The relationship between your diet, kidney disease, and type 2 diabetes can be a tricky one to understand since there are so many moving parts.
If you're curious about how your protein and electrolyte intake affects your health in the midst of kidney disease, or what foods you should avoid for kidney health, you came to the right place.
We've got some research-based answers to help bring some clarity to the fog.
Kidney disease in diabetes is caused by higher-than-normal blood sugar and blood pressure levels. If not taken care of appropriately, this health condition can progress to chronic kidney disease (CKD), which can make life more difficult.
The best way to avoid or slow the progression of kidney disease is to get your blood sugar and blood pressure to goal levels.
For information about how to better manage diabetes with diet please refer to our diabetes friendly food list, and choose more whole foods that are lower in carbohydrates.
However, as kidney disease progresses there are some nutrients that are normally filtered through the kidneys may need to be monitored. These include protein, sodium, potassium and phosphorus.
The average recommended protein intake for healthy individuals is 0.8g/kg/day. A low protein diet is set at 0.6-0.8g/kg/day.
You may have heard that people must restrict protein to help maintain kidney function.
The reason for limiting protein includes maintaining glomerular filtration rate (how well your kidneys are filtering) and decreasing albuminuria (protein leaking into urine).
But this concept and the actual amount of protein that is recommended is under some debate.
A meta-analysis of various low protein diet studies found that a diet of 0.6-0.8g/kg/day of protein did show decreased protein in the urine, but there was no significant change in kidney function in people with type 1 or type 2 diabetes. The average intake of protein for the low protein and control groups were 0.9g/kg/day and 1.27g/kg/day, respectively.
In another study, diabetic patients who were placed on a low protein diet (0.8g/kg/d) for one year saw no significant change in renal function.
Yes, limiting protein can aid in decreasing protein in the urine but there seems to be no clear evidence about whether this can actually slow down the progression of kidney disease.
Evidence does NOT suggest that people with diabetic kidney disease need to restrict protein intake to less than the average protein intake, which is 0.8g/kg/day.
Reducing salt intake may help with decreasing fluid retention, managing hypertension, and reducing cardiovascular risk, but it doesn't necessarily have a direct effect on slowing the progression of kidney disease.
In a systematic review evaluating the effect of altering dietary salt intake in people with CKD, decreasing salt intake was found to aid in decreasing blood pressure and reducing proteinuria.
So what is a good limit?
There is debate on whether the intake of <1.5g per day is beneficial in those with impaired kidney function, but it is suggested that intake of <3g per day may be needed to aid with management of fluid retention or proteinuria.
You need some sodium every day to maintain proper nervous system function, but you don't want to go overboard.
Of course, when we are looking at general healthy eating guidelines a main point is to avoid highly processed foods. When these are cut out or decreased in ones diet then we are eliminating a lot of high salt foods, which may be enough to stay below the 2300mg recommendation.
As kidney disease progresses you may need to limit dietary potassium intake depending on your blood levels. High potassium levels can lead to irregular heartbeat or a heart attack.
Your doctor or nephrologist (kidney specialist) should be the one to tell you if you need to limit these foods or not.
High potassium foods that are lower in carbs that you may see on our recommended food list include:
● Nuts and seeds
● Brussels sprouts
● Greens (except kale)
Low potassium foods that are lower in carbs that are part of our recommended food list include:
● Alfalfa sprouts
● Green beans
● Yellow squash
● Zucchini squash
As you can see, there are plenty of food options if you do get to a point where diet alternations are needed.
Phosphorus is another nutrient that may need to be restricted in the later stages of kidney disease, as kidneys in poor health become unable to filter it out and it builds up in the bloodstream.
Serum phosphorus levels >5.5mg/dL are associated with 20-40% higher mortality risk among patients with end-stage renal disease.
That being said, most people in earlier stages of kidney disease do not have to worry about limiting phosphorus.
Again, your doctor or nephrologist should be the one to tell you if you need to consider limiting phosphorus.
In it's inorganic form, phosphorus is a main component of many preservatives and additives in processed foods. These include enhanced or restructured meats, frozen meals, cereals, snack bars, processed or spreadable cheeses, instant products, refrigerated bakery products.
These inorganic phosphates in foods are more readily absorbed and have greater effect on your blood phosphorus levels in comparison to foods that naturally contain phosphorus.
Limiting processed foods prepared with phosphate additives is the healthiest way to decrease phosphate levels (plus, limiting processed foods will also have a positive impact on your overall health as well).
Common phosphate additives are listed in the table below. If you need to limit phosphorus in your diet, then make sure to avoid foods that have these things listed in the ingredients.
Bakery mixes, yeast-raised bakery products, cereals, dry powder beverages, flour, food bars, infant food, milk-based beverages, multivitamin tablets, yogurt
Breakfast cereal, cheese, condensed milk, cream, evaporated milk, flavored milk powders, gelatin, half and half, ice cream, imitation cheese, infant food, instant cheesecake, instant pudding, isotonic drinks, nonfat dry milk, pasta, pet food, processed cheese, starch, vitamin capsules, whipped topping
Cola beverages, dry powder beverages, egg yolks, gelatin, instant cheesecake, instant pudding, isotonic beverages, and process cheese custard pudding and no-bake cheesecake mixes
Cola beverages, carbonated and noncarbonated beverages
Meat, seafood, poultry, vegetables, cream, half and half, ice cream, whey, processed cheese, eggs, table syrup, toppings
Meat products, seafood, poultry, vegetable proteins, processed cheese, sour cream, dips, yogurt, eggs, table syrups, whipped toppings, pet food, vegetables, whey
Processed meat, poultry, seafood, processed cheese, potato products, ice cream, frozen desserts
Processed cheese, cheese products, imitation cheese, isotonic beverages, cooked breakfast cereals
Again, this limitation is usually only needed when kidney disease has progressed to end-stage kidney failure. At that point, dialysis may be needed and protein requirements increase.
Along with limiting inorganic phosphorus sources, your doctor may also prescribe medication called phosphate binders that you take with meals. These medications help eliminate phosphorus from your body.
In the earlier stages of kidney disease, you may not need to limit certain foods and the main recommendation is to avoid processed packaged foods and choose whole foods as much as possible.
If you do have diabetic kidney disease, then make sure you are following up with your primary care physician and/or nephrologist. They will be the ones to monitor your lab values and tell you if any dietary restrictions are necessary.