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Cyanocobalamin

The name vitamin B₁₂ (or B₁₂ for short) is used in two different ways. In a broader sense it refers to a group of Co-containing compounds known as cobalamins - cyanocobalamin (an artifact formed as a result of the use of cyanide in the purification procedures), hydroxocobalamin and the two coenzyme forms of B₁₂, methylcobalamin (MeB₁₂) and 5-deoxyadenosylcobalamin (adenosylcobalamin - AdoB₁₂). more...

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Chenodeoxycholic acid

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In a more specific way, the term B₁₂ is used to refer to only one of these forms, cyanocobalamin, which is the principal B₁₂ form used for foods and in nutritional supplements.

Pseudo-B₁₂ refers to B₁₂-like substances which are found in certain organisms, such as Spirulina spp. (blue-green algae, cyanobacteria). However, these substances do not have B₁₂ biological activity for humans.

Structure

B₁₂ is the most chemically complex of all the vitamins. B₁₂'s structure is based on a corrin ring, which, although similar to the porphyrin ring found in heme, chlorophyll, and cytochrome, has two of the pyrrole rings directly bonded. The central metal ion is Co (cobalt). Four of the six coordinations are provided by the corrin ring nitrogens, and a fifth by a dimethylbenzimidazole group. The sixth coordination partner varies, being a cyano group (-CN), a hydroxyl group (-OH), a methyl group (-CH₃) or a 5'-deoxyadenosyl group (here the C5' atom of the deoxyribose forms the covalent bond with Co), respectively, to yield the four B₁₂ forms mentioned above. The covalent C-Co bond is the only carbon-metal bond known in biology.

Synthesis

B₁₂ cannot be made by plants or by animals, as the only type of organisms that have the enzymes required for the synthesis of B₁₂ are bacteria and archaea.

Functions

Coenzyme B₁₂'s reactive C-Co bond participates in two types of enzyme-catalyzed reactions.

Rearrangements in which a hydrogen atom is directly transferred between two adjacent atoms with concomitant exchange of the second substituent, X, which may be a carbon atom with substituents, an oxygen atom of an alcochol, or an amine.
Methyl (-CH₃) group transfers between two molecules.

In humans there are only two coenzyme B₁₂-dependent enzymes:

MUT which uses the AdoB₁₂ form and reaction type 1 to catalyze a carbon skeleton rearrangement (the X group is -COSCoA). MUT's reaction converts MMl-CoA to Su-CoA, an important step in the extraction of energy from proteins and fats (for more see MUT's reaction mechanism)
MTR, a methyl transfer enzyme, which uses the MeB₁₂ and reaction type 2 to catalyzes the conversion of the amino acid Hcy into Met (for more see MTR's reaction mechanism).

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Advanced nutrition
From Flex, 2/1/06

SOY UPDATE

In the world of protein, soy has gotten a bad rap. After all, it's a vegetable protein. How good can a vegetable protein be, right? According to new research, the vegetable protein from soy is damn good. In fact, soybeans contain all eight essential amino acids and plenty of vitamins and other nutrients. Gram per gram, soy protein has an amino acid content that is similar to whey. In fact, soy protein is higher in some amino acids--such as arginine and glutamine, two critical amino acids for bodybuilders--than whey protein.

Quality aside, even bodybuilders who can accept that soy gets high marks as a protein source worry about its estrogenlike components. Soybeans contain high amounts of isoflavones. These powerful antioxidants have been linked to numerous health benefits, such as fighting certain types of cancer and reducing cholesterol levels.

What makes most men fearful of those isoflavones is the fact that their chemical structure closely resembles that of the female sex hormone, estrogen. Since bodybuilders want to keep their estrogen levels low to help them increase muscle mass, limit bodyfat and minimize fluid retention, most avoid soy protein like the plague. Many bodybuilders worry that the isoflavones will compete with the anabolic effects of testosterone to lessen muscle mass, increase bodyfat and fluid retention, and quite possibly cause the development of feminine features, including gynecomastia (quaintly referred to as "bitch tits"). Research presented at the 2005 Experimental Biology conference in San Diego, California, should put those fears to rest. Scientists in the Nutrition Division of Miami Research Associates (Florida) compared four different protein powders (soy protein concentrate, soy protein isolate, a soy/whey blend and whey protein isolate) for their ability to increase muscle mass and affect hormone levels--namely, testosterone and estrogen.

They fed 41 bodybuilders one of the listed protein shakes twice a day for 12 weeks. At the end of the period, they discovered that all of the protein supplements increased lean body mass by the same amount. Yes, soy protein increased muscle mass just as well as whey protein did. In addition, they found no difference in effects on testosterone or estrogen levels.

