Is dairy good for you?

With increasing levels of obesity and an aging population in the UK, the risk of cardiovascular disease and its potential costs are increased. Understanding how diets can modify that risk is vital. As dairy products are a staple part of most Western diets, it is therefore important to know whether these food have an impact on the risk of disease.

Background

Many people think dairy products are high in fat and cause an increased risk of heart disease. Tests on the chronic effects of milk and dairy produce on health are difficult to carry out and as such no adequate studies have been reported to date.

Some studies have been carried out which identify ‘risk markers’ for the disease rather than heart disease itself. While such tests can be helpful, there is increasing evidence that relying on single markers for complex food like dairy products can be misleading.

As a result, the most valuable evidence currently available is provided by ‘cohort’studies - long-term observations which compare people’s diets and their tendency to develop or die from cardiovascular disease.

Current position

The largest analysis published to date (Elwood et al. 2010) is based on 24 cohort studies. The table below shows an overview of the main findings:

The consumption of milk and dairy products and the risk of vascular disease and diabetes

Disease outcome Number of
disease events
Adjusted relative risk 1
(95% confidence limits)
Coronary heart disease 16,212 0.92 (0.80 - 0.99)
Ischaemic stroke 9,725 0.79 (0.68 - 0.91)
Type 2 diabetes 7,121 0.85 (0.75 – 0.96)
Death from any cause 5,092 0.87 (0.77 - 0.98)

Overall, the data provides no evidence that high consumers of milk and dairy products are at a higher risk of cardiovascular disease than those who eat low
amounts.

In fact, compared with the 20% of people who ate little or no dairy, the 20% who had the highest intake of dairy products had a reduced risk of cardiovascular disease: the reduced risk was equivalent to about 8% for coronary heart disease, 20% for ischaemic stroke and 15% for diabetes.

If these reductions were translated across the entire population, it would have a major effect on the occurrence and costs of cardiovascular disease.

It should be noted that whilst the data in the above table relate to the consumption of milk and dairy produce, milk is the most frequently identified. The same study tried to find research which analysed the effects of butter and cheese separately, but there was too little research available to allow firm conclusions to be drawn.

However, a recently-published study comparing those who ate equal amounts of dairy fat from cheese and butter showed a lower level of cholesterol in consumers
who ate cheese.

This supports other evidence that the impact of fat in individual foods depends not just on fat content, but on other components in the food which could affect how much fat is digested and absorbed. Similarly, there were too few studies available to compare the value of full-fat vs. fat-reduced milk.

It needs to be recognised that analysis of a number of cohort/observational studies does have limitations. Such studies can only give an overall picture and say nothing about the cause and effect of any outcomes.

However, results shown above are supported by other studies which indicate that higher milk consumers tend to have lower blood pressure than those who drink less milk. It may be that this is a key finding, as increased blood pressure is a recognised important risk factor for cardiovascular disease. This is supported by detailed studies which show that calcium and some proteins in milk can help lower blood pressure.

Animal Briefs is an initiative of The British Society of Animal Science, providing factual and impartial information on matters of topical concern.
This brief has been prepared by Professor Ian Givens, University of Reading, for the Society.

Further contact on this or any related matter should be with the Society. Email bsas@sac.ac.uk