% higher risk of CV events. Results for glycemic loads were similar.
Heart. Image credit: Explode / Shutterstock.com
Your geographical study is the largest study of its kind. Why is it important to study large populations and diverse diets for this type of research?
The study population is unique in that it includes people from 20 low, middle and high income countries across North America, Europe, South America, Africa and Asia. We know that the burden of non-communicable diseases is higher in low- and middle-income countries. 80% of CVD occurs in low- and middle-income countries where high-quality carbohydrate consumption is high.
Therefore, people in these regions benefit more by reducing their intake of high glycemic index foods such as reconstituted grains and this would be the same for low-income families. low income in high-income countries. Also, our results are strong in different numbers with different dietary patterns, which indicates that the results are widely relevant.
What advice should people be given regarding diet and heart health?
A mixture of corn grains with less refinement should be encouraged while at the same time encouraging a higher level of whole grains. Reductions in intake and improvements in carbohydrate quality are essential for better health outcomes.
We always encourage the selection of low-processed foods, higher consumption of fruits, vegetables, legumes, and whole grains over reconstituted grains as often as possible.
Do you believe that, with ongoing research, people will have a better understanding of a harmful diet?
We present new evidence and hope that diet guidelines in North America, with its multicultural population, reflect on these conclusions and encourage people to half to reduce their refined grain and sugar content and encourage more whole grains.
Also, public health policies should promote a variety of sources of carbohydrate consumption, resulting in consumption of foods from all types of grains, legumes, roots, tubers in motor. These messages should also be disseminated to the public by the media.
Fruit and vegetables. Image credit: monticello / Shutterstock.com
What are the next steps in your research?
Currently, I am studying associations of foods with different levels of processing and health outcomes and I hope to publish the results of this research soon.
Where can readers find out more?
- Jenkin D, Dehghan M., Yusuf S. et al. Glycemic Index, Glycemic Load and Cardiovascular Disease and Mortality. NEJM 2020
- Swaminathan S, Dehghan M., Yusuf S. et al. Associations of incoming grain mortality with cardiovascular disease and mortality across 21 countries in the Urban and Rural Epidemiological Study: A prospective cohort study. BMJ 2020
- Dehghan M., Mente A, Yusuf S. et al. Association of egg with blood lipids, cardiovascular disease, and mortality in 177,000 individuals in 50 countries. Am J Clin Nutr. 2020
- Dehghan M., Mente A, Yusuf S. et al. Association of milk intake with cardiovascular disease and mortality in 21 countries from 5 continents: A PURE study. The Lancet. 2018 S0140-6736 (18) 31812-9.
- Dehghan M., Mente A, Yusuf S. et al. Fat associations and carbohydrate intake with cardiovascular disease and mortality in 18 countries from 5 continents: A PURE study. The Lancet. 2017. 4; 390 (10107): 2050-2062.
- Miller V, Mente A, Dehghan M. et al. Fruit, vegetable, and legume intake and cardiovascular disease and mortality: The planned Urban Rural Epidemiology (PURE) study in 18 countries. The Lancet. 2017. 4; 390 (10107): 2037-2049.
About Dr. Mahshid Dehghan
Mahshid Dehghan is a researcher for the Nutritional Epidemiology program at the Institute of Population Health Research and nutrition director of the PURE study and INTERSTROKE study. Her main interests are to develop ways to measure the long-term dietary intake of individuals worldwide and to understand the impact of diet factors in the cause and prevention of cardiovascular disease and cancer.
She has published 64 papers and 2 book chapters. She holds two Masters in Clinical Nutrition and a Health Research Methodology and received her doctorate in Clinical Nutrition from Newcastle University, England, and completed postdoctoral training in Nutritional Epidemiology at McMaster University in Canada.