Health, as defined by the World Health Organization, is ‘a condition of total physical, mental and emotional well-being’. A number of other definitions have also been used over time for various different purposes. Some people believe that health is a state of being healthy or clean, whereas others think that it is the ability to perform activities without limitations or pain.

One way to think about health equity is to consider it from the perspective of the people who are most affected by poor health. It makes sense to think in terms of groups rather than people. For instance, what effects will poor health has on people who belong to racial or ethnic groups that suffer health disparities in other ways such as poverty and health care? What effect will it have on children, the elderly, women, men, or people in the middle?

Mental health, on the other hand, has often been seen as separate from physical health but that is changing. Most people are now satisfied with the idea that they derive a measure of good health from being happy, balanced, and well-organized. They want to be physically healthy, but they would prefer not to be sick. Their mental well-being is therefore less important than their physical well-being.

The third definition is quality of life, which can include the ability to enjoy one’s life without limitation, physical limitations, and without suffering any negative effects. This last item, the negative effects, is what has been called the fifth fundamental of public health. There is growing recognition that people are more likely to live a long and healthy life if they are healthy mentally as well. Mental health is the essential ingredient to improving health and illness rates.

How should these concepts be understood and where do they come from? Public health professionals agree that physical illness has become increasingly preventable through better nutritional choices and by making the decision to lead a healthy lifestyle. However, they acknowledge that more people are continuing to contract mental illnesses despite improvements in public health. People who contract a mental illness are at greater risk of serious injury or death because they have less energy, greater stress levels, and lower concentration. There are now numerous links between physical illness and mental illness, but exactly how they interact has remained unclear.

Health equity is the difference that exists between those who have more healthy physical conditions and those who have less. By making health equity a priority in health planning and policy, it is possible to realize the benefits of promoting good health. Just as the concept of health equity implies that everybody benefits when healthy bodies and minds are promoted, there is now increasing evidence that it is possible to improve health through better nutrition and active lifestyles. This concept can also be used to explain health disparities.