Is eating potatoes good for longevity? How to eat them to be healthy?

People often complain about rising food prices, but potatoes always seem to be one of the cheapest ingredients.

In terms of cost-effectiveness, few foods are as low-key as potatoes. Known as the “underground apple” and “the second bread,” potatoes are the fourth largest food crop in the world after corn, rice, and wheat[1], with more than 1 billion fans worldwide!

Potatoes can be said to be a crossover ingredient between vegetables and staple foods. Compared with various grains that provide carbohydrates, they have a high water content and low fat and energy density[2]. They are also rich in potassium, vitamin B, vitamin C, dietary fiber, and antioxidants, which are beneficial for controlling blood pressure and preventing scurvy[3].

However, people are also concerned that, as a vegetable, potatoes contain a lot of starch and have a high glycemic index (GI) after being cooked. Some foreign surveys and studies have found that eating large amounts of potatoes may pose health risks to people with obesity, diabetes, and cardiovascular disease [3].

Maybe you are a little confused:

So, is eating potatoes good or bad?

Besides, there are many ways to process and cook potatoes, such as French fries, stir-fried potato shreds, steamed potatoes, boiled potatoes, mashed potatoes... Which way is the healthiest?

(If you don’t have the patience to understand the detailed scientific evidence, you can focus on the bolded parts and the conclusion at the end of the article.)

Let’s first look at a group of epidemiological studies conducted in Western countries.

Data show that there is a high correlation between total potato intake and the risk of type 2 diabetes and colorectal cancer [5-7]. However, a systematic review of 13 clinical intervention studies found that there is still a lack of credible evidence for the correlation between potato intake and the risk of obesity and cardiovascular disease [8]. A study based on the Spanish population found that potato consumption in the elderly was not associated with the risk of hypertension [9]; a 13-year follow-up study of Swedish adults also found that total potato intake was not associated with the risk of cardiovascular events [10].

However, current research results on the relationship between potato intake and all-cause mortality are inconsistent: one study found that eating fried potatoes twice a week was positively correlated with all-cause mortality in a dose-dependent manner; while no significant association was observed between potato intake and all-cause mortality in North America and the Mediterranean region [11].

By the way, the so-called all-cause mortality rate includes all deaths due to health problems except accidents. Within a certain period of time, if the proportion of deaths due to illness among the same group of people who eat potatoes is higher than that of those who do not eat potatoes, and the more they eat, the higher the death rate, then it is speculated that eating potatoes may be detrimental to health and longevity.

Simply put: Studies conducted in Europe and the United States have found that eating potatoes may increase the risk of type 2 diabetes and colorectal cancer, but whether it will increase obesity, high blood pressure, cardiovascular risk and all-cause mortality risk has not yet been determined. But at least no benefits have been found in these aspects from eating more potatoes.

However, since the respondents of the above studies are basically residents of European and American countries, and there are differences between Eastern and Western people in dietary patterns and cooking methods, these conclusions may not necessarily apply to Chinese people.

The good news is that an article recently published in Nutrition magazine by Chinese scholars[12] suggests that, at least in China, eating potatoes is not harmful to health.

This study conducted nine dietary surveys on 14,117 Chinese residents aged 20 and above, including 7,623 women and 6,494 men, between 1989 and 2011. The dietary survey used weighing and 24-hour recall methods to collect family and individual food intake information, and analyzed the relationship between food intake and all-cause mortality risk over 12 years based on data from the civil affairs system.

Although the data from the nine dietary surveys may not represent the eating habits of all days in the 12 years, they are representative to a certain extent. Considering that this is a study conducted by Chinese people, the varieties and eating habits of potatoes are consistent with the actual situation in China, and the results are worth referring to.

Researchers found that, in general, Chinese people still love to eat potatoes. Only 42.5% of people basically do not eat potatoes, which is less than half. One of the highlights of the study is the classification and statistics of potato cooking methods. Stir-frying and deep-frying are classified as cooking with oil (fried potato), and steaming and boiling are classified as cooking without oil (non-fried potato).

The researchers divided potato eating into four categories: not eating at all, eating a small amount (≤26.7 grams per day), eating a moderate amount (26.7-66.7 grams), and eating a lot (≥66.7 grams).

The intake of potatoes cooked without oil was also divided into four levels: not eating at all, eating a small amount (≤16.7 grams per day), eating a moderate amount (16.7-44.4 grams), and eating a lot (≥44.4 grams).

Compared with those who did not eat potatoes, those who ate potatoes in small and moderate amounts had a 53% and 39% lower risk of death over 12 years, respectively. Potatoes cooked with oil were still beneficial when eaten in small or moderate amounts. However, if the amount of potatoes eaten was increased, the benefit of reducing the risk of death was gone, but it did not increase the risk of death.

