The Ultimate Guide To B Vitamins

Understanding how the B vitamins work in the body can help you maximize both health and performance.
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In the large and storied family tree of lettered vitamins, you’re probably most familiar with C and its connections to immune function. Yet B vitamins may be even more ubiquitous, headlining as a star player in many supplements for their ability to add a little pep to your step. B vitamins do more than just boost energy levels, however. There’s a lot more to know — and be wary of — when using them to support your training goals.

B complex vitamins are a group of water-soluble vitamins that exist together in many food sources. They work to support metabolism by acting as coenzymes that convert protein and carbohydrates into energy in the body. They also maintain skin and muscle tone, support the immune system, maintain nerve function and support cellular growth. The B complex vitamins are best supplemented in a formulation that contains them all in balance, and most daily multivitamins created for athletes include an abundance of B complex vitamins.

Supplement research over the years has noted the importance of B vitamins in exercise performance, primarily due to their involvement in energy production. The general population’s vitamin and mineral needs are met with a healthy, well-balanced diet, yet the latest evidence suggests that many athletes are vitamin deficient and likely unaware of being so. These deficiencies — especially in strength athletes and those who follow bodybuilding-style routines — are predicted to occur for several reasons:

  1. They tend to follow strict and limited diets with very little variety, especially during the competitive season.
  2. The body’s energy-producing metabolic pathways are pushed to the limit during intense training. As such, the requirements for some of the vitamins used in these pathways may increase.
  3. As the body’s metabolism adapts to heavy training, micronutrient requirements tend to increase.
  4. Exercise can lead to a loss of micronutrients in sweat, urine and feces.
  5. Vitamin requirements increase with greater muscle mass.

If you can relate to any or all of these five points, read on to find out more about B vitamins and how you can use them to keep your program on track. With each one we include the recommended doses for both general health and athletic types, including those of us who like to lift heavy things up and then put them back down.

B1

Thiamine (B1) maintains metabolism and promotes cells’ ability to produce energy from carbohydrates. It also plays a role in muscle contraction and conduction of nerve signals.

Sources: Legumes, liver, pork, whole grains

Signs of deficiency: Confusion, edema, impaired growth, muscle weakness and wasting, weight loss. Drinking alcohol can deplete the body’s thiamine levels.

Recommended daily allowance: 1.2 milligrams

Recommended athletic dose: 100 milligrams twice daily

B2

Riboflavin (B2) promotes carbohydrate metabolism and fatty acid oxidation (fat burning), and maintains healthy skin and vision.

Sources: Eggs, green vegetables, liver, milk, whole-grain products

Signs of deficiency: Cracks in lips, inflammation of tongue, sensitivity to sunlight

Recommended daily allowance: 1.3 to 1.7 milligrams

Recommended athletic dose: 100 milligrams twice daily

B3

Niacin (B3) helps the digestive system, skin and nerves to function properly. It is important in the process by which food is metabolized to produce energy. Some research suggests that taking too much niacin blunts fat burning during aerobic exercise. Yet when taken in adequate daily doses it may reduce cholesterol, enhance thermoregulation and improve energy availability during exercise.

Sources: Dairy products, eggs, enriched breads and cereals, fish, lean meats, legumes, nuts

Signs of deficiency: Niacin deficiency leads to a disease called pellagra, manifesting as digestive problems, inflamed skin and mental impairment.

Recommended daily allowance: 16 milligrams

Recommended athletic dose: 100 milligrams twice daily

B5

Pantothenic Acid (B5) is an underrated player in the B family. It acts as a coenzyme for acetyl coenzyme A (acetyl CoA), which plays a central role in energy production and metabolism. In addition, B5 is important in the breakdown of fats and carbohydrates for energy, and is critical to the manufacture of red blood cells as well as sex and stress-related hormones produced in the adrenal glands (situated atop the kidneys). Vitamin B5 helps to maintain a healthy digestive tract and assists the body in the use of other vitamins, particularly B2 and riboflavin.

Sources: Avocado, beef (especially organ meats such as kidney and liver), broccoli, cauliflower, chicken, corn, duck, egg yolk, kale, legumes, lentils, lobster, milk, peanuts, salmon, soybeans, sunflower seeds, sweet potatoes, tomatoes, turkey, whole grains

Signs of deficiency: Burning feet, depression, fatigue, insomnia, irritability, stomach pains, upper respiratory infections, vomiting

Recommended daily allowance: 5 milligrams

Recommended athletic dose: 100 milligrams twice daily

B6

Pyridoxine (B6) promotes protein metabolism and absorption, helps with red blood cell production and enhances fat metabolism. B6 is needed for the production of serotonin in the brain, which increases focus and mental health. It is also involved in norepinephrine production in the body, which regulates blood flow to skin and muscle, and fat metabolism in fat cells.

Sources: Dairy products, green leafy vegetables, legumes, liver, pork, whole grains

Signs of deficiency: Anemia, cracks in lips, kidney stones, nausea, skin disorders

Recommended daily allowance: 1.3 milligrams

Recommended athletic dose: 100 milligrams twice daily

B7

Biotin (B7 or H) is important in cell growth and metabolism of fats and amino acids. It has been shown to increase insulin sensitivity and help regulate blood glucose levels.

Sources: Almonds, carrots, eggs, onions, peanuts, salmon, sweet potatoes, tomatoes, walnuts

Signs of deficiency: Biotin deficiency is rare, since the body’s intestinal bacteria can produce it. However, eating raw egg whites can decrease biotin levels in the body, and a few digestive diseases may limit the body’s biotin production and absorption, leading to conjunctivitis (pinkeye), depression, dermatitis, hair loss, hallucination, numbness and tingling of the extremities, and tiredness.

Recommended daily allowance: No RDA established

Recommended athletic dose: 300 micrograms twice daily

B9

Folic Acid (B9 or M) is key in DNA (gene) synthesis and repair, and is an important contributor to protein metabolism and red blood cell formation. It is especially vital under conditions of rapid cell division and growth, which is why women are advised to take it during pregnancy. Finally, folic acid decreases homocysteine levels, reducing the risk of heart disease.

Sources: Bananas, beef (especially organ meats such as kidney and liver), green leafy vegetables, legumes, lemons, melons, orange juice

Signs of deficiency: Anemia, confusion, depression, diarrhea. Drinking alcohol can deplete the body’s folic acid levels.

Recommended daily allowance: 400 micrograms

Recommended athletic dose: 400 micrograms twice daily

B12

Cobalamin (B12) is a coenzyme involved in the production of serotonin and DNA, the latter of which makes B12 an important player in protein and red blood cell synthesis. Adequate vitamin B12 is needed for increasing muscle mass and the oxygen-carrying capacity of blood, and decreasing anxiety.

Sources: Beef (especially organ meats such as kidney and liver), eggs, fish, milk, oysters, shellfish

Signs of deficiency: Anemia, neurological disorders, numbness in fingers or toes

Recommended daily allowance: 2.4 micrograms

Recommended athletic dose: At least 100 micrograms twice daily

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