This question was sparked by the recent News Agency of Nigeria (NAN) article that was published on a number of news sites. Premium Times, Pulse Nigeria, Vanguard and Pharmanewsonline are just a few, albeit we counted seven.
The article claimed that excessive consumption of cold water has dire health consequences on the average person. It supposedly affects the veins, damages the heart and leads to a heart attack. A Warri-based paediatrician was quoted in the article as saying that: “excessive cold water consumption can cause the closure of four veins, and in the process lead to heart attack”.
It did not stop there but further asserted that excessive cold water consumption may also lead to cancer as a result of fats sticking to the liver.
As most gravitate towards that cup of cold water since we live in the tropics, this is unnerving news. But is it true?
Health authorities have long-established the ideals of how much water we should consume in a day. The eight glasses (2 litres of water) a day mantra is an all too familiar one. But what do we know of the temperature of the water we consume – should we be drinking cold or warm water and is there a disadvantage to choosing one over the other?
Cold water and the body
Cold water in the body cannot be completely harmful; after all, cold drinks have been, and are still used in treating fevers.
It is first important that we understand the absorption of water in the body, more specifically the stomach through the means of a physiological explanation.
The temperature in the stomach (which is also known as the core body temperature) is 37°C (98.6°F). A glass of cold water is about 4°C, (close to the temperature of ice) whereas room temperature or thermoneutral water is 22°C and warm water, anything above 30°C.
Your water temperature preference does alter this very core body temperature, but, and this is the key point – only for a duration. This is because the processes in the stomach are such that a cold drink does not remain cold in the body, but is acclimated to the stomachs environment with metabolic heat (this also goes for the food you eat).
It takes exactly five minutes for water to be absorbed from the stomach, and subsequently the bloodstream, after drinking. Within this five minute window, cold water is heated to maintain a stable core temperature, before making its way to the bloodstream. After this point, experts say, that the water is unaffected by temperature. Essentially the temperature of the water one ingests is inconsequential due to innate gastric adaptive responses.
William Gilman Thompson, in his book, best explains it when he said “one may begin a dinner with iced raw oysters, then take hot soup, and later conclude the meal with ice cream, followed by hot coffee…and yet throughout, the temperature of the stomach contents does not vary so much as half a degree.”
Given the background, we can say that the warnings in these articles hold no ground. If science tells us that cold water is always adjusted to the core temperature in the stomach of 37°C, then all the warnings of damage to various organs caused by cold water are inconceivable. Nevertheless, we examine each claim.
A heart attack is a life-threatening disease that results from a blocked coronary artery or arteries. Four veins can close leading to a heart attack, the NAN article claimed. But no scientific evidence was provided as proof of such a link. According to the National Heart, Lung and Blood Institute, the cause of a heart attack is the accumulation of fat and cholesterol (plaque) from years of exposure to modifiable risk factors. These modifiable risk factors are smoking, obesity, an unhealthy diet and physical inactivity. Other causes of a heart attack could also include coronary artery spasm- a tightening of the muscles in the artery.
If these claims were even possible, a process known as vasoconstriction, where the blood vessels become narrow, might be the most intelligible explanation, and this is stretching the facts. This process, which is cold-induced, can indeed lead to a heart attack in peculiar circumstances. However, research has shown that this (constricted blood vessels) occurs when a person is immersed in a pool of cold water or is exposed to an extremely cold environment and not when they ingest the water. Thence, this claim does not hold here.
This second part of the claim is based on a popular myth which claims that cold water results in the accumulation of fats which stick to the liver, causing cancer. What specific types of cancers though? We are not told as there is a multitude of cancers that vary depending on the part of the body affected.
It has been over a decade that this myth of an association between cold water and cancer has been in existence as it first surfaced in 2006. VeryWellHealth, Snopes, Hoax slayer, Says and Today have all addressed it in their various publications. This serves as proof that the claims made are only propagating a false narrative and should not be entertained any further.
Many of these articles make the point that the National Cancer Institute, a reputable source for all things cancer-related, made no mention of such a correlation. No such association was also made by any other health authorities; with the consensus being that it has no factual basis.
Additionally, an analogy often used, suggests a correlation between cold water and oils. This was employed in explaining the effects of cold water on the liver. It insinuated that drinking cold water with a meal containing fats/oils solidifies the food the way cold water solidifies oils in your kitchen drains. The resultant effect was, causing them to stick to the liver on getting there.
However, fats/oils are broken down in the intestines into bits known as chylomicrons before being carried to the liver. They do not remain in their “eaten form”, and neither does the water drunk. Hence, this is certainly improbable.
A third part to the claims made in the article states that “cold water makes the blood vessels to shrink thereby causing indigestion”.
Firstly, no studies support this assertion and while there are irrefutable benefits of warm water in aiding digestion, this does not necessarily translate to indigestion from cold water. Common causes of indigestion include eating too much, drinking too much, food intolerance, and/or taking some medicines on an empty stomach.
Even if this claim were true, it is hypothesised that cold water affects or slows down digestion as the stomach expends more energy ‘heating up’ cold water so that it is suitable for absorption. To this, we refer back to evidence of a clear-cut five-minute duration in which ALL contents in the stomach adjust to the core body temperature. A study stated in clear terms that these five minutes are the same for all persons. It only varies from person to person on the volume that leaves the stomach.
Moreover, the claim mixes up two distinct systems in the body (circulatory system and the digestive system). It is assuming that the water drunk moves straight into circulation, this being false. Although, blood vessels constrict in reaction to cold (vasoconstriction), however, this is not the case here as the water does not move directly into the blood vessels in its ingested state. It first undergoes absorption by the small intestine.
There is no evidence to support any of the claims made in the article. Health authorities have also said nothing of the sort. Instead, what we found is that the claims were underpinned by myths. You can have your drink of cold water.
Also, it is worth noting that these articles do make specific reference to excessive consumption (without defining what they meant by excessive consumption, like “how many glasses”). This further questions the veracity of the claims. However, we recognise that excessive consumption of anything is ill-advised. Nevertheless, it is far-fetched to suggest a correlation to a heart attack and cancer.