From: young@clpd.kodak.com (Rich Young)
Newsgroups: rec.food.veg
Subject: Re: Milk and calcium (here we go again)
Date: 24 Jan 93 18:12:33 GMT
Article-I.D.: pixel.1993Jan24.181233.27868
Reply-To: young@clpd.kodak.com
Organization: Clinical Diagnostics Division, Eastman Kodak Company
Originator: young@sasquatch

In article <C1CGKE.Mq1@wpg.com> russ@wpg.com (Russell Lawrence) writes:
>From article <1993Jan23.174154.349@pixel.kodak.com>, by young@clpd.kodak.com (Rich Young):
>> .....if blood calcium is high in 
>> the first place, perhaps due to increased consumption, then one 
>> might reasonably expect a similar rise in urinary calcium, regardless 
>> of diet...
>
>[see the abstract below]

	The abstract says nothing about high blood levels as they relate
	to urinary excretion.

	From FUNDAMENTALS OF CLINICAL CHEMISTRY, N. W. Tietz, Ph.D., ed., 
	"Calcium and Phosphate Metabolism", Donald Fraser, M.D., Ph.D., 
	Glenville Jones, Ph.D., Sang Whay Kooh, M.D., Ph.D., F.R.C.P.(C), 
	Ingeborg C. Radde, M.D., Ph.D., F.R.C.P.(C); W. B. Saunders, 1987:

	   URINARY Ca(T) is usually expressed as a 24-hour excretion rate;
	   the excretion depends on many variables including dietary intake
	   of calcium [1].  Ninety per cent of healthy men excrete less
	   than 300 mg./day, and 90% of healthy women excrete less than
	   250 mg./day [1,2,3,4,5].  Children excrete less than 6 mg. per
	   kilogram of body weight per day [1].

	[Note that the participants in Russell's quoted study changed from
	 an average excretion rate of 103 mg./day to an average excretion
	 rate of 150 mg./day.  The reference range for adults consuming
	 800 mg./day is 100-300 mg./day.]

	   In a voided urine sample, the ratio of the concentration of
	   calcium to creatinine (Ca:Cr) provides a convenient and fairly
	   reliable index of the rate of calcium excretion when muscle mass
	   is constant (i.e., not during growth).  The ratio of urinary 
	   Ca:Cr adults is normally less than 0.14 when both [analytes] are
	   measured in mg./dL.  A value greater than 0.20 (using mg./dL.)
	   in a fasting specimen signifies hypercalcuria [6].  The lower
	   limit of normal calcium excretion in urine is about 75 mg./day.

	[Note that the abstract Russell supplied makes no mention of
	 creatinine measurement.  Creatinine is involved in muscle tissue
	 metabolism.  It is the anhydride of creatine, which is synthesized
	 in various organs.]

	[1] Knapp, E. L. Factors influencing the urinary excretion of
		calcium. I. In normal persons. J. CLIN. INVEST. 28:182-96,
		1947.

	[2] Bijvoet, O. L. M. Kidney function in calcium and phosphate
		metabolism. IN: Metabolic Bone Disease, Vol. 1, L.V. Avioli
		and S.M. Crane, eds.; Academic Press, 1977, pp. 49-140.

	[3] Hodgkinson, A., et. al. The urinary excretion of calcium and
		inorganic phosphate in 344 patients with calcium stone of
		renal origin. BR. J. SURG. 46:10-18, 1958.

	[4] Nordin, B. E. C., et. al. Hypercalcuria and calcium stone
		disease. CLIN. ENDOCRINOL. METABOL. 1:169-183, 1972.

	[5] Robertson, W. G., et. al. The distribution of urinary calcium
		excretion in normal persons and stone formers. CLIN. CHIM.
		ACTA. 37:503-508, 1972.

	[6] Pak, C. Y. C., et. al. Ambulatory evaluation of nephrolithiasis.
		AM. J. MED. 69:19-30, 1980.

>> It is not clear that excessive consumption of vegetable protein
>> would not cause increased urinary excretion, but this is difficult
>> to test, since excessive consumption of protein from vegetable
>> sources is much less likely due to the decreased nutrient density
>> of most plant sources.  
>
>[see the abstract below]

	I should have said difficult to test epidemiologically.  A series
	of 12-day tests on 15 individuals is not necessarily representative
	of the eating habits of the population as a whole on a daily basis.

>> There is, however, at least one study which 
>> implicates cereal grains in bone loss, and another which mentions 
>> soy protein.  
>
>Post them.

	Barzel, U. S. Acid loading and osteoporosis. J. AM. GERIATRICS SOC.,
	September 1982.

	Allen, G. H. Protein-induced hypercalcuria: A longer term study.
	AM. J. CLIN. NUTR. 32:741-9, 1979.

>> My own opinion is that excessive protein consumption,
>> regardless of source, will increase urinary excretion of calcium.
>
>[see below]

	See above.


-Rich Young (These are not Kodak's opinions.)
Newsgroups: rec.food.veg