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Introduction to Nutritional Science

by Adam Gould
Introduction to Nutritional Science

‘Eating a healthy, balanced diet is an important part of maintaining good health.’

True, but simple as it sounds, does this actually help us on an individual basis?

After all, what defines a healthy, balanced diet? And is it realistic to expect everybody to have the time, resource & know-how to find the perfect balance?

The difficulty is that what works for one person, may not work for another. We all have different genetics, diets, conditions, & lifestyles.

However, by improving our overall understanding of how nutrition works we can make better decisions. So here is a quick introduction to the science of nutrition.

There are 2 main classifications; macronutrients and micronutrients.


These are nutrients that we need in relatively large quantities to survive.


Obviously, water is essential to life and important to nearly every part of your body, hence drinking enough of it is crucial to good health.

The effects of even mild dehydration can be severe; potentially causing headaches affecting brain function and damaging organs. Conversely, drinking far too much water can also be catastrophic for your health. So how much water do we need?

After numerous studies, the general consensus seems to be around 2-3 litres a day, but these average figures are dangerous when you consider how different we all are.

Luckily our bodies are pretty good at managing their own water requirements through a sophisticated internal feedback system, commonly known as ‘thirst’!

In fact, there’s little evidence suggesting that drinking more water than our body signals for offers any benefits, beyond the point of avoiding dehydration.

So, rather than drinking to prescription, modern scientists advise us to make sure we always have water nearby, listen to our bodies and drink whenever we feel thirsty.

Did you know?
The common recommended daily intake of 6 – 8 glasses of water is from a 1976 book ‘Nutrition for Good Health’ by McWilliams & Stare.

The authors wrote; ‘this can include fruit and veg, caffeinated and soft drinks, even beer’. Hence, contrary to some common advice, although pure water is preferable as it is calorie-free, other sources can adequately hydrate us.


‘Simple’ or ‘empty’ carbs are the sugars & processed starch in sweets, confectionary, and staple foods such as white bread and pasta. They are considered less healthy.

This is because simple carbs are very quickly broken-down and absorbed, providing a rapid energy boost but with only a fleeting feeling of fullness and causing a significant spike in blood sugar levels. This is bad for your waistline, and worse-still: frequent blood-sugar level spikes are the primary cause of type 2 diabetes.

Fibre and unprocessed starch, found in foods such as fruit, vegetables and grains, are ‘complex carbs’. These are a healthier option because the foods they are in often have more micro-nutritional value compared to sources of simple carbs, and they take much longer to break-down, leaving you fuller for longer and helping digestion.

Including more fibre in your diet can help reduce the risk of conditions such as diabetes, cardio-vascular disease & colorectal cancer.

Did you know?
You can test to see how good you are at processing carbohydrates. Simply start eating an unsalted cracker, then note-down how many seconds it is before it starts to taste sweet to you.

Less than 15 seconds: You are the ‘full’ carb type, meaning you can healthily obtain around 50% of your calories from carbs, with 30% from fat and 20% from protein.

15 – 30 seconds: You are the ‘moderate’ carb type, meaning you should aim to obtain 35% of your calories from carbs, 35% from fat and 30% from protein.

More than 30 seconds: You are the ‘restricted’ carb type, meaning you should aim to obtain around 25% of your calories from carbs, 40% from fat and 35% from protein.


Your body makes protein from amino acids, which are naturally occurring organic compounds. There are 20 types, 9 of which are deemed ‘essential’ because they cannot be produced by the body, they have to be ingested. 

‘Complete protein’, commonly found in meat, poultry, fish, egg and dairy foods, contains all of the essential amino acids your body needs. Unless you’re vegan, strictly vegetarian, a bodybuilder or an athlete – you probably get enough protein.

There are some great plant-based sources of complete protein such as Quinoa, Buckwheat, Hempseed, Blue-green Algae and Soybeans. However, these sources can be difficult to eat in mass & don’t contain as much protein as animal foods.

For vegans & vegetarians it is often more practical to combine multiple incomplete protein sources, e.g. nuts, seeds, grains & beans, to provide a complete protein diet.


Good fats are essential for maintaining brain health, hormone production, reducing inflammation, lubricating joints and absorbing certain vitamins. Bad fats can contribute to obesity, high cholesterol, liver disease and many other health issues.

Saturated fats from meat, dairy, snacks & baked foods (Also coconut oil, palm oil & cocoa butter) are considered ‘bad’ because they can raise bad cholesterol and disease risk if consumed excessively for a long period.

