5 vitamins for your kidneys

Your kidneys are responsible for filtering water and waste from urine and blood. About 15% of American adults have kidney disease, which impairs this process. Chronic kidney disease (CKD) increases a person’s risk of anemia, infections, nutrient deficiencies, and depression.

If you have CKD or are on dialysis, you may need to eat a renal diet that protects you from kidney damage by limiting phosphorus, potassium, and sodium. If you have kidney stones, you may need to restrict high-oxalate foods such as nuts, spinach, beets, and sweet potatoes. In either case, your healthcare provider may recommend taking vitamins D, B, and C or iron and calcium supplements to compensate for nutrient deficiencies while supporting kidney health. 

Just note: the data on the benefits and risks of supplementation remains unclear, particularly as it relates to using vitamin D and calcium supplements together. Recommendations also vary depending on multiple factors, including but not limited to; the stage of chronic kidney disease, whether someone is on dialysis, and the presence of kidney stone disease.

Vitamins and minerals for kidney health

People with healthy kidneys who eat a balanced diet tend to get enough vitamins and minerals to maintain kidney health. However, CKD patients and dialysis patients may need to limit or eliminate certain foods, which can cause nutrient deficiencies. In that case, your healthcare provider may recommend taking the following supplements for kidney health. Before taking any supplements, consult with your healthcare provider or pharmacist to avoid potential drug interactions and determine the best dose for you.

1. Vitamin D

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Vitamin D is by far the most important vitamin for kidney health, says David Bilstrom, MD, director of the International Autoimmune Institute & Bingham Memorial Center for Functional Medicine in Blackfoot, Idaho. This nutrient helps protect the kidneys against disease and injury.

Though several factors contribute to poor kidney health—including autoimmune conditions, chronic hypertension, and diabetes—there is also evidence that low vitamin D levels contribute to poor kidney function, says Vicki Shanta Retelny, RDN, author of Total Body Diet for Dummies.

Vitamin D supplements may interact with other vitamins or drugs, including:

• Calcium supplements or medications containing calcium
• Mineral oil
• Bile acid sequestrants
• Thiazide diuretics

Vitamin D dosage can vary wildly. While general dietary supplements start at 600 IU daily, some people with vitamin D deficiency require doses as high as 6000 IU daily. Some forms of Vitamin D are more beneficial than others, and the choice of which supplement to use should be guided by your kidney specialist.  

2. Iron

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About 15% of people with CKD are deficient in iron. Iron deficiency causes anemia, a problem with red blood cells and their ability to carry oxygen to the cells of the body. Fatigue, weakness, lightheadedness, and dizziness are common symptoms of anemia.

Iron supplementation is an integral part of treatment for many people with CKD, but the dosage is not one-size-fits-all. Your dose will depend on the type of supplement (oral versus intravenous) and level of deficiency. So, taking it under the supervision of a healthcare provider is essential when you have kidney problems.

You may need to take extra precautions if you are pregnant or breastfeeding. Because of possible interactions, avoiding eggs, dairy, whole-grain foods, and tea or coffee within an hour or two of taking iron is recommended. Additionally, iron supplements may interact with certain medications, such as antibiotics and antacids.

3. B vitamins

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Some research suggests that B vitamins such as B12 and B9 may be beneficial in some people with CKD. It is important to know that there has been no clear benefit shown, and some people experienced harm from taking high doses of B vitamins. For select CKD patients, Dr. Bilstrom recommends 1,000 mcg daily of methylcobalamin, an active form of B12, and 2,040 mcg 1-2 times daily of methyltetrahydrofolic acid, an active form of B9 (also known as folate).

Most B complex supplements include thiamine, riboflavin, niacin/niacinamide, vitamin B6, vitamin B12, folic acid, and pantothenic acid. Taking a B-complex vitamin may, in some people with deficiencies, be helpful for overall health. Riboflavin (B2) and thiamine (B1) may help reduce high blood pressure, a complication of CKD.

