Kind of carbs more important than quantity for cardiovascular health
Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Whereas previous studies have considered the link between overall carbohydrate consumption and CVDs, a new UK study looked at whether the types of carbohydrates consumed impacted cardiovascular health and found quality was more important than quantity.
CVDs are diseases affecting the heart and blood vessels. According to the World Health Organization (WHO), CVDs claim an estimated 17.9 million lives yearly.
Narrowing or blockage of the arteries supplying blood to the heart (coronary artery disease), strokes or aneurysms that affect blood flow to the brain (cerebrovascular disease), and diseases of the blood vessels in the arms and legs (peripheral vascular disease) are all included under the umbrella of CVDs.
Behavioral risk factors for CVDs are well-known and include an unhealthy diet and obesity, physical inactivity, smoking and the overuse of alcohol. Previous randomized controlled trials and observational studies have shown that, where diet is concerned, the amount of carbohydrates consumed does not impact cardiovascular health.
Carbohydrates are classified according to their chemical composition and include sugars.
Sugars are further categorized as either "free sugars" (that is, added by a manufacturer, cook or consumer, as well as sugars naturally present in honey, syrups, nectars, or unsweetened fruit juices) or "non-free sugars" (mostly naturally occurring sugars found in fruits, vegetables, and dairy products).
Public health agencies worldwide recommend limiting the intake of free sugars to reduce the risk of weight gain and dental decay. For example, the UK’s National Health Service (NHS) recommends that adults consume no more than 30 g (1 oz) of free sugars daily. For perspective, 30 g is equivalent to about seven sugar cubes.
A large new study out of the UK has examined the link between CVDs and the quality of carbohydrates consumed rather than the quantity.
Participants monitored their intake of 206 food items and 32 beverages using an online 24-hour dietary assessment tool. Carbohydrates were divided according to type and source.
Types of carbohydrates included free sugars, non-free sugars, and fiber. Sources of carbohydrates were refined grain starch (including white bread, white pasta and rice, cereals, pizza, crackers, cakes, pastries, and desserts) and wholegrain starch (including brown seeded and wholemeal bread, wholemeal pasta and brown rice, bran, and muesli).
Blood samples were taken from participants to measure blood fat (cholesterol and triglyceride) levels, and participants were monitored over years to see whether they developed CVDs.
Results showed that the intake of free sugars was significantly positively associated with CVDs generally and, more specifically, with coronary artery disease and stroke. Free sugar intake also resulted in elevated blood fat (triglyceride) levels. Conversely, a higher fiber intake was found to reduce the risk of CVDs.
Consistent with previous studies, the current study showed no association between the quantity of carbohydrates consumed and the risk of developing CVDs. Instead, the data suggest that the risk of CVDs depends upon the type of carbohydrate consumed, particularly the consumption of free sugars.
The study was published in BMC Medicine.