The USDA recommends 3 cups of milk or dairy a day. This is mostly to promote bone health. However, it has also been linked to increased cancer risk in some studies, others have supported health benefits. A recent study tried to sort out these conflicting results by separating milk from other dairy products and looking at death rates, heart disease, cancer rates and fractures.
What they found was surprising – adults who drank 3 or more glasses of milk a day died sooner, had more fractures as well as heart disease and cancer. Those with similar dairy intake, but from fermented dairy like yogurt, cheese, sour milk, etc. had a lower incidence of death and disease. The difference? Lactose content.
What is lactose?
Lactose is a sugar found in milk. When digested, it is broken down into glucose and galactose. Galactose has been linked to oxidation and inflammation – triggers for disease. The study authors hypothesized that the difference in lactose, therefore galactose intake with milk versus other dairy products is the cause of the difference if death and disease
What did they do?
The researches used 2 health registries of residents in Sweden where records are centralized, totaling over 61,000 women and 45,000 men and sent them questionnaires that looked at milk and dairy intake. They then followed their records from the early 1990’s until now, looking at death and disease rates. What they found was that women who drank 3 or more glasses of milk daily were:
- 1.9x more likely to die
- 1.4x more likely to get cancer
- 1.6x more likely to fracture a hip
In men, the effects were less pronounced:
- 1.1x more likely to die, mostly from cardiovascular disease
- no increase in fractures
They also messed marks of inflammation and oxidation in the blood of participants and found higher levels of both in those with higher milk intake.
So what does this mean?
There are some interesting associations based on this study.
- ingestion of milk, with it’s higher lactose content, may be linked to increase risk of disease
- ingestion of low lactose dairy products (yogurt, cheese) is associated with a decrease of disease
- moderate intake of milk is not associated with increased disease risk
There are some limits to this study
- the data is based on 1 or 2 food surveys, and subject to people’s memory and answers
- the population studied was very uniform – 2 or 3 counties in Sweden – which may limit generalizing to the population at large
- All subjects were over 39 years old so no conclusions can be made about children and young adults
- Lactose free milk was not evaluated
What can we take away from this?
- High amounts of lactose may contribute to disease based on its breakdown into oxidation and inflammation promoting compounds
- Dairy foods with low lactose contents are associated with lower death rates and illness
- Moderation again seem to be the word of the day – it is possible to have too much of a good thing!
The path to wellness begins with a proper diagnosis