Vitamin D2 seems to bring positive effects to prostate cancer, together with normal chemotherapy and radiotherapy treatments (1).

A cardioprotective effect of vitamin d2 has been shown to improve hyperglycemia and inflammatory processes (2).

Comparison between supplementation of vitamin D2 and D3 (3).

References________________________________

(1) Effect of Vitamin D Supplementation in Prostate Cancer: A Systematic Review of Randomized Control Trials.
Petrou S, Mamais I, Lavranos G, Tzanetakou IP, Chrysostomou S.
Int J Vitam Nutr Res. 2019 Apr 30:1-13. doi: 10.1024/0300-9831/a000494

(2) Cardioprotective effect of vitamin D2 on isoproterenol-induced myocardial infarction in diabetic rats.
El Agaty SM. Arch Physiol Biochem. 2018 Mar 8:1-10. doi: 10.1080/13813455.2018.1448423.

(3) Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis.
Tripkovic L, Lambert H, Hart K, Smith CP, Bucca G, Penson S, Chope G, Hyppönen E, Berry J, Vieth R, Lanham-New S.
Am J Clin Nutr. 2012 Jun;95(6):1357-64. doi: 10.3945/ajcn.111.031070. 

Vitamin D2 or ergocalciferol 

Vitamin D refers to two compounds, vitamin D2 ergocalciferol and vitamin D3 cholecalciferol. It plays an important role in the cell cycle and proliferation.

Vitamin D2 is derived from the irradiation of plant sterol, ergosterol and is provided by the foods we take.

The name "ergocalciferol" is derived from "ergosterol", a compound from which it is formed, and "calciferol", a term used for vitamin D compounds. The prefix "ergo-" comes from the Greek word "ergon" and it was named so because ergosterol was first isolated from ergot, a type of fungus. "Calciferol" comes from Latin "calcis" (lime) and "ferre" (to bear), reflecting the role of vitamin D in calcium metabolism.

The natural synthesis process of ergocalciferol. Ergocalciferol, also known as vitamin D2, is produced by plants, fungi, and yeasts in response to ultraviolet (UV) light. Simplified version:

• The process begins with the conversion of ergosterol, a compound found in the cell membranes of fungi and yeasts, into previtamin D2 when exposed to UV light.
• Previtamin D2 is then spontaneously isomerized to form vitamin D2 (ergocalciferol) by a heat-dependent process.

It appears in the form of a white powder. 

What it is for and where

Medical

Treatment of Vitamin D deficiency. Ergocalciferol is often used to treat Vitamin D deficiencies, which can occur due to inadequate diet, malabsorption, or limited sunlight exposure.

Prevention of Osteoporosis. Since it helps the body absorb calcium, Ergocalciferol can be used to prevent or treat osteoporosis.

Treatment of Rickets. Ergocalciferol can be used to treat rickets, a disease that causes weak or deformed bones in children due to a deficiency of Vitamin D.

Treatment of Hypocalcemia. Ergocalciferol can be used to treat hypocalcemia, a condition characterized by low levels of calcium in the blood.

It has a cardioprotective, anti-inflammatory and protective action against prostate cancer.

Vitamin D2 studies

• Molecular Formula: C₂₈H₄₄O
• Molecular Weight: 396.659 g/mol
• CAS: 50-14-6
• EC Number: 200-014-9
• UNIII: VS041H42XC

• Ergocalciferol
• Viosterol
• Calciferol
• Oleovitamin D2
• Diactol
• Deltalin
• Deratol
• Ercalciol
• Condol
• Ergorone
• Novovitamin-D
• Detalup

http://www.vitamindcouncil.org/health-conditions/depression/