In most cases, vitamin B does not interact with other drugs, but it’s important to tell your provider if you are pregnant or breastfeeding. Vitamin B dosage varies depending on the type (long-acting capsule vs liquid, for instance) and your condition. This supplement should only be taken if your kidney specialist recommends it. 

4. Vitamin C

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When kidney function is impaired, the body does not properly balance vitamins and minerals—especially water-soluble vitamins like vitamin C, says Retelny. Vitamin C supports your immune system and facilitates your body’s iron absorption, a key nutrient for anemia-prone CKD patients. 

The recommended daily vitamin C intake is 75 milligrams (mg) for adult females and 90 mg daily for adult males. Retelny says 60-100 mg per day can be part of a nutrition protocol for CKD. It’s important to know that high doses of vitamin C are not good for people with kidney damage. Too much vitamin C can build up in the kidneys, causing kidney stones to form. Other side effects of high vitamin C intake include nausea and diarrhea. A pharmacist or dietitian can help determine your safest, most effective dose. During the consultation, tell your healthcare provider if you are pregnant, breastfeeding, or have diabetes. Vitamin C can interfere with urinary blood sugar tests for diabetes patients.

5. Calcium

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Calcium is a vital mineral for overall health. It’s best known for building strong bones and teeth, but it also helps protect against high blood pressure and diabetes. People with CKD tend to have low vitamin D levels, which lowers the body’s ability to absorb calcium. So, in some cases, a provider may recommend calcium supplementation to CKD patients.

Of course, calcium is not a magic cure for poor kidney function. While calcium supplementation can help prevent kidney stones, too much calcium can sometimes increase the risk of kidney stones, especially when combined with vitamin D. Calcium can also interact with Dilantin (phenytoin) and tetracycline antibiotics (such as doxycycline, minocycline, and Vibramycin). As always, it’s important to consult a healthcare provider about whether calcium supplementation is right for you—and if so, how much you should take each day.

Kidney supplements that need more research

Research on vitamins, minerals, and herbal supplements intended to improve kidney health still needs to be completed, especially in CKD patients. A 2021 systematic review of the research found low-strength evidence that the following nutrition supplements had benefits for kidney function:

• Omega-3 fatty acids such as fish oil
• Fiber supplements
• Coenzyme Q10 (CoQ10)
• Probiotics

Some people also take N-acetyl cysteine (NAC) for kidney health. NAC is the supplement form of cysteine, an amino acid that helps create an important antioxidant called glutathione. In other words, NAC helps your body fight against harmful free radicals and inflammation. There is some evidence that NAC benefits people with CKD, but more research is needed.

Are kidney supplements beneficial?

Not everyone needs or benefits from kidney supplements.

“For healthy individuals who hydrate well with water throughout the day and eat a balanced, whole-food diet filled with lean protein sources, whole vegetables, fruits, grains, beans, lentils, nuts, and seeds, dietary supplements are not necessary for improving or maintaining kidney health and function,” says Retelny.

Supplements can be beneficial if you are not able to get the vitamins and minerals you need through the foods you eat. However, you should be skeptical of any supplements that claim to improve kidney health or cure CKD. After all, what your kidneys need to function depends on your current diet, underlying conditions, and overall health.

What vitamins can be hard on the kidneys?

People with chronic kidney disease are not able to filter blood efficiently, causing some vitamins to build up to unhealthy levels.

If you have CKD and are trying to optimize kidney function, it’s a good idea to avoid these supplements, which the National Kidney Foundation says tend to accumulate in the blood:

• Vitamin A
• Vitamin E
• Vitamin K

What to look for in vitamins for kidney health

The FDA does not approve dietary supplements for safety and effectiveness before they are sold to consumers. Consumers must do their due diligence before taking new vitamins. Remember that vitamins are not a magic bullet for better kidney health.

Dr. Bilstrom suggests looking for vitamins that have been third-party certified, meaning that they’ve been checked and approved by consumerlab.com, NSF International, U.S. Pharmacopeia, or some entity unrelated to the brand. He also suggests checking the label for GMP (Good Manufacturing Practices). These can help ensure that you’re taking a high-quality supplement that is most beneficial for your health.