Potato consumption and risk of all cause, cancer and cardiovascular mortality: a systematic review and dose-response meta-analysis of prospective cohort studies

Evaluating the Reproducibility and Verifiability of Nutrition Research: A Case Study of Studies Assessing the Relationship Between Potatoes and Colorectal Cancer

Background

The credibility of nutritional research is dependent on the rigor with which studies are conducted and the ability for independent assessment to be performed. Despite the importance of these, more work is needed in the field of nutrition to buttress the trustworthiness of nutrition research.

Objective

To develop and apply a process for evaluating the rigor, reproducibility, and verifiability of nutritional research, using the relationship between potato consumption and Colorectal cancer (CRC) as a case study.

Methods

We updated existing systematic reviews to include studies on potatoes and CRC, assessing their design, execution, and reporting quality. We attempted to reproduce and verify the results of included studies by requesting raw data from authors and following statistical methods as described in the publications. Rigor was evaluated using four different tools: ROBINS-E, STROBE-Nut, Newcastle-Ottawa scale, and additional criteria related to transparency.

Results

Eighteen studies were included, none of which publicly share data. We managed to access data for only two studies, successfully reproducing and verifying the results for one. The majority of studies exhibited a high risk of bias, with significant limitations in reporting quality and methodological rigor.

Conclusions

Research on the relationship between potato consumption and CRC risk is insufficiently reproducible and verifiable, undermining the trustworthiness of its findings. This study highlights the need for improving transparency, data sharing, and methodological rigor in nutritional research. Our approach provides a model for assessing the credibility of research in other areas of nutrition.

Is Starch Intake Associated With Periodontal Status? An 11-Year Longitudinal Analysis Among Finnish Adults

AIM

To evaluate the association between baseline starch intake (amount and sources) and changes in periodontal status over 11 years in adults.

METHODS

Adults aged 30-82 years, who participated in the Finnish Health 2000 survey and were re-examined in 2004/2005 and/or 2011 were included in the study. The consumption of total starch and six relevant food groups (potatoes, fried potatoes, roots and tubers, pasta, wholegrains and legumes) over the past year was determined at baseline with a validated food frequency questionnaire. The number of teeth with periodontal pocketing ≥ 4 mm (NTPP) was recorded during clinical examinations in 2000, 2004/2005 and 2011. The association between baseline starch intake and the 11-year change in the NTPP was tested in mixed-effects negative binomial regression models, adjusting for covariates.

RESULTS

A total of 1369 adults were included in the analysis. The mean NTPP was 4.1 ± 5.6, 6.3 ± 5.6, and 4.8 ± 5.9 in waves 1, 2 and 3, respectively. Baseline starch intake (in g/day or % energy intake) was not associated with changes in the NTPP after adjustment for covariates. In analysis by food groups, the baseline intake of wholegrains was negatively associated with the NTPP at baseline.

CONCLUSION

This study found no evidence of an association between baseline starch intake and changes in periodontal status. Baseline intake of wholegrains was associated with better periodontal status at baseline.

Potato Consumption and All-Cause and Cardiovascular Disease Mortality - A Long-Term Follow-Up of a Norwegian Cohort

BACKGROUND

Potatoes are a staple food in many traditional cuisines, yet their impact on long-term risk of cardiovascular disease (CVD) and mortality is unclear, hampering evidence-based dietary guidelines.

OBJECTIVES

This study aimed to examine the association between potato consumption and all-cause and CVD-specific death over a substantial follow-up period within a cohort predominantly consuming boiled potatoes.

METHODS

Adults from 3 Norwegian counties were invited to 3 health screenings in 1974-1988 (>80% attendance). Dietary data were collected using semiquantitative food frequency questionnaires at each screening to categorize weekly potato consumption (≤6, 7-13, or ≥14 potatoes/wk) and calculate daily cumulative mean intakes (grams/day). Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariable Cox regression to estimate HRs and 95% CIs for the association between potato consumption and risk of death from all causes, CVD, ischemic heart disease (IHD), and acute myocardial infarction (AMI).

