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Beyond the Banana

Last week I talked about the new nutrition label proposed by the FDA. Assuming the changes are accepted, there would be a new focus on potassium intake, so I thought it would be helpful to discuss the role of potassium and where to find it.

You may have heard about potassium as an electrolyte, which just means it has the capacity to conduct electricity. Electrolyte balance is crucial for normal function of cells and organs. Specifically, potassium plays a role in maintaining blood pressure and a regular heart beat, as well as muscle contraction. Don't forget when I say muscle, I don't just mean your biceps and your quads. Your heart is a muscle, and your body has smooth muscle that helps you digest food.

Additionally, potassium plays a role in insulin levels. If potassium levels are low, the pancreas does not secrete as much insulin in response to high blood sugars. This means that prolonged low levels of potassium could be a risk factor for type 2 diabetes.  

Very low potassium levels can lead to impaired muscle contraction and nerve transmission (causing constipation, abnormal heart rhythms, fatigue or weakness, muscle spasms, paralysis). What causes these low levels of potassium? Not getting enough through food is part of it. But more than likely it's also dehydration - it could be that illness with vomiting and diarrhea, or excessive sweating from heat or exercise, or taking medications like diuretics or certain antibiotics. 

So how much is enough? 

The recommended adequate intake (AI) for adults is 4,700mg per day. The "What We Eat in America," (WWEIA) survey asks Americans what they ate in the past 24 hours. This is used to determine whether we get too much or too little of specific nutrients. According to the data from 2009-2010, adults consume between 2,400mg and 3,000mg of potassium per day

Now from what I've seen, a big part of the reason we require so much potassium is that we consume so much sodium. When potassium is low, we are more sensitive to sodium. These nutrients work together in opposition to maintain balance in the body. The recommended intake for sodium is 2,300mg per day, and WWEIA indicates that adults consume between 3,000mg and 4,200mg.

In other words, we've got it backwards when it comes to our intakes of sodium and potassium. 

Now what??

I always recommend getting your nutrients from food as opposed to supplements. The good news is that if you eat a variety of foods, it's not hard to get potassium. You can find it in many fruits and vegetables (not just the well-known banana), as well as dairy, meat and legumes. A partial list follows, another good reference can be found here.

Veggies:

  • Spinach (1 cup) ---- 840mg
  • Beets (1 cup) ---- 520mg
  • Broccoli (1 cup) ---- 458mg
  • Potato (7 oz) ---- 888mg
  • Sweet potato (7 oz) ---- 450mg

Fruits:

  • Cantaloupe (1 cup) ---- 428mg
  • Banana (1 medium) ---- 422mg
  • Tomatoes (1 cup) ---- 427mg
  • Avocado (1 cup) ---- 728mg
  • Papaya (1 medium) ---- 502mg

Legumes:

  • Lima beans (1 cup) ---- 955mg
  • Lentils (1 cup) ---- 731mg
  • Kidney beans (1 cup) ----- 717mg

Meat:

  • Tuna (4 oz) ---- 600mg
  • Beef, 90% lean (4 oz) ---- 300mg
  • Chicken breast (4 oz) ---- 220mg

Dairy:

  • Skim milk (1 cup) --- 382mg
  • Greek yogurt (6 oz) ---- 240mg

Which high potassium foods do you like? Any you're willing to add to your diet?