what's the natural way to combat jet lag?

A couple of useful ways to reduce jet-lag is not to consume alcohol prior to or during a long flight. Air travel causes dehydration, exacerbating the effects of long distance air travel so it is important to drink plenty of fluids in the form of water based drinks and fruit juices.

Another helpful substance to complement good hydration is to inhale good quality essential oil of lemongrass or lemongrass and basil together. Dampen a cotton wool pad and pour two to three drops onto it. I doubt the other passengers would object to the aroma wafting temporarily into their space as it is a clean fresh smell and very 'unisex'. It is also a pleasant way to freshen up on board and after a meal - simply dampen cotton wool pads, pour a drop or two (no more) of the essential oil/s and use as face and hand wipes. You could also use the oils for a few days after your trip; if you are very lucky and can afford the time and cost of a massage, these oils will relax but invigorate. Foods? I don't know but good quality protein and iron-rich foods and lots of juicy fruit / fresh fruit salad, seems sensible. Hope you recover quickly!

i used to travel a lot Mayo clinic has a lot of info on jet lag. Try the drug free first and give it time. Even Melatonin has side effects,

You could force yourself to stay awake until your regular sleeping time in whatever time-zone you're in, so say you usually go to bed at 10pm, then you'd also do 10pm in your current time zone (even if it's a long wait). assuming it's that kind of jet-lag, ofc.

you could also expose yourself to daylight and eat something with a lot of protein in it (meats, eggs etc.) if possible to wake your body up. that could be handy if you need to re-sync your body clock.

melatonin gets your sleep schedule back.