Vitamin D3 is an essential nutrient for bone and immune system health; its main source is sunshine, and it is synthesized through the skin.

维生素d 3对骨骼和免疫系统来说，是一个重要元素，主要来源是通过太阳光照，由皮肤合成。

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For example, social contact can boost the development of the brain and immune system, leading to better health and less chance of depression later in life.

例如，社交可以促进大脑和免疫系统的发育，使人体更健康，并在以后的生活中降低负面情绪出现的几率。

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Optimism's benefits for physical health also extend beyond heart health, such as improved immune system function and increased life span.

乐观对身体健康的益处不仅限于心脏健康，还包括改善免疫系统功能和延长寿命。

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The immune system is stronger, so it also helps in terms of physical health.

免疫系统更强，所以对身体健康也有帮助。

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But no matter where locals enter the choppy waters or what time of year they jump in, folklore suggests that the effects of an invigorating swim improve the immune system and contribute to good health.

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Hepatitis A is rarely fatal, although those with liver disease or a weakened immune system could require hospitalization, according to the health department.

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Maintaining them requires health (ie, a good immune system) and grooming.

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