CHEMICAL NUTRIENTS THAT FUEL OUR BODIES

girlsinstem43
Sep 8, 2024
4 min read

Written by Mei Ying, Jia Yie, Suki Chan

Definition of a Healthy Diet

A healthy diet is a diet that maintains or improves overall health. A healthy diet provides the body with essential nutrition: fluid, macronutrients, micronutrients, adequate fiber and food energy.
It contains fruits, vegetables, and whole grains and may include little ultra-processed foods or sweetened beverages.

How Chemistry Relates to Our Diet

1. Carbohydrate

	Function : Provide energy to the body
Simple Carbohydrates : Monosaccharides Disaccharides Oligosaccharides	Complex Carbohydrates : Polysaccharides
Have one or two sugar molecules Known as empty calories as it doesn’t process fiber, vitamins and minerals	Have two or more sugar molecules Referred to starchy food Formed by polymerization of a large number of monomers
Monosaccharides ( Monomer )
Disaccharides ( Two monosaccharides )
Oligosaccharides ( Condensation of 2-9 monomers )

2. Protein

Composition	Made of amino acids linked by peptide bonds Elements: C, H, O, N, sometimes S
Structure of amino acid
Peptide bond	Formation: Condensation reaction (releasing H2O) Break: Hydrolysis catalyzed by enzymes.
Protein structure	Primary: Sequence of amino acids Secondary: Alpha-helix and beta-pleated sheets Hydrogen bonds Tertiary: 3D folding interactions between R groups Hydrophobic Interaction Ionic bonds Hydrogen bonds Disulfide Quaternary: Multiple polypeptide chains Forms functional protein
pH and heat sensitivity	High temperature cause denaturation (changing the shape of the active site) pH also affects structure.
Functions of protein	Catalyst: lowers activation energy of biochemical reactions Structural: Collagen/keratin Transport: Hemoglobin Signaling: Hormones Immune: Antibodies

3. Vegetables / Vitamin

Potassium	Maintain a healthy blood pressure.
Fiber	Decreased risk of coronary heart disease.
Vitamin A	Keeps eyes and skin healthy and helps protect against infections.
Vitamin C	Helps heal cuts and wounds and keeps teeth and gums healthy.
Folate	Reducewoman’s risk of child with a brain or spinal cord defect.
Magnesium	Form healthy bones and also interact with more than 300 enzymes in the body system.

4. Oil / Lipid

Vegetable oil vs animal fat

Type of oil	Vegetable oil	Animal fat
Composition	Oleic acid and linoleic acid (unsaturated fatty acids, UFA)	Monounsaturated acid, MUFA and saturated fatty acids, SFA
Molecular structure of respective acids	Oleic acid Monounsaturated (only 1 double bond) Linoleic acid Polyunsaturated (two or more double bonds)	Saturated fat No double bonds Monounsaturated fat Only 1 double bond
Effects on health	UFA increases high density lipoprotein cholesterol (HDL) and decreases low density lipoprotein cholesterol (LDL) in our blood due to cis double bonds. Trans double bonds fat increases LDL and lower HDL cholesterol levels.	SFA increases HDL, LDL and total cholesterol in our blood. Increase in LDL cholesterol in blood increases the risk of cardiovascular diseases and stroke.

Controversy of Vegetable Oil vs Animal Fat

Although vegetable oil is generally thought to be healthier than animal fat, recent studies show that certain vegetable oils are no better than animal fat.

Unhealthy vegetable oils include : corn oil, canola oil, sunflower oil and soy oil.
These oils do not come in natural form, hence they are highly refined in order to be extracted. Besides, they are highly polyunsaturated (PUFA), which makes them very unstable. As a result, when they're exposed to chemicals in the refining process, they're stripped of their antioxidants, vitamins, and minerals. Over time, PUFA becomes stored in the body fat, which may lead to inflammation.
Conclusion : a general misconception about oils is that all vegetable oils are healthier than animal fat, but we should take the nature of the oil into consideration. In this case, since the process of making butter does not require a complicated refinery compared to those vegetable oils mentioned, butter could be considered healthier.

5. Dessert

Colouring
Types of colorant	Natural: From plants, animals or minerals Artificial: Synthetic dyes (FD&C Red No.40, FD&C Yellow No.5)
Molecular structure	Natural: Multiple functional group Artificial: Azo group (N triple bond N) Aromatic group Multiple functional groups To enhance the stability and solubility
Affected by:
a.) Solubility	Water soluble: Synthetic dyes with sulfonate groups Fat soluble: Carotenoids with long hydrocarbon chain
b.) pH	Some colorants change colour with pH (eg. anthocyanins)
c.) Light stability	Natural: Sensitive to light, leading to photodegradation Artificial: More stable under light exposure
Flavouring
Type of flavouring	Natural: Essential oils, extracts and compounds from food sources (eg. vanillin from vanilla, limonene from citrus) Synthetic: Compounds mimicking natural flavours (eg. ethyl vanillin, isoamyl acetate)
Molecular structure	Esters, aldehyde, ketones, alcohols, acids and hydrocarbons Various functional group contributing to their specific chemical reactivity and sensory properties
Affected by:
Volatility	Most are volatile so it will have aroma Low molecular weight High vapour pressure (eg. ketones, small aldehydes and ester)
Solubility	Hydrophilic: Polar compounds (acid, alcohol) Lipophilic: Non-polar compounds (eg. terpenes, large hydrocarbons)
Chemical stability	Heat: can cause decomposition Light: photochemical reactions can degrade flavours Oxygen: oxidation can lead to loss of flavour

How do preservatives work?

Type of food preservative	Examples of food preservatives
Antimicrobials - inhibit the growth of pathogenic microorganisms in food	Benzoic acid; changes the internal pH of microorganisms to an acidic state that is incompatible with their growth and survival
	Natamycin; inhibits fungal growth by binding to sterol groups on the cell membrane
Antioxidants – delay or prevent the deterioration of foods by oxidative mechanisms	Ascorbic acid; terminates chain radical reactions during oxidation by transferring electrons Tocopherol; terminates free radicals by donating a hydrogen from the hydroxyl group on its chromane ring