So, it appears that in an effort to be cautious, many bodybuilders miss out on a great source of protein that offers a multitude of benefits. It offers many health advantages, including a possible decrease in the risk of prostate cancer. Also, other studies have indicated that its antioxidant content may help to improve muscle recovery following exercise. This, plus the fact that soy is a fast-digesting protein, makes it a great choice before and after workouts.

For best results, go with a mixed protein such as soy plus whey to get the benefits of both high-quality proteins. If you can't find a premixed product, purchase one container of soy and one container of whey and mix them evenly.

--Jim Stoppani, PHD

SOUPED UP

Q | I was at the 2005 Olympia expo and saw displays promoting high-protein soups. What's your take on this?

A | It's a nice protein gimmick--at FLEX, we support almost any product that helps you get in your daily protein allotment. Every bodybuilder should take in at least one gram of protein per pound of bodyweight each day. For some bodybuilders, this can be the biggest day-to-day challenge. Many foods that are high in protein are also hard to consume in large enough quantities to give you all the protein you need. (See the "Protein Quotas" sidebar.) Some are also expensive.

Protein technology has advanced dramatically over the years, and now there are many products that can help you accomplish job one as far as nutrition is concerned. Consider trying different products to see which ones work best for you.

In addition to protein soup, here are just a few of the available products and new protein foods: protein breakfast cereals, protein cookies, protein dessert bars, protein pasta, protein coffee creamer, protein pudding and even high-protein ice cream.

One of the best ways to become familiar with new products is to visit a bodybuilding or fitness expo. Often, you can try new protein technology foods right there or get free samples to try at home. Another way is to find a health-food or bodybuilding-nutrition store and talk to the staff about which products they like.

Whether you rely on new protein products, whole-food protein sources or powders and shakes, the most important thing is to find protein foods that taste good to you, fit your budget and help you to get in a gram of protein per pound of bodyweight each day.

--Steve Stiefel

GUNTER SCHLIERKAMP'S HIGH-CALORIE DIET

"Many people thought I looked as good as I ever have at the 2005 Mr. Olympia. But many people were also surprised to see how much food I was eating while I was on my 'diet' during the weeks before the show. When you weigh 300 pounds and have a large amount of muscle mass, you absolutely must consume a large number of calories just to maintain that mass. Shedding bodyfat for a bodybuilding show is a balancing act of eating all the calories you need to keep your muscle mass while cutting calories low enough to encourage bodyfat burning. That's true no matter how much you weigh. It's just that in my case, the calories for maintaining muscle mass are considerably higher than they are for a smaller bodybuilder.

--Gunter Schlierkamp

JUICE WITH JACK

Like Joe Weider, nonagenarian Jack LaLanne keeps revolutionizing the bodybuilding and fitness industry. Whereas Weider continues his emphasis on the sport of bodybuilding, magazines and his eponymous nutrition company, LaLanne has recently become a proponent of health and fitness products through infomercials. Both of these men suffered derision, which typically comes from being ahead of one's time--never mind that they were both correct. Today, they continue to reap the rewards of a persistent belief in their pioneering fitness philosophies.

As part of that legacy, LaLanne is now busy marketing his sleek new Power Juicer Elite. This model is powerful enough to juice whole pieces of fruit, including cherries and plums with their pits. This makes processing juice much easier since it eliminates cutting and prep work. The juicer is also great for making higher protein "milk," such as soy, rice and nut milk. "You can also use the fiber-rich pulp for making spreads, dips, breads and soups," LaLanne says.

FLEX has long been a proponent of using juicers to enhance nutrition. A vegetable juicer can instantly boost your intake of daily nutrients--it's much easier to get several servings of vegetables in liquid form. Although juicing removes the fiber, many of the other nutrients are still contained in the juice. The only caveat is that although vegetable juice is low in calories, they count toward your daily carb consumption. Vegetable juice can have a greater impact on blood sugar and insulin levels than whole vegetables, which are digested more slowly because of the fiber in them, and juice provides less satiety than its whole counterparts.

To add protein and other nutrients to your diet, give LaLanne's juicer a try. As an alternative to do-it-yourself fresh juice, try the offerings at Jamba Juice, Whole Foods Market or other stores that sell vegetable, fruit and protein-food juices.

--Steve Stiefel

WAY TO B

Q | My preworkout supplement contains 10,000% of the daily value of vitamin [B.sub.12]. Is that safe?

A | In a word, yes. The risk of vitamin [B.sub.12] toxicity is so low that an upper intake level has not been established--there are no known adverse effects from consuming high levels of the vitamin. Although getting 10,000% of the daily value (DV) of [B.sub.12] from a supplement may seem excessive, remember that supplements are concentrated forms of nutrients. So the level is not that high considering that just three ounces of clams--a whole food--provide about 1,400% of the DV.