Trans-fats, or partially hydrogenated oils, are used in food manufacturing and are definitely ‘bad’. They are non-essential and can have damaging health effects. The WHO have called on governments to eliminate trans-fats from foods entirely, hence most commercial food producers do not use them.

Unsaturated fats can actively support better health so are considered ‘good’. Studies have found a higher intake of Monounsaturated fats, found in Olives, Nuts & Avocados, alongside a lower intake of saturated and trans fats, can lower LDL (bad cholesterol) & improve HDL (good cholesterol) levels.

Polyunsaturated fats, such as Omega 3, are definitely ‘good’. They can help maintain heart health, reduce triglycerides & support joint, eye & brain health. Most of these positive effects are as a result of reducing inflammation.

Did you know?
It’s the relative proportions of omega fats ingested that is most important. The recommended ratio is around 3:1 of Omega 3 to 6 respectively.

Omega 9 is considered non-essential because the body can produce it, whilst the average western diet contains very high levels of omega 6 already.

That is why Omega 3 supplementation is so popular in the west, as scientists advise this will get your body closer to the correct levels for optimal health benefit.


These are nutrients that we need in relatively small quantities to maintain good health. Click here to find out more about individual vitamins and minerals,

Your body is a finely tuned machine that needs small but adequate amounts of various vitamins & minerals to function. Some nutrients are deemed ‘essential’, meaning your body cannot produce them itself, they have to be ingested.

If you cannot provide your body with enough of any of these materials, your health can suffer. If a deficiency, or surplus, of any given nutrient goes on for a long time, then there can be serious health implications.


Vitamins are organic compounds that help the body function effectively. There are two types: water-soluble and fat-soluble vitamins.

Water-soluble vitamins include all the B vitamins and vitamin C. These cannot be stored, they leave the body in urine, hence a more regular supply is needed.

The most common water-soluble vitamin deficiencies in the UK are B12 & B9. B12 deficiency is more likely to occur in vegans and vegetarians whilst B9 deficiency is often a result of not eating enough green vegetables.

Fat-soluble vitamins include vitamins A, D, E and K. The body stores these in fatty tissue and the liver. Reserves of these vitamins can stay in the body for days, or longer.

Vitamin D, despite being the only vitamin we can absorb from the sun, is a common deficiency in the UK with studies indicating up to 74% of people are below the optimum level for wellbeing whilst around 27% are deficient.

Did you know?
The word “vitamin” is derived from the Latin “vita,” meaning life, and “amine,” because vitamins were originally thought to contain amino acids


Minerals are inorganic elements of which small amounts are required by the body to function in all sorts of ways. 3 main reasons they are necessary are to build strong bones & teeth, control fluids inside & outside cells, and metabolise food into energy.

Around 4% of your body is made up of minerals and they come from a wide variety of food sources.

 ‘Major’ minerals refer to those we need to absorb more than 100mg of a day, whilst ‘minor’ minerals are needed in smaller quantities.

Iron deficiency anaemia is the most common deficiency in the world and in the UK, whilst iodine deficiency is also common. However the mineral sodium, or salt as we know it, is often found to be at excess levels and is linked with high blood pressure.

Did you know?
Electrolytes are chemicals that conduct electricity when mixed with water. Important electrolytes sodium and potassium are lost through sweating.

Muscles & neurons rely on the movement of electrolytes through the fluid inside, outside, or between cells. Levels must be balanced to maintain health.


This is not a full picture of the science of nutrition, there are other types of nutrient that can affect our health such as probiotics and phyto-chemicals, which we'll be looking at in subsequent articles.

Nonetheless, we hope this overview of the basic principles and classifications, and how scientists look at the food we eat, has been useful in helping you understand a little more how your own body works and how best to treat it.

It’s no secret that a perfectly varied and balanced diet can provide all the vitamins & minerals a person needs to maintain good health, and the NHS provide a fantastic document with help and advise on how you can achieve this; The Eatwell Guide.

However, our ability to absorb nutrients can deteriorate with age or due to certain genetics, conditions and illnesses. Furthermore, many people simply do not have the time, budget or taste for certain foods, or follow specialised diets which might mean they are missing key nutrients.

It’s in these situations that the right health supplementation can be an easy and cost-effective way of filling, or protecting against, a gap in your nutritional intake.

by Adam Gould
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