Vitamin D supplements aren’t ‘rat poison’

13 April 2023
What was claimed

Sources of vitamin D, apart from the sun, are poisonous, because high doses can be used as a rodenticide.

Our verdict

Vitamin D3 can be used to kill rats, but is safe for people at normal and higher doses and some people need to supplement to maintain good health. It is possible to overdose on the vitamin if very high doses are taken over a long period.

A Facebook video with thousands of likes and shares makes false claims about vitamin D and calls it rat poison. 

The video shows the Wikipedia pages for Vitamin D and Cholecalciferol. Cholecalciferol is another name for Vitamin D3, the form of the vitamin best for supplementing for most people. The video itself was previously posted on TikTok by a profile selling “natural plant-based” vitamin D products.

We have previously covered false claims that useful medications are poisonous or harmful, as well as vice versa—false claims about potentially harmful substances being good treatments for disease. Most medications, at large enough doses, will be dangerous. This doesn’t mean they aren’t safe or effective at normal doses.

The video is captioned: “If you get your vitamin D from anywhere other than the Sun then you're being poisoned”.

This is false.

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Poison or essential?

Vitamin D increases the amount of calcium absorbed in the gut, as well as playing a role in balancing the amount of calcium and phosphate in the body, needed for proper bone growth and repair. Low levels of vitamin D can cause various bone and muscle problems, including rickets and osteoporosis which increases the risk of serious and life-threatening broken bones.

The NHS says that during spring and summer most people should be able to get all the vitamin D they need from the sun. This isn’t the case in winter, and people need to either get enough from their diet, or supplement, to maintain healthy levels.

The video shows us the first line in the cholecalciferol Wikipedia page which describes it as “a type of vitamin D that is made by the skin when exposed to sunlight”—but the narrator does not highlight this. 

Instead, he moves further down the article beyond the information about safe and effective doses of the vitamin to the “Use as rodenticide” section. This begins with the sentence “Rodents are somewhat more susceptible to high doses than other species and cholecalciferol has been used in poison bait for the control of these pests”.

Later he goes on to claim “They’re calling rat poison a vitamin” and then near the end of the video that “Cholecalciferol is specifically designed to kill by producing hypercalcaemia [high calcium levels in the blood]”.

Cholecalciferol isn’t the only substance used both in human medicine and to kill rodents. Warfarin, a blood thinning drug, was historically used as a rodenticide, and now significantly reduces the risk of death from clots and strokes for millions of people worldwide.

Moderation in all things

Taking too much vitamin D over long periods of time can indeed cause hypercalcaemia. But at normal doses, this is very unlikely. 

UK, EU and US health boards have reached a consensus that 4,000 IU (international units) a day would not have a noticeable risk to health, and single doses of 300,000 IU would not either, if spaced out by three months.

Prescribed doses are significantly lower than this, at 400 IU a day to prevent deficiency and higher initial doses to treat deficiency reaching a maximum of 300,000 IU over six to ten weeks.

Various groups of people are advised to take vitamin D, if they are at risk of deficiency. This includes older people, people who have reduced exposure to the sun, and people with health issues that may reduce their intake through food. Some may be prescribed this by their doctor.

People with certain medical conditions, such as those already with hypercalcaemia, may not be able to take vitamin D supplements as they may interact with some medications, such as certain blood pressure or heart disease drugs.

Cholecalciferol is also naturally present in some foods, with other foods fortified with it. The video notes this, referring to “this toxic chemical, this rat poison that they're putting in the milk”.

Milk isn’t generally fortified with vitamin D in the UK, unlike the US. There, fortified milk will contain between 100 and 150 IU per 8-ounce serving (around 237ml). This means to breach the upper limit of 4000 IU through milk, a person would have to drink over six litres of it every single day.

The information included in this article contains the latest evidence and official guidance available at the time it was written. This is not a substitute for medical advice. If you require specific medical advice please consult your GP.

Featured image courtesy of Cat Ball

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