The presentation shows how person with renal stones are more at risk of recurrent stone formation. How dietary modification can prevent further stone formation.
2. Introduction
Kidney stones are one of the most common disorders of the
urinary tract.
Kidney stones affect about 12% of men and 5% of women by
the time they are 70 years old.
Men are about twice as likely to form kidney stones as
women.
Most people who experience one episode of kidney stones will
experience another and many go on to have multiple
recurrences. Aside from the extreme pain involved in passing a
kidney stone there is also the danger of permanent damage to
the kidney.
3. Why Dietary Control is Important
Those who have formed one calcium oxalate stone have a
50% chance of forming additional stones within 10 years
(Menon & Resnick, 2002).
With appropriate education, patients can exercise some control
over stone disease and reduce their chances of forming
stones through dietary modifications and medication.
4. Metabolic Causes of Kidney Stones
Hypercalciuria - Calcium is absorbed from food in excess and is lost
into the urine. This high level of calcium in the urine causes crystals of
calcium oxalate or calcium phosphate to form in the kidneys or
elsewhere in the urinary tract.
Hyperuricosuria - Uric acid metabolism (gout). Meat, fish, chicken
are restricted due to breakdown products that produce uric acid
crystals.
Hyperoxaluria - the body produces too much oxalate, a salt. When
the urine contains more oxalate than can be dissolved, the crystals
settle out and form stones.
Cystinuria - too much of the amino acid cystine, which does not
dissolve in urine, is voided, leading to the formation of stones made
of cystine.
Renal tubular Acidosis a condition in which the kidneys are unable
to excrete normal amounts of acid.
5. Dietary Causes of Renal Stones
High Low
Dehydration Water intake
Foods rich in Oxalate Calcium than Recommended
Animal protein – Meat, Egg, Low Magnesium
Chicken
Salt – Sodium Potassium than Recommended
Phosphate – Aerated Citrate or Citric Acid (Vit C)
carbonated drinks
Obesity – Weight Gain Dietary Fiber
6. Water
A simple and most important lifestyle change to prevent stones is
to drink more liquids - water is best.
Someone who tends to form stones should try to drink enough
liquids throughout the day to produce at least 2 litres of urine in
every 24-hour period.
It is not the quantity of fluid consumed that is important, but
rather the fluid voided that should be measured. Patients living in
hot or dry conditions, or who exercise and perspire
significantly, will need to drink even more liquid to maintain
adequate urine output.
7. Dehydration
Kidney stones tend to develop more frequently in the summer
months, Because we sweat more when we are hot, we need
even more water to replace what we are losing.
One can tell if one is well hydrated if the colour of the urine is
clear to very light yellow. If your urine is bright yellow, you
need to drink more fluids.
water reduces the concentration of the minerals that might
crystallize into stones.
8. Oxalate combines with calcium - insoluble Calcium Oxalate crystals
Less than 50 mg of oxalate per day in the diet.
Foods high in Oxalate Content
Almonds Peanuts
Amla Phalsa
Amaranth, tender Rhubarb
Beets Soy products (tofu)
Blackberries Spinach
Chocolate/cocoa /chocolate drink mixes Strawberries
Cashew nuts Swiss chard
Okra Tea
Gooseberries Wheat bran
Grapefruit Raspberries (black)
9. Food Portion Oxalate (mg) Calcium (mg)*
Beet greens, cooked 1/2 cup 916 82
Rhubarb, stewed, no sugar 1/2 cup 860 52
Spinach, cooked 1/2 cup 750 122
Beets, cooked 1/2 cup 675 16
Swiss Chard, cooked 1/2 cup 660 50
Spinach, frozen 1/2 cup 600 122
Cocoa, dry 1/3 cup 254 36
Okra, cooked 1/2 cup 146 50
Sweet potatoes, cooked 1/2 cup 141 14
Peanuts 1/3 cup 113 23
Tea 1 cup 75 0
Pecans, halves 1/3 cup 74 11
Wheat germ 1/4 cup 67 12
10. Myth - Dietary Calcium & Kidney Stones
A recent study conducted Brigham and Women’s Hospital
and Harvard Medical School on more than 90,000 women,
showed "that women with the highest intake of dietary calcium
had the lowest risk of kidney stones."
