One of the consistent remedies for HG is vitamins Bs, specifically b6. In fact, an antiemetic just came back on the market that contains b6. The standard suggestions (which I am doing) is to take 50mg of B6 (P5P) along with vitamin C 3x a day as a preventative, and then 50 mg b6 (P5P - which is the activated version of b6)) along with a half a tablet of Unisom morning and night when pregnant and already nauseous (this was my pregnancy saver both times). My research has led me to believe that it's a little more complicated than just taking your Bs, because, not surprisingly, the quality and kind really do matter.
Ideally we would be getting our vitamins completely from our foods. Much of my efforts so far have done that - eating raw liver, drinking kombucha, and eating other naturally fermented foods. These all contain b vitamins, especially the raw liver.
One of my weird pregnancy quirks is that I crave alcohol and carbonation. Those are my only, legit cravings. With my first pregnancy I craved beer - I had never liked beer before. Now, I love a nice cold porter. With my second I craved red wine. I also craved carbonated beverages, whether sparkling water or soda (the latter of which I never drink outside of pregnancy, ugh). I now have a theory, and that theory is B Vitamins. Traditionally fermented beers and other such drinks are quite high in vitamin Bs. I think a biological part of me knew that's what I needed, unfortunately our carbonated beverages are no longer traditionally fermented. So in a sad irony, drinking soda and other carbonated beverages actually depleted me even further of my precious Bs. They are also bladder irritants (diuretic), which furthered my dehyrdration and nutrient depletion cycle.
So I was happy when I did some looking into my kombucha and its b vitamin content. While it has a low b vitamin content over all, they are extremely bioavailable as the drink as a whole is synergistic. It stands to reason that ingesting small amounts of a nutrient daily is probably more beneficial than taking a mega-dose of a nutrient - most of which will be peed out anyway. Add that to its alkalinizing affect and liver support, and I've been tackling a number of my "prevent HG" areas for nearly a year unknowingly!
One of the most fascinating things I've come across is a podcast about genetics and HG and the necessity of b vitamins in the body's whole process of methylation. It of course affects the liver. It illuminates the problem with folic acid that pregnant women are told to take (and, in fact, everyone who eats processed foods are forced to take). Please give the podcast a listen to, you won't regret it. I'd explain further, but I don't fully understand it all myself. I am, however, fascinated by it.