How Chocolate Affects The Kidneys

If you have kidney disease, you often need to follow a specific diet to help your kidneys function more effectively. This diet might mean giving up some of your favorite foods. Where does chocolate fit into a healthy lifestyle if you have kidney problems?

The health benefits of chocolate

Chocolate is made from cocoa beans, which contain cocoa flavanols. These compounds have plenty of medically proven benefits. There are some advantages to adding a little chocolate to your diet if your doctor says it's okay. As with all things, moderation is key. 

Obtaining those health benefits relies on the type and quality of chocolate you consume.  Low-quality chocolate containing high levels of milk, sodium, sugar, and preservatives is far from a healthy option. On the other hand, high-quality dark chocolate containing a high percentage of cocoa (above 85%) offers health benefits if you have kidney disease.

Several studies¹ shows that chocolate consumption has neuroprotective, anti-inflammatory, and cardioprotective effects. Consuming chocolate can mitigate some kidney disease complications.

So, what are these benefits?

Antioxidant properties

You may have noticed how oxygen affects metal. Over time, the metal rusts and corrodes. Although we need oxygen to live, it can have the same damaging effect on our cells. This is oxidation. 

Antioxidants are substances that protect your cells from the effects of oxidation. One class of antioxidants is flavonoids,² a polyphenoliccompound. You can find flavonoids in fruits, vegetables, chocolate, and more. Cocoa products have a greater antioxidant capacity and higher amounts of flavonoids per serving than all teas and red wines.

These compounds protect against heart disease and atherosclerosis, two major conditions often associated with kidney disease.  

Cardiovascular improvements

Dark chocolate provides two major benefits to your cardiovascular system: It lowers blood pressure and cholesterol.

For those at risk of heart disease, a 2012 study³ found that daily chocolate consumption was a cost-effective way to reduce the chances of a cardiac event. It reduces total cholesterol and LDL cholesterol while lowering blood pressure. These all are important factors in controlling kidney disease.

Another randomized controlled trial⁴ investigated the impact of cocoa flavanols (CF) on the cardiovascular system of end-stage kidney disease patients on dialysis. It reported a significant improvement of vascular function by 53% over the short term. When participants took CF-rich supplements for 30 days, the researchers noted an increase in baseline function by 18%. 

The study reported that the impressive reversal in artery narrowing is comparable with the effects of statins in patients with end-stage kidney disease.

High potassium content

You've probably heard that high sodium/salt intake harms your health. Modern diets contain far too much sodium, making it difficult for the kidneys to remove water.

This causes fluid accumulation in the body, eventually leading to hypertension (high blood pressure). Hypertension strains the kidneys, causing or worsening kidney disease. 

Potassium is an essential mineral that helps the body remove excess sodium from the blood. With a proper potassium-to-sodium ratio, you can limit the negative effects of sodium. Dark chocolate has a surprisingly high potassium content. However, some chocolate snacks also have high sodium levels, so always check the nutritional information.

The harmful elements of chocolate

Although chocolate has many health benefits, there are some downsides to chocolate consumption. This especially applies to milk chocolate candy bars, so it’s important to stick to high-quality dark chocolate in small amounts.

Potassium

We've already seen high potassium levels listed as a benefit, so why is it harmful? Potassium reduces the effects of sodium without much downside for most people. However, that relies on your body's ability to process the potassium properly to use its sodium-reducing properties. 

Those with kidney disease often can't eliminate high amounts of potassium efficiently, which could cause hyperkalemia (high potassium levels in the blood). It’s best to consume potassium in moderation, and your physician will advise you on how much you should limit your intake. 

Phosphorus

Like potassium, high phosphorus levels are harder to eliminate if you have kidney disease. Many chocolate products are high in phosphorus. Unlike potassium, nutritional labels don’t often list phosphorus levels. This can make it hard to determine which chocolate products you can eat when you have kidney disease.

It’s best only to consume 20–30g of dark chocolate with a minimum percentage of 70% pure cocoa.

Sodium

Chocolate products can be high in sodium. If the sodium-to-potassium ratio is unfavorable, you lose all the benefits of getting the potassium in the first place. Sodium is hard for the body to get rid of, so your blood pressure will go up if you have too much. 

Saturated fat

The fat build-up in the cardiovascular system isn't good for you. Although good fat benefits your body, saturated fats are primarily empty calories that can cause heart and cardiovascular problems. 

However, most of the saturated fat in dark chocolate is in the form of stearic acid, which research⁵ suggests is non-atherogenic. This means it doesn’t cause plaque build-up in your arteries. A meta-analysis⁶ of 60 controlled feeding trials concluded that stearic acid doesn’t impact cholesterol, meaning it is cholesterol-neutral.

Some chocolate products, particularly milk chocolate, are high in other harmful saturated fat. Be sure to balance your nutritional intake when eating chocolate, and keep your daily saturated fat consumption at reasonable levels.

Sugar

Many non-dark chocolate products are high in sugar, which largely provides empty calories without much nutritional benefit. For those with diabetes or pre-diabetes, too much sugar can raise your blood sugar levels. This will worsen your diabetes symptoms and your kidney disease. Everyone should limit the amount of added sugars they eat in a day. If you have diabetes, you should look at the nutritional labels of your favorite chocolate products before eating them.

The lowdown

Dark chocolate has many health benefits, including lowering blood pressure, improving vascular system function, and reducing total cholesterol and LDL. These significant benefits could reduce chronic kidney disease or kidney failure complications.

However, milk chocolate bars can also harm those with kidney disease. The key is to stick to high-quality dark chocolate in small amounts: 20–30 grams daily with pure cocoa levels of 85% and above will provide the most benefits. Avoid candy bars and milk chocolate as they are high in ingredients that can worsen kidney disease.