food

During this freezing weather, the food put out by householders is the only form of sustenance that the birds have. 在这种严寒的天气里，住户们放在外面的食物成了鸟儿们唯一的粮食。

the ability of food to provide people and animals with what they need to make them strong and healthy

A stick of celery does not provide much sustenance. 一把芹菜提供不了多少营养。

emotional or mental support

When her husband died, she drew sustenance from/she found sustenance in her religious beliefs. 丈夫死后，她从宗教信仰上寻求精神寄托。