Tag Archives: kidney stones

August 26, 2012 · 2:00 AM

Kidney Stones on the Rise

“Ah hah! There it is, stuck in the ureter.”

MedPage Today in May, 2012, reported a substantial increase (70%) in the prevalence of kidney stones in the U.S. over the last two decades. Stone prevalence rose from 5.2% to 8.8% of the population.  Prevalence was based on the periodic National Health and Nutrition Examination Survey, which asked participants, “Have you ever had kidney stones?”

Stone prevalence began rising even earlier.  Again according to the third NHANES, prevalence increased from 3.8 percent in the period 1976 to 1980 to 5.2 percent in the years 1988 to 1994.

Older studies estimated that one in 10 men and one of every 20 women will have at least one painful stone by the age of 70.

What are kidney stones make of?  

Three out of four patients with kidney stones form calcium stones, most of which are composed primarily of calcium oxalate or, less often, calcium phosphate.  Pure uric acid stones are less than 10 percent of all stones.

Why the increased stone prevalence?  Does diet count?

Unfortunately, the article doesn’t offer any speculation as to why kidney stones are more prevalent.  Kidney stones have a genetic component, but our genes have changed very little over just two decades.  I wonder if diet plays a role.

UpToDate.com reviewed diet as a risk factor for kidney stones.  Some quotes:

There are several dietary factors that may play an important role in many patients: fluid, calcium, oxalate, potassium, sodium, animal protein, phytate, sucrose, fructose, and vitamin C intake. Lower intake of fluid, calcium, potassium, and phytate and higher intake of sodium, animal protein, sucrose, fructose, and vitamin C are associated with an increased risk for calcium stone formation. The type of beverage may also influence the risk. The effect of calcium intake is paradoxical, with a decreased risk with increased dietary calcium and an increased or no change in risk with calcium supplements.

The combination of dietary factors may also have a significant impact upon stone risk. As an example, the Dietary Approaches to Stop Hypertension (DASH) diet is high in fruits and vegetables, moderate in low-fat dairy products, and low in animal protein. Based upon an analysis of three large cohorts, adherence to a DASH-style diet lowered the risk for kidney stones among men, older women, younger women, high body mass index (BMI) individuals, and low BMI individuals. Thus, the DASH diet is a reasonable option in the attempt to reduce the risk of stone recurrence.

Higher sucrose [table sugar] intake is associated with an increased risk of stone formation in younger and older women.
Standard advice to prevent initial and recurrent kidney stones is to avoid low urine output.  Do that by drinking plenty of fluid.
Although I pay about $400 a year for access to UpToDate, they offer free public access to some of the website.  Here’s the UpToDate poop sheet on kidney stones.
Extra credit:  Medical conditions that predispose to kidney stones include primary hyperparathyroidism, obesity, gout, diabetes, and medullary sponge kidney.

Comments Off on Kidney Stones on the Rise

Filed under Uncategorized

Tagged as , , , ,

October 24, 2009 · 10:59 PM

My Ketogenic Mediterranean Diet: Day 54 + Potassium Deficiency

The Monument Valley Navajo Tribal ParkWeight: 154 lb

Transgressions: TNTC (too numerous to count)

Exercise: none

Comments

The Potassium Problem

My current food intake on the Ketogenic Mediterranean Diet appears to be low in potassium, which might have long-term health consequences if followed for many months or years.  According to the Linus Pauling Institute’s Micronutrient Information Center, adequate potassium intake apparently decreases blood pressure, reduces salt sensitivity, decreases risk of kidney stones, and protects against osteoporosis and stroke. 

These associations between higher potassium intake and lower condition rates are based mostly on observational studies of populations in which some people eat little potassium and others eat a lot.  It’s assumed that people with higher potassium intake are eating more fruits and vegetables, not taking supplements. 

The Linus Pauling Institute agrees with the U.S. Institute of Medicine’s  “Adequate Intake” value for potassium of 4,700 mg daily for average adults.  The current U.S. Food and Drug Administration Daily Value is about 3,500 mg.  I’m only getting 2,000 mg/day now. 

Multivitamin/multimineral supplements in the U.S. provide a maximum of 99 mg potassium (by law?).  I bought a potassium gluconate supplement at CVS Pharmacy last night: 90 mg potassium, a drop in the bucket.  I dropped into a Hi Health vitamin store (health food store?) today and would swear I saw a combined magnesium and potassium supplement that contained 150 mg potassium. 

Excess potassium intake can be life-threatening in certain situations such as kidney impairment and use of medications like potassium-sparing diuretics and ACE inhibitors. 

Relatively high meat intake tends to create an acidic environment in the body, which our bones help to buffer or counteract.  In the process, calcium in our bones is mobilized and can be lost through urine.  The end result after many years is osteoporosis: thin brittle bones easily broken.  And perhaps calcium-containing kidney stones.  These are traditional concerns about high-protein diets. 

Many fruits and vegetables are considered naturally alkaline, tending to counteract the acid production of other foods. 

I see sporadic reports about potassium bicarbonate supplementation acting as an acid buffer and reducing urinary calcium loss.  Potassium citrate may do the same.  Even potassium chloride may reduce urinary calcium loss separate from any acid buffering capacity (which it shouldn’t have, anyway).  Are those supplements available without a physician’s prescription?  Health food store perhaps?  [Not in Hi Health.]  Would a salt substitute containing potassium chloride be a reasonable source of potassium? 

How about reducing fruit and vegetable consumption, replacing them with a potassium bicarbonate supplement?  Probably not a fair trade.  The food has myriad other nutrients that probably promote health and longevity. 

These potassium-related health concerns are much less bothersome, perhaps nonexistent, when I admit that very few people will follow a very low-carb ketogenic diet for longer than several months.  But it’s an issue.