Another question you may want to ask is why preworkout supplements would contain [B.sub.12] in the first place. The answer is that [B.sub.12] is effective at promoting better workouts. Vitamin [B.sub.12] exists in two primary forms: methylcobalamin and cyanocobalamin. Methylcobalamin is typically referred to as the active form of [B.sub.12] and is involved in the conversion of homocysteine to methionine.

This is important because high blood levels of homocysteine have been associated with increased risk of cardiovascular disease. The conversion of homocysteine to methionine lowers the amount of homocysteine in the blood.

Vitamin [B.sub.12] is also involved in a number of other physiological processes. It helps in the production and utilization of energy from dietary fat and protein, especially during exercise. In other words, without [B.sub.12], our bodies would be much less efficient at utilizing energy from protein and fat.

When a body is less efficient at using energy, calories are more likely to get stored as fat. Vitamin [B.sub.12] is also indirectly involved in the production of hemoglobin, the oxygen-carrying molecules in red blood cells. Adequate hemoglobin production is important because low levels of it are associated with fatigue and shortness of breath, and these can take away from strength, endurance and overall physical health.

Vitamin [B.sub.12] is very easily attainable from food sources. Aside from clams, it's naturally found in oysters, salmon, sardines, meat, eggs and dairy products. Fortified breakfast cereals are also a rich source of vitamin [B.sub.12]. Vitamin [B.sub.12] is also an ingredient in most multivitamins, B-vitamin complexes and some preworkout/energy supplements.

So don't be afraid of large doses of vitamin [B.sub.12]. It plays a number of important roles in your body. Most B-complex supplements provide 50-500 micrograms (mcg) of [B.sub.12] and some standalone [B.sub.12] supplements offer up to one milligram (1,000 mcg). Although 50-100 mcg of [B.sub.12] are adequate, taking up to six milligrams, as found in a preworkout supplement, is safe.

--Steve O'Reilly, RD, LD

MO JO

How do most Americans get antioxidants? The answer may surprise you: in coffee.

Although coffee is high in antioxidants, it is not as high as foods such as blueberries and many other dark berries. The difference is that Americans don't eat a lot of dark berries and they do drink a lot of coffee. They get a significant percentage of their total antioxidant intake from the brew--more than from any other single food item (in second place for providing antioxidants is tea).

In fact, most of the recent research on coffee has been quite positive. For a while, coffee was demonized by researchers looking at its more harmful effects (links to heart attacks, cancer, etc.). Lately, though, coffee has been shown to be a benign stimulant that can help burn bodyfat, curb appetite, increase energy production and boost performance in the gym. It does so with almost no calories, when taken black.

As far as FLEX is concerned, the only problem with coffee consumption is that it can inhibit sleep for people who are sensitive to its stimulant effects.

DOWNING'S MEAL MEMO

"When it comes to nutrition, everyone's looking for a magic pill," Garrett Downing tells FLEX. "But I've always found that when you do the simple things regularly, you get the best results." This is true when it comes to Downing's workout nutrition.

"A lot of bodybuilders overlook the importance of simple carbs around the time of their workouts. Every bodybuilder seems to have heard the protein message loud and clear, but, since dealing with carbs is a little trickier, a lot of bodybuilders undervalue them and don't always do what they should."

Downing stresses that it's important to go light on simple carbs (e.g., sugar, honey, white bread) most times of day, but that it's also critical to load up on them before and after workouts. "Simple carbs drive the protein and really boost gains. I rely on dextrose, which is the best form of simple carbs for bodybuilders seeking to add muscle mass."

Dextrose (or glucose) is harder to find than table sugar (a mix of glucose and fructose). "I go in with a couple of bodybuilding friends and buy a big five-pound package of it," Downing says. "It costs only three to four bucks apiece. It's cheap and it goes a long way. The only problem is that it looks like a drug deal when we're standing out on the street, scooping white powder into Ziploc bags to divide it up."

Downing recommends a preworkout shake that includes 40-80 grams (g) of dextrose and a postworkout shake with as much as 100 g. Add 40-50 g of whey protein to each of these shakes, plus glutamine, creatine and arginine, if those supplements are part of your nutrition plan.

"Bodybuilding nutrition is built on a simple equation: eat quality foods to add quality mass."

--Victor Martinez

MUSCLE MORSELS During diet phases, dramatically increase your fiber consumption to help decrease bodyfat levels. Use this formula: eat at least 2 g of fiber for every 10 pounds of bodyweight each day. That's about 40 g of fiber for a 200-pound bodybuilder.

MUSCLE MORSELS If you don't take in sufficient vegetables, grill them ahead. Cook enough asparagus, zucchini, peppers and broccoli to last three or four days. Grilled vegetables taste great, have no added calories and can be easily reheated.