A recent News Blog conveyed evidence that milk consumption is associated with osteoporosis in a dose responsive manner. 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, 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
- Lilford RJ. Two Provocative Papers on Diet and Health. NIHR CLAHRC West Midlands News Blog. 12 December 2014.
- Ding M, Huang T, Bergholdt HKM, et al. Dairy consumption, systolic blood pressure, and risk of hypertension: Mendelian randomization study. BMJ. 2017; 356: j1000.