The RenalTracker Team
April 12, 2019

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It's no question that when you need more energy for your daily activities, especially during intense activities, you would need an increased intake of starchy foods (usually called Carbs). 

But when you have CKD, indulging in too many carbs can have a detrimental impact on your condition. This is because most carbohydrates such as rice, bread, fruits, sugar, cereals- and sugar-rich foods can also have high levels of sodium, potassium, and phosphorus. 

bread with no carbs written

Carbohydrates and CKD

High carbohydrate consumption has been associated  to promote insulin resistance and obesity. Considering how diabetes and obesity are related to increased risk of CKD, following a low carbohydrate could help manage kidney function. Nevertheless, further studies are still needed to show the direct impact of carbohydrates on kidney function. 

Carbohydrate is a nutrient found in foods and drinks that is turned into glucose, the most simple form of sugar, after digestion. Glucose is the body’s primary source of energy. Any food or drink with carbs can raise your blood sugar; however, there are certain types that raise your blood sugar at a faster rate. Carbohydrates have 2 types -simple and complex. 

Simple carbohydrates may be found in a range of food sources where most of the FIBER is already removed or simply not present at all, like table sugar and other forms of sugar; but, often times and inconspicuously, simple carbohydrates are found in  completely processed food items such as cakes, pastries, boxed juice, soda, crackers, etc or semi-processed, such as pasta, bread. These food sources raise blood sugar levels quickly.

On the other hand, complex carbohydrates, where starches and fiber fall under,  raise blood sugar at a slower rate because they take longer to  metabolize compared to simple carbs. Complex carbs contain higher amounts of fiber and are, therefore, more filling.

types of carbs

Although complex carbs raise your blood glucose levels more slowly, consuming high amounts of carbohydrate can still raise your blood sugar level significantly.

Most people are concerned about the amount of carbs they consume as it seems to lead to their unwanted weight gain. If weight cannot be managed, then it could lead to chronic inflammation.  However, choosing the right carbohydrate sources could deter risks of developing chronic illnesses. If you have diabetes, other than CKD, you would also, then, need to be more cautious of your carbohydrate intake to manage your blood sugar and  mineral levels.

Recommended Daily Intake for Carbohydrates

For a normal, healthy person, the Dietary Guidelines for Americans suggests that the carbohydrate intake should be between 45-65% of total daily calories. This means that for people who consume 2,000 calories daily, their carbohydrate consumption is somewhere between 900 and 1,300 or between 225 and 325 grams. 

carbohydrates meaning

For a normal, healthy person, the Dietary Guidelines for Americans suggests that the carbohydrate intake should be between 45-65% of total daily calories. This means that for people who consume 2,000 calories daily, their carbohydrate consumption is somewhere between 900 and 1,300 or between 225 and 325 grams. 

The amount of carbohydrates you need is dependent on nutritional status,  weight and activity level. Generally speaking, 3 to 6 servings of carbohydrates per meal are recommended. You can talk to your renal dietitian for personalized servings sizes. To learn more about carbohydrate and portion sizes, you can refer to our blog Carbohydrate Counting for CKD Patients

On the other hand, if your lab results show elevated levels of sodium, phosphorus,and potassium (SPP),  consider minimizing these carb sources in your diet: 

1. Whole-Wheat and Whole-Grain Bread

It used to be that people with CKD were suggested to limit whole grains in their diet because of higher potassium and phosphorus content. However, recent studies suggest reconsidering whole grains into the renal diet. This is because there has been data suggesting that the body’s ability (bioavailability) to absorb whole grains is low amidst their high phosphate content. 

The low bioavailability is connected to the body’s lack of phytase, an enzyme needed to release phosphorus from phytate. Phytate is the main storage form of phosphate found in whole grains. Since some CKD patients feel that the kidney diet has few options, adding whole grains will add variety into their diet. 

