Skip main navigation

New offer! Get 30% off one whole year of Unlimited learning. Subscribe for just £249.99 £174.99. New subscribers only. T&Cs apply

Find out more

Diet related diseases

Any of the nutrient-related diseases and conditions that cause illness in humans falls within the category of nutritional disease.

Diet has a profound impact in human life and plays an important role in our health. Any of the nutrient-related diseases and conditions that cause illness in humans falls within the category of nutritional disease.

Nutritional diseases include deficiencies or excesses in the diet, obesity and eating disorders, and also chronic diseases such as cardiovascular disease, hypertension, cancer, and diabetes mellitus. Nutritional diseases also include hereditary metabolic disorders that respond to dietary treatment, the interaction of foods and nutrients with drugs, food allergies and intolerances, as well as developmental abnormalities that can be prevented by diet.

Food and Health

The interaction between food and health is quite complex and many questions about how food contributes to our health still remain opened. Given the multifactorial nature of chronic diseases and the great diversity of the diet, it is really difficult to prove a causal role of a specific dietary element on disease development.

The World Health Organization states that eating a variety of foods and consuming less saturated and industrially-produced trans-fats, sugars and salt are essential for a healthy diet. To the contrary, an unhealthy diet and lack of physical activity may lead to increased disease risk.


Fat is one of the three macronutrients in our diet. The implication of fat on disease has been debated for a long time. Eating foods with fat is certainly part of a healthy diet. However, eating too much fats and certain oils, like saturated and industrially-produced fats, can increase the risk of heart disease and stroke.

The type of fat is important in relation to health. The quality of dietary fatty acids can differentially modulate circulating cholesterol levels and the risk of cardiovascular diseases and other metabolic diseases.

There are two general types of fats: saturated fats and unsaturated fats:

  • Saturated Fat: Saturated fat contains only single bonds in the carbon chain of the fatty acids. The chain is “saturated” with hydrogen atoms. Each chain is densely compacted and therefore, saturated fat is typically solid at room temperature. Saturated fats have been shown to elevate the LDL cholesterol (bad cholesterol) in the blood. Saturated fat is mainly found in animal products, such as the streaks of fat in the meat, lard, and dairy foods, although they can also be found in some plant sources, such as palm oil and coconut oil. Saturated fats are also commonly found in many industrial and packaged foods such as cookies, snacks, industrial pastries, and many processed foods.
  • Unsaturated fats: Unsaturated fat contains at least one double bond between two carbons of the fatty acids. In natural food products this double bond typically has “cis” configuration, so the hydrogen atoms are on the same side of the double bond. As a result, unsaturated fats are typically liquid at room temperature. However, there is another type of unsaturated fat that raise public health concerns. These are known as TRANS fats in which the double bond has “trans” configuration. That means that hydrogens are on opposite sides of the double bond causing the carbon chain to remain straight. Unsaturated trans fats can be found naturally in some foods derived from cattle, sheep or goat; or produced artificially during an industrial process called hydrogenation. Hydrogenated oils are used in food industry because they improve the texture of certain foods and resist rancidity longer than un-hydrogenated oils, and thus, increase the shelf life.

Scientific evidence indicates that artificial trans fats are known to elevate the amount of LDL cholesterol and decrease the amount of HDL cholesterol, the good cholesterol in the blood. In this way, trans fats promote the buildup of arterial plaques and increase the risk of heart disease. To avoid trans fat, check food labels and look for the amount of trans fat listed. The European Food Safety Authority (EFSA) states that:

Trans fat intakes should be as low as is possible within the context of a nutritionally adequate diet.


There is a concerning misconception about the link between carbohydrates and health. Carbohydrates comprise a wide range of compounds in food, and some of them are relevant for our health.

  • Fiber: is a type a carbohydrate with many benefits for human health. Interestingly, fiber cannot be digested by human digestive enzymes. Thus, it remains almost undigested until it reaches the large intestine where it is metabolized by gut microbes which generate short-chain fatty acids conferring health benefits. Another benefit of fiber-rich foods such as whole grains is related with their ability to slow the release of glucose into the blood circulation after digestion.
  • Sugars: A high intake of food rich in free sugars results in a fast release of glucose into the blood. In response to that rapid glucose increase, our body releases a large amount of insulin, a key hormone that lowers the glucose levels in the blood. However, the abrupt increases in glucose and insulin lead to unstable glucose levels that are associated with overeating, obesity and other adverse health effects including glucose intolerance and insulin sensitivity, type-2-diabetes, and cardiovascular risk factors.

According to the European Food Safety Authority the term “sugars” is used to cover monosaccharides and disaccharides, and the term “added sugars” refers to sucrose, fructose, glucose, starch hydrolysates (glucose syrup, high- fructose syrup) and other isolated sugars used as such or added during food preparation and manufacturing, usually as a sweetener or as a preservative for longer shelf life. The top sources of sugars are soft drinks, fruit drinks, flavored yogurts, cereals, cookies, candy, and most processed foods. But added sugar is also present in products that you may not think of as sweetened, like soups, bread, meats, and sauces.


Hypertension is a major global health concern since high blood pressure can lead to heart disease, stroke and death. Scientific evidence indicates that decreasing sodium intake can reduce blood pressure. So, limiting highly salted foods, processed foods, and so-called fast foods may improve our cardiovascular health.

The Mediterranean Diet

As we have seen, considering individual nutrients and food components, for example, by limiting saturated fat, added sugar and sodium, provides a good starting point to evaluate the quality of our diet. However, the full impact of diet on health extends far beyond and must be evaluated by the examination of the overall dietary habits rather than individual nutrients.

In this regard, the Mediterranean Diet, inspired by the eating habits of southern European countries, is one of the most well-studied dietary patterns. This diet includes abundant plant-based foods (fruit, nuts, vegetables, legumes, cereals), olive oil as the principal source of fat, a high to moderate intake of fish, a moderate or low consumption of eggs, poultry and dairy products (principally cheese and yogurt), a low consumption of processed meats, red meat and sweets.

Scientific studies indicate that high adherence to the Mediterranean diet reduces the risk of chronic diseases and overall mortality as it might have a protective effect against cardiovascular disease, among other chronic diseases.

As we have seen in this video, diet has a determinant role in our health. An unbalanced diet may increase our risk to suffer some chronic diseases. A balanced and varied diet should avoid excessive intake of certain food constituents, but it is of utmost importance to understand that healthy eating habits should be also complemented with a balanced lifestyle for a healthy life.

This article is from the free online

Introduction to Food Science

Created by
FutureLearn - Learning For Life

Reach your personal and professional goals

Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.

Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.

Start Learning now