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by Dr. Eleanor Kellon

Considering all the important tasks L-methionine performs, it is perplexing you don't hear or read more about it.

L-methionine is one of the essential amino acids, meaning the horse must get his supply from the diet because the body cannot manufacture it. Methionine is a structural amino acid which means you can find it in all proteins in the body, from skeletal muscle to hemoglobin, antibodies and enzymes. Methionine is also required for the initiation of building proteins in the body.

Methionine can be converted to the other two sulfur containing amino acids, cysteine and cystine. Sulfur bonds between cystine amino acids strengthen the structure of hooves, hair, tendons and ligaments.

Methionine is required for the production of:

  • Taurine - central to health of the heart, nervous system and eyes
  • L-carnitine - a carrier that is necessary to burn fats for energy
  • Metallothionein - a protein which binds excess dietary minerals, and toxics, and carries them back into the bowel for excretion
  • Creatine - the carrier of high energy bonds for muscle contraction
  • Glutathione - the body's master antioxidant

Methionine also functions as a methyl group donor by being the precursor for SAM. Transfer of methyl groups (transmethylation) is involved in a host of body functions including:

  • Detoxification reactions in the liver
  • Production of epinephrine
  • Regulation of the activity of DNA
  • Production of the active form of the vitamin folic acid
  • Recycling of methionine
  • Regulation of the immune response
  • Recycling of glutathione into an active form
  • More is never better even with a nutrient this important, but unfortunately we really don't even know what the equine methionine requirement is! A look at the most common things fed to horses quickly shows they are mostly on the low end for methionine (see chart available at

    Hays also vary in methionine content quite a bit, based on both their protein content and the type of hay. Levels are dropping in many areas since pollution controls have greatly reduced the levels of sulfuric acid in the air, which was serving as a natural sulfur fertilizer.

    The current best guess for methionine requirement in adults is that it is 1/2 to 1/3 of the lysine requirement. If your horse has outward signs consistent with inadequate methionine such as weak hoof structure, consider supplementing with 2500 to 5000 mg of methionine/day. This is commonly paired with 7 to 10 grams of lysine, another amino acid that is often deficient.

    Uckele Health & Nutrition, maker of CocoSoya®, offers formulas that provide Methionine support.

    Tri-Amino helps maintain strong muscles, healthy weight, and supports a healthy topline with the three most essential amino acids. Lysine aids in bone health and immune function. Methionine plays a role in the synthesis of structural proteins, especially hooves and connective tissues, and hair and mane coat. Threonine aids in healthy immune function.

    DL-Methionine is a highly concentrated source of the essential amino acid DL-Methionine. Supports the health and integrity of the body proteins, joints, tendons, ligaments and other connective tissues. Also promotes healthy liver function and detoxification.

    Dr. Eleanor Kellon, VDM
    Dr Eleanor Kellon, DVM

    About Dr. Kellon

    . Dr. Eleanor Kellon, staff veterinary specialist for Uckele Health & Nutrition, is an established authority in the field of equine nutrition for over 30 years, and a founding member and leader of the Equine Cushings and Insulin Resistance (ECIR) group, whose mission is to improve the welfare of horses with metabolic disorders via integration of research and real-life clinical experience. Prevention of laminitis is the ultimate goal.

    Uckele Health & Nutrition, maker of CocoSoya, is an innovation-driven health company committed to making people and their animals healthier. On the leading edge of nutritional science and technology for over 50 years, Uckele formulates and manufactures a full spectrum of quality nutritional supplements incorporating the latest nutritional advances.

    This article originally appeared on and is published here with permission.

    Find more informative articles in our section on Health & Education.

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