Aardappels
tegen hoge bloeddruk*
Uit een kleine Amerikaanse studie blijkt dat het dagelijks eten van aardappelen
de bloeddruk duidelijk kan verlagen, zonder te zorgen voor extra gewicht. Een
maand lang kregen 18 deelnemers dagelijks twee keer een portie van 6-8 kleine
aardappelen, in de schil gekookt. Na afloop bleek de bovendruk
(systolische druk) met 3,5 % en de onderdruk
(diastolische druk) met 4,3% verlaagd te
zijn.
Deze
verlaging wordt volgens de onderzoekers veroorzaakt door de bioactieve stoffen
in aardappelen waaronder verschillende vitamines en mineralen zoals kalium. Bij het frituren
en bij hoge temperaturen bakken van aardappelen worden deze gezonde bioactieve
stoffen echter grotendeels vernietigd. "Over het algemeen denken mensen bij aardappelen aan veel
zetmeel (koolhydraten) en calorieën, doch in werkelijkheid bevat een gekookte aardappel zonder boter of saus, slechts 110 calorieën en ontzettend veel gezonde stoffen en
vitaminen, aldus de onderzoekers. In het onderzoek werden paarse aardappelen
gebruikt, die wellicht iets meer bioactieve stoffen bevatten doch volgens de
onderzoekers geven witte of rode aardappelen een vergelijkbaar effect.
Potatoes may help reduce blood pressure without affecting weight
A new study conducted by chemistry professor Joe Vinson at the University of Scranton in Pennsylvania has revealed that spuds may be suffering from an undeserved, ill reputation as a fattening, nutritionally empty food. Although they rank high on the glycemic index, potatoes are mistakenly considered unhealthy, when they are, in fact, loaded with vital nutrients that may help fight against obesity and hypertension.
"Mention 'potato' and people think 'fattening, high-carbs, empty calories'. In reality, when prepared without frying and served without butter, margarine or sour cream, one potato has only 110 calories and dozens of healthful phytochemicals and vitamins. We hope our research helps to remake the potato's popular nutritional image," said
Vinson.
A raw potato, however, contains higher amounts of indigestible fiber, in the form of starches, and will only provide about 77 calories per 100 grams. Aside from an assortment of minerals and vitamins, such as vitamins C, B6, B1 and B3, potatoes (especially colored ones) are also high in potassium, magnesium, iron, zinc and phosphorus, as well as carotenoids and natural phenols. Surprisingly, 100 grams of raw potato can provide nearly a quarter of the daily requirement of vitamin C for an average
individual.
Professor Vinson tested the health benefits of purple potatoes on a group of 18 overweight and hypertensive individuals, who were given 6 to 8 potatoes with skins, twice a day, over the period of a month. Vinson explained that he picked purple potatoes as they are especially rich in carotenoids - the plant pigments that are found in most colored vegetables, including apricots, carrots, algae and dark leafy vegetables.
Since the human body cannot synthesize carotenoids on its own, these precious phytochemicals must be obtained directly from food sources. They are involved in a wide array of metabolic processes, and most have important antioxidant activity, reducing the risk of cancers and prolonging life-span.
Vinson's science team closely monitored the patients' systolic and diastolic blood pressure during the trial period, and they recorded a drop of 4.3% in average diastolic pressure and of 3.5% in average systolic pressure by the end of the month. These figures are especially impressive, considering the short time-span of the trial. More notably, none of the participants involved gained any weight or reported any other negative health
changes.
Professor Vinson based his hypothesis for this research on previous studies which had shown that phytochemicals in potatoes may have proprieties that rival synthetic ACE-inhibitor drugs, who are famed for their numerous adverse reactions. Vinson also believes that potatoes, along with other organic vegetables, including broccoli, spinach and Brussels sprouts, may provide an effective, natural way of managing hypertension. In addition, the professor warns against consuming fried potatoes, as high cooking temperatures destroy the precious phytochemicals in them, while leaving only the starches, saturated fat, and some minerals.
For the near future, Vinson is preparing to test the health benefits of white potatoes, which, although lacking in pigment, may also harbor unexpected health
benefits. (September 2011)
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