It is important to look well after your body and particularly voice as a speaker.

Like singers do as well you need to hydrate your vocal cord to keep them in shape.
The best product is still water, maybe a drop of fresh lemon-juice in it.

Saliva too much or too little will affect your ability to speak in shape.

• Saliva increasers are
• milk or dairy product,
• sour juices, sour fruits
• candies
• chewing gum

The fastest method to have a minimum of saliva is breathing through your mouth and drink nothing.
Your voice would get a metal sound and you can hear a clicking or smacking sound when you open your mouth to speak.
If you eat food that is prepacked or flavoured with a lot of spices and salt it will increase you being thirsty and increase saliva.

Another element is you energy as a speaker

A temporary energetic state caused by caffeine is not a solution to stay fit and cope with the longer duration of giving energy to your audience. Energy drinks have the same destructive effect. Apart from that, the bubbles what might causes unexpected and unwanted extra sound from you as a speaker with burbs.

Alcohol should be avoided as well, even the day before you speak, if you want to have a balanced energy.

Heavy food, heavy to digest needs to be avoided because it takes a lot of energy from the body to digest.

Long term energy suppliers as bread, grains and nuts will boost your energy longer and more supportive. Some people prefer protein like chicken breast or turkey.
If you need some help with what kind of long-term energy suppliers fit with you as a specialist in healthcare and food for advice.

Sugar in the raw form or in sugar in fruits are preferred above white and heavy sweetened food.

Overall:
Drink a lot of flat water. Eat light and protein rich food. Eat pure and freshly prepared food and you will do fine as a speaker.