Calcium is believed to neutralize the absorption of oxalate, has
been linked to kidney stone formation."
For those taking calcium supplement the risk of kidney
stones increased slightly. “Calcium supplements are often not
taken in conjunction with meals, limiting the calcium’s ability
to neutralize the absorption of oxalate." This is why diet to
increase calcium intake, and avoid supplements.
11. Dietary Protein and Kidney Stones
A small amount of dietary protein can be converted to oxalic acid
in the body and excreted as such in the urine. In addition, dietary
protein is known to enhance calcium excretion in the urine.
When the average dietary protein was reduced from 86.5 to 54
g/day there was a reduction in urinary calcium excretion of
nearly 50% (from 9.35 to 6.45 mmol/day).
Most protein-rich foods may also increase urinary uric acid
levels. This is because most high-protein foods (except milk)
usually contain a large amount of purines that breakdown into
uric acid.
The risk of kidney stone formation seems greater from animal
than vegetable proteins,
12. Animal Protein
• The higher sulfur amino acid content of animal compared to
vegetable proteins may increase calcium excretion. In addition,
excess sulfur-containing amino acids will increase a rare form
of kidney stones (containing cystine) in people with an
inherited metabolic defect.
13. Magnesium
Take a magnesium supplement of at least the US RDA of 300-350
mg/day (more may be desirable in order to maintain an ideal 1:2
balance of magnesium to calcium)
A vitamin B6 and magnesium deficiency may also cause stone
formation. A Swedish research group found that taking both daily
stopped stone formation in 90% of their patients. Magnesium, like
calcium, can bond with the oxalate and acts as a inhibitor of the
formation of calcium oxalate crystals in the urine.
The mean stone episode rate decreased from 0.8 to 0.08 stones/year
on Magnesium supplement and 85% of the patients remained free of
recurrence during follow-up, whereas 59% of the patients in the
control group continued their stone formation. (Johansson and
Backman U)
14. Sodium
Diets low in sodium are effective in reducing stone formation by
decreasing the excretion of calcium. Because calcium and
sodium compete for reabsorption in the renal tubules, excess
sodium intake and consequent excretion result in loss of calcium
in the urine.
High-sodium diets are associated with greater calcium excretion
in the urine (Lemann, 2002).
Aim for < 3000 milligrams of sodium per day.
15. To reduce the sodium in your diet:
Enjoy your food without added salt. Use vinegar, herbs, &
spices to flavor your foods instead of salt.
Cook without salt.
Check food labels. If the food contains more than 250
milligrams of sodium per serving, it contains too much
sodium. In general, the more processed a food is, the greater is
its sodium content
16. Potassium and kidney stones
• In one study of over 45,000 men, those whose daily intake of
potassium was more than 4.3 grams per day were 50% less
likely to develop kidney stones than those with potassium
intakes of less than 3 grams per day.
• Potassium rich foods as fruits and vegetables.
17. Soft or Carbonated Drinks
• Not only dehydrates making one more prone to kidney stones,
but also contains phosphates, which is linked to higher kidney
stone recurrence.
• Dark soft drinks tend to contain oxalates, which further
increase one's susceptibility to kidney stones.
• Any caffeinated beverage is dehydrating, so for every cup of
a caffeinated beverage you drink, do drink another glass of
filtered water.
• Sugary drinks tend to mess with calcium and magnesium
absorption, once again increasing one's risk for kidney stones.
18. Your body must buffer the acidity of soft drinks with calcium
from your own bones. As this calcium is eliminated through
your urine, it slowly forms kidney stones.
Carbonated beverage consumption has been linked with
diabetes, hypertension, and kidney stones, all risk factors for
chronic kidney disease.
With kids drinking so much in the way of sugary drinks and
soda pop now, children as young as 5 are being afflicted with
kidney stones.
19. Citrate
• The citrate acts as an inhibitor to stone formation. Lemonade
made with frozen concentrate, real lemon juice or real lemons
is one of the fluids recommended for its citrate content.
• Orange and carrot juices are high in citrates which inhibit
both a build up of uric acid and also stop calcium salts from
forming. (Carper, J. "Orange Juice May Prevent Kidney
Stones," Lancaster Intelligencer-Journal, Jan 5, 1994)
20. Weight
Curhan and colleagues (1998) found that "the prevalence of
stone disease history and the incidence of stone disease were
directly associated with weight and body mass index.