On the other hand, maybe I worry too much.  Remember, the foods I choose are giving me 2,000 mg potassium daily.  The total potassium could be lower or higher depending on one’s choice of food items.  I have the 1993 edition of Understanding Nutrition, a popular college textbook in basic nutrition.  The table of Recommended Dietary Allowances doesn’t even list potassium.  The text mentions an estimated minimum requirement for potassium of 2,000 mg/day.  The Canadian minimum requirement was 1,170 mg/day. 

About My Diet Transgressions

After 53 days of very low-carb eating, I decided to take a break, a cheat day.  The family was celebrating a milestone.  We drove 2 hours and 20 minutes, one way, to eat at Eat At Joe’s Barbecue in Wikiup, Arizona.  Best Texas-style barbecue outside of Texas.  I had brisket, baked beans, half a roll, cole slaw, stuffed jalapenos, Shiner Bock beer, and cherry pie.  Probably ate 3,500 calories today instead of my usual 1,850.  Expect my weight will be up 2–3 lb tomorrow.  We’ll see how far and how long this transgression sets me back.  All in the name of Science, of course.

–Steve

Update October 25, 2009

At the supermarket today I found an over-the-counter potassium supplement for anyone wanting more non-food potassium in their diet:  Morton Salt Substitute.  A quarter teaspoon has 610 mg potassium.  It contains potassium chloride, fumaric acid, tricalcium phosphate, and monocalcium phosphate.  The container carries a warning: “Consult a physician before using any salt substitute.”  I found it on the shelf near the regular salt.  I also saw a product that was half salt (NaCl) and half potassium chloride (KCl).  I haven’t tried Morton Salt Substitute yet.  It’s a cheaper source of potassium than a potassium gluconate supplement.   

-Steve

3 Comments

Filed under My KMD Experience

Tagged as , , , , , , , , ,

June 30, 2009 · 2:00 AM

Are High-Protein Weight-Loss Diets Safe and Effective?

Animal protein

Animal protein

According to researchers at Tufts University, high-protein weight-loss diets may be effective and safe except for people prone to kidney stones, chronic kidney disease, and people with diabetes.  Long-term effects on bone health – osteoporosis, specifically – might be a problem.

High-protein weight-loss diets have been popular for a while.  “Protein Power” by Drs. Michael and Mary Eades is an example.  The Atkins diet may be, too.  If you increase the protein in your diet, you generally are decreasing carbohydrates or fat, or both, at the same time.   

I found a scientific review article from way back in 2002 and thought I’d share some of the highlights.  The authors seem very thorough; the article has 150 citations of other research articles. 

Note that the RDA – recommended dietary allowance – for protein is 0.8 gm/kg.  The typical U.S. resident eats about 1.2 gm/kg of protein daily, which is about 15% of total energy (calorie) intake.   Public health agencies recommend that we get 15% of our energy from protein, 30% from fat, and 55% from carbohydrate.  The authors of the study at hand propose that a high-protein diet be defined as:

  • protein intake of at least 25% of energy in weight-stable individuals, or
  • at least 1.6 gm/kg (of ideal body weight)  in people actively losing weight

Here are some of the authors’ points I found interesting:

  1. Higher-protein meals do seem to suppress hunger and enhance satiety, so high-protein dieters probably eat less (average 9% less calories).  It’s unknown if the effect lasts longer than six months.  Most of the evidences is much shorter-term.
  2. High-protein intake increases the thermic effect of feeding, meaning energy expenditure increases simply as a result of eating protein.  In other words, it takes energy to process the food we eat.  Compared with fats and carbohydrates, protein contributes twice as much to the thermic effect of feeding.  Most of the thermic effect of protein results from protein synthesis, i.e., the production of new proteins, which requires energy.  This has a minimal influence on body weight. 
  3. The authors write that “these studies do not support a role for high dietary protein in preventing loss of lean tissue during negative energy balance [actively cutting calories to lose weight], provided that dietary protein intake at least meets the RDA.”   
  4. They found only one study comparing a high-protein diet (25% of calories) with a low-fat, high-carbohydrate diet (12% protein).  Both diets were 30% fat.  Both groups could eat all they wanted.  Weight and fat loss were greater in the high-protein group, about twice as much. 
  5. High-protein diets over the long run may cause low-grade metabolic acidosis, leading to net loss of body calcium through the urine, with associated weak bones and kidney stones.   Animal proteins in particular do this.  Bone loss may be alleviated by calcium supplementation.  Fruits and vegetables may counteract the acidosis effect.  Nearly all of these statements are based on short-term studies.
  6. People with chronic kidney disease (ask your doctor) have slower disease progression and live longer if they limit protein to the RDA level. 
  7. Animal protein intake is directly related to risk of symptomatic kidney stones.
  8. Protein produces a blood glucose response, although not as much as with carbohydrate.  Insulin response is also seen.  In type 2 diabetics, the insulin response to 50 grams of animal protein was the same as to 50 grams of glucose.  A few studies suggest that in type 2 diabetics a high-protein diet may be detrimental to glucose control and/or insulin sensitivity.  Also note that people with diabetes are prone to chronic kidney disease, which could be worsened with a high-protein diet.  

Take-Home Points

See first paragraph.  The article authors may have different opinions now, based research published over the last seven years. 

Steve Parker, M.D.

Reference:  Eisenstein, Julie, et al.  High-protein weight-loss diets:  Are they safe and do they work?  A revew of the experimental and epidemiologic data.  Nutrition Reviews, 60 (2002): 189-200.

Comments Off on Are High-Protein Weight-Loss Diets Safe and Effective?

Filed under Diabetes Complications, Protein, Weight Loss

Tagged as , , , , , , , , ,