D&D: Diet and Depression

Mental health has been moving the ranks in terms of public health priorities. From Bell's "Let's Talk" campaign to various campus initiatives, there has been a lot of talk about stigma, disorders, and treatments related to mental health. Given the increasing rates of depression, it only seems appropriate that we pay full attention to depression as we would to other diseases like cardiovascular disease (CVD) or diabetes.

Given all the good research that's going on today, however, there's one link that seems to be much less explored: diet and depression.

Some research has shown that depression shares many of the same underlying mechanisms as cardiovascular or metabolic diseases; that is, foods high in trans fats (e.g., fast food) can increase risks of CVD and depression, CVD and depression are linked to pro-inflammatory changes in the body, and both diseases are thought to contain endothelial dysfunction.

In a paper published last year by Sanchez-Villegas and Martinez-Gonzalez, the authors recognize that diet could be an important contributor to and treatment target for depression. However, they also point out that there are few studies in this area, and those that do exist are of lower quality and often prone to bias. In other words, a lot of preliminary research exists, but there is a demand for more high-quality studies, Randomized Control Trials, and Systematic Reviews to confirm initial findings.

Mental health is a huge issue in today's society. There's definitely a lot of good work going on in supporting individuals with depression, but diet could be a crucial piece of the puzzle when it comes to prevention and treatment.



Sources: 

1.

Sanchez-Villegas A, Martínez-González MA. Diet, a new target to prevent depression? BMC Medicine. 2013 Jan 3;11(1):3. 

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. 

Probiotics: "Faecing" the evidence

Probiotics - you've likely seen this word on yoghurt packages and other dairy/fermented products. What exactly are they and do they really help us? 

Probiotics are living micro-organisms that are thought to bring benefits to the human digestive system when ingested in certain amounts. These benefits include improved immune function, vitamin production, and better digestion. One common clinical test done to measure the performance of a person's digestive tract involves measuring the intestinal transit time (ITT), or the time it takes for food to go through your system (implying how well the intestines are working). Too slow (e.g., constipation) or too fast of an ITT (e.g., diarrhea) can both imply dysfunction of a person's intestinal tract. 

In one systematic review study of 11 randomized-control trials, it was concluded that ingestion of certain strains of probiotic bacteria could lower ITT, which was especially seen in older adults and those with constipation (who have too high of an ITT). This supports the notion that probiotics may be a good alternative treatment for constipation, as long as it doesn't go as far as to cause diarrhea. 

Now, what about probiotic use in healthy individuals? It seems that the evidence is scarce and contradictory. The authors of the systematic review claimed that the evidence is weak with regards to probiotic use in healthy individuals (who are not experiencing abdominal symptoms or pain). In fact, it's not even conclusive as to whether probiotics help with symptoms such as abdominal pain or symptoms, so is lowering ITT really that important besides, of course, helping with constipation? 

So, before you start investing in twice-the-price "miraculous" probiotic yoghurt, talk to your physician or dietitian to see if probiotics are right for you! 



Sources:

1.

Miller LE, Ouwehand AC. Probiotic supplementation decreases intestinal transit time: Meta-analysis of randomized controlled trials. World J Gastroenterol. 2013 Aug 7;19(29):4718–25. 

Yoga and Breast Cancer

When you think of "exercise", what's the first image that pops up in your head? A person jogging? A gym? What about yoga? In exploring the benefits of exercise, it's sometimes easy to ignore the less "mainstream" forms of exercise such as yoga. Seen as a form of mind-body therapy, yoga is thought to have many benefits for psychological and physical aspects.

In a recent randomized control trial, breast cancer survivors with cancer related fatigue either underwent educational sessions (control group) or 12 weeks of Iengar yoga (intervention group). Results showed that those who did the yoga showed improvement in biological inflammatory factors (e.g., a transcription factor called NFkB) and even changed the gene expression to reduce inflammatory response in their bodies. Both groups also showed improvements in perceived stress, and the yoga group especially improved in terms of their vigor.

Although this study applies to a very specific group of people, it adds another piece to the "yoga puzzle" and supports the idea that yoga is not just a mind exercise, but also has important physical benefits. So the next time you're considering taking on a new form of physical activity, consider yoga!



Source:

Bower, J. E., Garet, D., Sternlieb, B., Ganz, P. A., Irwin, M. R., Olmstead, R. and Greendale, G. (2012), Yoga for persistent fatigue in breast cancer survivors. Cancer, 118: 3766–3775. doi: 10.1002/cncr.26702

High-Intensity Interval Training

High-intensity interval training, or HIIT, is a commonly used term in exercise circles. Generally, this refers to a form of exercise which switches back and forth between intervals of high-intensity and intervals of low-intensity exercise. In contrast to HIIT, there's moderate intensity continuous training (MICT), where one exercises at a consistent, medium intensity. There is some variation between what defines "high/medium/low intensity" and how long these intervals are, but HIIT is commonly seen as one of the most effective forms of exercise.

In a systematic review from September 2013, the researchers looked at 13 studies which included patients with chronic lifestyle-related diseases like coronary heart disease, obesity, and hypertension. Although there were some differences between studies (like how they defined levels of intensity and the length of exercise), generally HIIT was more effective than MICT in increasing max O2 volume (breathing ability) and cardiac function, and lowering blood pressure, fasting glucose, and oxidative stress/inflammation. In fact, HIIT even showed a greater improvement in quality of life and enjoyment of exercise!

Take home message: There's overwhelming evidence that exercise is beneficial for health, but not all exercise is the same. Although HIIT seems to have greater benefits than MICT, there are other considerations like safety and physical constraints. Consult your physician if a prescribed exercise plan is right for you, and what type of exercises would most benefit you.


Sources:

1.

Weston KS, Wisløff U, Coombes JS. High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: a systematic review and meta-analysis. Br J Sports Med. 2013 Oct 21;bjsports–2013–092576.