Frequently Asked Questions

A balanced diet refers to an eating pattern that includes an adequate variety of foods across all major food groups — vegetables, fruits, whole grains, lean proteins, and healthy fats — in proportions that meet the body's nutritional needs without excess of any single nutrient category. Public health bodies in many countries publish dietary guidelines that outline general proportions and variety recommendations for adult populations. The concept acknowledges that no single food provides all necessary nutrients, and that variety over time is central to dietary adequacy.

Macronutrients are the three main categories of energy-providing nutrients: proteins, carbohydrates, and fats. They are consumed in larger quantities (grams per day) and provide the body with calories for energy as well as structural components for growth and maintenance. Micronutrients — vitamins and minerals — are required in much smaller amounts (milligrams or micrograms per day) and do not provide energy directly. Instead, they act as cofactors in enzymatic reactions, support immune function, enable metabolism, and contribute to structural processes such as bone formation. Both categories are essential for normal physiological function.

Dietary fiber consists of plant-derived carbohydrates that resist digestion in the small intestine and pass into the large intestine largely intact. There are two main types: soluble fiber (found in oats, apples, beans, and lentils), which dissolves in water to form a gel-like consistency in the digestive tract, and insoluble fiber (found in whole wheat, vegetables, and nuts), which adds bulk to stool and supports regular bowel movement. Fiber also serves as a substrate for the gut microbiota — the community of microorganisms in the large intestine — which ferment certain types of fiber as part of their metabolic processes.

Antioxidants are compounds that can neutralize free radicals — reactive molecules produced during normal metabolic processes and through environmental factors such as ultraviolet light and air pollution. Free radicals can interact with cellular components including DNA and proteins, and the body has natural defense systems as well as dietary antioxidants to manage this activity. Common dietary antioxidants include vitamin C (found in citrus, strawberries, and bell peppers), vitamin E (found in nuts, seeds, and vegetable oils), beta-carotene (found in orange and yellow vegetables), selenium (found in Brazil nuts, fish, and eggs), and various polyphenols found in berries, green tea, and dark vegetables.

Vitamin D is a fat-soluble vitamin that plays a recognized role in calcium absorption, bone mineralization, and immune system function. It is unique among vitamins in that the body can synthesize it through a photochemical reaction in the skin when exposed to ultraviolet B radiation from sunlight. Dietary sources include oily fish (such as salmon, mackerel, and sardines), egg yolks, and fortified foods such as certain dairy products and plant-based milks. In countries or seasons where sunlight exposure is limited — as is often the case in Switzerland during winter months — dietary sources become proportionally more relevant as a means of maintaining adequate vitamin D status.

Zinc is a trace mineral that serves as a cofactor for over 300 enzymes involved in processes including protein synthesis, DNA replication, immune function, wound healing, and normal cell division. It is present in a wide variety of foods, with particularly notable concentrations in pumpkin seeds, legumes, whole grains, nuts, and various animal-sourced foods including lean meats and shellfish. As zinc from plant sources has a lower bioavailability due to the presence of phytates (compounds that can inhibit mineral absorption), individuals consuming predominantly plant-based diets may need to consider the diversity of their zinc sources.

The B-complex vitamins are a group of eight water-soluble vitamins that share a role in cellular metabolism. They include thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9), and cobalamin (B12). Each has distinct functions: for example, B12 is involved in nerve cell maintenance and red blood cell formation; folate is important in DNA synthesis; and thiamine is central to carbohydrate metabolism. They are found across a broad range of foods including whole grains, legumes, eggs, dairy products, leafy green vegetables, and meat. Vitamin B12 is found almost exclusively in animal-sourced foods, making it a common consideration for those following plant-based diets.

Omega-3 fatty acids are a family of polyunsaturated fatty acids that the human body cannot synthesize in sufficient quantities, making them "essential" fatty acids that must be obtained from food. The main types are alpha-linolenic acid (ALA), found in plant foods like flaxseeds, chia seeds, hemp seeds, and walnuts; and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found primarily in oily fish such as salmon, mackerel, herring, and sardines, as well as in algae-based sources. EPA and DHA are incorporated into cell membranes and are associated with various physiological roles according to nutritional research literature.

Dietary reference values (DRVs) are estimates of nutrient intake that cover the needs of most healthy individuals in a defined population group. They are typically published by national and international public health authorities and are intended as planning tools for population-level dietary assessment, not as precise individual targets. A common reference value is the Recommended Daily Allowance (RDA) or its equivalent, which is set to meet the needs of approximately 97–98% of healthy individuals in a given age and sex category. Actual individual requirements vary and can be influenced by factors such as activity level, absorption efficiency, existing nutrient status, and metabolic conditions. DRVs are useful for general orientation but should not be interpreted as precise personal requirements.

Bioavailability refers to the proportion of a consumed nutrient that is absorbed from the digestive system into the body and made available for use in physiological processes. The bioavailability of a nutrient varies depending on its chemical form (e.g., heme iron from animal sources has higher bioavailability than non-heme iron from plants), the food matrix it is consumed in, the presence of other dietary components that enhance or inhibit absorption, the individual's digestive health, and their current nutritional status. For example, vitamin C consumed alongside non-heme iron is known to enhance iron absorption. These interactions illustrate why the overall dietary pattern — rather than individual nutrient amounts in isolation — is a more meaningful indicator of nutritional adequacy.

The recommendation to consume a variety of foods reflects a well-established principle in nutrition science: that different foods provide different combinations of nutrients, and no single food or small set of foods can provide the full range of essential nutrients in adequate quantities. Variety applies both within food groups (consuming different types of vegetables, different protein sources, different whole grains) and across food groups. This approach reduces the likelihood of nutrient gaps and exposes the body to a wide range of beneficial compounds including vitamins, minerals, fiber, and phytonutrients. It also tends to make diets more sustainable and enjoyable over time, which contributes to dietary consistency.