Mining for Minerals

When summer roles around I'm reminded of the comment of one of my sons whenhe was little: "Summer is a sweaty time". Maybe his remark lacked a little elegance, but I think he hit the nail on the head. And with all theperspiration brought about by summer's heat, comes a loss of two particularly important minerals: potassium and magnesium. I bet you don't lose much sleep worrying about the status of these minerals in your body(and I don't mean to imply they're only important if you perspire), but a well-balanced diet pays special attention to potassium and magnesium for a variety of reasons. Let me explain. Potassium is an interesting mineral (well, dietitians find it interesting) because of the many functions it performs in the body. First of all, though it's commonly associated with sodium, in contrast to sodium it is concentrated within the cells...nerve and muscle cells are especially rich in potassium. The main functions of potassium are the same as those of sodium: maintenance of fluid balance and volume. But it also has a role in carbohydrate metabolism, enhancement of protein synthesis and muscle contraction and nerve impulse conduction.Whoa! Do you really care about that? Maybe not, but I bet you care about reducing your risk of developing high blood pressure...and that's where having a goodly amount of potassium in your diet comes into play. We have almost proof positive that the interplay between calcium, potassium and magnesium has a tremendous impact on blood pressure. That brings us to the second interesting fact about potassium...where you find it. In my many years as a dietitian I noticed that whenever I asked a patient about what foods they would choose for potassium they invariably said bananas and oranges. They were right: those are excellent sources, but they ignored three equally good, if not better sources, avocado, milk and baked potato with the skin. There's actually a third interesting thing about potassium, one that wasn't well known until recently, and that's the role that this mineral plays in reducing the risk of osteoporosis. A number of recent studies have shown that potassium is associated with increased bone mass in adults. We're not exactly sure what the connection is, but it's thought to be due to the way in which potassium reduces the loss of calcium in the urine. I find it extremely interesting that one food, milk, should contain as a package the many nutrients necessary for bone health. Yes, milk contains calcium, and yes, it is rich in potassium, and then comes magnesium.Here's a bit of trivia for your next cocktail party: The village of Epsom inEngland was where people first noticed that drinking from a pool of bitter-tasting water made them feel healthfully purified. Later in the 17th century, sure enough somebody crystallized its salts and marketed "Epsom Salts" to great acclaim. It wasn't until the eighteen hundreds that magnesium was identified as the key ingredients in the salt and it became well known for its use in photographic flashes, flares, and as a metal valued for its lightness in space-age technology. But enough of trivia...what does magnesium have to do with your health? I fear it would bore you to tears if I droned on about the many, many functions of magnesium but at the risk of a little eye glazing I'll mention its role in glucose and fatty acid metabolism, amino acid activation, nervous activity and muscle contraction. Of all its jobs, however, none is more important than its role in bone metabolism. For my money, this is as good an explanation as any as to the inappropriateness or perhaps better said, inefficiency, of adding calcium to various beverages: all that peoplewill get is the added calcium and as we know, healthy bones and a healthy body depend on a whole toolkit of minerals and vitamins, not just calcium. Of commonly eaten foods, in the portions usually consumed, dairy products are the best sources of magnesium followed (in order of decreasing content) by breads and cereals, vegetables, meats and poultry, and fruits. On an indivual basis the best sources are peanuts, banana and avocado. It's interesting that bananas, avocados and milk are such great source of both these minerals...there must be a recipe in there somewhere.Let me hasten to point out that Milk of Magnesia ought not be considered a dietary source of magnesium. It acts by drawing water from cells into the intestine and by increasing intestinal movement. So, the bottom line, if milkof magnesia is used as an antacid, could be a serious bout of diarrhea.Overuse of the product could pose a serious threat to those with kidney problems. Magnesium is to plants what iron is to animals. Just as iron is the "core"atom of haemoglobin, magnesium is the "core" atom of chlorophyll, the green pigment that enables plants, in the presence of light, to transform carbon dioxide and water into carbohydrates. It thus has some claim to being, next to carbon, the element most important to life.Given the above information, we might well conclude that the most importantfood trend as we ease into the third millenium has been the popularity ofthe smoothie! What better way to cool down on a hot summer day than with these tasty combos of ice-cold milk or yogurt and a variety of fruits and berries. Potassium and magnesium may not be on your mind as you quaff them down, but your body will thank you for it!