Is meat eating a possibility? I have been vegan (no animal products) for over 5 years but recently have encountered many health issues (unable to digest many plant protein, leaving no viable protein to eat), including some meat in my diet seems to be the only option (I can't tolerate any grains or beans anymore).

I would try to source as ethically as I could, but it does of course, still involve the killing of another.

Is there any way this is acceptable? Or should one sacrifice their health, if necessary?
If you eat vegetables or grains, it can indirectly cause the death of animals like snails and earthworms, due to clearing of land, ploughing, pesticides, weeding etc.

If you wear clothes made of cotton, it can indirectly cause the death of animals like snails and earthworms, due to clearing of land, ploughing, pesticides, weeding etc.

If you use banknotes made of paper, or buy or use anything made of paper, it can indirectly cause the death of animals, when trees got chopped down for the manufacturing of paper.

If you use any plastics or fuel for your car or banknotes made of polymer, it can indirectly cause the death of animals due to drilling for petroleum and gas.

If you throw rubbish away, it can indirectly cause the death of animals, because some of that trash ends up in the sea or landfills.

If you buy anything metal (including all electronics), it can indirectly cause the death of animals due to mining.

If you drink treated water from the tap, it can indirectly cause the death of small animals from the process of filtration and chlorination.

If you use electricity, it can indirectly cause the death of animals from the process of clearing land for building hydroelectric dams, or the billowing of smoke from a plant that burns hydrocarbons.

When you pay any kind of taxes, even indirectly e.g. through purchasing goods, the money from it may be used by the government to buy weapons and train soldiers for killing humans.

Basically, the Buddha taught that to break the first precept, you must have the intention to kill and then actually kill. This applies to directly causing the deprivation of life. For e.g. hitting a mosquito would be directly killing it.

By buying frozen meat or vegetables from the supermarket, or using paper or banknotes or wearing clothes or drinking treated water or using electricity or using electronics (including the computer or smartphone you are reading this on), you did not have any intention to kill anyone and you did not in fact kill anyone. Therefore, you do not break the first precept this way.