And in brown and black skin, the discolouration may appear as a darker grey or slate-blue hue, effectively creating an inadvertent tattoo. (Pexels Photo)
By Michelle Spear, University of Bristol, The Conversation
When an 84-year-old man in Hong Kong went to hospital with an enlarged prostate, doctors were startled to see that his skin – and even the whites of his eyes – had turned silver-grey. A deeper investigation revealed silver deposits permeating his tissues, turning him a hue more often reserved for science fiction.
Far from a one-off oddity, in 2007 press reports described Paul Karason as a “blue man” after he attempted to cure sinus and skin problems by ingesting a homemade silver chloride solution – and there are many other examples.
These striking cases reveal a profound truth: our bodies can display the residue of what we consume. The adage “you are what you eat” usually refers to overall health and nutrition, but that phrase can be startlingly literal when our skin takes on unexpected colours.
The cases above illustrate dramatic instances of the condition known as argyria, in which silver particles accumulate in the body.
Silver was once a mainstay in medical treatments for its antimicrobial properties. But modern evidence shows that consuming or absorbing too much can transform one’s skin in ways that seldom fade. In argyria, silver ions circulate through the bloodstream and become embedded in the dermis, a layer beneath the surface where the body cannot easily clear them. This is the layer that tattoo pigments reside in.
Sunlight compounds the effect by triggering a process called photoreduction, which turns silver ions into metallic silver or related compounds. As a result, affected lighter skins adopt a bluish or greyish tinge. And in brown and black skin, the discolouration may appear as a darker grey or slate-blue hue, effectively creating an inadvertent tattoo.
A similar phenomenon, albeit rarer, is chrysiasis, in which gold deposits infiltrate the skin. Historically, gold-based therapies were occasionally prescribed for inflammatory disorders, and in some cases, patients who received these treatments developed a distinctive slate-grey or grey-purple discolouration that, much like argyria, could not be easily undone.
Pigments from the plate
Orange, yellow and red pigments exert the most influence over skin, and orange seems to reign supreme. This shade, often associated with carrots, sweet potatoes and pumpkins, comes from carotenoids, a class of pigments naturally found in plants.
Carotenoid pigments are fat soluble. When consumed, they are absorbed in the small intestine and transported via lipoproteins in the bloodstream to be stored primarily in fat-rich tissues, including the subcutaneous layer of the skin. This storage gives the skin a characteristic golden hue, most notably when carotenoid-rich foods are consumed in high quantities.
Of the many carotenoids found in nature, beta-carotene is the star player: a strong orange tint and high “bioavailability” – the term used to describe drug absorption – make it particularly influential.
Humans metabolise (break down) carotenoids in a selective way. Enzymes in the intestines and liver turn beta-carotene into vitamin A, which is crucial for vision, a healthy immune system and healthy skin.
However, not all ingested beta-carotene undergoes this transformation. Excess amounts remain in their pigment form and are deposited in the skin, particularly in areas like the palms of the hands and soles of the feet, where the thicker layer of skin highlights the pigment’s presence.
The reason the skin turns orange lies in the chemical structure of carotenoids. Beta-carotene’s molecular makeup absorbs light in the blue spectrum, reflecting orange light back to our eyes. Other carotenoids, such as lutein and zeaxanthin (found in leafy green vegetables), which lean toward yellow, are less conspicuous because they are either less abundant in the diet or not as prominently stored in the skin.
Research has shown that a carotenoid-rich diet, which can enhance a healthy golden glow, is often perceived as more attractive than sun-induced tanning. But moderation is key. The 90s juice brand Sunny Delight never really recovered from the controversy of orange-stained Sunny D kids.
Naturally occurring dietary pigments such as anthocyanins, betalains and chlorophyll offer many health benefits, but rarely leave a mark.
Anthocyanins, found in berries, red cabbage and purple carrots, provide the deep reds, purples and blues we associate with these foods. Known for their antioxidant properties, they are water-soluble, meaning they are quickly metabolised and therefore unlikely to leave a mark on the skin.
Similarly, betalains, the pigments responsible for rich reds and yellows, offer detoxifying and anti-inflammatory benefits but are excreted by the body without a visible effect on skin tone. Excess ingestion may, however, cause urinary and faecal colour change.
These colourful tales carry more than an aesthetic message. They highlight the fine balance required in our relationship with the substances we ingest. From wholesome pigments to unintended consequences, they serve as a vivid reminder that while food may be medicine and may be transformative, we are, quite literally, what we eat.
Michelle Spear, Professor of Anatomy, University of Bristol
This article is republished from The Conversation under a Creative Commons license. Read the original article.
