Lower nocturnal blood glucose response to a potato-based mixed evening meal compared to rice in individuals with type 2 diabetes

Perspective: Potatoes, Quality Carbohydrates, and Dietary Patterns

Potatoes have long been a staple food in many cultures and cuisines, but they have gained a reputation as a low-quality carbohydrate source that should be avoided in the diet. Historically, this view has been justified by citing the glycemic index of potatoes as the main indicator of their quality. However, their nutrient composition should also be considered. The association of potatoes with energy-dense Western dietary patterns has also contributed to a perception that potatoes are inherently unhealthy. Although some studies have suggested an association between potato consumption and increased risk of health problems, such as type 2 diabetes, these associations may be confounded by fried potato intake and are strongest at intake levels higher than average consumption rates. Epidemiologic data suggest total potato intake is not a health risk in Eastern populations and can be consumed as part of a healthy diet. Furthermore, clinical trial data demonstrate that potatoes' health impact, irrespective of preparation, is similar to legumes and comparable with refined grains, with few deleterious effects found. These findings highlight the importance of moving beyond the glycemic index and adopting a more nuanced evaluation of the epidemiologic data to better understand the health impact of potato intake. Ultimately, the negative reputation of potatoes stems from an overinterpretation of their glycemic index and association with unhealthy Western dietary patterns, as well as oversimplification of the epidemiologic data. By considering carbohydrate quality, it becomes clear that potatoes can be part of a healthy diet given the proper consideration.

French-fried potato consumption and energy balance: a randomized controlled trial

BACKGROUND

Epidemiologic observations suggest increased potato consumption correlates with weight gain, adiposity, and diabetes risk, whereas nut consumption is associated with weight control and metabolic health. Randomized controlled trial (RCT) data indicate humans respond to changes in energy intake in single dietary components and compensate for extra energy consumed.

OBJECTIVES

We completed an RCT testing whether increased daily potato consumption influences energy balance [specifically, fat mass (FM)] compared with calorie-matched almond consumption.

METHODS

A 30-d RCT of 180 adults prescribed calorie-matched (300 kcal/d, n = 60 participants/group) than consumed 1 of the following: 1) almonds (almond group), 2) French fries (potato group), or 3) French fries with herb/spices mix (potato + herb/spices group). Baseline and 30-d FM were measured by DXA (primary outcome), with secondary outcomes including body weight and carbohydrate metabolism markers [glycated hemoglobin (HbA1c), fasting blood glucose and insulin, HOMA-IR)]. A subset of 5 participants/group participated in a postprandial meal-based tolerance test.

RESULTS

A total of 180 participants were randomly assigned [gender: 67.8% female; mean ± SD age: 30.4 ± 8.7 y; BMI (in kg/m2): 26.1 ± 4.2; and weight: 75.6 ± 15.4 kg], with 12 dropouts and 3 terminations. No significantly different FM changes were observed between almond and potato consumption [combined ± herb/spices; mean ± SE almond: 230.87 ± 114.01 g; potato: 123.73 ± 86.09 g; P = 0.443], fasting glucose (P = 0.985), insulin (P = 0.082), HOMA-IR (P = 0.080), or HbA1c (P = 0.269). Body weight change was not significantly different in the potato groups combined compared with the almond group (P = 0.116), but was significantly different among the 3 groups (P = 0.014; almond: 0.49 ± 0.20 kg; potato: -0.24 ± 0.20 kg; potato + herb/spices: 0.47 ± 0.21 kg). In meal tests, significantly lower post-prandial glucose and insulin responses to almonds compared with potatoes were observed (P = 0.046, P = 0.006, respectively), with potato + herb/spices having intermediate effects.

CONCLUSION

There were no significant differences in FM or in glucoregulatory biomarkers after 30 d of potato consumption compared with almonds. Results do not support a causal relation between increased French fried potato consumption and the negative health outcomes studied. This trial was registered at clinicaltrials.gov as NCT03518515.

Low-Glycemic Index Diets as an Intervention in Metabolic Diseases: A Systematic Review and Meta-Analysis

We aimed to investigate the effects of a low-glycemic index (GI) diet on the body mass and blood glucose of patients with four common metabolic diseases by conducting a systematic review and meta-analysis of studies comparing a low-GI diet (LGID) and other types of diet. Search terms relating to population, intervention, comparator, outcomes, and study design were used to search three databases: PubMed, Embase, and the Cochrane Library. We identified 24 studies involving 2002 participants. Random-effects models were used for 16 studies in the meta-analysis and stratified analyses were performed according to the duration of the intervention. The systematic review showed that LGIDs slightly reduced body mass and body mass index (BMI) (p < 0.05). BMI improved more substantially after interventions of >24 weeks and there was no inter-study heterogeneity (I² = 0%, p = 0.48; mean difference (MD) = -2.02, 95% confidence interval (CI): -3.05, -0.98). Overall, an LGID had superior effects to a control diet on fasting blood glucose (FBG) and glycosylated hemoglobin. When the intervention exceeded 30 days, an LGID reduced FBG more substantially (MD = -0.34, 95% CI: -0.55, -0.12). Thus, for patients with metabolic diseases, an LGID is more effective at controlling body mass and blood glucose than a high-GI or other diet.