Let's talk about why citrus oils are so powerful for supporting immunity. It's one thing to know they're amazing, but another to really understand why!
d-Limonene and Citrus
Most citrus oils contain at least 60% d-limonene. The largest amounts of d-limonene (also known as (+)-limonene) are found in the citrus oils--such as Grapefruit, Orange, Clementine and Tangerine--which contain amounts ranging from 80-95%. Lemon, Mandarin, and Tangelo oils contain amounts ranging from 65-80%.
Why do we care? Research on d-limonene is significant. I know we can't assume that results from animal research (ugh!) will be the same as results from human use. That being said, there's still a lot to gain from this information.
Immunostimulant effects of d-limonene seen in rodent studies include stimulating lymphocyte proliferation (4), increasing the total white blood cell count (5), increasing the number and phagocytic activity of macrophages (1,2), and stimulating antibody production (5). Natural killer cell activity was enhanced in vitro by d-limonene (3).