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In the news: Potassium May Play a Role in Weight Loss; More on the Vitamin D – Cancer Connection

Role for Potassium in Weight Control?

It’s too early to say whether potassium might help with weight control, but the intriguing findings of a new study raise the possibility that it might.

The novel idea comes from Israeli researchers who found that participants in a weight loss study who achieved bigger reductions in their body mass index (BMI) consumed more potassium than those with only modest BMI decreases. BMI is a measure of body fat based on height and weight; A BMI of 30 or more indicates obesity.  

The study (1), which is ongoing, is looking at the effects of lifestyle changes and a diet based on a moderate low calorie, high protein Mediterranean diet in people with metabolic syndrome. This analysis was conducted using data from the first 68 men and women to complete the 1-year study. At the start of the study, the average BMI was 35. By the end of the 1-year period, BMI had declined by an average of 9.4.

Interestingly, potassium intake more strongly predicted a decline in BMI than many of the usual factors that are associated with weight loss such as cutting back on overall calories and sugar. The thirty participants whose fall in BMI was above the average reduction had upped their potassium intake by 25%. Those whose decline in BMI was below the average reduction had an increase in dietary potassium of only 3%. How potassium may be working to promote weight loss isn’t known, but the authors theorize that it might involve reducing inflammation, improving insulin sensitivity or subtle effects on energy balance.

This isn’t the first study to observe a link between potassium intake and weight loss. A recent meta-analysis of epidemiological data from several Asian studies, for example, concluded that high potassium intake was associated with lower odds of having obesity and the metabolic syndrome. But observational studies can’t prove that potassium is truly a factor in reducing BMI. Going forward, the Israeli researchers will be looking at the potassium-weight loss relation-ship in more detail.

Meanwhile, consuming more potassium makes good sense. Following either of two proven health-promoting diets, the Mediterranean and the blood pressure-lowering DASH diets, entails increasing potassium intake for example. And importantly, we’re not getting enough of this important mineral.

National Health Surveys have shown that only about 10% of men and less than 1% of women consume the daily recommended intake of 4.7 or more grams of potassium. Eat more fruit, vegetables, dairy, beans and fish to get more of this important mineral.

More on the Vitamin D & Cancer Connection

The results of observational studies suggest that higher blood levels of vitamin D are linked with lower cancer incidence and death, but the findings of intervention trials have not been clear cut or even somewhat confusing. The large VITAL trial, for example (see Staying Healthy, Dec 2018) failed to show that 2,000 IU vitamin daily for 5 years could lower the risk of invasive cancer (any type), yet it did find lower death from cancer for vitamin D v. placebo.

Two new studies offer further pieces of the puzzle. In the first study from Japan2, supplemental vitamin D did not improve relapse-free survival at 5 years for those who had undergone surgery for digestive tract cancers. But a subgroup analysis suggested some benefit for patients who started out with low blood vitamin D levels (20 - 40 ng/mL) at the study’s start.

In the second study (3), which followed more than 3800 Australians for about 20 years, lower vitamin D levels were associated with higher risk of colorectal and breast cancer, but not overall cancer risk.

As many experts have said, the jury is still out on vitamin D and cancer. So, for now, avoiding low blood levels of vitamin D is a sound strategy.

References

1. Tal B, et al. Increment in dietary potassium predicts weight loss in the treatment of the metabolic syndrome. Nutrients. 11:1256, 2019.
2. Urashima M, et al. Effect of vitamin D supplementation on relapse-free survival among patients with digestive tract cancers: The AMATERASU randomized clinical trial. JAMA 321:1361-69, 2019.
3. Zhu K, et al. Lower serum 25-hydroxyvitamin is associated with colorectal and breast cancer, but not overall cancer risk: a 20-year cohort study. Nutr Res. 67:100-7, 2019.