This evidence map has identified a large body of epidemiological evidence that evaluated potato intake with cardio-metabolic disease outcomes and categorized outcome data according to the quantified methods of potato intake, as reported in individual studies. Among studies that quantified potato intake, there was an increased risk of type 2 diabetes, weight gain, and SBP, but not for clinical endpoints of CVD and CVD mortality. However, among studies that provided frequency information on potato intake, without specifying the quantity of potatoes consumed, the associations with overall CVD risk factors or outcomes were less conclusive. In studies of dietary pattern or score, dietary patterns that included French fries or potato chips were associated with an increased cardio-metabolic risk or CVD mortality. Notably, such associations were not observed for dietary patterns that contained non-fried types of potatoes (baked or boiled), which emphasizes that the fried types of potato preparations along with associated types of foods consumed with potatoes may increase the cardio-metabolic risk.
The most consistent results from studies that quantified potato intake found that an increased consumption of potatoes was generally related to an increased risk of weight gain and type 2 diabetes. For body weight, two cohorts reported by subgroups of potatoes (such as baked/boiled, fries, or chips) showed unfavorable outcomes, irrespective of the type of potato preparations, and one cohort that reported results for any type of potato also found an unfavorable outcome. This may be attributed to the high content of starches or refined carbohydrates in potatoes as it has been reported that the amount of starches or refined carbohydrates contained in foods was most associated with weight gain rather than other dietary metrics that are currently believed such as fat content or energy density [
12]. Also, potatoes have glycemic index (GI) values in a relatively high range regardless of the cooking method [
13]. For diabetes, most cohorts conducted in the USA reported unfavorable outcomes associated with total potato intake, whereas one study conducted in China and another conducted in Iran reported a favorable outcome for type 2 diabetes. It suggests that the dietary pattern may be of particular importance in evaluation of potato intake and health outcomes, considering that different types of potatoes are consumed in different cultures (e.g., mashed or fried potatoes in Western diet; boiled potatoes in Asian and Mediterranean diets) [
14]. Although potatoes have been condemned as unhealthy due to high carbohydrate content and GI, they are rich in potassium, magnesium, vitamin C, B vitamins, fiber, and polyphenols [
13‐
15], each of which is associated with a decreased risk of chronic disease. However, most often potatoes are not consumed alone [
4] and therefore, it may be more important to assess the effects of potatoes along with the type of diet or dietary patterns rather than assessing the effects of potatoes on outcomes of interest. The different types of potato preparations are often co-consumed with different types of diet [
16,
17]. For example, French fries are commonly served with fast foods (such as burgers and sodas), potato chips as a snack, and baked/boiled potatoes are part of a meal. The differences in co-consumed diets may explain the difference in our evidence mapping results. Further careful evaluations of dietary patterns may help understand the inconsistencies in the results across studies quantified potato intake.
Description of existing literature
Two meta-analyses have been published on the association of potato intake with risk of chronic disease and mortality [
14,
15]. A previous systematic review of 20 prospective cohort studies, which focused on various types of mortality as outcomes, reported no association between total potato intake and risk of all-cause and cancer mortality as well as insufficient evidence accumulated for CVD mortality [
18]. However, another meta-analysis of 28 reports from prospective studies showed that a one daily serving (150 g/d) increase in total potato intake was associated with an 18% (95% CI, 10-27%) increase in risk for type 2 diabetes and 12% (95% CI, 1-23%) increase in risk for hypertension while reporting no association with risk of all-cause mortality, CHD, stroke, and colorectal cancer [
19]. French fries consumption that was specified only in a smaller subset of the included studies showed a stronger positive association with type 2 diabetes (RR, 1.66; 95% CI, 1.43-1.94) and hypertension (RR, 1.37; 95% CI, 1.15-1.63) risks. A meta-analysis of six cohort studies showed that an increase of one daily serving of total potato intake was associated with a 20% (95% CI, 13-27%) increase in risk of type 2 diabetes [
20]. More recently, one large-scale meta-analysis of 185 prospective studies and 58 RCTs was published on the relationship between carbohydrate quality (i.e., dietary fiber, glycemic index/load, and whole-grain intake) and chronic disease outcomes; however, no specific data was available on potato intake [
21].
Strengths and limitations
Increasingly, evidence mapping methods are currently used to identify gaps and topics for future systematic reviews. Our review identified a variety of epidemiological methods used in evaluation of potato intake and chronic disease outcomes. The strengths of our approach include evaluation of different types of observational designs as well as the different types of evaluations (quantity of potato intake versus dietary pattern studies). Our review identified that there are sufficient number of studies available for conducting a future systematic review.
The limitation of evidence mapping includes lack of critical appraisal of individual study quality. Observational studies using food frequency questionnaires are often limited by the participants recall bias. Nonetheless, among eligible studies, there was considerable heterogeneity regarding potato intake; they were consumed as boiled, fried, or both and studies often failed to report subgroup analyses by types of potato preparation. Among studies that quantified potato, only a few cohorts contributed to the majority of the data. This may impact the generalizability to larger populations. Studies that provided intake data in terms of frequency per week intake of potato had incomplete information on the total intake per week or per day, precluding their utilization in future meta-analysis to assess a dose-response relationship. Although we included only observational studies, there was heterogeneity in the way outcome data was reported with some studies reporting results for longitudinal data, while others reported results for cross-sectional or case controls.