Nutmeg is the seed of the fruit which grows on the tree Myristica fragans, the same fruit from which Mace is derived.

Composition
Nutmeg is a spice that contains volatile oils comprised of alkyl benzene derivatives (myristicin, elemicin, safrole, etc.), terpenes and myristic acid. Additional compounds identified in nutmeg are glyco-conjugates such as p-cymene-7-ol, eugenol, methoxyeugenol and alpha-terpineol.

Benefit
Nutmeg may have aphrodisiac properties and this herb may be useful in enhancing libido.

Nutmeg research study as aphrodisiac
Aphrodisiacs activity of 50% ethanolic extracts of Myristica fragrans ( nutmeg ) and Syzygium aromaticum (clove) in male mice: a comparative study.
BMC Complement Altern Med. 2003.
Spices are considered as aphrodisiacs in the Unani System of Medicine. In order to explore the sexual function improving effect of Myristica fragrans and Syzygium aromaticum Merr. & Perry. (clove) an experimental study was conducted in normal male mice. The extracts (50% ethanolic) of nutmeg and clove were administered (500 mg/kg; p.o.) to different groups of male Swiss mice. Mounting behaviour, mating performance, and general short term toxicity of the test drugs were determined and compared with the standard drug Penegra (Sildenafil citrate). The extracts of the nutmeg and clove were found to stimulate the mounting behaviour of male mice, and also to significantly increase their mating performance. The drugs were devoid of any conspicuous general short term toxicity. The extracts (50% ethanolic) of nutmeg and clove enhanced the sexual behaviour of male mice and appear to be aphrodisiacs.

An experimental study of sexual function improving effect of Myristica fragrans Houtt.
BMC Complement Altern Med. 2005. Tajuddin, Ahmad S. Department of Ilmul Advia (Unani Pharmacology), Faculty of Unani Medicine, Aligarh Muslim University, Aligarh, India.
Myristica fragrans Houtt. has been mentioned in Unani medicine to be of value in the management of male sexual disorders. The present study was undertaken to evaluate the aphrodisiac effect of 50% ethanolic extract of nutmeg along with its likely adverse effects and acute toxicity using various animal models. The suspension of the extract was administered (100, 250 and 500 mg/kg, p.o.) to different groups of male rats daily for seven days. The female rats involved in mating were made receptive by hormonal treatment. The general mating behaviour, libido and potency were studied and compared with the standard reference drug sildenafil citrate. Likely adverse effects and acute toxicity of the extract were also evaluated. Oral administration of the extract at the dose of 500 mg/kg, produced significant augmentation of sexual activity in male rats. It significantly increased the Mounting Frequency, Intromission Frequency, Intromission Latency and caused significant reduction in the Mounting Latency and Post Ejaculatory Interval. The extract was also observed to be devoid of any adverse effects and acute toxicity. The resultant significant and sustained increase in the sexual activity of normal male rats without any conspicuous adverse effects indicates that the 50% ethanolic extract of nutmeg possesses aphrodisiac activity, increasing both libido and potency, which might be attributed to its nervous stimulating property. The present study thus provides a scientific rationale for the traditional use of nutmeg in the management of male sexual disorders.

I am a journalist and I was hoping you could provide a comment for me. I am currently in Tanzania, working on an article about nutmeg. Specifically about the phenomenon of using nutmeg instead of alcohol (which is prohibited within the Muslim population in Zanzibar) as an aphrodisiac. I attended a wedding there and they said that in the morning of the wedding, the put some nutmeg in their porridge to "make the women loose" and make them dance better. Does nutmeg really work as an aphrodisiac? They also claim it works on women, not men (that it's like a viagra for women). What do you think about that?
   I have not done extensive personal and professional studies with this spice as an aphrodisiac, but based on limited research and experience, and my understand of herbal aphrodisiacs, I would doubt the effects would be noticeable the same day, they may take a day or two to be noticed when used in high dosages. It could increase energy levels and I think it would work in men, too. Just about all sex enhancing herbs and spices work both in men and women.

I’ve seen that it works as an aphrodisiac for men, is this true? Should you sprinkle it on a meal — or should you use the oil?
   As of 2012, a search on Medline did not reveal any studies done in humans with this spice regarding its sexual benefits. There have been several animal studies, notably in male rats, that have shown administration of nutmeg increased mounting frequency and libido. Therefore it appears that this spice could be of benefit as a sexual stimulant in humans.

Anti-bacterial
Anticariogenic activity of macelignan isolated from Myristica fragrans against Streptococcus mutans.
Phytomedicine. 2006.
The occurrence of dental caries is mainly associated with oral pathogens, especially cariogenic Streptococcus mutans. Preliminary antibacterial screening revealed that the extract of nutmeg, widely cultivated for the spice and flavor of foods, possessed strong inhibitory activity against S. mutans. The specific activity and fast-effectiveness of macelignan against oral bacteria strongly suggest that it could be employed as a natural antibacterial agent in functional foods or oral care products.

I’ve read that nutmeg has anti-bacterial properties — should you use the powder when you cook to prevent E. coli, listeria and salmonella? Are there any foods it works best with?
   I am not aware of such detailed studies regarding which foods are best to cook with nutmeg in order to reduce bacterial counts. Some Petri dish and lab studies have shown this herb to have antibacterial properties, but detailed studies are needed with different foods at different temperatures and different organisms to determine the details of potential anti-germ benefits.

Sleep
I’ve read that a sprinkle of nutmeg on top of warm milk helps people sleep. How might this work?
   I am not aware of the sleep benefit of such usage. I doubt small amounts would induce sleep.