RESULTS

Among 77,297 participants with a mean baseline age of 41.1 y (range: 18.0-63.9 y), we observed 27,848 deaths, including 9072 deaths due to CVD, over a median follow-up of 33.5 y. Participants who consumed ≥14 potatoes/wk had a lower risk of all-cause death compared with those consuming ≤6 potatoes/wk (HR: 0.88; 95% CI: 0.84, 0.93). Potato consumption was associated with a minor, inverse risk of death due to CVD, IHD, and AMI. In continuous analyses of cumulative intakes, each 100 g/d increment was associated with 4% lower risk of death from all causes (HR: 0.96; 95% CI: 0.94, 0.98), CVD (HR: 0.96; 95% CI: 0.93, 0.99), IHD (HR: 0.96; 95% CI: 0.91, 1.00), and AMI (HR: 0.96, 95% CI: 0.91, 1.01).

CONCLUSIONS

In this cohort with a generally high consumption of predominantly boiled potatoes, we find modest, inverse associations between potato consumption and death from all causes, CVD, and IHD.

Potatoes - a scoping review for Nordic Nutrition Recommendations 2023

Potatoes comprise a common staple food in the Nordic and Baltic countries and contribute to the diet with vitamins, minerals, dietary fibre and phytochemicals. However, potatoes may also be consumed in processed forms with added fat and salt, which raises concerns about possible adverse health effects. The aim of this scoping review is to describe the overall evidence for the role of potatoes as a basis for setting and updating food-based dietary guidelines in the Nordic Nutrition Recommendations 2023. PubMed was searched for systematic reviews and meta-analyses, and evidence was extracted on relevant health outcomes. Current available evidence indicates that moderate consumption of potatoes is not associated with a substantial risk of chronic diseases, and that they may be part of a healthy diet. However, the health effects vary greatly depending on cooking methods, and studies indicate that the intake of French fries/fried potatoes should be limited. Overall, the evidence regarding health effects of potatoes is very limited, and possible associations need to be further investigated.

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.

Healthy and Unhealthy Plant-Based Diets and Glioma in the Chinese Population

Plant-based diets have been suggested to help prevent various chronic diseases, including cancer. However, there are few reports on central nervous system tumors, and data on dose-response relationships are lacking. This individual-matched case-control study included 506 cases and 506 controls. The overall plant-based diet index (PDI), the healthy plant-based diet index (hPDI), and the unhealthy plant-based diet index (uPDI) were calculated using dietary information collected through a food frequency questionnaire, with higher scores indicating better adherence. We analyzed the relationship of plant-based diets with glioma. After adequate adjustment for confounders, PDI was associated with a reduced glioma risk (OR = 0.42, 95% CI: 0.24-0.72). Conversely, uPDI was associated with an elevated glioma risk (OR = 8.04, 95% CI: 4.15-15.60). However, hPDI was not significantly associated with glioma risk (OR = 0.83, 95% CI: 0.48-1.45). For subgroups, PDI was not significant in analyzing young age, BMI, or any pathological subtypes. The restricted cubic spline function showed a significant dose-response relationship between PDI (p-nonlinearity< 0.0001) and uPDI (p-nonlinearity= 0.0711) and glioma. Further analysis found that refined grains had the greatest effect on gliomas in the less healthy plant-based food group. Therefore, following a plant-based diet was linked to a lower risk of glioma, especially when consuming fewer unhealthy plant-based foods.

The healthful plant-based diet index as a tool for obesity prevention-The healthy lifestyle community program cohort 3 study

Background

World-wide the prevalence of obesity is high, and promoting a shift toward more healthful and more plant-based dietary patterns appears to be one promising strategy to address this issue. A dietary score to assess adherence to a healthy plant-based diet is the healthful plant-based diet index. While there is evidence from cohort studies that an increased healthful plant-based diet index is associated with improved risk markers, evidence from intervention studies is still lacking.

