Fatty acids in milk
Milk contains a wide range of saturated fatty acids, and you can see a list of the fat content of milk here. As you can see the most abundant fats are myristic acid (14:0), palmitic acid(16:0), stearic acid (18:0) and olieic acid (18:1 cis-9), and so it is these that will be explaining in greater detail:
Myristic acid (14:0) – Myristic acid is a saturated fat which is quite common in animal fats and vegetable fats. Large amounts dietary mysteric acid is associated with elevated serum levels of LDL, or ‘bad cholesterol’, but this doesn’t necessarily mean it poses a risk to your health. This particular fatty acid is quite a small fatty acid (only contains a 14 carbon long chain), which means that it is converted into usable energy in the body much faster than other longer fats. Apart from its uses as energy, It is often incorporated in human cell membranes to act as an ‘anchor’ as it is highly hydrophobic (repels water) and helps maintain cell membrane structure.
Palmitic acid (16:0) – Palmitic acid is also a saturated fat, but with a longer carbon chain than myristic acid. It is the most abundant fatty acid in the body, and excess carbohydrates in the body will usually get converted into palmitic acid to be stored as energy or undergo further reactions and become converted in to other fatty acids. Like myristic acid, high consumption of palmitic acid is associated with raised LDL levels, but again,this doesn’t necessarily pose a risk to your health. Its primary role in the body is really as a source of energy, and the body can convert palmitic acid into energy with relative ease.
Stearic acid (18:0) – Stearic Acid is also a saturated fatty acid, with a longer carbon chain than the previous 2 mentioned. This longer chain means that converting this fatty acid into usable energy takes more time, and so it is not a good source of energy. It is primarily found in animal fat, but can be found in vegetable fats in smaller quantities. Steric acid has been shown to protect nerve cells against oxidative stress, and can also reduce the risk of thrombosis, which will reduce the risk of cardiovascular diseases. Unlike the previous 2 fatty acids, stearic acid is not associated with raised serum levels of LDL.
Oleic acid (18:1) – Oleic is a mono-saturated fatty acid, meaning it contains 1 double bond in its carbon chain, and because of this it exists in 2 forms; the cis form and trans form. In milk, it is only the cis form which is found in any significant quantities. Oleic acid is found in both vegetable oils and animal fats. In a 10 year study on cis-oleic acid it was shown that consumption can reduce the risk of developing depression and other mood related ailments. Further studies have also shown that increasing the amounts of cis-oleic acid in your diet can reduce LDL levels, serum triglyceride levels and blood pressure; providing protection against CVD.
Branched-chain fatty acids – Milk contains is relatively abundant in branched-chain fatty acids, which make up to 2g of 100g of milk. Although collectively they only make up a very small percentage of milk, they have demonstrated remarkable health benefits. A number of studies have shown that various branched chain fatty acids inhibit cancer cell production, the most effective of which are 14-methylpentadecanoic acid and 13-methyltetradecanoic acid, both of which are found in milk and make up approximately 200mg of 100g respectively of milk fat.
Butyrate – Milk fat is one of the few dietary sources of butyrate, which is a short chain fatty acid like myristic acid, but is far less abundant in modern diets. Studies on butyrate have shown it can inhibit the growth of cancer cells and cause apoptosis (cell death) in a variety of established cancer cells. There is also increasing evidence that buytrate increases the uptake of a number of nutrients such as vitamin D.
Sphingomyelin – Sphingomyelin is one of the many phospholipids which are found in milk. In recent years it has been subject to a lot of research which has brought to light some very promising anti-carcinogenic properties. One study in particular showed that sphingomyelin induced apoptosis in cancerous cells in the colon. It can also reduce the number of aberrant crypt foci in the colon, which are abnormal tube like glands which are thought to lead to the development of cancer cells.
Proteins in milk
The majority of proteins in milk are part of the family called caseins. These proteins include beta-lactoglobulin, alpha-lactalbumin, immunoglobulins, lactoferrin, and various minor whey proteins such as transferrin and albumin. Both caseins proteins and whey proteins have a very high PDCAA, which means their amino acid content is very similar to that of our requirements. These proteins are also slowly digested (especially the ceasin proteins) and provide the body with a slow ‘trickle’ of amino acids after a meal.
