In Japanese, the word for "beneficial" would be the same as the word for "good," which is 良い So the phrase, "Vegetables are beneficial for your health" would be: 野菜は健康に良いです。 A more complex word for "beneficial" would be 有益（ゆうえき), so you could also say: 野菜は健康に有益です。 But, this is a fairly bookish term and would likely not be used in daily conversation. I hope this helps! Let me know if you need anything else.

自然な感じだと「野菜はあなたの健康のために良いです。」かな。 辞書で調べるとbeneficialは「有益、役に立つ」と書いてますね。