The undesirable components
Whole milk, cheese, butter and many other dairy products contain high levels of saturated fat, cholesterol and animal protein all of which are not required in the diet and have been linked to a wide range of illnesses and diseases. For example, excess saturated fat and cholesterol in the diet is associated with an increased risk of heart disease and stroke. Cross cultural studies show that as the consumption of saturated fat, cholesterol and animal protein increases from country to country, so does the incidence of the so-called diseases of affluence such as obesity, heart disease, diabetes, osteoporosis and certain cancers. It has been suggested that this is because of genetic differences between different races. However, when people migrate from an area of low incidence of the so-called affluent diseases to an area of high incidence, they soon acquire the same high incidence shared by the population into which they have moved. This correlation must then be attributed, at least in part, to environmental factors such as diet and lifestyle. So if you can increase the risk of disease by changing your diet and lifestyle, it stands to reason that you can reduce the risk of disease by changing your diet and lifestyle. The World Health Organisation (WHO) state that there are major health benefits in eating more fruit and vegetables, as well as nuts and whole grains and moving from saturated animal fats to unsaturated vegetable oil-based fats (WHO, 2003).
In addition to saturated fat, cholesterol and animal protein, a wide range of undesirable components occur in cow’s milk and dairy products. The modern dairy cow is prone to both stress and disease. In the UK, cows suffer from a range of infectious diseases including brucellosis, bovine tuberculosis, foot and mouth disease, viral pneumonia and Johne’s disease. As a result of an infectious disease a wide range of contaminants can occur in milk. Mastitis (inflammation of the mammary gland) is a widespread condition affecting cattle in the UK in which all or part of the udder suffers from an infection caused by bacteria entering through the teat (Dairy Co, 2013b). Mastitis may be referred to as subclinical (no symptoms) or clinical whereby symptoms include swelling, pain, hardness, milk clots or discoloured milk. The cow responds to the infection by generating white blood cells (somatic cells) which migrate to the affected area in an effort to combat the infection. These cells, along with cellular debris and necrotic (dead) tissue, are a component of pus and are excreted into the milk. Mastitis treatment and control is one of the largest costs to the dairy industry in the UK. Financial losses arise from:
- Milk thrown away due to contamination by medication or being unfit to drink
- A reduction in yields due to illness and any permanent damage to udder tissue
- The extra labour required to tend to mastitic cows
- The costs of veterinary care and medicines
- The cost of reduced longevity due to premature culling
Source: Dairy Co, 2013b.
The number of somatic cells in the milk (the somatic cell count) provides an indication of the level of infection present. These measurements are taken from the milk bulk tank and not from individual cows, so milk from a diseased cow is diluted, especially in larger herds. The somatic cell count usually forms part of a payment structure to farmers with defined thresholds of concentration determining the qualification for bonus payments or penalty charges. Indeed, milk contracts often define several somatic cell count thresholds and any respective bonus for attaining them (Dairy Co 2013c). In most developed dairy industries various regulatory limits are applied to milk for human consumption. In the European Union the somatic cell limit is a maximum of 400,000 cells per ml in bulk milk (Dairy Products (Hygiene) Regulations 1995). This means that milk containing 400 million pus cells per litre can be sold legally for human consumption. So one teaspoonful of milk could contain up to two million pus cells! It could be even worse, as concerns have been raised about the efficiency of cell counting techniques (Berry et al., 2003).
Goat’s milk is no better. According to the Universities Federation for Animal Welfare (UFAW), 65 per cent of goat milk samples will have a cell count greater than 1,000 million cells per litre (Mowlem, 2011). Mastitis effects the quality of milk in many ways; the total protein content is decreased, the amounts of calcium, phosphorus and potassium content are decreased, the taste deteriorates (becomes bitter), and the levels of undesirable components rise. These include enzymes such as plasmin and lipase, and immunoglobulins (Blowey and Edmondson, 2000). Mastitis is treated with antibiotics delivered directly into the udder. These drugs can also end up in the milk, so milk from treated cows must not be marketed until the recommended withholding period has elapsed. Mastitis occurs in around 50 per cent of cows in the UK (Blowey and Edmondson, 2000).
Recent studies show that the value of mammalian milk is not just nutritional but that it contains a variety of factors (biologically active molecules) with additional qualities that have a profound role in the survival and health of the offspring consuming it. These biologically active molecules include enzymes, hormones and growth factors. In 1992, Pennsylvania State University endocrinologist Clark Grosvenor published an extensive review of some of the known bioactive hormones and growth factors found in a typical glass of cow’s milk in the US. The list included seven pituitary (an endocrine gland in the brain) hormones, seven steroid hormones, seven hypothalamic (another brain endocrine gland) hormones, eight gastrointestinal peptides (chains of two or more amino acids), six thyroid and parathyroid hormones, 11 growth factors, and nine other biologically active compounds (Grosvenor et al., 1992).
Other biologically important proteins and peptides in milk include immunoglobulins, allergens, enzymes, casomorphins (casein peptide fragments) and cyclic nucleotides (signalling molecules). The concern here is that these signalling molecules that have evolved to direct the rapid growth of the offspring for which they were intended. So, cow’s milk, ‘designed’ to turn a calf into a cow, may initiate inappropriate signalling pathways in the human body that may lead to illnesses and diseases such as cancer.
All milk produced by mammals is a medium for transporting hundreds of different chemical messengers. Human breast milk is a dynamic, multifaceted infant food containing a wide range of nutrients and bioactive factors needed for human infant health and development: macrophages, stem cells, immunoglobulins, cytokines, chemokines, growth factors, hormones, oligosaccharides, glycans and glycosaminoglycans (Ballard and Morrow, 2013). While many studies of human milk composition have been conducted, components of human milk are still being identified. Mammalian milk ‘communicates’ between the maternal mammary epithelia and the infant’s intestinal system directing and educating the immune, metabolic and microflora systems within the infant (German et al., 1992). Indeed, research indicates that many of these molecules survive the environment of the infant’s gut and are absorbed into the circulation where they may exert an influence on the infant’s immune system, intestinal tract, neuroendocrine system, or take some other effect. This has evolved as a useful mechanism between mothers and infants of the same species, but the effects of bioactive substances in milk taken from one species and consumed by another are largely unknown. The concern is that the bioactive molecules in cow’s milk may direct undesirable regulation, growth and differentiation of various tissues in the human infant. Of particular concern for example is the insulin-like growth factor 1 (IGF-1) which occurs naturally in milk and has been linked to several cancers in humans (see IGF-1).