This shows that eating potatoes is more beneficial than harmful to Chinese people. If potatoes are used to partially replace the same amount of white rice, they can provide less calories, fat and carbohydrates, and more dietary fiber, vitamin C and vitamin B6[13].

Fan Zhihong said: According to my personal understanding, replacing rice with a small amount of potatoes can not only increase vitamin C, vitamin B1, vitamin B2 and vitamin B6, but also increase dietary fiber and potassium.

Even eating it as a stir-fry or stew is good, because for Chinese people, insufficient potassium intake, excessive sodium intake, and insufficient dietary fiber are common problems. Potatoes are the cheapest high-potassium food, and they have soft dietary fiber and some resistant starch, which may help prevent the risk of diseases such as stroke. China has 2 million deaths from stroke each year...

So why do some studies find that potato intake in Western countries is positively correlated with all-cause mortality? The reason may be due to differences in cooking methods.

The Chinese people's favorite potato dishes cooked with oil are usually fried potato slices and fried potato shreds. Although oil is needed for fried potatoes, the proportion of saturated fat in the cooking oil used by Chinese people on a daily basis is relatively low. In addition, because the potato shreds are relatively crispy and the cooking time is short, they also provide more resistant starch and retain all dietary fiber. In particular, cooking with vinegar is beneficial for maintaining VC and lowering GI value. Therefore, if you reduce the amount of rice appropriately, enjoying half a plate of spicy and sour fried potato shreds may still have more benefits than disadvantages. Of course, even so, you still need to be careful not to put too much salt and oil when cooking potato shreds.

However, Westerners often eat French fries and potato chips. Due to the high temperature during frying, 75% of the fat will be absorbed by the potatoes within 1 to 4 minutes[14]. In addition, fast food restaurants usually fry the French fries repeatedly to keep them crispy.

Therefore, Westerners consume more fat when eating fried potatoes than when they stir-fry potatoes, and frying oil contains high levels of saturated fat. In addition, the high temperature during the frying process will destroy the vitamins and antioxidants in potatoes, produce harmful substances such as acrylamide, heterocyclic amines, and trans fatty acids[14], and reduce their nutritional value.

In addition, studies have shown that potatoes can retain most of their vitamin C during oil-free cooking processes such as baking, boiling, and microwave heating[19]. Moreover, when compared based on the same calorie content, plain potatoes are more filling than ordinary white rice and white flour foods. If you use steamed or baked potatoes without oil or salt to replace part of the rice and steamed bread, it will not actually increase your dietary calorie intake.

Potatoes cooked to a soft state contain starch that is very easy to digest, which is beneficial for people with poor digestion and absorption. However, since French fries and mashed potatoes are made from the most easily digestible and softest potato varieties, their GI value will be very high after being cooked to a soft state, which is not suitable for people with diabetes, hypertension, or those who are trying to lose weight [5, 17, 18].

If potatoes are paired with meat containing a lot of fat, such as potatoes stewed with pork belly or potatoes stewed with beef brisket, the potatoes will fully absorb the fat stewed from the meat, and it will be even less suitable for people who are losing weight to eat as a dish.

It is recommended that patients with chronic diseases or people who want to lose weight use baked or steamed potatoes to replace some of the rice and steamed buns, or mix potatoes with other foods. On the premise of ensuring food safety, cold shredded potatoes are a good way to eat them. After steaming the potatoes, adding vinegar and other seasonings to mix is ​​also good. Research data shows that adding vinegar to boiled potatoes can reduce the GI value by 43%.

Recent research in our laboratory has also found that the GI value of potatoes can vary greatly when they are heated in different states. The same potato has a GI value of 83 when it is soft, but only 52 when it is crispy.

To sum up, we can draw the following inferences about eating potatoes healthily:

1. Overall, for Chinese residents, eating potatoes in moderation has more benefits than disadvantages.

2. If you want potatoes to help you lose weight and reduce fat, you should replace the same amount of white rice with original steamed potatoes or boiled potatoes. This will get you more dietary fiber, potassium, VC and multiple B vitamins without increasing your calorie and fat intake.

3. In addition to staple foods, eating a small amount of potato dishes cooked with a small amount of oil is still good for health, but if the amount eaten is too large, it cannot be guaranteed to be helpful to health.

4. Potatoes are a food that easily absorbs fat. When fried, they quickly absorb frying oil, and when stewed, they absorb the fat released by meat. Eating a large amount of potatoes that have absorbed fat in addition to staple foods is not good for weight loss, blood sugar control, and blood lipid control.