Methods

A lifestyle intervention was conducted with mostly middle-aged and elderly participants from the general population (n = 115). The intervention consisted of a 16-month lifestyle program focusing on a healthy plant-based diet, physical activity, stress management, and community support.

Results

After 10 weeks, significant improvements were seen in dietary quality, body weight, body mass index, waist circumference, total cholesterol, measured and calculated low-density lipoprotein (LDL) cholesterol, oxidized LDL particles, non-high-density lipoprotein cholesterol, remnant cholesterol, glucose, insulin, blood pressure, and pulse pressure. After 16 months, significant decreases were seen in body weight (-1.8 kg), body mass index (-0.6 kg/m2), and measured LDL cholesterol (-12 mg/dl). Increases in the healthful plant-based diet index were associated with risk marker improvements.

Conclusions

The recommendation of moving toward a plant-based diet appears acceptable and actionable and may improve body weight. The healthful plant-based diet index can be a useful parameter for intervention studies.

Starch intake, amylase gene copy number variation, plasma proteins, and risk of cardiovascular disease and mortality

BACKGROUND

Salivary amylase, encoded by the AMY1 gene, initiate the digestion of starch. Whether starch intake or AMY1 copy number is related to disease risk is currently rather unknown. The aim was to investigate the association between starch intake and AMY1 copy number and risk of cardiovascular disease (CVD) and mortality and whether there is an interaction. In addition, we aim to identify CVD-related plasma proteins associated with starch intake and AMY1 copy number.

METHODS

This prospective cohort study used data from 21,268 participants from the Malmö Diet and Cancer Study. Dietary data were collected through a modified diet history method and incident CVD and mortality were ascertained through registers. AMY1 gene copy number was determined by droplet digital polymerase chain reaction, a risk score of 10 genetic variants in AMY1 was measured, and a total of 88 selected CVD-related proteins were measured. Cox proportional hazards regression was used to analyze the associations of starch intake and AMY1 copy number with disease risk. Linear regression was used to identify plasma proteins associated with starch intake and AMY1 copy number.

RESULTS

Over a median of 23 years' follow-up, 4443 individuals developed CVD event and 8125 died. After adjusting for potential confounders, a U-shape association between starch intake and risk of CVD (P-nonlinearity = 0.001) and all-cause mortality (P-nonlinearity = 0.03) was observed. No significant association was found between AMY1 copy number and risk of CVD and mortality, and there were no interactions between starch intake and AMY1 copy number (P interaction > 0.23). Among the 88 plasma proteins, adrenomedullin, interleukin-1 receptor antagonist protein, fatty acid-binding protein, leptin, and C-C motif chemokine 20 were associated with starch intake after adjusting for multiple testing.

CONCLUSIONS

In this large prospective study among Swedish adults, a U-shaped association between starch intake and risk of CVD and all-cause mortality was found. Several plasma proteins were identified which might provide information on potential pathways for such association. AMY1 copy number was not associated with CVD risk or any of the plasma proteins, and there was no interaction between starch intake and AMY1 copy number on disease risk.

Low-Energy Dense Potato- and Bean-Based Diets Reduce Body Weight and Insulin Resistance: A Randomized, Feeding, Equivalence Trial

We evaluated the effect of diets low in energy density (1 kcal/g) and high in either potatoes (Potato) or pulses (Bean) on blood glucose control in participants with insulin resistance. We hypothesized that the Potato and Bean diets would have equivalent effects. This was an 8-week randomized, parallel design, controlled feeding study comparing Potato and Bean diets (50-55% carbohydrate, 30-35% fat, 15-20% protein). Equivalence was prespecified as the mean change in the blood glucose concentration for Potato that was within ±20% of the Bean diet. Thirty-six participants (age: 18-60 years, body mass index: 25-40 kg/m2) with insulin resistance (homeostatic model assessment of insulin resistance [HOMA-IR] >2) were enrolled. Body weight was measured, and subjects underwent a mixed meal tolerance test at baseline and after 8 weeks. Intent-to-treat (ITT) and completer analyses were conducted. Equivalence between the two diets in the area under the curve for serum glucose was attained within ±10%, but the reduction from baseline was not statistically significant. For the Bean diet, insulin (area under the response curve: -2136.3 ± 955.5 mg/[dL∙min], P = .03) and HOMA-IR (-1.4 ± 0.6, P = .02) were lower compared with baseline. ITT and completer analyses were similar, except that HOMA-IR was also reduced by the Potato diet (-1.3 ± 0.6, P < .05). Compliance with the diets was 87-88%, and body weight was reduced in both diets (Potato: -5.6% ± 0.6%; Bean: -4.1% ± 0.6%, P < .001) with no significant difference between the two diets. Potato and Bean diets low in energy density were equally effective in reducing insulin resistance and promoting weight loss in individuals with impaired blood glucose control. Clinical Trial: The trial was registered with ClinicalTrials.gov Identifier: NCT04203238.

