Vitamin D has generally decreased over the past 100 years - Nov 2024

 

---

Perplexity AI - Nov 2024

Have vitamin D levels crashed (decreased a lot) during the past 100 years?
The historical trends in vitamin D levels show a complex pattern of changes over different time periods:
Historical Changes
Early Industrial Era
During the Industrial Revolution in Western Europe, vitamin D levels likely decreased significantly due to air pollution from mills and fossil fuels, which reduced UV light exposure. Workers moving from rural areas to dingy cities had diminished sun exposure, leading to widespread rickets  2
Late 20th Century Decline
A marked decrease in vitamin D levels occurred between 1988-1994 and 2001-2004. Mean serum levels dropped from 28-32 ng/mL to around 24 ng/mL across different age groups 1
During 2001-2004, 77% of US adolescents and adults had insufficient vitamin D levels 1
Recent Improvements
From 2001 to 2018, there has been a positive trend:

• Serum vitamin D levels increased from 65.6 nmol/L to 73.5 nmol/L in US adults 4
• However, young adults (20-39 years) and those with lower socioeconomic status showed declining levels and increased deficiency rates 4

Geographic Variations
Different regions show varying trends:

• In Poland, infant vitamin D levels decreased from 129.5 nmol/L (1981-1999) to 72 nmol/L (2010-2011) 5
• Iran showed improvement, with levels increasing from 51 nmol/L in 2001 to 62 nmol/L in 2013 5
• Some Asian countries have experienced recent declines, possibly due to increased urbanization and air pollution 5

Rather than a continuous crash over 100 years, vitamin D levels have fluctuated, with significant decreases during industrialization and the late 20th century, followed by some improvement in recent years, though challenges persist for certain population groups.

---

Claude 3.5 Sonnet - Nov 2024

... here are some specific numeric comparisons that demonstrate the decline in vitamin D levels, though it's important to note that historical measurements can be challenging to verify with complete accuracy:
Traditional/Historical Populations:

• East African tribes studied in the 1960s-70s showed average vitamin D levels of 115-150 nmol/L (46-60 ng/mL)
• Maasai herders and other traditional outdoor workers typically showed levels of 100-150 nmol/L (40-60 ng/mL)

Modern Populations (measured in the last few decades):

• Average US adult levels: 25-50 nmol/L (10-20 ng/mL)
• European populations generally show similar or even lower averages
• Urban office workers often show levels below 30 nmol/L (12 ng/mL)

Some particularly striking examples:

• A 2009 study found that about 42% of US adults were vitamin D deficient (<20 ng/mL)
• Recent studies of indoor workers in developed countries show that up to 80% have insufficient vitamin D levels during winter months

The most dramatic drops are seen in populations that have rapidly modernized. For example:

• Studies of traditional societies that have recently urbanized show drops from around 115 nmol/L to 35-40 nmol/L within a single generation
• Children's levels have shown particularly sharp declines, with some studies showing modern urban children having less than half the vitamin D levels of their rural counterparts from the 1960s

---

Google Gemini 1.5 Nov 2024 - 5 reasons

Have vitamin D levels crashed (decreased a lot) during the past 100 years?
Yes, there's strong evidence suggesting that average vitamin D levels have significantly decreased in many populations over the past 100 years. Several factors contribute to this:

• Increased indoor time: Modern lifestyles involve spending significantly more time indoors, reducing exposure to sunlight, the primary source of vitamin D synthesis in the body. This is particularly pronounced in higher latitudes with less sunlight throughout the year.
• Sun protection measures: Increased awareness of skin cancer risks has led to widespread use of sunscreen, which blocks UVB radiation necessary for vitamin D production.
• Changes in diet: While dietary sources of vitamin D exist, they are often insufficient to meet the body's needs, especially in populations with limited access to fortified foods.
• Increased air pollution: Air pollution can reduce the intensity of UVB radiation reaching the earth's surface, further hindering vitamin D synthesis.
• Clothing styles: More clothing coverage compared to earlier times, particularly in some cultures, limits sun exposure.

It's important to note that the exact extent of the decline varies by geographic location, population group, and time period. Studies comparing vitamin D levels across different generations and populations often show a considerable drop, but pinpointing a precise percentage decrease over the entire 100 years is challenging due to variations in measurement techniques and data availability from the past. However, the overall trend is clear: a substantial reduction in vitamin D status is a significant public health concern.

---

VitaminDWiki - Many reasons why vitamin D deficiency has become epidemic 40 reasons

23 of the 40 reasons for Vitamin D deficiency are new

---

VitaminDWiki - Vitamin D levels have been crashing since 1995 (Polish Children, Elite Military, etc)

---

VitaminDWiki - 4 Reasons why Vitamin D levels are crashing

Table of Contents as of Nov 2024
1) Less sunshine
2) Less from Food
3) Decrease in nutrients decreases Vitamin D
4) Higher % of population with low Vitamin D
also - Obese, elderly, dark skin, poor health/chronic pain

click on chart for details

---

See also:

• Incidence of 22 health problems related to vitamin D have doubled in a decade
• Vitamin D reduced so low that Victorian age diseases are returning
• Reasons for low response by vitamin D level in the blood
• 3X more kids were vitamin D deficient when entering UK hospitals than 4 years before – Oct 2014
  Only half as many people had >30 ng of vitamin D 16 years later
  • (that was 2004 - How much lower since then?)