Wednesday, August 29, 2012

Homoarginine Improves BMD

Protein, and the amino acids from which they are built, are important for maintaining muscle mass. Just look at all the buff athletes chugging down whey protein shakes at your local gym. But what about protein for bone health? A debate rages over just how much dietary protein is enough and how much is so much that it becomes detrimental to bones? This is a common question my patients often ask.

Research shows that diets high in protein from red meat and dairy, contributes to a heavy acid load, a condition ripe for excessive bone resorption. Reducing protein intake, especially from these sources, is wise. But a problem arises when people become fearful of protein. A diet low in quality protein is devoid of important amino acid building blocks necessary for muscle and bone formation.

Of the most common 20 amino acids found in dietary protein, 10 of them are termed "essential." These essential amino acids must be obtained from food because your body is unable to manufacture them.  L-lysine is an essential amino acid and important for bone health. It is also commonly deficient, especially in the vegetarian diet.

Lysine aids in the absorption of calcium and it is a necessary component of bone collagen cross-linkage formation. Lysine is also necessary for the formation of another amino acid, homoarginine.

The amino acid homoarginine (an analog [similar] to L-arginine) is synthesized mainly in the kidneys. For years, scientists have known that homoarginine is important for nitric oxide production and energy metabolism making it extremely important for vascular health and heart function (low levels of homoarginine are associated with a high incidence of sudden cardiac death) but new research shows that homoarginine is also important for skeletal health.

In a recent paper published in Osteoporosis International, researchers (Pilz et al., 2012) found homoarginine deficiency to be associated with high bone turnover and low bone mineral density (BMD). A key enzyme (L-arginine:glycine amidinotransferace or AGAT) is necessary for the conversion of lysine to homoarginine in the kidneys and if any of these players are missing (i.e. lysine, enzyme, or kidney function), blood levels of homoarginine will drop.

Lysine rich foods are red meat, pork, poultry, fish, eggs, and cheeses. All common in the American diet but, unfortunately, acid forming. Because of this, vegetarians as well as those individuals wishing to avoid excess acid forming proteins, often become deficient in lysine and therefore unable to manufacture adequate amounts of homoarginine. Strict vegetarians can obtain their lysine from legumes such as soy, beans, peas, lentils, and peanuts. Quinoa is also fairly high in lysine. For individuals not on a vegetarian diet, but trying to maintain a more neutral body pH conducive for healthy bone remodeling activity, you need to remember that not all acidic foods are bad. Protein is important for the construction of bone. Wild-caught sea food, naturally raised poultry, and grass-fed beef are good sources of quality animal protein as well as lysine. In addition, supplementing with Osteo-pHBalance (an alkalinizing formula with potassium), is packed with spirulina and chlorella, which are both good sources of lysine.

Pilz S., A. Meinitzer, A. Tomaschitz, et al. 2012 Associations of homoarginine with bone metabolism and density, muscle strength and mortality: cross-sectional and prospective data from 506 female nursing home patients. Osteoporosis Int 10.1007/s00198-012-1950-9.

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