Nutrition Basics

 

Nutrition
Nutrition consists of the functional components in food that an organism must obtain in order for it to grow and flourish. Nutrition simply put is a collective term for all of the nutrients required by an organism to sustain life and promote health.

“Nutrition is the intake of food, considered in relation to the body’s dietary needs. Good nutrition – an adequate, well balanced diet combined with regular physical activity – is a cornerstone of good health. Poor nutrition can lead to reduced immunity, increased susceptibility to disease, impaired physical and mental development, and reduced productivity.” – (World Health Organisation)

Nutrients
Nutrients are the organic and inorganic substances found in plant and animals material deemed biologically functional to an organism’s physiological demands. Simply put, nutrients support the functioning of an organism on a cellular level. There are two types of nutrients; Essential nutrients, of which the body cannot biosynthesize (or can but in inadequate amounts) which must be obtained from diet and non-essential nutrients, of which the body can biosynthesize in sufficient quantity.

“Food provides a range of different nutrients. Some nutrients provide energy, while others are essential for growth and maintenance of the body. Carbohydrate, protein and fat are macronutrients that we need to eat in relatively large amounts in the diet as they provide our bodies with energy and also the building blocks for growth and maintenance of a healthy body. Vitamins and minerals are micronutrients which are only needed in small amounts, but are essential to keep us healthy. There are also some food components that are not strictly ‘nutrients’ but are important for health, such as water and fibre.” – (British Nutrition Foundation)

Macro/micro-nutrients
There are six main essential nutrients carbohydrates, fats, protein (the macronutrients), vitamins, minerals (the micronutrients) and water which is also considered an essential nutrient.

Macro-nutrients are generally obtained from the diet in amounts ranging anything from tens of grams to hundreds of grams. For example the protein requirements are based on the “RNI” (Reference Nutrient Intake) and for an average UK adult is 0.75g per kg of body weight, which is 53g for a 70kg adult. Compare this to carbohydrate requirements, based on “DRV’s” (Dietary Reference Values), which are 50% of total energy intake which would be 313g on a 2500 kcal diet.

Micronutrients however, are required in far smaller amounts and are measured in milligrams and micrograms. Intakes are based on the RNI’s and are based. The dietary recommendations for intakes of B12 for example are so small the amount needed would fit on the tip of a pin since only 1.5 micrograms is required.

Non-essential nutrients are nutrients which do not need to be directly obtained via the diet since they are indirectly obtained via substrates and can be synthesised endogenously (within the body). Non-essential nutrients mainly consist of the non-essential amino acids, but also nutrients such as inositol (vitamin B8) and certain minerals are also considered non-essential, although this does not undermine the importance of these nutrients for our health.

Phytochemicals
There are of course very important components of foods that do not get official recognition as “essential nutrients” although their exclusion from this category might mislead one to think they’re not as important. They are, and arguably more so when the aim is to optimise health. Phytochemicals are beneficial non-nutritive components of foods such as vegetables, fruits, whole grains, herbs, nuts and seeds. These plant chemicals include phenols, terpenoids, sulfurs compound, pigments and other antioxidants, all of which have shown to promote significant health benefits and may have specific preventative implications for certain disease including cancer and cardiovascular disease.  

Is diet enough to obtain all the nutrition we need?
Absolutely. Most people should be able to get all the nutrients they need by eating a healthy, varied diet, including multiple colours and fruit and vegetables. However, there are a few exceptions where supplementation may be wise or even necessary. For example, if a woman is planning to conceive a child it is recommended they take a folic acid (vitamin B9) supplement to prevent congenital birth defects. Unless of course you can consistently consume at least 300 mcg of dietary folate, supplementation is a sensible option. Spina-bifida can occur in Mothers whose B9 intake is insufficient before conception and particularly during the first 12 weeks of pregnancy. Vitamin D is another vitamin in which it is difficult to obtain in sufficient amounts all year round from food and sunlight alone. This is even more the case for vulnerable groups such as pregnant women, the elderly, Muslims who veil the skin, those with dark pigmented skin such as Asians and Africans, children and also Caucasians with fair skin. Current research now supports the idea that most people would benefit from vitamin D supplementation as current intakes and levels of UVB exposure are inadequate, especially for building reserves for winter. Moderate to high dose supplementation may also be a necessary requirement for those or are clinically deficient as to consistently raise serum levels from deficiency status into adequate ranges, which even then could take months.

 

Bibliography

Barros, L. and Ferreira, I. (2017). Editorial: Phytochemicals and their Effects on Human Health. Current Pharmaceutical Design, 23(19).

Holick, M., Binkley, N., Bischoff-Ferrari, H., Gordon, C., Hanley, D., Heaney, R., Murad, M. and Weaver, C. (2011). Evaluation, Treatment, and Prevention of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline. The Journal of Clinical Endocrinology & Metabolism, 96(7), pp.1911-1930.

Nutrition.org.uk. (n.d.). What are nutrients? – British Nutrition Foundation. [online] Available at: https://www.nutrition.org.uk/healthyliving/basics/what-are-nutrients.html [Accessed 20 May 2016].

R, J, BERRY et al. (1999) PREVENTION OF NEURAL-TUBE DEFECTS WITH FOLIC ACID IN CHINA. The new England journal of medicine. [Online] Available from: http://folictrial.org/wp-content/uploads/2009/09/Prevention-of-neural-tube-defects-with-folic-acid-in-China.pdf [Accessed on 7.2.15]

Who.int. (n.d.). WHO | Nutrition. [online] Available at: http://www.who.int/topics/nutrition/en/ [Accessed 20 May 2016].