Potato Consumption and Risk of Cardiovascular Mortality and Type 2 Diabetes After Myocardial Infarction: A Prospective Analysis in the Alpha Omega Cohort

Background

Higher potato intake, especially French fries, was unfavorably associated with cardiometabolic endpoints in population-based studies. Little is known about this in patients with ischemic heart disease (IHD).

Objective

Total and boiled potatoes and French fries intake were examined in relation to cardiovascular disease (CVD) mortality, all-cause mortality, and type 2 diabetes mellitus (T2DM) risk in Dutch post-myocardial infarction (MI) patients of the Alpha Omega Cohort.

Methods

We analyzed 3,401 patients (60–80 years, 78% male), free from T2DM at baseline, with an MI ≤ 10 years before enrolment. Diet was assessed at baseline (2002–2006) using a 203-item validated Food Frequency Questionnaire (FFQ) that includes potato preparation methods. Cause-specific mortality was monitored through December 2018, and T2DM incidence (self-reported physician diagnosis and/or prescribed anti-diabetes medication) was monitored during the first 40 months of follow-up. Multivariable Cox models were used to obtain hazard ratios (HRs) for fatal endpoints and incident T2DM in tertiles of potato intake.

Results

Patients had a median total potato intake (mainly boiled) of 111 g/d, 96% consumed >1 serving (200 g) per week. French fries were consumed by 48% of the patients (median of 6 g/d among consumers). During >12 years of follow-up (38,987 person-years), 1,476 deaths occurred of which 641 were from CVD, 394 were from IHD, and 119 were from a stroke. Total and boiled potatoes were not associated with CVD mortality, but a higher risk of all-cause mortality was observed (HR: 1.07; 95% CI: 1.01, 1.14; per 50 g/d). Potato consumption tended to be positively associated with incident T2DM (186 cases; HR: 1.11, 95% CI: 0.94, 1.32; per 50 g/d). Results for French fries were inconsistent for all outcomes.

Conclusion

In Dutch post-MI patients, potatoes (mainly boiled) were not associated with CVD mortality but possibly adversely associated with all-cause mortality and T2DM risk. These findings warrant confirmation in other IHD patient cohorts. The Alpha Omega Cohort is registered at ClinicalTrials.gov as NCT03192410.

Frequency of Boiled Potato Consumption and All-Cause and Cardiovascular Disease Mortality in the Prospective Population-Based HUNT Study

