The effects of light on metabolism have been known for over 100 years. John Harvey Kellogg in Light Therapeutics recounts some of the observations as of 1910.(1)
“An animal eliminates more carbon dioxide under the influence of light than when confined in the dark. This has been found to be true of hibernating animals also. Starving animals lose less weight at night than during an equal number of hours of daylight, although kept equally quiet. Certain animals, as crabs, when painted with dark varnish, are quickly killed, although unaffected by transparent varnish.
Eggs develop more rapidly when exposed to the influence of sunlight than when kept in the dark. This is also true of the larvae of insects.
Oxidation of living tissues is increased by the action of sunlight, while in human beings, as well as in animals, less carbon dioxide is eliminated at night than during the same number of hours of daylight, even though an equal degree of quiet be observed .
Country children, who are more exposed to sunshine than those in the city, are much healthier in appearance and less subject to rickets, tuberculosis and other grave disorders. Cretinism is most frequently found in deep valleys from which the direct rays of the sun are largely excluded. Eskimo women suffer from amenorrhea during the long polar night.”
Since the publication of Dr Kellogg’s book in 1910 science has developed a much deeper understanding of the workings of metabolism while technology has developed more advanced lighting systems.
In the 1960s Endre Mester performed some experiments with the newly designed laser. (2) Intending to cut cancerous tumours out of lab animals the Hungarian physician instead found that the light source did not cut but rather increased the rate of wound healing in the animals and sped the regrowth of hair around the shaved area.
It was later discovered that the laser had been calibrated incorrectly and was of a much lower power than had been requested by the Mester. Mester’s discovery of the healing effects of low intensity laser became the basis of the field known as low level laser therapy (LLLT) or photobiomodulation (PBM). There are many other names used to describe the process.
In the decades between discovery of photobiomodulation and the current day thousands of studies have been published on various mechanisms and maladies in human and animal subjects. Since the 1990s there have been a number of publications on the effects of photobiomodulation on the thyroid gland.
The thyroid gland controls the energetic metabolism of the organism. Kellogg notes in the above passage the effect of light on oxidation and exhalation of carbon dioxide. Thyroid hormone allows for more efficient use of oxygen by the cell in the generation of energy leading to increased metabolic rate and production of carbon dioxide as a “byproduct”.
The literature surrounding thyroid and photobiomodulation is based on thyroid hormones, hypothyroidism and the autoimmune processes that lead to autoimmune hypothyroidism or Hashimoto’s syndrome.
The main treatments for hypothyroidism include synthetic T4 (levothyroxine or Synthroid.) T4 is secreted by the thyroid gland and is a precursor to T3. In order to be properly metabolically active the T4 hormone must be converted by other organs to T3. A common problem with T4 supplementation and hypothyroidism is that the conversion to T3 is limited for some reason. T4 can be converted to the active thyroid hormone T3 or alternatively to reverse T3 (RT3.)
RT3 is structurally similar to T3 but has the opposite effect functionally. RT3 blocks T3 from accessing the cell and activating metabolism. So there are a number of problems when supplemental T4 is not efficiently converted to T3.
It is possible to supplement T3 along with synthetic T4 to approximate rate and ratio production from a healthy thyroid. Sometimes it is found that some people need more T3. Liver problems and the factors that set up elevated levels of reverse T3 can cause a need for higher levels of T3 or lower levels of T4.
Before the advent of synthetic thyroid hormones hypothyroidism was treated with animal glands and then with processed porcine or bovine glands. This product is known as natural desiccated thyroid or NDT and contains a similar ratio of T3 and T4 to what are found in normal human thyroid gland production.
Access to these medications in some places can be tricky. Doctors are sometimes uneducated and more often than that scared of T3. Hypothyroidism can make someone miserable and sick for years, decades even. An excess of thyroid hormone (T3) however can kill you quickly. The hesitancy around T3 isn’t entirely unjustified.
Combined with the problem of access to appropriate medicines there is the problem of the autoimmune process which is a major cause of hypothyroidism. Antibodies like thyroid peroxidase (anti-TPO or TPOab) affect thyroid hormone production. In some people it seems that adequate medication can limit the autoimmune processes but in others these processes to continue.