Whole grains are also rich in fiber, improves digestive health, lowers cholesterol, and decreases heart disease risk. Eating fiber-rich foods such as whole grains can prevent the risk of obesity and type 2 diabetes, conditions that can exacerbate kidney functions. 

You may want to slow down on whole wheat and whole grain bread if your lab results show elevated SPP. On a low-potassium, low-phosphorus renal diet, refined, white flour bread may be a good choice for you.

Whole-wheat and whole-grain bread contain about 69 mg of potassium and 57 mg of phosphorus per serving. White bread, on the other hand, contains only 28 mg of both nutrients. 

Starchy food

It is essential that you talk with your dietitian which type of whole grains will suit your kidney diet. In general, you can incorporate whole grains with lower potassium and phosphorus content into your diet such as barley, buckwheat, bulgur, wild rice, and popcorn.  Try to slow down on refined or enriched grains such as white flour, white rice, and degermed cornmeal.

Sodium is often also high for both kinds of bread, so it's advisable to read labels thoroughly and look for low-salt or low-sodium options.

2. Oatmeal and Other Bran Cereals

Oatmeal is considered to be a healthy, whole food item.  A cup of oatmeal, when cooked, contains about 143 mg of potassium and 157 mg of phosphorus. This is why oatmeal is, unfortunately, another food that might be wise to restrict from the diet of  kidney disease patients.  

Meanwhile, bran cereals are refined carbohydrates that are digested faster by the body, causing unhealthy increases of blood sugar levels. They can also result in mood and energy fluctuations, as well as fat build up. Eating refined carbs can leave you feeling hungry soon, causing you to overeat, and over time this could develop to insulin resistance and type-2 diabetes. Refined carb diets have also been associated with heart disease, obesity, and high blood pressure.

Thankfully, the National Kidney Foundation (NKF) has a list of cereal recommendations. Here are a few of the cereal brands that you can add into your renal diet:

Aside from white rice, there are also other alternatives, such as:

  • Apple Jacks
  • Barbara's (Cinnamon Puffins, Corn Flakes, etc.)
  • Cascadian Farms (Chocolate O's, Cinnamon Crunch, etc.)
  • Corn Pops
  • Fruit Loops
  • Health Valley Rice Crunch-Ems
  • Honey Smacks
  • Kashi (Honey Sunshine, Indigo Morning, etc.)
  • Puffed Rice
  • Trix

3. Potatoes

When it comes to starchy staple foods, potatoes easily come to mind. It's also a very versatile vegetable because of the myriad ways it can be prepared and served.

However, they are also saturated with potassium. On average, a potato contains about 610 mg of potassium while sweet potatoes have about 540 mg (potassium), when baked.

potatoes sweet potatoes

You can reduce potassium content in these veggies through leaching. There are two common ways to do this:

  1. To reduce their potassium content by about 50%, simply chop up potatoes into small, thin pieces and boil them in water for 10 minutes, at least.

  2. You can also peel, dice, and soak potatoes for 2-4 hours in tap water. This is also known as double cooking, and has been proven to leech off more potassium from the vegetable.

4. Other High Carbs Foods

Besides the carb sources above, you may also want to steer clear or minimize eating these foods:

  • dark-colored colas
  • granola
  • hard candies
  • Milk/ white chocolates
  • soft drinks
  • Sugar (granulated, powder or cube)

The Bottomline

Carbohydrates are a great source of energy and can have a place in your kidney diet so long as they are from natural sources and consumed within your dietary requirement in mind. If your lab test shows an increased level of blood sugar and minerals, consider steering clear or minimizing the carb sources mentioned above.  Alternately, you can include in your renal diet carbohydrates alternatives that are gentle on your kidneys such as berries, bagels, grapes, cherries, cauliflower, broccoli, eggplants. If you're not sure about a certain food item, always ask the opinion of a health professional, whether it be your doctor or your renal dietitian. That way, you can be more confident that what you're getting are only the good things for your kidneys.