Low carb diets fight back.

A diet rich in soy and whey protein, found in products such as soy milk and low-fat yogurt, has been shown to reduce breast cancer incidence in rats. (Photo credit: Wikipedia)

In a recent study published in the annals of internal medicine, researchers from Italy followed 215 patients who were overweight and found that a low carbohydrate diet (called the mediterranean diet which obtained less than 50% of calories from carbohydrates) was superior for the control of glucose levels in type 2 diabetics.

Unfortunately this study did not have an index of the degree of atherosclerosis present in both groups. This would have been helpful as low carbohydrate diets have recently been found to increases the risk of atherosclerosis despite improvements in cholesterol levels. This risk has been postulated to be based on inability to repair damage caused during the process of atherosclerosis. It seems that carbohydrates may be needed to jump start the repair process in normal people.

The finding however will directly impact patients with type 2 diabetes where glucose control is directly linked to retinal damage kidney damage, nerve damage and cardiovascular risk. Patients will also derive benefit from the weightloss which occurs which will directly result in reduced resistance to their own endogenous insulin levels.

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Low carbs diets....bad for you?

low carb (Photo credit: daBinsi)

Low carbohydrate diets are known for their ability to jump start weight loss. High protein diets such as the Atkin's diet have been associated with no increase in cholesterol and have been credited with higher initial weight loss than traditional caloric restriction.
Recently we have reported research that high protein diets are unexpectedly associated with increased risk of cardiovascular mortality.





The current study carried out in a mouse laboratory model has shown that when fed a low carbohydrate diet the mice developed more hardening of the arteries that led to restriction of blood flow to vital tissues. The mice fed on a low carbohydrate diet were also less likely to be able to compensate for interruption to blood flow to vital organs. This occurred despite the absence of an increase in serum cholesterol implying that these effects were modulated via mechanisms independent of traditional risk factors for atherosclerosis.

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The implications for patients on low carbohydrate diets could be unfortunate as this is the second study in a short period of time to bring to light a possible negative role of high protein diets which usually go hand in hand with low carbohydrate diets.

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Obesity and chronic kidney disease.

Almost every possible human ailment has been somehow linked to obesity. It is therefore no surprise that obese patients have significantly more risk of developing kidney disease. In fact there is a discrete entity that has been described which is known as obesity related glomerulopathy. Which is dysfunction of the filtering apparatus of the kidney as a result of obesity. The glomerulopathy is associated with distinct structural changes that can be seen on biopsy. The disease usually runs a mild course and rarely does it damage the kidneys sufficiently to require dialysis.

However population based studies have demonstrated that obesity puts you at increased risk of requiring dialysis when compared to the non obese. The mechanism acting here is unlikely to be due to obesity related glomerulopathy and is largely unknown.

However there are theories that fat cells have the ability to produce hormones that act on the kidney such as leptin, adiponectin and tumour necrosis factor. These agents are known to cause inflammation in various tissues of the body. They have also been implicated as playing a role in other diseases of the kidney. The risk of severe renal disease is higher with each additional condition present in addition to being obese. So in the obese and hypertensive with diabetes and low levels of the good cholesterol(HDL), the highest risk of developing end stage renal disease occurs.

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The risk can be reduced by treating each associated disease. So good blood pressure control to the lowest possible blood pressure that does not result in dizzyness when you stand suddenly, blood sugar that is well controlled, increasing good cholesterol (HDL) and lowering bad cholesterol (LDL.) are all indicated to improve outcomes.

In terms of weight loss, a reduction of risk occurs for every point reduction in BMI achieved. Therefore ANY weight loss, no matter how small the amount will be beneficial, with the biggest losers gaining the most.

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Study suggests protein intake linked to heart attack and stroke innormal people.

Most patients with chronic kidney disease will be referred to a dietician as part of their management. The standard of care has been to provide a normal protein diet of about 0.80 grams protein per kg of body weight. However some researchers believe that dietary protein intake be restricted even further as some studies suggested that decreased dietary protein intake would prolong the survival of the kidney in chronic kidney disease.

