Nutrition Action November 2010 : Page 5
C O V E R S T O R Y DROPPING ACID D in muscle tissue. And in a couple of small studies, treatment with D increased the number of vitamin D receptors and the size of the type 2 muscle cell fibers. And extreme vitamin-D-defi ciency is associ-ated with a defi cit of the type 2 fibers. These are the fast-twitch fi bers that are your fi rst responders when you are losing your balance. It is well documented that inadequate D levels are associated with higher risk of falling. So vitamin D is re-ally important for muscle. Q: Do most people get too little vita-min D? A: Yes. Sixty percent of people in the U.S. and Europe get too little vitamin D. The percentages are higher in theMiddle East and Southeast Asia. Themost important source of vitamin D is sun exposure, which increases the body’s production of vitamin D. The diet is not rich in D. There’s a little in fatty fi sh and in eggs, but by and large,most people with-out sun exposure will need a supplement. Q: You were on the panel that set the current Recommended Dietary Allow-ances for vitamin D. Are the RDAs too low? A: Yes, we still have the 1997 values— 400 International Units for adults aged 51 to 70 and 600 IU for people over 70—and they are too low. People aged 60 and older need 800 to 1,000 IU a day to keep blood levels at 30 nanograms per milliliter. But we’ll just have to wait to see what the panel will do this time around. Q: What if you’re low in vitamin D and are producing too much acid? A: In animal experiments, we’re trying to determine the precise effects that both vitamin D and an acid load have on muscle at the cell level to see whether there is any interaction. It could be that vitamin D doesn’t function well in an acid environment. That’s our hypothesis. We’ll have those results soon, and it’s going to be very exciting. It might open some new avenues for research. OTHER NUTRIENTS Q: What nutrients are crucial just for bone? A: Calcium is huge. In meta-analyses, there’s about a 20 percent reduction in the risk of fractures when people are given both calcium and vitamin D.We also found a lower risk of tooth loss when we h people over 65 ve 65 take both c vitamin D for three years. However, calcium without vitamin D may not be as protective of bones or teeth. lciu an supplements H Q: Does potassium matter? A:We did a trial to figure out whether it was the potas-sium or the bicarbonate or if you needed the combina-tion. And it turned out it was the bicarb. Potassium had no impact on short-term indicators of bone loss or muscle wasting. Potassium is great for other things like blood pressure. Q: And vitamin K? A: It was promising for a while, but vitamin K1— that’s what’s in lettuce and other dark leafy green vegetables—had no impact on rates of bone loss in three or four large trials. There is interest in some of the other K compounds but at higher, pharmacologic doses, not what you would get in foods. Q: What about magne-sium? A:We haven’t made much progress with magnesium, simply because it’s so hard to get an indicator of the body’s magnesium status. The blood level doesn’t tell you that, and there’s no easy assay to measure tissue levels. It’s analogous to the osteoporosis fi eld prior to bone-density scans. You couldn’t get a handle on what the bones were doing in a large number of people. Q: Does excess salt harm bones? A: Salt—sodium chloride— isn’t good because it causes calcium leaching. It can tip you into a calcium deficit if you have a borderline cal-cium intake and are eating a lot of salt. In order to get rid > > > > > Yo dh Fruits Raisins (¼ cup) Apricots (4) Kiwi fruit (2) Watermelon (2 cups) Pear (1) Orange (1) Apple (1) Pineapple or Strawberries (²/³ cup) Peach (1) Vegetables (½ cup cooked unless noted) Spinach Zucchini Carrot Tomato, raw (1) Cauliflower Lettuce, raw (3 cups) Green beans Broccoli Asparagus Miscellaneous Olive oil (1 Tbs.) Sugar (1 tsp.) Butter (1 Tbs.) Milk chocolate (1.5 oz.) Cereal & Grains Bread, whole wheat (1 slice) Bread, white (1 slice) Rice, white (½cup cooked) Rolled oats (1 cup cooked) Dairy & Eggs Ice cream, vanilla (1 cup) Soft cheese (1 oz.) Wholemilk (8 oz.) Fruit yogurt, wholemilk (6 oz.) Eggs (1 large) Hard cheese (1 oz.) Cottage cheese (½ cup) Fish,Meat, & Poultry (5 oz. raw) Haddock Beef or Pork, lean only Chicken, no skin Turkey, no skin Beverages Red wine (5 oz.) White wine, dry (5 oz.) Draft beer (16 oz.) Coca-Cola (12 oz.) Source: J. Am. Diet. Assoc. 95: 791, 1995. NUTRITION ACTION HEALTHLETTER ■ NOVEMBER 2010 5 Here’s the potential renal acid load (PRAL) for a sample of foods. Look for foods with gh negative PRALs (like fruits and veg-bles) to neutralize high positive PRALs. Wh l list only whole milk and full-fat yogurt? You’d have to ask the German researchers who compiled the data in the 1990s. H fo et PRAL -8.4 -6.7 -6.1 -5.3 -4.8 -4.2 -3.4 -3.1 -2.4 -12.6 -4.1 -3.8 -2.6 -2.5 -2.1 -1.6 -0.9 -0.4 0.0 0.0 0.1 1.0 0.8 1.6 2.7 8.7 0.8 1.2 1.7 2.0 4.1 5.4 9.6 9.7 11.2 12.4 14.1 -3.5 -1.8 -1.0 1.5 Photo:©Frédéric T./fotolia.com.