Are potatoes linked to high blood pressure?
Dr K K Aggarwal
Yes, says a new study from the Brigham and Women's Hospital and Harvard Medical School. In a report published May 2016 in the BMJ, researchers from these institutes state that eating boiled, baked, mashed or as chips is linked to increased risk of developing high blood pressure.
The researchers combined the results of three large US studies (Nurses’ Health Study, Nurses’ Health Study II and Health Professionals Follow-up Study) that followed over 187,000 men and women for more than 20 years, who did not have hypertension at baseline. A questionnaire was used to evaluate consumption of potato in diet, including how often the participants ate potatoes and in which form. Baked, boiled and mashed potatoes formed one category; French fries and potato chips formed two separate categories.
When compared with less than one serving a month, consuming four or more servings of baked, boiled or mashed potatoes in a week was linked to an increased risk of high blood pressure in women, but not in men. Higher consumption of potato chips was linked to an increase risk of high blood pressure in both men and women. Potato crisps were linked to an increased risk of high blood pressure in either men or women.
· Potatoes have a high glycemic index and are linked to obesity.
· An easy to grow vegetable, potatoes are an inexpensive source of vitamin C and potassium. Although potatoes are technically a vegetable, they are usually eaten as a starchy food, in much the same way as bread, pasta and rice.
· Potatoes are a healthy nutrient-dense food when they are cooked without salt or fat. They provide significant amounts of fiber, potassium, vitamin C, vitamin B6 and folate and are low in calories.
Ayurveda has been teaching that potatoes consumption is linked to diabetes and obesity because of the sweet taste and recommends eating potato+ fenugreek leaves (methi) in preference to potatoes alone. Methi leaves being bitter neutralize the sweet taste of potato.
A study in January 2013 issue of the American Journal of Clinical Nutrition shows that people who enjoy a high-glycemic diet, such as white bread and potatoes are at an increased risk of type 2 diabetes. Each 100 grams of sugar per 2,000 calories led to a 45 percent higher risk of type 2 diabetes.
Also soaking potatoes in water before frying cuts down on the formation of the suspected carcinogen acrylamide. Acrylamide is created when starch-rich foods are cooked at high temperatures, (120 C) such as frying, baking, grilling, broiling or roasting. Raw or even boiled potatoes test negative for the chemical. Boiling and microwaving appear less likely to form acrylamide as the coking does not involve very high temperatures. Longer cooking times increase the amount of acrylamide produced when the temperature is high enough.
Potato chips and French fries contain high levels of acrylamide compared to other foods, with lower levels also present in bread and cereals. Acrylamide, is harmful to health and may cause cancer in animals.
The formation of acrylamide can be reduced by just soaking potatoes before frying. In a study published in Journal of the Science of Food and Agriculture, researchers tried three different approaches. They washed raw French fries, soaked them for 30 min, and soaked them for 2 hours. This reduced acrylamide levels by up to 23%, 38% and 48%, respectively, but only if the fries were cooked to a light color. It’s not clear whether the same reductions could be achieved if French fries are cooked to a deep, dark brown.
The cooking and re-cooking of fried foods in the same fry pan or broiler is the main cause. Even a thoroughly washed iron skillet can still have submerged carcinogens collected from previous use. Most restaurants uses the same rancid cooking oil for days or even weeks and even reusing it after washing the pot.
Cigarette smoking is another source of acrylamide.
Ayurveda does not recommend deep frying and has been advocating low temperature cooking for centuries.
1. The BMJ: 'Potato intake and incidence of hypertension: results from three prospective US cohort studies
2. The BMJ editorial: 'Are there bad foods or just bad diets?'
3. British Nutrition Foundation: 'New nutritional insights for health professionals'
4. NHS Choices: '5 A DAY: what counts?'
5. AHDB Potatoes, a division of the Agriculture & Horticulture Development Board: 'Market Intelligence, In-home Consumption'