Controversial Aspects of Vitamin D Recommendations in Modern Medicine

The current Recommended Dietary Allowance (RDA) for vitamin D, set at 600 IU, has been a subject of controversy in the medical community. This figure, described as arbitrary and established by committee, is considered insufficient by some experts, equating to only about 1.8 minutes of sun exposure in summer.

Historically, sunbathing (heliotherapy) was widely used to treat various conditions including tuberculosis, asthma, osteoporosis, and even cancer before the advent of antibiotics and vaccines. However, modern medical advice has shifted towards avoiding sun exposure and promoting sunscreen use, citing concerns about vitamin D toxicity.

Challenging these concerns, a study by the University of Illinois Chicago found no toxicity at doses between 200,000 to 1,000,000 IU, suggesting that past toxicity reports were likely due to manufacturing issues rather than the vitamin itself. Vitamin D3 is highlighted as an important immune modulator, and the Institute of Health's recommendation of 600 IU has been criticized. Two other organizations found errors in this recommendation, suggesting it should be around 8,895 IU instead.

The presentation of this data to top vitamin D researchers has reportedly met with negative reactions, drawing parallels to the historical mistreatment of the professor who discovered folates and was initially disbelieved.

Correlations between latitude and diseases such as multiple sclerosis, breast cancer, and diabetes have been observed, with lower risks noted closer to the equator where sun exposure and vitamin D levels are typically higher.

A historical overview of vitamin D recommendations shows a complex evolution:

- Early 1900s: Rickets were common

- 1918-1920: Sun therapy and cod oil were used for rickets

- 1922: Vitamin D was discovered

- 1946: 400 IU recommended to prevent rickets

- 1950-1970: Despite increased awareness of vitamin D benefits, recommendations remained at 400 IU

- 1980: Recognized benefits for the immune system and chronic diseases, but still 400 IU

- 1997: Institute of Medicine updated RDAs, introducing Adequate Intake (200 IU for adults, 400 IU for 51-70, and 600 IU for over 70)

- 2010: RDAs updated to 600 IU for adults under 70, and 800 IU for over 70

While 400 IU was the general recommendation, prescribed medications often contained 50,000 IU. Campaigns against sun exposure and promoting sunscreen use have contributed to widespread vitamin D deficiency, which has been linked to melanoma, a type of skin cancer that often develops in non-sun-exposed areas.

Vitamin D is crucial for 2,700 different genes, and various factors including skin colour, age, weight, and genetic resistance can affect vitamin D absorption. Some critics suggest that modern medicine and pharmaceutical companies may be promoting low vitamin D intake, despite its importance for overall health.