Runner's World Essential Guides (3 page)

Isolated from cow’s milk, whey protein is a rich source of all the amino acids muscles need. Studies show it helps build lean body mass and increase strength. But its main advantage over other protein supplements, such as soy and casein, is that it’s very quickly absorbed by the body, “which makes it an excellent choice for postrun recovery,” says Forsythe. Runners who struggle to eat enough protein after workouts may want to try adding whey to recovery meals, according to Forsythe.

How to Pop It:
A Canadian study found 10 grams (or two tablespoons) of whey isolate boosts muscle protein synthesis postexercise. Add it to smoothies, oatmeal, pancake batter, and yogurt.

When buying multivitamins, check the bottle for the National Science Foundation (NSF) mark—a guarantee the product delivers what it says and is free of contaminants. Here are a few other supplements to consider:

Push Back:
These pills may not be as effective as their labels claim—and can actually be dangerous

Acai:
This fruit is high in antioxidants. But reports that acai extract speeds weight loss are unfounded—not a single study backs up this claim.

Beta-Carotene:
When consumed through fruits and vegetables, beta-carotene may reduce risk for some cancers. But research shows taking high doses in supplements may raise risk for certain cancers and even death.

Resveratrol:
Research shows this red wine antioxidant is linked to a lower risk of heart disease. But it’s not clear whether resveratrol itself or a combination of nutrients is actually at play.

Quercetin:
Research using mice has found some evidence the flavonoid (found in apples and onions) may boost athletic performance, but studies with people found no such effect.

Vitamin E:
Studies have found the vitamin does not reduce risk for heart disease or cancer. In fact, Harvard researchers found supplementing may raise stroke risk. Stick with natural sources, like nuts, avocado, and olive oil.

You may not know it—or look it—but part of you is five billion years old. The mineral part, that is. That’s because 22 different minerals make up roughly 5 percent of your body weight, and every atom of those minerals was present in rocks when the earth was formed over five billion years ago.

We get our minerals when we drink water that once trickled through rocks, and when we eat vegetable and animal products nourished by the earth’s mineral-rich crust. These prehistoric metals perform many complex and vital duties in our bodies; they help balance body fluid levels, control muscle contractions, carry oxygen to working muscles and regulate energy metabolism.

Yet, many of us runners don’t get enough of them, in part because we run. There’s evidence that vigorous exercise accelerates mineral loss through sweat and urine, which may put you at risk for deficiencies. Okay, okay, you take a multivitamin with minerals. Unfortunately, mineral absorption from supplements is typically very poor. Plus, supplemental minerals often interact with other nutrients in ways that hamper absorption.

Here’s the latest on three of the most important minerals: magnesium, chromium, and zinc, each of which plays a key role in exercise. We explain their function in the body, how much you need, and ways to ensure you’re getting enough.

For years, researchers have known that magnesium plays a critical role in endurance performance. Magnesium mainly exists in muscles and bones, where it assists with muscle contractions and energy metabolism. Studies with lab animals and people show that magnesium deficiency reduces endurance, and that low blood levels of magnesium are associated with decreased aerobic capacity. Unfortunately, this low level of circulating magnesium has been seen in runners after marathons, and probably resulted from mineral loss via sweating.

Researchers believe that low magnesium levels reduce production of a substance called 2,3-DPG (for our purposes, simply “DPG”), which is essential for oxygen delivery to exercising muscles. So, theoretically, increasing magnesium intake should boost DPG levels, thereby improving oxygen delivery and in turn boosting aerobic capacity and performance.

One classic study done at Lenox Hill Hospital in New York tested this magnesium—DPG connection with trained runners. Subjects took either a placebo or a magnesium supplement (at twice the RDA) for two weeks. Runners were tested on the treadmill before and after supplementation. Result: The extra magnesium failed to boost circulating DPG level or max VO2, (the maximum capacity of an individual’s body to transport and use oxygen during incremental exercise) nor was there any difference in perceived exertion among subjects.

