Aging in humans resembles chronic low-grade vitamin C deficiency. By David Archibald.

One of the predecessor animals of humans lost the ability to make vitamin C in the Eocene, 40 to 60 million years ago. The world was a lot warmer then and most land areas were covered with rain forest. There was plenty of vitamin C available all year round in the fruit of the flowering plants that had evolved not long before. …

Then Antarctica drifted over the South Pole, the Antarctic ice sheet appeared and the current ice age began. The world became colder and drier. There was no longer a year-round supply of vitamin C from fruit. The human range expanded to all the climatic zones. Most of humanity now lives with a chronic vitamin C deficiency. …

The recommended daily allowance for vitamin C in Australia is 45 mg per day and we consume 110 mg per day on average. That is still less than 10% of what other omnivores use. Most of us are living our lives chronically vitamin C deficient. …

Vitamin C has a big role in slowing aging by better connective tissue integrity, lower frailty and slower immune senescence. Aging in humans resembles chronic low-grade vitamin C deficiency. …

Vitamin D regulates several hundred genes related to immune response to pathogens and cancer. There is a negative correlation between the vitamin D level in the blood and the incidence of sepsis, viral infections, cancer and most other diseases. The main role of vitamin D is bone turnover. Once the vitamin D level in the blood falls below 40 ng/ml, the thyroid gland starts producing parathyroid hormone which takes over that role, freeing some vitamin D for more immediately vital roles. The average Australian blood level is 25 ng/ml so most Australians live their lives with a chronic vitamin D deficiency. The incidence of most diseases would halve at 50 ng/ml. There is increasing benefit up to at least 80 ng/ml. Getting there will take supplementing at between 5,000 IU and 10,000 IU of vitamin D per day, depending on weight.

Much, much more at the link.