As with my last post, I have not done a specific post on black walnut leaf (Juglans nigra). It was cited as reducing peroxynitrite which is suspected to cause environmental illness/multiple chemical sensitivity.
- “the most valuable and cited medicinal plant species [for dental problems] used by the traditional drivers are Juglans regia”
- “The medicinal plant species with highest fidelity level was of … Juglans regia … each cited 100% for ..easy digestion …” 
- “The essential oils from three different samples of. J. nigra contained (E)-caryophyllene (17.3%-20.4%) and germacrene D (7.1%-22.5%) with smaller amounts of juglone (1.0%-8.8%), alpha-hydrojuglone (1.0-9.5%), and delta-cadinene (3.8%-8.7%). J. regia leaf oil, devoid of juglone, showed allelopathic activity, while J. nigra leaf oil was less phytotoxic.” 
- “The essential oil and its major components exhibited broad spectrum inhibition against all the bacterial strains with Gram-positive(Staphylococcus epidermidis MTCC-435, Bacillus subtilis MTCC-441, Staphylococcus aureus) being more susceptible to the oil than Gram-negative bacteria.(Proteus vulgaris MTCC-321, Pseudomonas aeruginosa MTCC-1688, Salmonella typhi, Shigella dyssenteriae, Klebsiella pneumonia and Escherichia coli).” 
- “Walnut leaves selectively inhibited the growth of Gram positive bacteria, being B. cereus the most susceptible one (MIC 0.1mg/mL). Gram negative bacteria and fungi were resistant to the extracts at 100mg/mL.” 
- “The zones of inhibition due to the … Juglans regia leaf extracts ranged from 17.6 mm against P. acnes, 15.7 mm against S. aureus and 15.5 mm against S. epidermidis, respectively….These zones of inhibition were… less… to those obtained from doxycycline or clindamycin…. may be beneficial in treating acne especially when they are known to have anti-inflammatory activities. ” 
- “derum (Juglans regia; walnut tree) …The most sensitive organisms were A. viscosus, followed by S. mutans, S. salivarius, with L. casei being the most resistant.” 
Black Walnut Leaf (actually Walnut Leaf) is far more effective against a variety of Staphylococcus than the Lactobacillus tested. Folklore from tribal area in India and Pakistan had it helping with digestion and with bad teeth bacteria.
It continues to be in the recommended list of herbals.
Note: There are no studies for FM/CFS/IBS.