Milk allergy – Milk allergy (different from lactose intolerance which is explained below) is an immune reaction to one or more proteins in milk, usually the immunoglobins. This allergic reaction can have a number of symptoms, but the most common is inflammation of the digestive tract, which can lead to discomfort and sometimes blood in the stool.
Immune system proteins – Milk contains 2 major immune proteins; lactoferrin and immunoglobins. Lactoferrin can bind to a vast number of bacteria cell walls and oxidise them, which results in the bacteria dying. In addition to this, lactoferrin has also demonstrated anti-inflammatory properties, an ability to improve bone formation and is thought to act as a probiotic for Lactobacilli spp. Although these benefits are minimal, they do exist and will contribute to human health.
Aside from having an allergic reaction, milk protein’s primary benefit for humans is a source of high quality protein, with minor benefits to the balance of gut micro-flora.
Carbohydrates in Milk
Lactose – Lactose is the primary carbohydrate in milk, and is a disaccharide made up of glucose and galactose, and it is lactose which is responsible for milk intolerance (also called lactose intolerance). Lactose intolerance is a result of the body not being able to produce the enzyme lactase which breaks lactose down, and the most common symptom is flatulence and stomach discomfort. For lactose tolerant people, lactose is digested in the same way as all simple carbs – quickly. In one pint of milk there is almost 7 teaspoons of simple sugars (nearly 30g), which will rapidly broken down and absorbed into the blood stream, where it can be converted into energy or stored as glycogen or fat.
Oligosaccharides in milk – Oligosaccharides are a relatively abundant in milk, but can also be found in various fruits and vegetables such as bananas or garlic. These oligosaccharides are known prebiotics, and promote the growth of probiotics, especially bifidobacter spp. The oligosaccharides can help promote probiotics in two ways, the first is by acting as a energy substrate which only bifidobacter spp can use, thus increasing their food supply which will raise their population. Secondly, the oligosaccharides can inhibit pathogens from adhering to the epithelial cells in the gut, which prevents them from proliferating. This will allow more resources, such as food, to be available for probiotics and allow their population to grow.
Micro-nutrients in milk
Fat soluble vitamins in milk – Whole milk contains a significant quantity of vitamins A, D and E. However, with semi-skimmed and skimmed milk the quantities of these are significantly reduced as they are fat soluble. Vitamin D is found in few foods but can be synthesised in the skin when in contact with UV light. It plays a range of roles in the body such as reducing cancer cell proliferation, improving cardiovascular health, improving bone density and it is vital for the correct functioning of the immune system.
Vitamin E’s primary role in the human body is protecting the cell membrane from oxidative damage. Oxidative stress is linked to a number of diseases such as cancer and is a cause of inflammation, which again, leads to a variety of ailments. As vitamin E helps prevent the development of a number of ailments it is essential to human health, but in order for it’s antioxidant capacity to be taken full advantage of adequate vitamin C is needed.
Milk is relatively abundant in vitamin A, and a 200ml glass of whole milk will provide you with nearly 10% of your RDA.
Vitamin A plays a very important role in the immune system, gene expression and is essential for correct functioning of the eyes.
Water soluble vitamins in milk – The quantity of water soluble vitamins is very similar from whole milk to skimmed milk as the fat content has no effect on them. Milk contains a host of B vitamins, which all play a crucial role in metabolism, immunity and the nervous system.
Minerals in milk – Milk is a fantastic source of minerals, the most abundant of which are calcium, phosphorous, zinc and magnesium. Calcium plays a vital role in maintaining bone density and helps regulate the pH of the blood. Phosphorus also plays a key role in maintaining healthy bones, but also is vital for tissue growth and membrane function (cell membranes are made of phospholipids which contain Phosphorus). Magnesium also plays a role in bone formation, and is also needed for nerve development and function. Unlike the other 3 major minerals in milk, zinc has no direct contribution to bone structure, but it is a vital component of over 300 enzymes, and is especially important in healing and fighting infections.
Summary – is milk good for you?
As long as you are not intolerant or allergic to milk, there is absolutely nothing wrong with drinking milk. It offers a number of health benefits, and can be enjoyed guilt free (within reason).