Few studies have assessed the association between potato consumption and mortality, especially cardiovascular disease (CVD) mortality. Our objective was to investigate the association between consumption of boiled potatoes and all-cause and CVD mortality in a Norwegian population. We used data from the population based HUNT3 study in Norway, with data on boiled potato consumption frequency in 2006–2008 from 49,926 males and females aged 20 years or above. All-cause and CVD mortality were identified during 10 years follow-up through the national Cause of Death Registry, which is virtually complete. We used Cox regression to estimate hazard ratio (HR) with a 95% confidence interval (CI) for death controlling for potential confounders, and conducted additional analyses stratified by sex, body mass index (BMI) ±25 kg/m², and age ±65 years. There were 4,084 deaths and 1,284 of these were due to CVD. Frequency of boiled potato consumption was not associated with all-cause mortality, nor with CVD mortality. Compared to those individuals who consumed boiled potatoes less than once weekly, those who reported to consume boiled potatoes 1–3 times per week had an adjusted HR (95% CI) of 1.12 (0.89, 1.41) for all-cause mortality and 1.20 (0.78, 1.86) for CVD mortality. Individuals who consumed boiled potatoes 4–6 times per week had HRs of 0.97 (0.78, 1.21) and 1.03 (0.68, 1.55), for all-cause and CVD mortality, respectively, whereas those who consumed boiled potatoes more than once daily had HRs of 1.04 (0.83, 1.29) and 1.09 (0.73, 1.63) for all-cause and CVD mortality, respectively. There was no evidence of differential associations for males vs. females, nor between people with BMI ± 25 kg/m². The associations between frequency of boiled potato consumption and all-cause mortality showed different patterns between those younger vs. older than 65 years, with a tendency of increased risk only in the oldest age group. In conclusion, frequency of consumption of boiled potatoes was not associated with all-cause or CVD mortality in the HUNT population in Norway.

Potato consumption and risk of cardio-metabolic diseases: evidence mapping of observational studies

BACKGROUND

Recent systematic review of clinical trials concluded that there was no convincing evidence to suggest an association between potatoes and risk of cardio-metabolic diseases.

OBJECTIVE

Summarize observational study data related to potato intake and cardio-metabolic health outcomes in adults using evidence mapping to assess the need for a future systematic review.

METHODS

We searched MEDLINE®, Commonwealth Agricultural Bureau, and bibliographies for eligible observational studies published between 1946 and July 2020. Included studies evaluated potato intake in any form or as part of a dietary pattern with risk for cardio-metabolic diseases. Outcomes of interest included cardiovascular disease (CVD), cerebrovascular diseases, diabetes, hypertension, blood lipids, and body composition.

RESULTS

Of 121 eligible studies, 51 reported two different methods to quantify potato intake (30 studies quantified intake as either grams or serving; 20 studies reported times per week; one reported both methods) and 70 reported potato as part of a dietary pattern and compared higher vs. lower intake, linear change, or difference in potato intake among cases and controls. Studies that quantified potato intake as either grams or serving reported the following outcomes: diabetes (8 studies); cerebrovascular stroke (6 studies); five studies each for CVD, systolic and diastolic blood pressure, and hypertension; three studies each for body mass index, body weight, CVD mortality; two studies for myocardial infarction; and one study each for blood glucose, HOMA-IR, and blood lipids. Higher potato intake was associated with an increased risk for blood pressure and body weight, and the results of all other outcomes observed no association. Potato consumption as part of dietary pattern studies reported a negative association between fried form of potato and all or most cardio-metabolic risk factors and diseases.

CONCLUSION

Evidence mapping found sufficient data on the association between potato intake and cardio-metabolic disease risk factors to warrant for a systematic review/meta-analysis of observational studies.

Processed potatoes intake and risk of type 2 diabetes: a systematic review and meta-analysis of nine prospective cohort studies

The current cohort study shows the inconsistent association between potato consumption and the risk of type 2 diabetes mellitus (T2DM). Therefore, we conducted a systematic review and dose-response meta-analysis of published prospective cohort studies to quantitatively estimate this association. We searched PubMed, Embase, MEDLINE, Web of Knowledge, and the Cochrane Library up to September 2019 for all published articles. Seven of the articles reported nine cohort studies with 383,211 participants, with 23,189 T2DM cases that met the inclusion criteria and were included for our analysis. The results of random effects model pooled relative risk (RR) showed an association between potato intake and the risk of T2DM (pooled RR = 1.13, 95% CI: 1.02-1.26, p > 0.01). In the subgroup analysis, French fries, long-term follow-up, large sample size, and high-quality studies were associated with an increased T2DM risk. Further, a linear dose-response analysis indicated that 100 g/day increment of total potato (RR = 1.05, 95% CI: 1.02-1.08) and French fries (RR = 1.10, 95% CI: 1.07-1.14) consumption may increase the risk of T2DM by 5% and 10%, respectively. Our meta-analysis showed that potato consumption, especially French fries consumption, was associated with increased T2DM risk.

