Call for Increased Potassium Intake to Lower BP, Cut Deaths

September 14, 2010

September 14, 2010 (Vlaardingen, the Netherlands) — Dutch scientists are highlighting the fact that most people around the world eat too little potassium; upping consumption to the recommended level of 4.7 g per day would lower population systolic blood pressure by up to 3.2 mm Hg, thereby reducing stroke mortality by 8% to 15% and heart disease mortality by 6% to 11%, they have estimated [1].

This effect "is of similar magnitude to what can be achieved by lowering sodium intake and highlights the importance of dietary strategies focusing on both reducing sodium intake and increasing potassium intake," say Linda A J van Mierlo (Unilever R&D, Vlaardingen, the Netherlands) and colleagues in their research letter in the September 13, 2010 issue of the Archives of Internal Medicine.

Senior author, nutritionist Dr Johanna M Geleijnse (Wageningen University, the Netherlands), told heartwire that increasing potassium intake to optimal levels across populations as a whole would have "an enormous impact on the number of people who would die from stroke and coronary heart disease" and would be more effective than treating all hypertensives.

What most people don't realize is that the vast majority of heart attacks occur in those who are untreated with slightly above-average BP.

"The focus is mostly on people with severe hypertension who need medical treatment, but what most people don't realize is that the vast majority of heart attacks occur in those who are untreated with slightly above-average BP." People can easily consume more potassium simply by adhering to dietary guidelines and eating "a couple of tomatoes or bananas or whole-grain foods," she stresses.

Asked to comment on this new work, nutritionist Katharine Jenner (Consensus Action on Salt & Health [CASH], London, UK) told heartwire : "This research letter emphasizes that an increase in potassium intake, in addition to a decrease in sodium intake, is likely to have a positive effect on lowering blood pressure and therefore reducing our risk of having a stroke, a heart attack, or heart failure.

"It is very important that people try to eat more fruit and vegetables to increase the potassium in their diets," Jenner adds. "However, the simplest and cheapest way of lowering your blood pressure is to reduce your sodium intake by eating less salt."

Potassium Intakes Lowest in China, Medium in US and UK

van Mierlo and colleagues searched PubMed and contacted health authorities worldwide for national population-based dietary surveys conducted from 1990 to 2009 that included data on potassium intake in more than 1000 adults. They defined the recommended level of potassium intake at 4.7 g per day--as recommended by the US Institute of Medicine [2]--and supposed the effect of dietary potassium on systolic BP to be a 1-mm-Hg reduction per 0.6-g/day increase in intake--based on estimates from the INTERSALT study--and assumed this relationship to be linear.

Population BP data were obtained for Finland, the UK, and the US, representing populations with relatively high, medium, and low potassium intakes. For these countries, they estimated the potential impact of increasing potassium intakes on population systolic BP levels and classification in different systolic BP categories.

Potassium intake vs recommended levels [Source: Dr Johanna M Geleijnse]

They found that in 21 countries across North America, Europe, Asia, and Oceania, the mean potassium intakes ranged from 1.7 g per day, in China, to 3.7 g per day in Finland, the Netherlands, and Poland [3]. Mean intakes in women were generally lower than in men.

Based on the data from Finland, the UK, and the US, they then calculated that a hypothetical increase in potassium intake to 4.7 g per day would shift the population systolic BP distributions to 1.7 to 3.2 mm Hg lower in these Western countries, which "is in the same order of what can be predicted for a reduction in sodium intake from 9 g to 5 g per day."

This theoretical increase in potassium intake in these countries would increase the percentage of men and women in the optimal systolic BP category (<120 mm Hg) by approximately 2% to 5% and 4% to 8%, respectively, and decrease the percentage of men and women with systolic BP levels in the higher range (>140 mm Hg) by approximately 2% to 5% and 4%, respectively, they point out.

Focus on Salt Reduction Good, But Potassium Should Not Be Neglected

Geleijnse says that there has been "a lot of attention for reducing sodium intake--and that's a good thing, because it's an important risk factor for hypertension," but potassium intake should not be neglected, because potassium has the effect of reducing salt sensitivity. Boosting potassium intake would also reduce the risk of kidney stones and possibly also cut the risk of osteoporosis, she says.

Foods rich in potassium include most fruits and vegetables, whole grains, dairy products, and coffee, she notes, speculating that the last might explain the higher-than-average potassium intakes seen in countries such as the Netherlands, although she stresses that intake there is still suboptimal. Commenting on the very low intake of potassium seen in China, she speculates that this might be due to the fact that the Chinese do not consume much dairy food or drink much coffee.

It is possible to increase potassium intake relatively easily, she stresses, pointing out that there are remote populations, such as the Yanomamo Indians in Brazil, "who have a very high potassium intake of 8 g per day."

Manufacturers should ensure that the natural levels of potassium in foods are maintained.

But Geleijnse remains cognizant of the practicalities of modern life and says that while it is laudable to recommend that people eat unprocessed food whenever possible, this is often impractical for people with busy lives and families: "I am all for the food industry reformulating their products to be healthier." One way in which this can be achieved is for the food industry to put back the potassium that is currently removed during the processing of food. "Manufacturers should ensure that the natural levels of potassium in foods are maintained," she observes.

She is also torn on the subject of "low-salt" alternatives, which actually contain potassium. While these do reduce sodium intake (and also increase potassium consumption), the use of such products means that people do not become accustomed to less salty foods, which is the ultimate aim, she says.

And asked whether people could simply take mineral supplements, she said that this is a possibility, "because in studies where they have given potassium supplements they did find lower blood pressure," but she cautions that it has been shown that the particular salt of potassium consumed is key. "The anion seems to be important, with evidence that potassium chloride is less effective than potassium citrate, for example," she says.

van Mierlo and two coauthors are employees of Unilever R&D, Vlaardingen, the Netherlands. Unilever markets some foods that are enriched with potassium. Geleijnse declares no conflicts of interest.

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