Dietary habits play a significant role in the health and mortality of all humans. Imbalances between the consumed fuels and expended energy results in either starvation or excessive reserves of adipose tissue, known as body fat.[149] Poor intake of various vitamins and minerals can lead to diseases that can have far-reaching effects on health. For instance, 30% of the world's population either has, or is at risk for developing, iodine deficiency.[150] It is estimated that at least 3 million children are blind due to vitamin A deficiency.[151] Vitamin C deficiency results in scurvy.[152] Calcium, Vitamin D, and phosphorus are inter-related; the consumption of each may affect the absorption of the others. Kwashiorkor and marasmus are childhood disorders caused by lack of dietary protein.[153]
Also, the natural sugar in fruit does affect your carbohydrate intake — especially if you eat a lot of fruit. This may temporarily raise your blood sugar or certain blood fats. However, this effect is lessened if you are losing weight. If you have diabetes or any other health conditions or concerns, work with your doctor to adjust the Mayo Clinic Diet for your situation. For example, people with diabetes should aim for more vegetables than fruits, if possible. It's a good idea to snack on vegetables, rather than snacking only on fruit.

For people who are healthy, a healthy diet is not complicated and contains mostly fruits, vegetables, and whole grains, and includes little to no processed food and sweetened beverages. The requirements for a healthy diet can be met from a variety of plant-based and animal-based foods, although a non-animal source of vitamin B12 is needed for those following a vegan diet.[29] Various nutrition guides are published by medical and governmental institutions to educate individuals on what they should be eating to be healthy. Nutrition facts labels are also mandatory in some countries to allow consumers to choose between foods based on the components relevant to health.[30]
Natural foods and "all natural foods" are widely used terms in food labeling and marketing with a variety of definitions, most of which are vague. The term is often assumed to imply foods that are not processed and whose ingredients are all natural products (in the chemist's sense of that term), thus conveying an appeal to nature. But the lack of standards in most jurisdictions means that the term assures nothing. In some countries, the term "natural" is defined and enforced. In others, such as the United States, it is not enforced.

Food safety and food security are monitored by agencies like the International Association for Food Protection, World Resources Institute, World Food Programme, Food and Agriculture Organization, and International Food Information Council. They address issues such as sustainability, biological diversity, climate change, nutritional economics, population growth, water supply, and access to food.