5. Try not to fry potatoes, as this will increase calories and fat, destroy antioxidants, and produce acrylamide, a suspected carcinogen. Baking with skin, boiling, or microwave heating can preserve more nutrients.

6. Soft potatoes have a high GI value, but crisp potatoes have a significantly lower GI value. Diabetic and hypertensive patients can choose crispy fried potatoes, or add vinegar and other condiments to cold potatoes to lower the GI value and delay the rise of blood sugar.

In short, potatoes are good things in themselves. Whether they are healthy or not, and whether they will make you gain weight and raise your blood sugar, depends on how you eat them. If you eat them wrong and gain weight, don’t blame the potatoes!

References:

[1] King JC, Slavin J L. White potatoes, human health, and dietary guidance.[J]. Advances in Nutrition (Bethesda, Md.), 2013,4(3): 393S-401S.

[2] Anderson GH, Soeandy CD, Smith C E. White vegetables: glycemia and satiety.[J]. Advances in Nutrition (Bethesda, Md.), 2013,4(3): 356S-67S.

[3] Camire ME, Kubow S, Donnelly D J. Potatoes and Human Health[J]. Critical Reviews in Food Science and Nutrition, 2009,49(10): 823-840.

[4] McGill CR, Kurilich AC, Davignon J. The role of potatoes and potato components in cardiometabolic health: a review.[J]. Annals of Medicine, 2013,45(7): 467-73.

[5] Muraki I, Rimm EB, Willett WC, et al. Potato consumption and risk of type 2 diabetes: results from three prospective cohort studies[J]. Diabetes Care, 2016,39(3): 376-384.

[6] Halton TL, Willett WC, Liu S, et al. Potato and french fry consumption and risk of type 2 diabetes in women.[J]. The American Journal of Clinical Nutrition, 2006,83(2): 284-290.

[7] Asli LA, Olsen A, Braaten T, et al. Potato consumption and risk of colorectal cancer in the Norwegian women and cancer cohort[J]. Nutrition and Cancer, 2017,69(4): 564-572.

[8] Borch D, Juul-Hindsgaul N, Veller M, et al. Potatoes and risk of obesity, type 2 diabetes, and cardiovascular disease in apparently healthy adults: a systematic review of clinical intervention and observational studies[J]. The American Journal of Clinical Nutrition, 2016,104(2): 489-498.

[9] Predimed SAS P. Potato consumption does not increase blood pressure or incident hypertension in 2 cohorts of Spanish adults[J]. The Journal of Nutrition, 2017,147(12): 2272-2281.

[10] Larsson SC, Wolk A. Potato consumption and risk of cardiovascular disease: 2 prospective cohort studies[J]. The American Journal of Clinical Nutrition, 2016,104(5): 1245-1252.

[11] Veronese N, Stubbs B, Noale M, et al. Fried potato consumption is associated with elevated mortality: an 8-y longitudinal cohort study[J]. The American Journal of Clinical Nutrition, 2017,106(1): 162-167.

[12] Chen X, Jiao J, Zhuang P, et al. Current intake levels of potatoes and all-cause mortality in China: a population-based nationwide study[J]. Nutrition, 2020: 110902.

[13] Shi Z, Taylor AW, Hu G, et al. Rice intake, weight change and risk of the metabolic syndrome development among Chinese adults: the Jiangsu nutrition study (JIN).[J]. Asia Pacific Journal of Clinical Nutrition, 2012,21(1): 35-43.

[14] Pedreschi F, Cocio C, Moyano P, et al. Oil distribution in potato slices during frying[J]. Journal of Food Engineering, 2007,87(2): 188-97.

[15] Zhang Y, Huang M, Zhuang P, et al. Exposure to acrylamide and the risk of cardiovascular diseases in the National Health and Nutrition Examination Survey 2003–2006[J]. Environment International, 2018,117: 154-163.

[16] Storey ML,Anderson P A. Changes in mean intake of fatty acids and intake of saturated and trans fats from potatoes: NHANES 2005-2006, 2007-2008, and 2009-2010.[J]. Advances in Nutrition (Bethesda, Md.), 2015,6(3): 376S-82S.

[17] Borgi L, Rimm EB, Willett WC, et al. Potato intake and incidence of hypertension: results from three prospective US cohort studies[J]. British Medical Journal, 2016,353: i2351.

[18] de Souza RJ, Mente A, Maroleanu A, et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies[J]. British Medical Journal, 2015,351: h3978.

[19] Lachman J, Hamouz K, Musilová J, et al. Effect of peeling and three cooking methods on the content of selected phytochemicals in potato tubes with various color of flesh[J]. Food Chemistry, 2013, 138: 1189-97.

Author: Wu Tong (student)

Scientific guidance and revision: Fan Zhihong