Why these results? Magnesium supplementation may have been superfluous in this case, as the male runners’ diets already contained more than the magnesium RDA of 350 milligrams (the RDA for women is 280 milligrams). In other words, more does not mean better. Yet, if you’re one of those people who don’t get enough, your endurance may be suffering. Because oversupplementation can cause diarrhea and can interfere with calcium absorption and metabolism, try to get your magnesium from food sources, such as nuts, molasses, whole grains and dark green, leafy vegetables.

Die-hard believers say this little metallic dynamo burns body fat while it builds muscle. No wonder chromium has become the supplement of choice for so many runners, bodybuilders, even dieters. But before you sprint to the nutrition depot for a truckload, let’s take a closer look.

Most minerals work as enzyme helpers during metabolism. Not so with chromium, which assists the hormone insulin in processing carbohydrates. Insulin also helps manufacture new proteins, which is where the theory of chromium as a muscle-builder originates.

And the theory does sound reasonable; unfortunately, it just doesn’t pan out. Much of the recent chromium craze is based on a slew of flawed studies showing that chromium supplements (in the form of chromium picolinate) improve muscle gains during strength training. Yet, in a more recent, well-designed study on football players, those who weight-trained four days a week while taking 200 micrograms of chromium saw no increase in muscle mass compared to a placebo group.

As for endurance athletes, research on runners has shown that exercise speeds chromium loss via the urine following exercise. This has led some researchers to believe that endurance athletes need more chromium, particularly since they tend to eat a high-carbohydrate diet that requires more insulin (hence more chromium) for carbohydrate processing.

But is this the case? And what about supplementation? First of all, scientists don’t have enough hard information to firmly establish an RDA for chromium. Chromium is difficult to measure in foods, plus we can’t even track whether we’re getting enough. Therefore, there’s a range, 50 to 200 micrograms, that is designated as safe and adequate. And, chances are, you’re getting that much.

Just beware of eating too many refined foods, such as white bread and sweets, which are not only low in chromium but may boost your need for it (to help process carbohydrates). And, as with magnesium, stick with food sources rather than a supplement. Getting too much chromium, which could only happen via supplementation, can hamper your absorption of iron and zinc. Some chromium-rich foods are wheat germ, nuts and—surprise, surprise—beer.

With this mineral, a little really does go a long way. Though you have only about two grams of it in your body, zinc works in tandem with more than 100 different enzymes, many of which participate in energy metabolism. Zinc is also essential for a healthy immune system. In fact, endurance exercise seems to reduce zinc levels in the body, which may be part of the reason why runners are more prone to colds and upper respiratory tract infections immediately following races or tough workouts.

In one study, athletes had twice the zinc loss through urine following a six-mile run compared to when they didn’t exercise. When you realize that a small amount of zinc is also lost in sweat, and that many people don’t get their RDA to begin with, you see why up to 40 percent of athletes may have below-normal levels of zinc in their blood.

Part of the problem is that runners tend to shy away from the best sources of zinc—oysters, clams, liver and several other meats—because of meat’s relatively high fat content. That’s understandable, but you can also get zinc from low-fat foods such as wheat germ, fortified breakfast cereals and black-eyed peas.

Unlike with magnesium and chromium, supplementation may be the best way to ensure you get your RDA for zinc (15 milligrams for men; 12 for women). Look for a vitamin/mineral supplement containing no more than the RDA. Remember that high-fiber foods and the tannins found in coffee, some teas and wine can hamper zinc absorption, so plan your zinc intake accordingly.

Also, keep in mind that too much zinc blocks the absorption of copper, which in turn hampers iron absorption. Admittedly, you’d have to get a lot of zinc to do this, as copper deficiency normally results from zinc intakes of six times the RDA. Lastly, you should know that over-supplementation with zinc has been shown to lower “good” HDL cholesterol and raise “bad” LDL cholesterol.

You’ll notice an increasing amount of shelf space devoted to gluten-free foods, including cookies, crackers, and cereals. Eat at restaurants such as Chili’s, P.F. Chang’s, or Boston Market, and you can order gluten-free chicken-noodle stir-fry and chocolate cake for dessert. Add to this all the books and Web sites professing the benefits of gluten-free eating, and suddenly carb-loving runners can’t help but wonder if a diet without gluten is worth biting into.

