Dairy products and cancer?

There has been a lot of buzz in recent years about milk and cancer. Specifically, studies have linked dairy consumption with increased risk of some cancers, as cow's milk contains estrogen and progesterone - both hormones that are linked to breast, ovarian, endometrial, testicular, and prostate cancers.

 However, as we all know, the media really likes to "boost" up these findings with scare-tactic messages like "Time to take milk off the menu". In fact, certain ingredients in milk have also shown to decrease risk of certain cancers such as colorectal cancer. And let's not forget other nutritional benefits of dairy, like its great source of calcium.

One recent study pooled the results of 14 prospective cohort studies looking at the links between dairy and pancreatic cancer. Previous studies looking at this association had inconsistent results, but this study found that was found that consumption of milk, cheese, yoghurt, ice cream, calcium, and Vitamin D was not significantly associated with pancreatic cancer risk.

Although this study only looks at one type of cancer, it does support the ideas that 1) More evidence is needed in the field of dairy vs. cancer before solid conclusions can be made 2) The media too often forgets the other side of the story in order to go for the "shock factor". In the meantime, it's probably not a good idea to throw out all your yoghurt and milk, but I'd say moderation is a safe bet.




Sources:

http://www.psychologytoday.com/blog/nourish/201303/time-take-milk-the-menu
http://www.drweil.com/drw/u/QAA400175/Does-Milk-Cause-Cancer.html
http://www.ncbi.nlm.nih.gov/pubmed/24631943

How much exercise is enough?

Exercise has a variety of benefits which have been much explored in the scientific literature. A resounding question, however, is "How much exercise is enough?". This question is especially important for individuals with hypertension (i.e., those with high blood pressure), as exercise has been shown to have profound effects on cardiovascular health.

In a study by Takata et al., 207 participants with high blood pressure were divided into 5 groups of different exercise levels: sedentary, 30-60min/wk, 61-90min/wk, 91-120min/wk, and >121min/wk. As expected, the sedentary group showed no improvements in blood pressure levels, whereas every other group did show decreases in blood pressure. The 61-90min/wk group had greater improvements than the 30-60min/wk group, but anything beyond 90min did not have a significant impact.

These results support several claims: 1) Exercise is important to cardiovascular health 2) Even fairly small amounts of exercise can show significant improvement in blood pressure 3) There is an unofficial "limit" to exercise after which blood pressure effects are not as significant. Although these notions are still supported, it should be noted that the time durations were chosen by the researchers and do not necessarily represent how much the average individual should exercise.


Source:

1.

Ishikawa-Takata K, Ohta T, Tanaka H. How much exercise is required to reduce blood pressure in essential hypertensives: a dose–response study. American Journal of Hypertension. 2003 Aug;16(8):629–33. 

Too much protein as bad as smoking?

Whether you follow one of the many low-carb/high-protein diets, frequent the gym for some "massive gains", or simply enjoy eating meat and cheese, there is one thing in common: lots of dietary protein. Although high-protein diets can help build muscle in the short-term, few studies have been done to show the effects in the long-run.

A study published on March 4th shows that too much protein consumption in middle aged people can have devastating long-term effects. In people aged 50-65, those who reported eating high amounts of protein (20% of calories from protein) had a 75% increase in mortality and 4 fold increase in risk of cancer death in the following 18 years; these effects are comparable to those of smoking! Outcomes were especially bad when proteins were derived from animal sources like meat, eggs, and cheese, but not as bad when from plant sources. However, in participants over the age of 65, higher protein consumption helped to lower these risks. 

Why does high protein have different effects in different age groups? The scientists think that this is linked to a growth hormone in the body called IGF-1, which increases with higher protein consumption. High levels of IGF-1 helps the body to grow but may also increase the risk of cancer. Older individuals have naturally lower amount of IGF-1, so eating more protein can help lower mortality as well as preserve muscle mass. 

The long-term effects of high protein diets are not quite conclusive, and this study has several weaknesses which may limit its applicability. However, with a growing body of evidence supporting the risks of a high-protein diet, we may want to think twice before we load up on meats, eggs, and cheese. 

Just some food for thought.

1.

Levine ME, Suarez JA, Brandhorst S, Balasubramanian P, Cheng C-W, Madia F, et al. Low Protein Intake Is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population. Cell Metabolism. 2014 Mar;19(3):407–17.