circular wrote:Good question, but I'm guessing that the probiotics have some beneficial effects the non-fermented group may not be getting regularly any othe way, in addition to benefits of the lower saturated fat intake, at least in some. Weren't they saying that the lower fat fermented group did better than the lower fat non-fermented group?
Good point, iirc, consumption of fermented dairy tends to cause increased production of SCFA in the gut, which has various health benefits. However, looking at the full paper at
https://sci-hub.tw/10.1017/S0007114518002830 I see lots of potential confounders:
Compared with men in the lowest quartile of fermented dairy product intake, men in the highest quartile were more likely to live in a rural area and less likely to be current smokers. They also had higher intakes of energy, fibre, and fruits, berries and vegetables, and lower intakes of MUFA and PUFA, and consumed less alcohol. Compared with men in the lowest quartile of non-fermented dairy product intake, men in the highest quartile were more likely to live in a rural area and to be current smokers, and less likely to be physically active or married, and they had fewer years of education. In addition, they had higher intakes of energy, fibre and SFA, and lower intakes of MUFA and PUFA, and fruits, berries and vegetables.
Their models seems to attempt to take these factors (and many others) into account, but I wonder about synergistic interaction. (They acknowledge this in the discussion.)
Some points from the Discussion (emphasis mine):
Total dairy product intake had no association with the CHD risk, but in the subgroup analyses, fermented dairy products had an inverse association whereas non-fermented dairy products had a direct association with the risk. Further analyses of low-fat and high-fat categories showed that only lowfat fermented dairy product intake was inversely associated with the CHD risk. Butter or cheese were not associated with the risk, but total milk intake was associated with a higher risk. Neither lowfat nor high-fat milk consumption was associated with the CHD risk, however.
...
For example, in the KIHD, low-fat fermented dairy products comprised mostly of sour milk and, in much lower amounts, of low-fat yogurt and cultured buttermilk known as viili(30), and high-fat fermented dairy products were mainly cheese, whereas yogurt comprised a significant amount of the fermented dairy product intake in the Dutch cohorts(27,31). As two previous meta-analyses found no significant association between yogurt consumption and CHD risk(21,32), the type of fermented dairy food might also matter. Even though yogurt, viili and sour milk are somewhat similar products regarding fermentation, fat content and viscosity, the different ways these products are consumed might affect the outcomes. In Finland, for example, sour milk has been a common lunch or dinner beverage, whereas yogurt and viili are snack-like products and can be often combined with berries, muesli or added sugar, for example. These combinations are difficult to account for in statistical analyses but could have divergent effects on health.
...
High SFA intake could also explain the observed association with total non-fermented dairy product intake but adjusting multivariate models further for SFA intake had no effect on the association. [So much for my initial hypothesis - Brian. Also, they had additional interesting things to say about high SFA dairy in the discussion.]