Tag Archives: Milk

More Bad News for Unfermented Milk

A recent News Blog conveyed evidence that milk consumption is associated with osteoporosis in a dose responsive manner.[1] Contrary to that, observational studies have shown that milk consumption is associated with slight reduction in blood pressure. The osteoporosis data is consistent and the effect is large, while the hypertension evidence is inconsistent, and the magnitude of effect is rather small. Anyway, a recent large re-analysis of observational evidence from cohort studies,[2] using an instrumental variable, finds no improvement in blood pressure in association with increasing dairy product consumption. The instrumental variable is genotypes associated with lactase deficiency. Not surprisingly, people who cannot digest lactose consume less dairy products. Randomised trials also show no association between dairy intake and blood pressure, although follow-up is limited in these studies. Unsurprisingly, the quoted study is not able to distinguish between fermented and unfermented milk, and hence does not shed light on the galactose hypothesis. This hypothesis says that galactose is somewhat toxic in adults who would be better off sticking to fermented milk products where galactose has been converted to lactic acid.

— Richard Lilford, CLAHRC WM Director

References:

  1. Lilford RJ. Two Provocative Papers on Diet and Health. NIHR CLAHRC West Midlands News Blog. 12 December 2014.
  2. Ding M, Huang T, Bergholdt HKM, et al. Dairy consumption, systolic blood pressure, and risk of hypertension: Mendelian randomization study. BMJ. 2017; 356: j1000.

The Payback from Improving Availability of Donor Human Milk for Premature Babies

CLAHRC WM is collaborating with the African Population Health Research Centre (APHRC) in the evaluation of donor milk banks in slums (informal settlements) in Kenya. The initiative is led by PATH,[1] which has had considerable success in establishing an altruistic donor service in South Africa. The donor milk is donated to hospital wards caring for premature infants.

There is excellent evidence that donor human milk is superior to ‘formula’ in babies whose mothers are unable to express breast milk. As a result of passive immunity, and also because it has nutritional properties that formula is not able to replicate, donor human milk reduces the risk of neonatal infection.[2] In particular, it reduces the dangerous condition of necrotising enterocolitis (NEC).[3][4] NEC can be fatal and may also require surgery that may have permanent consequences – particularly the ‘short bowel syndrome’. The decreased infection risk resulting from use of donor milk is associated with a measurable decrease in mean length of stay.[5]

One concern is that the mothers of infants who receive donor milk may be less likely to initiate breast feeding at a later date for psychological or physiological reasons. The evidence does not bear out this concern and, if anything, these mothers, perhaps inspired by the altruism of the donors, are more likely to breastfeed.[6][7] If so, this may be expected to augment the benefits of donor milk and also reduce the mother’s risk of developing breast cancer later in life.[8]

The benefits do not seem to end there. There is observational evidence, recently reinforced by a substantial study from Brazil,[9] that cognitive ability in later life is improved by human milk. There is a dose-response effect and the results remain after extensive statistical adjustment for confounders. There is also some experimental (RCT) evidence for a beneficial effect on IQ.[10] Improved IQ is correlated with earning power [11] and, we must assume, payback to society.[12]

To summarise the benefits of breastfeeding we offer the following Influence Diagram (Causal Pathway: Model):

CI - Improving Availability of Donor Human Milk Fig 1

A health economic analysis of promotion of breastfeeding for older children (not premature infants specifically) found that the intervention ‘dominated’ – reduced short-term benefits (less infection) and the contingent cost savings (reduced hospital stays) meant that interventions to promote breastfeeding are cost-saving, not just beneficial for health.[12][13]

There have been two studies of the cost-effectiveness of a donor milk service for premature babies. Both found that the service was cost-effective. The first study was based on a hypothetical baby who was very premature (28 weeks gestational age), rather than an observed mean intervention effect observed at the group level.[14] The calculated benefits might therefore be exaggerated. The second study was based on only 175 propensity scored low birth weight infants.[5] The risk of sepsis decreased with increasing dose of human milk, and total costs obtained from the hospital billing system were lower in proportion to the amount of human milk consumed. However, most infants received some human milk, so the infants could not be divided into a control and intervention population, and the above correlation between outcome and volume of donor milk consumed may have been confounded by factors that determine both access to human milk and sepsis, notwithstanding propensity scoring. Both the above studies were American.

