The Science Nook on Carbohydrate Quality and Health Outcomes

by Jenna Koroly, MS, RD, CSOWM, CDN

Low intake of carbohydrates is oftentimes the basis of diet trends, such as the ketogenic and paleolithic diets. However, it is important to understand that carbohydrates come in many different forms–from processed snacks such as pretzels and cookies, to whole foods such as beans, oats, fruits, and vegetables. The below study examines how different qualities of carbohydrates influence clinical outcomes.

Study

Carbohydrate Quality and Human Health: A Series of Systematic Reviews and Meta-Analyses

Journal: The Lancet

This systematic review and meta-analysis series of 185 prospective studies and 58 randomized controlled trials included 4635 adults and nearly 135 million person years of data. The studies’ foci were carbohydrate quality and health outcomes. Studies including participants with chronic diseases were excluded.

The carbohydrate qualities that the present research looked at were: dietary fiber content, whole grains, and glycemic index. The outcome measurements included: mortality, cardiovascular disease, type 2 diabetes, and cancers.

The authors found that:

1. Higher intakes of fiber were associated with a 15-30% decrease in all-cause and cardiovascular related mortality, incidence of coronary heart disease, incidence of stroke and stroke related mortality, type 2 diabetes, and colorectal cancers compared to lower intakes of fiber

2. Higher intakes of fiber were associated with significantly lower bodyweight, systolic blood pressure, and total cholesterol compared to lower intakes of fiber

3. Risk reduction was greatest when intake of fiber was 25-29 g per day, with the data suggesting amounts greater than 30 g per day may offer additional benefits

4. Similar results were seen when looking at fiber coming from different food sources, as well as insoluble and soluble fiber

5. Higher intakes of whole grains were associated with a 13-33% decrease in all clinical outcomes (listed above)

6. No significant differences were found in outcomes when comparing intake of lower glycemic and higher glycemic foods [i]

For the Patient and Caregiver

Worldwide, most individuals consume less than 20 g of fiber per day [i]. Consider how much you eat by trying the following exercise: write down everything you typically eat and drink in one day. Now circle all the sources of fiber you currently eat such as: whole grains (oats, quinoa, 100% whole wheat bread), beans, legumes, nuts, seeds, spinach, kale, collard greens, broccoli, cauliflower, brussels sprouts, asparagus, berries, apples, pears. Plug in where you can increase fiber consumption, aiming for a fiber source at each meal and snack. Don’t hesitate to get creative by adding berries to your Greek yogurt, flax or chia seeds to your smoothie, and greens to your omelets, soups, and pasta dishes. To get an idea of how much fiber different foods contain, take a look at this list.

For the Healthcare Team

Encourage patients to increase intake of fiber sources via highlighting the features of a plant-based eating pattern. Refer patients to dietitians as necessary who can guide the patient on foods to add into their diets in a practical way and can develop a personalized meal plan. Based on the present research, consider focusing on encouragement of high fiber foods rather than low glycemic foods, in order to provide overall health benefits and decreased risk of overweight, cardiovascular disease, type 2 diabetes, and cancers.

Reference:

[i] Reynolds A, Mann J, Cummings J, Winter N, Mete E, Morenga LT. (2019). Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet. http://dx.doi.org/10.1016/S0140-6736(18)31809-9