In a small study in 50 patients and 100 controls in Korea, it was found that the HS-Omega-3 Index correlated positively with bone mass (Moon et al, 2012). In a first intervention trial, omega-3 fatty acids built up bone density and had a synergistic effect with physical exercise (Tartibian et al, 2011).
Another small study in Korea found a low HS-Omega-3 Index to be a risk for ischemic or hemorrhagic stroke (Park et al, 2009). In a retrospective analysis of the large intervention trial JELIS, EPA reduced the incidence of stroke (Tanaka et al, 2008). Currently, omega-3 fatty acids are investigated to find out, whether they reduce traumatic, ischemic or other brain damages. Results from animal models are encouraging (e.g. Zendedel et al, 2015). Intervention trials in humans remain to be conducted.
Sleep apnea depends on cerebral regulation of breathing. Partly this depends on the HS-Omega-3 Index. In 350 patients, the severity of sleep apnea correlated inversely with DHA (Ladesich et al, 2011). Per standard deviation higher DHA, a patient was 50% less likely to be classified as severe sleep apnea (Ladesich et al, 2011). More research is ongoing.
According to our unsystematic experiences, patients with chronic polyarthritis adjust themselves to a HS-Omega-3 Index of 15% (unpublished). In a meta-analysis of randomized intervention trials, omega-3 fatty acids improved symptoms like morning stiffness, or joint pain (Goldberg & Katz, 2007). Other topics are currently investigated.