Working with colleagues above, we propose a comprehensive health economic model that takes account of long-term outcomes and that can be populated with country-specific data. The base-case model will be populated with evidence from systematic reviews,[12][13] and we propose to use Bayesian techniques to ‘down weight’ observational evidence using the Turner and Spiegelhalter method.[15]

— Richard Lilford, CLAHRC WM Director
— Celia Taylor, Senior Lecturer

References:

  1. PATH. Models of milk banking in South Africa. Seattle, WA: PATH, 2011.
  2. Arslanoglu S, Ziegler EE, Moro GE. Donor human milk in preterm infant feeding: evidence and recommendations. J Perinat Med. 2010; 38: 347-51.
  3. Lucas A, Cole TJ. Breast milk and neonatal necrotising enterocolitis. Lancet. 1990; 336: 1519-23.
  4. Quigley M, McGuire W. Formula versus donor milk for feeding preterm or low birth weight infants. Cochrane Database Sys Revs. 2014; 4: CD002971.
  5. Patel AL, Johnson TJ, Engstrom JL, Fogg LF, Jegier BJ, Bigger HR, Meier PP. Impact of early human milk on sepsis and health-care costs in very low birth weight infants. J Perinatol. 2013; 33: 514-9.
  6. Arslanoglu S, Moro GE, Bellù R, Turoli D, De Nisi G, Tonetto P, Bertino E. Presence of human milk bank is associated with elevated rate of exclusive breastfeeding in VLBW infants. J Perinat Med. 2013; 41(2): 129-31.
  7. Vázquez-Román S, Bustos-Lozano G, López-Maestro M, et al. Clinical impact of opening a human milk bank in a neonatal unit. An Pediatr (Barc). 2014; 81(3): 155-60.
  8. Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and breastfeeding: collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries, including 50 302 women with breast cancer and 96 973 women without the disease. Lancet. 2002; 360: 187-95.
  9. Victora CG, Horta BL, Loret de Mola C, Quevedo L, Pinheiro RT, Gigante DP, Gonçalves H, Barros FC. Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil. Lancet Glob Health. 2015; 3(4): e199-205.
  10. Horta BL, Victora CG. Long-term effects of breastfeeding: a systematic review. Geneva: World Health Organization. 2013
  11. US Environmental Protection Agency. The benefits and costs of the clean air act, 1970 to 1990, appendix G, lead benefits analysis. Washington, DC: Environmental Protection Agency, 1997.
  12. Renfrew MJ, Pokhrel S, Quigley M, et al. Preventing disease and saving resources: the potential contribution of increasing breastfeeding rates in the UK. UNICEF. 2012.
  13. Kramer MS & Kakuma R. Optimal duration of exclusive breastfeeding. Cochrane Database Sys Revs. 2012; 8: CD003517.
  14. Arnold LDW. The Cost-effectiveness of Using Banked Donor Milk in the Neonatal Intensive Care Unit: Prevention of Necrotizing Enterocolitis. J Hum Lact. 2002; 18(2): 172-7.
  15. Turner RM, Spiegelhalter DJ, Smith GCS, Thompson SG. Bias modeling in evidence synthesis. J R Stat Soc Ser A. 2009; 172: 21–47.

Two Provocative Papers on Diet and Health

People are always extremely interested in research on diet and health. Who would have thought that milk was so bad for you? Not only does milk increase risk of heart disease, but it aggravates the one condition that one might have supposed it would protect against, namely osteoporosis. Why doesn’t this high calcium drink prevent calcium loss from bone? The sugar in milk is lactose, a disaccharide derived from glucose and galactose. Galactose may be great for babies, but it is a powerful oxidant, and oxidants are harmful for adults. So it turns out milk aggravates osteoporosis leading to more fractures.[1] However, if you ferment the sugar to lactic acid, for example in producing yoghurt or soured milk, then these negative associations disappear. So the loss of bone in elderly people is not a calcium deficiency disease in most cases, and milk is positively harmful for bone maintenance. Most animals become lactase deficient, losing the ability to digest lactose after weaning.[2] This is not just an accident; it protects them from the harmful effect of galactose. For some reason humans are not so lucky and retain the enzyme. We therefore need to pre-ferment our lactose before consumption. Not surprisingly, a lively correspondence ensured after publication of this provocative paper, but the authors mount a convincing defence.

The question of what sort of diet to take to lose weight is a long-standing controversy – low carbohydrate or low fat? Well a recent randomised trial shows that a low carbohydrate option is much superior in terms of both weight loss and lipid profile.[3] I don’t think we should be surprised: very high carbohydrate diets are an anomaly that would not have occurred in human evolution before the relatively recent discovery of agriculture. It is a pity that the good Dr Atkins didn’t live to see his theory vindicated.

— Richard Lilford, CLAHRC WM Director

References:

  1. Michaëlsson K, Wolk A, Langenskiöld S, Basu S, Warensjö Lemming E, Melhus H, Byberg L. Milk intake and risk of mortality and fractures in women and men: cohort studies. BMJ. 2014; 349: g6015.
  2. Desai BB. Handbook of Nutrition and Diet. New York, NY: Marcel Dekker, Inc. 2000.
  3. Bazzano LA, Hu T, Reynolds K, Yao L, Bunol C, Liu Y, Chen C-S, Klag MJ, Whelton PK, He J. Effects of Low-Carbohydrate and Low-Fat Diets: A Randomized Trial. Ann Intern Med. 2014; 161(5): 309-18.