The food you eat every day has a huge effect on your health. Decades of research have produced study after study showing links between diet and serious illness. A healthy diet can prevent heart disease, hypertension, diabetes, gastrointestinal disorders, some forms of cancer, blindness and birth defects. It matters if breakfast is a donut or a bowl of crushed oats, if your sandwich is ham and cheese or hummus and tomatoes, and regardless of whether dinner is roast beef or salmon. Many other food choices you make affect both the length and quality of your life.

Most people probably know that the healthy food they eat influences the health of their body. Healthy food choices help maintain and stimulate heart health, strong muscles and achieving an appropriate weight. Also, the mood can be influenced by what a person eats, so the mood will be much better after eating a green salad or properly cooked vegetables than fast food. Researchers study the effects of dietary choices on people’s mood and mental health.

There are many unanswered questions such as:

– Can vitamin deficiencies contribute to depression?
– Do food supplements improve the emotional state of those suffering from nutritional deficiencies?
– What amount of a supplement will increase mental health?

What types of nutrients stimulate mental health?

Studies on the connection between food and mood have been quite limited and their results are mixed. As there are still many unanswered questions, dietary changes intended to replace medical treatment in the case of mental disorders such as depression are not recommended.

Limited evidence suggests that certain nutrients can improve a person’s emotional state. All these nutrients can be found in a balanced diet, in addition, adequate nutrition could increase physical and emotional tone.

Omega-3 fatty acids improve the health of the heart by reducing the level of bad cholesterol in the body and increasing the values of good cholesterol. The positive role of omega-3 on mental health has also been demonstrated, as it can influence the way the brain sends signals throughout the body. Omega-3 fatty acids are found in seafood, fish (salmon, herring, sardines, mackerel), flax seeds, flax oil and nuts.

Tryptophan is an amino acid that the body needs to produce serotonin. People suffering from depression have a low level of serotonin. Currently, the effects of tryptophan for treating depression are being researched. Tryptophan is found in the composition of red meat, turkey, and lean meat products. Magnesium is a nutrient that helps the body produce energy and contributes to the proper functioning of the muscles, arteries and heart. Currently, the role that magnesium supplements could have in treating depression is also being studied. Manganese is found in green leafy vegetables, nuts and avocados. These nutrients can be found very often in vegan food recipes.

Folic acid and vitamin B12 are part of the vitamin B group that plays an important role in the function of metabolism and the production of blood cells. They influence the production of dopamine and noradrenaline. In many cases, depressed people have low levels of these substances, so increasing the levels of folic acid and vitamin B-12 can increase the response to specific drugs to treat depression.

In particular, it is important not to eat more calories than you burn each day.

The following sections describe current health problems that are influenced by your diet. For each disease, you will find a list of foods and nutrients that can reduce the risk of developing that disease as well as a list of foods or food components that can increase the risk of developing the disease.

Healthy today, harmful tomorrow?

Science involves research, intuition and luck. But even the most promising ideas have to make their way through a hierarchy of studies before scientists can draw firm conclusions. To be considered reliable, the findings must be replicated by other studies and in different groups of people. In this process, the findings of apparently reliable studies can be overturned by newer research. This fact can be frustrating for people trying to make healthy choices.

To make sense of conflicting reports, think of scientific studies as scales. Some studies will report that a certain food is useful for disease prevention and others will say that it is not. But as more studies are published and the volume of piles of evidence increases, the scale will pull in one direction or the other, favoring one set of conclusions.

Apart from the quantities of studies, take into consideration the type of study for which the report is made. If you begin to understand the different types of research and which types are most trustworthy, you can decide how much credence to give to food and health study reports.

• Give the least confidence to laboratory studies. Test-tube experiments or laboratory tests involving animals can suggest how and why the underlying biochemistry might work, but these findings may not automatically translate to humans.

• Observational studies conducted on individuals, in which researchers follow large groups, often for decades, require moderate attention. Such examples are the Women’s HealthInitiative, the Nurses’ Health Study, and the Health Professionals Follow-up Study (all cited in this report). Using questionnaires and other methods, scientists gather data at regular intervals as thousands of participants simply go about their lives. Most risk factors cannot be tested directly on people, but by comparing those who stay healthy with those who get sick, scientists try to identify the factors that might make the difference. This category includes types of epidemiological studies called group, longitudinal, prospective and control.

• Give the greatest importance to experimental studies on human subjects. Within them, the researchers control what happens. In the case of nutrition and health studies, this usually means testing a diet or behavior change. Often clinical tests, experimental studies start on a small scale and, if they are successful, are repeated with several and different groups of people. In this category are randomized controlled trials. If properly conducted, they are considered the gold standard—the most credible studies of all. Volunteers participating in these studies are randomly assigned either to a group testing a drug, food, dietary supplement, or other experimental treatment, or to a control group whose members receive a placebo or the standard treatment or diet for comparison. If possible, both the volunteers and the researchers are “blinded”, which means that they do not know who is in a certain group until the end of the study.

The media covers all kinds of shocking studies, but reporters sometimes fail to put a study in context by explaining the type of research reported and what kind of questions it can honestly answer. Remarkable new discoveries make headlines, often giving the false impression that the results are definitive. Also, studies often make the news precisely because they contradict a large body of evidence in a particular field, which may remain more compelling despite a single new contrasting finding.