Without light there is no life. Literally. It was Dutch scientist Jan Ingenhousz who through a series of experiments in 1779 showed that light is required for photosynthesis, the process that makes life on earth possible by allowing plants to capture carbon dioxide from the air while simultaneously releasing the oxygen we need to breathe. Plants either directly or indirectly produce all the food we require to live. The light that makes photosynthesis possible encompasses wavelengths in the 400-700 nanometer range which is termed “visible light” since this is the range of wavelengths to which our eyes respond. As Isaac Newton demonstrated in 1666, visible light can be separated into the colours of the rainbow, namely violet, indigo, blue, green, yellow, orange and red, by passing through a prism. These colours, known as the visible spectrum, represent different wavelengths with blue at the 400 nm end of the spectrum and red at 700. We cannot see wavelengths below 400, termed “ultraviolet,” or those above 700, referred to as “infrared.”
Given the critical importance of visible light for photosynthesis, it was natural for scientists to wonder about other possible effects that light of different wavelengths could have on life. Today, we know that while ultraviolet light in small doses can stimulate the production of vitamin D in the skin, excessive doses can cause skin damage. But what other effects might light have? We have learned, for example, that exposure to blue light at night suppresses melatonin production and delays the onset of sleep. As a result, we are advised to avoid television as well as laptop and phone screens one hour before bed. On the other hand, research has also shown that exposure to certain wavelengths can have a beneficial effect. This has given rise to a burgeoning industry based on “light therapy” that ranges from the utterly nonsensical to the potentially helpful.
Let's start with the nonsense. “Intravenous light therapy,” as advertised by some clinics, involves inserting a small fiberoptic catheter into a vein and shining laser light (usually red, blue, or green) directly into the bloodstream. This is claimed to restore mitochondrial function, reduce oxidative stress and inflammation, enhance immune function, increase energy, improve mood and augment cognitive function. Weasel statements like "commonly used in the treatment of Lyme disease, cancer support and chronic fatigue" abound. Yes, it may be true that IV light therapy is commonly used for these conditions at these clinics, but that doesn't mean it is used effectively. There is no clinical evidence that IV light therapy is effective for any disorder, and neither is any efficacy physiologically plausible. Light does not travel through the bloodstream for any significant distance since it is readily absorbed by hemoglobin in red blood cells preventing any effect on tissues. There are also potential risks of causing inflammation of a vein or infection at the site of insertion of the optical cable.
Like with many other pseudoscientific interventions, ranging from herbal supplements to coffee enemas, IV light proponents make the claim of “detoxifying” the body. What toxins are removed are never identified. The claim is meaningless. Some clinics also offer “photoluminescence therapy” whereby some of the patient’s blood is removed and exposed to ultraviolet light before being reinfused. This is said to boost immunity, treat chronic infections and even cancer. There is no clinical evidence for such treatment and neither photoluminescence nor IV light therapy is approved by FDA or Health Canada.
Let’s now turn to some forms of light therapy that are potentially beneficial. “Photobiomodulation,” also referred to as “low-level laser therapy” or “red/near infrared light therapy,” is a legitimate treatment for some conditions although outcomes are often overstated by marketers of the devices used. These devices range from face masks and helmets to panels of bulbs and flashlight-like tubes that usually emit a combination of red light with wavelengths in the 630-660 nanometer range and near-infrared light between 810-880 nanometers. The shorter wavelengths have a cosmetic effect on the skin with claims of improving acne, reducing fine wrinkles and redness while boosting collagen production and elasticity. Although there is some clinical evidence for these claims, the benefits are very modest and may not be noted by an objective observer.
Benefits can be more significant when it comes to tendonitis and joint or musculoskeletal pain. In the case of osteoarthritis, red light therapy can reduce pain and stiffness. Some patients find relief from neck and back pain and even neuropathic pain. However, significant effects are only noted when the therapy is used several times a week over several weeks and the device has to have the right wavelength and wattage which is measured in terms of milliwatts delivered per square centimeter, 30-100 for skin effects and around 200 for pain relief.
There are also various helmets, caps, headbands and combs that claim to stimulate hair growth in the case of male or female pattern hair loss that are supported by clinical trials. An increase of some 30-40 hairs per square centimeter compared with placebo is possible. This is noticeable, but hardly dramatic, and requires repeated 30-minute sessions 2-4 times a week for at least six months. Results are better if used in conjunction with topical 5% minoxidil, or in the case of men, with both topical minoxidil and oral finasteride.
“Endolaser therapy” should not be confused with any of the mentioned light therapies. This is an established medical procedure to treat bulging, enlarged, “varicose” veins by inserting a catheter through a small skin puncture using local anesthesia. A thin laser fiber is threaded through the catheter and near-infrared light at 1470 nanometers heats up the water component of blood and that heat then causes the vein to collapse.
Finally, “photodynamic therapy” is an established treatment for some cancers. A photosensitizing drug that concentrates in tumours is administered either orally or intravenously and is subsequently activated with visible or near-infrared light through an optical fiber to release reactive oxygen species that kill cancer cells. For example, porfimer sodium concentrates in lung or esophageal tumours that can then be exposed to red laser light at 630 nm to destroy cancerous cells.
I hope this discussion shines some light on the various forms of light therapy and specifically spotlights the shadowy clinics that make baseless claims of efficacy for intravenous light therapy.
