Potatoes are one of the world’s most popular food crops.
They are commonly eaten as a snack or fast food, such as potato chips or French fries, which are undoubtedly unhealthy in large amounts. But are boiled or baked potatoes also unhealthy?
Recently, a team of Danish researchers conducted a meta-analysis of studies examining the association of potatoes with obesity and diabetes. Below is a detailed summary of its findings.
Potatoes are a major staple in the Western diet.
They are mainly composed of starch, which makes up 9–23% of their raw weight (1).
Starch is a complex carb composed of chains of glucose molecules. It is easily digested and may cause spikes in blood sugar levels when eaten on its own.
Foods like potatoes generally rank high on the glycemic index, which is a measure of how much a particular food increases your blood sugar level (2).
This was a systematic review and meta-analysis of studies examining whether eating potatoes raises the risk of obesity, type 2 diabetes or heart disease.
This was a systematic review and meta-analysis of studies investigating whether potatoes cause obesity, type 2 diabetes or heart disease in healthy adults.
The researchers searched for all relevant articles using several major electronic databases.
The inclusion criteria included the following:
- The study had to include adults aged 18 or older.
- The participants had to be free of diabetes or heart disease.
- Intervention studies had to use white or yellow potatoes.
- Intervention studies had to compare potatoes with other sources of carbs.
- Single-meal studies were excluded.
Bottom Line: This was a systematic review and meta-analysis of studies examining the effects of potatoes on weight gain, obesity, type 2 diabetes and heart disease.
The Selected Studies
A total 103 articles were fully assessed, but only 13 met all of the inclusion criteria. Below are summaries of the included studies, all of which were prospective observational studies.
Mozaffarian D, et al. Changes in diet and lifestyle and long-term weight gain in women and men. New England Journal of Medicine, 2011.
This large prospective observational study in American adults showed that eating 1 serving of potatoes (all types combined) daily was linked with a slight weight gain (1.28 lbs) over a 4-year period.
The study also showed that French fries were associated with the most weight gain (3.35 lbs), whereas boiled, baked or mashed potatoes were much less fattening.
Halkjær J, et al. Dietary predictors of 5-year changes in waist circumference.Journal of the American Dietetic Association, 2009.
Each 60 calorie-per-day increase in potato consumption was linked with a 0.1 cm increase in waist circumference in women over a 5-year period. This association was not statistically significant in men.
French SA, et al. Predictors of weight change over two years among a population of working adults: the Healthy Worker Project. International Journal of Obesity and Related Metabolic Disorders, 1994.
High intakes of French fries were significantly associated with weight gain in women.
Halkjær J, et al. Food and drinking patterns as predictors of 6-year BMI-adjusted changes in waist circumference. British Journal of Nutrition, 2004.
This study found no significant links between eating potatoes and waist circumference.
Linde JA, et al. Specific food intake, fat and fiber intake, and behavioral correlates of BMI among overweight and obese members of a managed care organization. International Journal of Behavioral Nutrition and Physical Activity, 2006.
This study found no significant association between total potato consumption and body mass index (BMI). However, when French fries were examined separately, they were significantly associated with a higher BMI.
Halton TL, et al. Potato and french fry consumption and risk of type 2 diabetes in women. American Journal of Clinical Nutrition, 2006.
Eating potatoes was linked with an increased risk of type 2 diabetes in American women. However, this only applied to obese participants with a body mass index (BMI) higher than 30.
In contrast, French fry consumption increased the risk of type 2 diabetes irrespective of people’s BMI.
Salmerón J, et al. Dietary fiber, glycemic load, and risk of non-insulin-dependent diabetes mellitus in women. The Journal of the American Medical Association, 1997.
A high intake of potatoes was linked with an increased risk of type 2 diabetes.
Villegas R, et al. Prospective study of dietary carbohydrates, glycemic index, glycemic load, and incidence of type 2 diabetes mellitus in middle-aged Chinese women. Archives of Internal Medicine, 2007.
Eating a lot of potatoes was linked with a decreased risk of type 2 diabetes in middle-aged Chinese women.
Salmerón J, et al. Dietary fiber, glycemic load, and risk of NIDDM in men.Diabetes Care, 1997.
High consumption of potatoes was not associated with an increased risk of type 2 diabetes in American men when French fries were excluded.
However, when French fries were examined separately, they were found to be significantly linked with an increased risk of type 2 diabetes.
Liu S, et al. A prospective study of fruit and vegetable intake and the risk of type 2 diabetes in women. Diabetes Care, 2004.
Potato consumption was not significantly associated with the risk of type 2 diabetes in women.
Hodge AM, et al. Glycemic index and dietary fiber and the risk of type 2 diabetes. Diabetes Care, 2004.
Total potato consumption was not significantly linked with the risk of type 2 diabetes in men and women.
Feskens EJM, et al. Dietary factors determining diabetes and impaired glucose tolerance. Diabetes Care, 1995.
This prospective observational study had a 20-year follow-up. It found that higher intakes of potatoes were associated with lower 2-hour blood sugar levels.
Joshipura KJ, et al. Fruit and vegetable intake in relation to risk of ischemic stroke. The Journal of the American Medical Association, 1999.
This study in American adults that were followed for 8–14 years found no significant links between potatoes and ischemic stroke.
Finding 1: Potatoes Were Not Consistently Associated with Obesity
Five observational studies examining the association of potatoes with weight gain or obesity were selected.
They included a total of 170,413 participants and had follow-ups ranging from 2 to 20 years.
This is probably because French fries are high in unhealthy fat and associated with fast food and unhealthy dietary habits (8).
Bottom Line: Observational studies examining the association of potatoes with body weight have provided mixed results.
Finding 2: Potatoes Were Not Consistently Linked with Diabetes
Seven of the included studies examined the association of potatoes with type 2 diabetes (T2D). They included a total of 326,675 participants.
Their results were mixed. Two studies in American women linked high total potato consumption with an increased risk of T2D (9, 10), whereas other studies suggested that potatoes may protect against T2D (11, 12).
This is likely because French fries are high in unhealthy fat. Additionally, those who eat a lot of them are generally less health-conscious.
Bottom Line: Observational studies examining the association of potatoes with the risk of type 2 diabetes have provided inconsistent results.
Finding 3: Potatoes Were Not Associated with Heart Disease
The researchers included only one study investigating the association of potatoes with heart disease.
This prospective observational study consisted of two large cohorts, including a total of 114,276 participants who were followed for 8–14 years (14).
Eating potatoes was not significantly linked with an increased risk of ischemic stroke.
Bottom Line: Potatoes were not significantly linked with an increased risk of heart disease.
Although this meta-analysis didn’t have any apparent faults, the conclusions were based on weak evidence.
No long-term randomized controlled trials met the inclusion criteria, and all of the included studies were observational.
Summary and Real-Life Application
This study showed that potatoes are not consistently linked with an increased risk of weight gain, obesity, type 2 diabetes or heart disease in apparently healthy people.
However, most studies suggest that eating a lot of French fries may increase the risk of chronic disease.
Since all of the studies had an observational design, the true association of potatoes with obesity, type 2 diabetes and heart disease remains unclear.
Well-designed, long-term randomized controlled trials are needed before any solid conclusions can be reached.