But is there an effect of higher protein intake on cardiovascular disease as well. The current study analyzed data from 8461 individuals and followed these people who incidentally did not have renal disease for about 6.4 years. The daily protein intake was scientifically measured based on the amount of protein breakdown products produced in the urine (this is one of the most accurate means of determining the actual protein intake of a patient). The data was then compared to determine if there was any relationship between protein intake and cardiovascular disease and renal function.















The study demonstrated that protein intake was associated with cardiovascular events (heart attack and stroke) but not associated with worsening of kidney disease.

The conclusion therefore is that in the general population high protein intake, such as promoted by many weight loss systems may increase your risk of heart attack and stroke, but does not increase your risk for kidney disease.

Kidney News: Food additives can Kill

food sources of magnesium: bran muffins, pumpkin seeds, barley, buckwheat flour, low-fat vanilla yogurt, trail mix, halibut steaks, garbanzo beans, lima beans, soybeans, and spinach (Photo credit: Wikipedia)

A little known but important fact outside of the kidney care community is that phosphates are a major cause of disease in patients with kidney problems. The problem is particularly severe in patients who are on dialysis. Phosphate is present in many foods. However skilled dieticians are able to reduce the phosphate content of the diet through specifically tailored meal plans and procedures to prepare the food so that phosphate content is as low as possible.

Dietary advice aside the major means of removing toxins from the body in patients with kidney disease, which is dialysis is not particularly helpful in patients as phosphate is very slow to be removed by conventional dialysis. The only modality that seems to have a profound effect on phosphate removal is long nocturnal hemodialysis, the benefit here is that phosphate removal is primarily tied to the the length of time that you are dialysed.

So if phosphate is present in many foods and beverages, particularly sodas and conventional dialysis does not perform well in its removal, then we end up with phosphate accumulation in dialysis patients. Since not everyone has access to nocturnal hemodialysis the answer would seem to be reducing phosphate intake.

However even with dietary manipulation phosphate has been slowly creeping back into the diet of patients on dialysis through an unsuspected mechanism.

Food additives are substances added to food in order to preserve and give longer shelf life in most cases. Frequently the phosphate content of the food additive is not available to the dietician when planning the diet sheet of the dialysis patient and as such the dietary advice may have very little effect on overall phosphate intake. Proper labelling of foods would of course solve this problem but this is not yet a requirement.

But what exactly does high phosphate levels cause?

The problem with phosphate is that it is one of the substances that make up bone and as such it is regulated by a hormone known as PTH. High phosphate stimulates PTH levels, elevated PTH somehow affects the cardiovascular system contributing to increased stiffness of the blood vessels and increased risk of cardiovascular disease.

What can be done?

Focused education on the need to be aware of the phosphate content of food may result in lower phosphate intake if alternative preservative and additive food sources can be accurately identified. In other words educate, create the need and someone will provide the service of low phosphate food.

A recent review of the phosphate content of food is available here

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News: DASH diet reduces kidney stones.

[caption id="attachment_653" align="alignright" width="300" caption="kidney stones"][/caption]

photo credit: manda_wong

The DASH diet which is an eating plan that follows heart healthy guidelines to limit saturated fat and cholesterol, was found to reduce the incidence of kidney stones in an article published in the august issue of the Journal of the american society of nephrology.

The study was carried out because diet is thought to play a major, yet not entirely clear role in the development of kidney stones. The dash diet was chosen because it represents a novel potential means of preventing stone formation. The increased consumption of fruits and vegetables increases urinary citrate, which inhibits calcium stone formation with a normal to high calcium intake which decreases oxalate absorption from the intestines. However due to increased levels of vitamin C (which is also associated with kidney stone formation) the researchers were unclear if the diet would have an overall beneficial effect.

The study combined three large prexisting groups of patients over 50 years of follow up. The conclusions arrived at are therefore likely to be statistically sound.

The overall conclusion of the study was that a diet high in fruits and vegetables moderate in low-fat dairy products and low in animal protein (which has been essentially replaced by plant protein including legumes and nuts) decreased the risk of kidney stone formation.

Importantly this statement was independent of age, body size, hypertension, diabetes, total caloric intake, fluid intake, caffeine and alcohol intake.
Therefore one of the most important things you can do to prevent kidneys stones is to have a healthy diet along the guidelines that have previously been put forward, see the DASH diet PDF download at the start of the article.