milk and dairy products

see also:

• lactation
• the lactating patient in ED
• diets and healthy foods

• human breast milk is an amazing substance capable of being the sole food intake to sustain the rapid growth of babies
• the far majority of infants have a gut enzyme, lactase, which can digest the lactose in milk, however, expression of the gene declines as the child gets older so many adults are relatively intolerant of lactose - the gene to allow high lactase production persistent into adulthood arose some 5000-4000yrs ago in Europe.
• it appears our ancestors started consuming animal milk and milk products in the neolithic period around 9,000–10,000 years ago, coinciding with animal domestication.
  • it may have started with the domestication of sheep in Anatolia and Mesopotamia and the processing of milk fats was evident at this time
  • this was followed by milk from goats and cattle 8000-9000 years ago in eastern Sahara, SW Asia and the Near East before spreading to Europe and South Asia
  • it became widspread in Europe, the Balkans and Africa by 7000-6000 yrs ago despite lactose intolerance
  • Funnel Beaker Culture in Nth England and Scandinavia 4100-2800BC brought herding of domesticated cattle, sheep, and goats from the Near East via the Balkans
  • lactase persistence mutations emerge in Europe and spread 5000-4000 yrs ago while pastoralism extended to horses, donkeys, buffalo, camels and yaks
• making cheese allowed the creation of a longer lasting nutritious food and involves adding an enzyme (typically rennet) to milk to coagulate it and create curds while the remaining liquid, called whey, needs to drip away from the curds using a sieve or muslin cloth.

• human breast milk is tailored to the needs of the developing infant and contains key maternal immune factors as the infant's immune system is very much under-developed until at least 3 months of age
• has 1-2% protein with a whey:casein ratio of 60:40
  • alpha-lactalbumin is a key whey protein in human breast milk, making up 20-25% of total milk proteins and offers a balanced supply of essential amino acids (esp. tryptophan and cysteine), binds calcium and zinc to aid mineral absorption, interacts with proteins like sCD14 to protect them from gut degradation, aiding immunity and microbial colonization without inflammation, and digests easily for infant gut tolerance, while its partial digestion yields antimicrobial peptides, enhancing infant defenses
• has 2-4% fats which are rich in DHA/ARA for brain development
• has 6-7% lactose which provides more energy carbohydrates
• has 0.03% sodium
• it can be problematic at times:
  • maternal medications, radioactive contrast agents or other substances may pass through to breast milk and potentially effect the baby
  • lactation issues may limit supply
  • gastro-intestinal illness in the baby may temporarily not be able to process human milk or any other milk

• do not have the maternal immune factors that human milk has (immunoglobulins (IgA), enzymes, and oligosaccharides for gut/immune health) nor do they have the correct constituent's for young babies
• not recommended for infants under 12 months
• for microbiologically safe consumption, they should undergo Pasteurisation otherwise there is risk of transmission of pathogens such as tuberculosis (TB), Listeria monocytogenes / Listeriosis, etc.
  • Australian standards mandate pasteurization for safety
• most commercial animal milks are “homogenised” to ensure the fats stay mixed in the milk and do not float to the top as cream
• many commercial animal milks are further “Standardized” processed to adjust constituents such as fat levels, calcium levels, etc
• ultra-high temperature (UHT) processing creates milks for longer shelf life without refrigeration
• some milks have had the lactose content removed to create “lactose free milk”
• some children have allergies to the proteins in animal milks

• has about twice the amount of protein and with much more casein (whey:casein ratio of 20:80) which can create a burden to human infant kidneys
  • only has 3.5% of its proteins as alpha-lactalbumin
• has more fats and much of this is saturated fats and lack essential PUFAs
• has 4-5% lactose and thus less energy carbs
• has 0.05% sodium which can overload immature human infant kidneys
• 240mL contains 150 calories, 8g protein, 8g fat, 12g lactose, 300mg calcium
• a large 2026 study suggests higher dairy consumption, up to two servings a day was associated with a 22% reduction in the odds of developing metabolic syndrome and this appears to be related to calcium intake¹⁾

• constituents
  • 20-35% fats (33% for cheddar)
  • 20-30% protein
  • 1-3% carbohydrates including lactose
  • 1-4% minerals / salts - cheeses can add considerably to the daily salt intake and potentially worsen hypertension and congestive cardiac failure
• microbiologic hazards
  • whilst cheeses, especially hard cheese generally last much longer than fluid milk without refrigeration, some cheeses can pose pathogenic risks
  • unpasteurised cheeses such as many soft goat's milk cheeses, run a risk of Listeria monocytogenes / Listeriosis and also E.coli O157:H7, Salmonella, Campylobacter
    • Listeria is a particular issue, especially amongst immunocompromised people, pregnant women and neonates.
• environmental impacts
  • it requires 4-10L of milk to make 1kg of cheese
  • this is a significant environmental impact - farm milk production drives most impacts (enteric methane, feed); cheese processing contributes 10-35% extra green house gases via energy/heating. Whey valorization (e.g., animal feed) reduces burdens by 10-20%; hard/aged cheeses have higher impacts due to more milk needed.
  • green house gas production for a hard cheese is some 12x that of fluid milk and about 4x that of coffee beans per kg

• some yoghurts may have beneficial effects upon the the GIT microbiome
• avoid most flavored yogurts despite having 4.5 star health ratings including “fat free” ones generally have high glycaemic indices with excess amounts of sugar, modified starch, tapioca starch, gelatin, citric acid, ultra-processed “fruit”, pectin gum, other additives which are likely to adversely impact gut microbiome rather than improve it with “probiotics” and are more puddings than healthy yogurts while the reduced fat ones also generally have less dairy protein
• check the ingredients, and look for plain real yoghurt (eg. plain Chobani Greek yogurt, Jalna, Barambah Organics, Mungalli Creek) is naturally acidic and does not need added citric acid so if this is present, it is probably a long way from being natural yoghurt

• have advantages that they generally do not contain saturated fats, have minimal if any lactose, tend not to cause allergies, and production requires ~25% of the greenhouse gas production, 10% of land, and generally, much less water usage compared to cow's milk production
• however:
  • are generally poor in quality and amount of protein (although the protein in soy comes close to cow's milk quality)
  • do not provide natural B12/iodine as does cow's milk
  • require added calcium to be an adequate cow's milk replacement as source for calcium
  • whether they are actually good for you is debatable but for those who cannot have animal milks they may be a reasonable alternative

• made from soy beans
• soy has oestrogenic effects and these may be harmful in significant amounts for certain people
• 240mL contains 80 calories, 7-8g soy protein, 4g fat, 1g lactose, 3g other carbohydrates, 300mg calcium if fortified

• made from almonds
• lacks nutritional benefits as is low-calorie and has minimal protein
• low greenhouse gas production but water-intensive requiring 371L water per liter
• 240mL contains 30-40 calories, 1g protein, 3g unsaturated fat, 0g lactose, 1g other carbohydrates, 450mg calcium if fortified

• made from oats
• offers creaminess and fiber (beta-glucans for heart health) but has inadequate protein and higher glycemic impact with 16g total carbohydrates so will not be great for diabetics or those with metabolic syndrome, or those wishing to maintain muscle bulk
• 240mL contains 120 calories, 3g protein, 5g fat, 0g lactose, 7g sugars, 9g other carbohydrates, 350mg calcium if fortified