God bless August, even though it is sometimes too hot. Harvest begins in earnest. The corn is sweet. Peaches are juicy and squirt in your nose. And glorious heirloom tomatoes are here in force.
Is there anything tastier than a juicy red or yellow tomato of one of the many wonderful heirloom varieties like Brandywine, Black Prince, Purple Cherokee, San Marzano and many others? You know, those large and irregularly shaped, strangely named fellows who hardly seem related to the perfectly round, uniformly red, and usually tasteless vegetables (actually a fruit) that masquerade as tomatoes most of the year.
You can make most of a meal with these tomatoes and some burrata (the soft form of mozzarella that is really tasty). Add a piece or two of fresh corn and you’re done. You won’t miss the protein for that meal. Our family has reveled in the tomato feast for weeks at almost every dinner and many lunches. I even had some for breakfast last week.
If you are trying to control your weight at all, heirloom tomatoes are your friend. Tomatoes average only about 5 calories per ounce. A large heirloom tomato may weigh 8 to 10 ounces, so you are talking all of 40-50 calories. Have two if you want.
Tomatoes are an excellent source of potassium. They contain 75 mg potassium per ounce (about 2 milliequivalents or mEq) and cost 5 calories per ounce. That’s 2.5 cal/mEq. Bananas yield 105 mg (2.7 mEq) of potassium per ounce but cost 26 calories per ounce, or about 10 cal/mEq. So bananas cost about 4 times as much in calories as tomatoes for the same amount of potassium.
When we need to supplement potassium because of losses caused by medicines such as diuretics, the amount needed is frequently 20 mEq daily. That would be achieved by eating a 10 oz. (1 large) tomato or 7.5 oz. (2 small) bananas. But the tomatoes cost you 50 calories and the bananas about 200. That matters for anyone challenged by weight. When higher potassium replacement is occasionally required (such as 40 mEq/day), we generally recommend tablets, each of which contains 10 or 20mEq of potassium and no calories.
I’ll try to explore the nutrient density of other foods in the next few months. Such knowledge can help us make smarter food choices.