Both vitamin D and omega-3 fatty acids elicit dose-dependent, tissue-specific changes in immune cell development, balance among immune cell types, and the efficacy of the immune response. Different populations of immune cells metabolize omega-3 fats using diverse enzymes that create a variety of pro-resolving mediator (PRM) metabolites. Within cells, vitamin D produces distinctive responses upon interacting with numerous types of nuclear receptors that are unique to particular tissues. These effects are often limited by tissue concentrations of these essential nutrients.
Results from -omics investigations indicate that vitamin D nutritional status influences T-helper cell differentiation into Th1 and Th17 lines, and vitamin D sufficiency facilitates the training of T-helper cells towards immune tolerance. Previous research into early immune alterations in multiple sclerosis (MS) suggests that higher intakes of omega-3 fats and of flavonoids may protect against pathogenic changes in T-helper and T-regulatory cell activity that are implicated in MS, while greater consumption of omega-6 fatty acids may aggravate these maladaptive shifts in immune balance.
For this double-blind, placebo-controlled clinical trial, 25,871 US adults from all over the country were randomized to receive placebo, 2000 IU vitamin D3, 1000 mg omega-3 fatty acids, or 2000 IU D3 plus 1000 mg omega-3s daily over the course of a 6-year trial. The median follow-up period among participants was 5.3 years. Participants’ mean age was 67.1 years; men were at least 50 years of age while women were at least 55 years old. Subjects were assessed medically on an annual basis, and diagnoses for autoimmune disease were confirmed by expert review. The primary study endpoint was total incidence of autoimmune disease as well as incidences of rheumatoid arthritis, autoimmune thyroid disease, psoriasis, polymyalgia rheumatica, and all other combined autoimmune conditions. Secondary study points included many individual autoimmune conditions and probable (but unconfirmed) autoimmune disease.
Clinical Impact of Vitamin D and Omega-3s on Autoimmunity
Vitamin D and omega-3 fatty acids influence the activity of immune cells’ nuclear receptors, and dietary omega-3 sufficiency ameliorates cell membrane responses.
More importantly, though, vitamin D and omega-3s exert considerable control over the replication and functional programming of maturing immune cells as well as ultimate balance among T-helper cell, macrophage, and other critical cell populations of both innate and adaptive immunity. These essential regulatory nutrients are increasingly recognized for their impact on immune health outcomes.