However, the magnitude of the associations was consistently
greater among women".
Obesity increases the risk of kidney stones, but it's theorized
that insulin resistance, a common condition in obese people,
increases the amount of calcium in the urine. This, in turn,
contributes to the formation of crystals that develop into kidney
stones.
21. • Men > 220 pounds had a 44% increased risk of developing kidney
stones compared with < 150 pounds. Older women in the same
high-weight category had an 89% increased risk for kidney stones,
while heavy younger women had a 92 % increased risk. (Taylor).
• Men in the highest category of BMI had a 33% increased risk as in
the lowest category. Older women in the highest category had a 90
% increased rate and younger women more than double the risk.
• Women with the largest waist circumferences had a 71% greater
risk of kidney stones compared with the lowest waist
circumferences. Men had a 48% greater risk.
• Men who had gained > 35 pounds since they were 21 had a 39%
higher risk of getting stones compared with men whose weight
remained stable. Similarly, older women who had gained the same
amount of weight since they were 18 had a 70% increased risk
while younger women had an 82% increased risk.
22. Dietary Fiber
Fiber is the indigestible part of plants.
There are two types of fiber: soluble (dissolves in water) and
insoluble. Both provide important functions in the body.
Insoluble fiber (found in wheat, rye, barley, and rice) help to
reduce calcium in the urine. It combines with calcium in the
intestines, so the calcium is excreted with the stool instead of
through the kidneys.
Insoluble fiber also speeds up movement of substances
through the intestine, so there will be less time for calcium to
be absorbed.
23. Sugar
Kidney stones are associated with high sugar intake, so eat less
(or no) added sugar (J. A. Thom, et al "The Influence of Refined
Carbohydrate on Urinary Calcium Excretion," British Journal of
Urology, 50:7, 459-464, December, 1978)
There is evidence that one third of the population shows increased
risk factors for kidney stone disease after consuming sugar. These
effects of sugar consumption are thought to be due to the
increased secretion of insulin, which results in increased calcium
excretion by the kidneys. (Blacklock NJ et al)
24. Alcohol
People should have no more than two drinks-two 12-ounce
servings of beer or two 5-ounce servings of wine or two 1.5-
ounce servings of hard liquor-a day.
Alcohol per se does not lead to kidney stone formation. It
does make stone sufferers pass more urine that can lead to a
dehydrated state. Alcohol likewise indirectly inhibits the
kidneys’ ability to excrete uric acid from the human body.
Cases of men who regularly drink alcoholic beverages (about
two to four bottles a day) like beer upped their risks of
suffering from gout, which can lead to stone formation.
25. Vitamin B
B-6 deficiency produces kidney stones in
experimental animals.
B6 (10 mg a day) lowers the amount of oxalate in the urine.
In high doses, it is also used medically to treat kidney stones.
B-6 deficiency is very common in humans.
B-1 (thiamine) deficiency also is associated with stones
(Hagler and Herman, "Oxalate Metabolism, II" American
Journal of Clinical Nutrition, 26:8, 882-889, August, 1973)
26. Dietary vs Drug Therapy
In addition to dietary counseling physicians may utilize
various pharmacological agents such as thiazide diuretics,
phosphates, allopurinol and potassium citrate to treat
patients with recurrent calcium oxalate kidney stones.
Urinary citrate drops with increasing urinary acid content so a
diet high in whole grains, fruits and vegetables may be
more effective than potassium citrate supplementation
alone because such a diet will reduce urine acidity and
increase potassium, magnesium, and citric acid intake.[Pak CY]
However, none of these agents have been proven as
effective as a high fiber diet low in salt, animal protein and
oxalate rich foods. [Goldfarb S]
27. Also a diet lower in animal protein, salt and higher in fiber
has other health benefits so it seems reasonable for physicians
to emphasize dietary therapy for the treatment and
prevention of kidney stones.
All medications can have adverse side effects. The benefits of
reduced stone formation from prescription drug therapy is
unlikely to prove greater than the long-term adverse effects
associated with the use of the pharmaceutical agents.
However, physicians may want to consider the use of
supplemental potassium-magnesium citrate as an adjunct to
dietary therapy particularly in patients who do not comply
with the low salt and meat diet.