The association of food quality score and cardiovascular diseases risk factors among women: A cross-sectional study

Introduction: Limited studies are available regarding the relationship between Food Quality Score (FQS) and cardiovascular disease (CVD) risk factors. Thus, this study was aimed to investigate the association of FQS with CVD risk factors in women.

Methods: This cross-sectional study was carried out among 368 women aged 20-50 years who randomly selected from health centers across Tehran, Iran. Dietary intake was collected using a reliable and validated food frequency questionnaire (FFQ). The FQS includes vegetables, fruits, whole grains, yogurt, nuts and legumes, coffee, refined grains, desserts and ice cream, sugar-sweetened beverages, red meats, fried food consumed outside the home, processed meats, potato and potato chips. Standard methods were used to assess blood pressure, biochemical and anthropometric measures. Multivariate logistic regression was used to examine the association between FQS and CVD risk factors.

Results: Participant mean age and body mass index (BMI) were 30.7 ± 6.9 years and 24.3 ± 4.0 kg/m2, respectively. After taking potential confounders into account, FQS had no significant association with risk of overweight and obesity [Odds ratio (OR): 1.1, 95% confidence interval (CI): 0.68, 1.8; P = 0.683], diabetes (OR: 0.62, 95% CI: 0.22, 1.74; P = 0.374), metabolic syndrome (OR: 0.36, 95% CI: 0.10, 1.32; P = 0.127), hypercholesterolemia (OR: 0.54, 95% CI: 0.29, 1.01; P= 0.051), or hypertriglyceridemia (OR: 1.63, 95% CI: 0.71, 3.70; P = 0.244).

Conclusion: The results showed that FQS was not significantly associated with CVD risk factors among women. Prospective cohort studies are warranted to confirm our findings.

Potato consumption and the risk of overall and cause specific mortality in the NIH-AARP study

BACKGROUND

Potato consumption has been hypothesized to be associated with higher risk of hypertension, diabetes, and colorectal cancer.

OBJECTIVE

The aim of this study was to examine the association between potato consumption and the risk of overall and cause specific mortality in the large prospective National Institutes of Health-AARP (NIH-AARP) Study.

DESIGN

The NIH-AARP study recruited 566,407 persons, aged 50-72 years in 1995-1996. We excluded subjects that reported a history of chronic disease at baseline. Potato consumption data from a validated food frequency questionnaire completed at baseline was used in Cox proportional hazard models to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for overall and cause specific mortality. Final models were adjusted for potential risk factors for mortality.

RESULTS

Among 410,701 participants included in this analysis, 76,921 persons died during the 15.6 years of follow-up. Eating baked, boiled, or mashed potatoes, French fries or potato salad seven or more times per week was associated with higher risk of overall mortality, in models adjusted only for age and sex (HR C4 vs C1 = 1.17, 95%CI = 1.13, 1.21). These results were attenuated in fully adjusted models (HR C4 vs C1 = 1.02, 95%CI = 0.97, 1.06). Potato consumption was not associated with risk of mortality caused by cancer (HR C4 vs C1 = 1.04, 95%CI = 0.97, 1.11), heart disease (HR C4 vs C1 = 1.00, 95%CI = 0.93, 1.09), respiratory disease (HR C4 vs C1 = 1.16, 95%CI = 0.99, 1.37), or diabetes (HR C4 vs C1 = 0.91, 95%CI = 0.71, 1.19). We tested for an association with different preparation methods and found limited evidence for differences by preparation method. The only statistically significant association was that for French fry consumption with cancer-related mortality (HR C4 vs C1 = 1.27, 95%CI = 1.02, 1.59), a finding for which uncontrolled confounding could not be ruled out.

CONCLUSION

We find little evidence that potato consumption is associated with all-cause or cause-specific mortality.