So what can photobiomodulation do for hypothyroidism?
Multiple human and animal studies over the last 20 years show that light can increase the levels of T4 in the blood approaching or reaching normal levels (2-15)and holding for a period of months after cessation treatment. Some improvements are retained years after the last treatment but for all benefits treatment must be repeated about every 3 months.
Photobiomodulation also has been shown to normalise the active thyroid hormone T3. (2-15) The thyroid stimulating hormone (TSH) is produced by the pituitary gland. Levels of TSH normally increase when the levels of thyroid hormones decrease. Photobiomodulation is shown to lower TSH as it increases T3 and T4.(2,3,5,6,7,8,15)
The most commonly assessed indicator of autoimmune hypothyroidism or Hashimoto’s is the thyroid peroxidase antibody (anti-TPO or TPOab). We now have multiple human and animal studies show that properly dosed light therapy can normalise thyroid peroxidase antibodies (2,5,6,9,16) while normalising TSH and thyroid hormones.
Other examinations of complications in autoimmune hypothyroidism include ultrasounds of the thyroid gland assessing structural abnormalities like goiter. Human studies with light therapy show that alterations in gland structure begin to normalise with appropriate treatment.
Since the Chernobyl nuclear disaster in Ukraine in the 1980s Ukraine and Russia have become leading experts in autoimmune hypothyroidism. Ionising radiation increases levels of hypothyroidism in the population. Consequently the studies from these countries are very detailed in their examinations of the autoimmune processes. These studies show reversing of the autoimmune processes from photobiomodulation. Appropriate light therapy stimulates regenerative processes within the thyroid gland and in the thymus gland. Interestingly one study shows that PBM can protect against ionising radiation
Other observations from the studies included improved vascularisation of the thyroid gland, a decreased need for thyroid medication after receiving photobiomodulation therapy, decreased facial swelling or oedema, improved quality of life, improved work productivity and an increase in anti-inflammatory cytokines (proposed to be beneficial in autoimmune hypothyroidism).
Many other metrics have been observed alongside PBM treatment of hypothyroidism including those related to heart disease. I’m sure some of the readers will be familiar with Dr Broda O. Barnes work on hypothyroidism and heart disease. I’ll be discussing the implications of light therapy in that context in future articles too.
Dosing is an extremely important factor in photobiomodulation. The effect known as the biphasic dose response has been known for some time. This effect is the description that a certain dose ranges needed for beneficial effect and then exceeding that dose range mitigates or lowers the therapeutic effect.
Light therapies can improve hormone and antibody count or affect them negatively.
A number of studies on endocrine glands (testicles) have shown negative results in animal models(17,18). Though these results are still hotly debated I think that they provide enough information to elicit caution when dosing light.
In my search for on autoimmune hypothyroidism and photobiomodulation I came across a few studies that seem to show negative results which I will discuss in more depth in future articles.
One animal study showed a clear decrease in thyroid hormones T3 and T4 with a concurrent increase in thyroid stimulating hormone TSH.(19) This is the normal pattern seen in hypothyroidism and could lead to the conclusion that improperly dosed photobiomodulation can cause hypothyroidism.
Laser therapy can crash thyroid hormone (T3) levels. T4 and TSH follow.
Antibodies and other markers of autoimmunity were not tested in this study. Though this is only one study the metrics used for dosing are in some ways this is similar to every other study published. So at this point it might be safer to assume it as proof of the dangers of improperly doused photobiomodulation rather than an outlying error. Time will tell.
Patreon supporters of resonantfm can access the referenced spreadsheet databases and referenced articles on PBM and hypothyroidism via this page (***). In the coming weeks I will be posting more in-depth articles looking at the dosing metrics used in human and animal studies. All the articles and references databases will be available to resonant FM patriot supporters.
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Much of this data was brought to my attention by Vladimir Heiskanen of Valtsus blog. I’m going to look at this subject from a different angle and I’d recommend reading his excellent articles if you haven’t already.
Thanks for reading. Patrons please check out the linked post at the top if you’re interested in access to the database.
Back with more soon…