Vitamin D, the sunshine vitamin, is one of the most important vitamins in our body. It has long been known to facilitate our body’s absorption of calcium and phosphorus, leading to strong, healthy teeth and bones. Today, scientists now know that almost every cell in our body has a vitamin D receptor, and that it is responsible for many things other than calcium and phosphorus. There even seems to be a link with kidney stones, although the question is whether vitamin D causes them, or helps to prevent them.
What Are Kidney Stones?
When certain chemicals are present in too high concentrations in the urine, they crystalize. Over time, they grow into larger masses, eventually becoming stones. If these stones go through the urinary tract, they can cause tremendous pain, particularly if it gets stuck somewhere. In almost every case, a kidney stone happens when calcium combines with either oxalate or phosphorus, and this is where a possible vitamin D link comes in.
Causes of Kidney Stones
Kidney stones are a result of a build-up of certain of certain chemicals or substances. Most commonly, these are:
• Cystine (which helps our body to build protein)
• Uric acid (one of our body’s waste products)
It is also possible for certain medical conditions to cause kidney stones, particularly if they affect the levels of any of the substances above. Additionally, people who do not drink sufficient fluids, particularly water, are at an increased risk of developing kidney stones. This is because the kidneys will struggle to function properly.
Some people also have recurrent kidney stones. This means that new stones form almost continuously. Risk factors for recurrent kidney stones include:
• Eating a low fiber, high protein diet
• Being bed bound or otherwise inactive
• Having a family history of kidney stones
• Having multiple urinary or kidney infections
• Having kidney stones in the past, particularly before the age of 25
• Having only one functioning kidney
• Having had surgery on the digestive system, particularly an intestinal bypass
• Having a small intestine disease, particularly inflammation of the gut, known as Crohn’s disease
Lastly, there is quite a lot of evidence that shows certain types of medication increase the chances of developing kidney stones, particularly recurrent ones. Medications that can lead to this include:
• Vitamin D supplements
• Calcium supplements
• Certain antibiotics
• Certain anti-epileptic drugs
• Some antiretroviral drugs, most particularly those used in the treatment of HIV
Types of Kidney Stones
There are four main types of kidney stones to be aware of, each of which tends to be caused by different factors. The table below highlights this in greater detail.
|Type of Kidney Stone||Details||Causes|
|Calcium stones||These are the most common type and exist as a result of excess calcium in the urine. These stones tend to be either spiky and rough, or large and smooth.||· Hypercalcuria, an inherited medical condition that leads to calcium build-up in the urine.
· Hypervitaminosis D, meaning you have too much vitamin D in your system.
· Kidney disease
· Certain types of cancer
|Struvite stones||This type of stone is generally the consequence of a lengthy urinary tract infection. Women are more likely to develop struvite stones.||Infections|
|Uric acid stones||When urine becomes too acidic, uric acid stones can start to form.||· Diets with high levels of protein, particularly meat.
· Gout or other similar conditions that stop the body from properly breaking down various chemicals.
· A genetic condition that increases levels of acidity in the body.
|Cystine stones||This is the rarest type of kidney stone.||Cystine stones are caused by cystinuria, which is an inherited condition. It affects the acidity level of urine.|
The Role of Calcium
It is very important that you consume the right amount of calcium. Too little calcium means that your level of oxalate will rise, which can lead to calcium oxalate stones. Too much calcium, on the other hand, can also lead to kidney stones. Additionally, the body has to have sufficient levels of vitamin D in order to be able to actually use the calcium. Too little vitamin D and your body won’t absorb it and use it, possibly leading to kidney stones. Similarly, too much vitamin D will use too much calcium, also leading to kidney stones.
Vitamin D and Kidney Stones
Vitamin D works as a pleiotropic hormone. While there are five different kinds of vitamin D (1 through 5), only vitamins D2 and D3 are the nutritional ones. Through sequential hydroxylations, vitamin D becomes active, where it starts to interact with receptors and benefit the body. Almost every cell of our body has a vitamin D receptor in it, which makes it a true ‘super vitamin’. Yet, almost 60% of the population in this country has a deficiency. Deficiency is also particularly common in people with kidney stones.
The table below examines the various studies that have taken part examining the link between vitamin D and kidney stones.
|Epidemiological||169 adults with kidney stones||None||There was no link between the concentration of vitamin D and excretion of calcium in urine.|
|757 people with kidney stones, 15,529 people without kidney stones||None||The levels of vitamin D were the same across the participants, regardless of whether or not they had kidney stones. The study concluded that high vitamin D levels do not cause kidney stones.|
|106 men with recurrent kidney stones, 109 people in a control group||None||Vitamin D levels were much higher in the group of men with kidney stones. They also had higher levels of phosphorus and calcium in their urine.|
|75 adults with kidney stones||None||A positive correlation was noted between urine excretion of vitamin D and calcium.|
|111 adults with kidney stones, 57 of which had calcium stones, and 44 people in a control group||None||There was a positive correlation between urine excretion of vitamin D and calcium in both the groups of people with kidney stones and in the control group.|
|160 people with kidney stones, 217 people in a control group||None||There was no difference between levels of vitamin D and calcium in the group of people with stones or in the control group.|
|108 adult males with kidney stones||None||There was a positive link between levels of vitamin D and calcium excretion in urine.|
|Interventional||29 adults with high levels of calcium in urine||Calcium supplementation before and after vitamin D supplementation||There was no change in overall calcium excretion|
The table above demonstrates one thing very clearly: more research has to be done into the link between vitamin D, calcium and kidney stones. Until further research are done, the conclusion is that kidney stones are not caused by either a deficiency or excess of vitamin D. Evidence to support that includes:
• There are many types of kidney stones caused by many different things.
• Calcium oxalate stones are the most common type.
• Only once a stone is analyzed can a treatment be developed.
• Drinking lots of water each day, which does not contain any vitamin D, has been found to be most beneficial in treating kidney stones of all types.
Resources and References:
5 Steps for Preventing Kidney Stones – How to avoid kidney stones. (Harvard Health Publications)
Does Vitamin D Help with Kidney Stones? – Effect of vitamin D on kidney stones. (Vitamin D Council)
Study: Vitamin D Supplements May Not Raise Risk for Kidney Stones – Vitamin D supplements and kidney stones. (WebMD)
Kidney Stones NOT Caused by Vitamin D – Vitamin D and kidney stones. (GrassRootsHealth.net)
Kidney Stone Risk Associated with Long Term Vitamin D and Calcium Intake – Long-term intake of vitamin D and calcium supplements and kidney stones. (Medical News Today)
Vitamin D and Kidney Stone Disease – Link between kidney stones and vitamin D. (NIH.gov)