Going gluten-free is, without a doubt, essential for runners with celiac disease (CD) and gluten intolerance (GI), says Julie McGinnis, R.D., a dietitian who has GI and runs the Web site
www.theglutenfreebistro.com
. Both disorders can cause stomach cramping, diarrhea, constipation, bloating and, in the case of CD, nutrient malabsorption; eliminating gluten prevents symptoms. But what about the rest of us? Can runners without CD or GI expect any health or performance benefits from giving up gluten—a protein in wheat, spelt, kamut, barley, and rye? It’s a question athletes are asking. The Garmin-Transitions pro cycling team even eats gluten-free when racing, claiming it helps performance by easing inflammation and digestion.

But most runners shouldn’t give up their bagels and pasta. Lara Field, R.D., a marathoner and dietitian who works with celiac patients at Comer Children’s Hospital at the University of Chicago, says for healthy runners there is no evidence whatsoever that gluten-free eating offers any performance benefits over a balanced diet that contains gluten. “The theory that removing wheat from your diet is going to ease inflammation and digestion and speed exercise recovery just doesn’t hold up for most,” says Field.

Of course, you’re doing yourself a favor if you replace heavily processed gluten-containing foods with more nutritious whole foods, like fruits, vegetables, nuts, and beans, says McGinnis. She points out that some of the most nutrient-dense whole grains, such as buckwheat, quinoa, brown rice, and teff, provide complex carbs, fiber, iron, and B vitamins.

Field warns that a poorly planned switch to gluten-free can backfire, leading to an inadequate intake of complex carbs, vitamins, and minerals found in runner staples. And, while there are lots of healthy gluten-free packaged foods, “not all are nutritional bell ringers,” Field says. “Some people associate ‘gluten-free’ with ‘healthier,’ but a runner who isn’t careful could end up eating a lot of refined carbs and added fats, leading to weight gain.”

Nor is it easy (or inexpensive) to go gluten-free. The wheat protein is in a dizzying array of products, including soups, deli meats, salad dressings, cheese spreads, roasted nuts, energy bars, veggie burgers, condiments, sauces, and ice cream in the form of malt flavoring, soy sauce, and other seasonings. “It takes a keen eye to spot gluten on food labels,” says Field.

McGinnis encourages runners who believe gluten could be causing them stomach trouble to speak to their doctor. Those who test negative for celiac but continue to experience symptoms can try strictly eliminating gluten from their diet for 7 to 10 days to test for a gluten sensitivity. “If you find this clears up your woes and your runs improve, gluten is likely the culprit,” McGinnis says.

But before making any major changes to your diet, seek the guidance of a registered dietitian. “Overhauling your diet to weed out gluten can get overwhelming fast,” says Field. At the Web site
www.eatright.org
, you can find a local dietitian who specializes in gluten-free living and can help eliminate some of the guesswork to ensure you meet all your nutritional needs. And runners who eat pasta, bread, and other gluten-containing foods with no ill effects can feel confident knowing that sticking to your balanced diet is a great way to get all the nutrients your body needs, so you can run your best.

Delicious options any runner could love

King Soba 100% Buckwheat Noodles:
Use fast-cooking soba noodles made from buckwheat flour in place of traditional pasta.
kingsoba.com

Bob’s Red Mill Gluten-Free Pancake Mix:
This flapjack mix is made with sorghum flour, a good source of fiber.
bobsredmill.com

Vega Whole Food Energy Bars:
Pleasantly moist, these plant-based bars are packed with protein, fiber, and omega-3 fats.
www.myvega.com

Ruth’s Foods Chia Goodness Cereal:
Rich in fiber and healthy fats, this hardy cereal will keep you full.
www.ruthsfoods.com

Amy’s Rice Crust Spinach Pizza:
With its crunchy crust, this frozen pizza tastes similar to traditional pies.
www.amys.com