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. 

Food for thought: Low-Carb Dieting

From check-out line magazines to TV ads, we're constantly bombarded with messages of "dieting" and weight loss. With titles like "15 tips to successful weight loss" and "New celebrity diet", I can't help but to wonder where the evidence is behind all these bold claims.

One diet in particular, the low-carbohydrate diet, has been a topic of discussion for many years. It's known that a high-fat, low-carbohydrate diet (aka ketogenic diet) that can be beneficial in protecting children with epileptic seizures; but in this case, the sugar intake needs to be so low that the liver begins converting carbohydrate and fat stores into ketone bodies, which are thought to reduce cases of seizure. However, for the average person looking to lose weight, such an extreme diet is hardly recommended.

In a recent study, it was shown that a low-carbohydrate diet does have some benefits. In a 6 month study, 39 participants were told to choose either a low-carbohydrate vegan (and high-protein/fat from gluten, soy, nuts, and vegetable oil) or a high-carbohydrate (low fat) vegetarian diet. The results showed that the low-carbohydrate diet was slightly more beneficial when it came to weight loss. Of course, the glaring question here is, what kind of biases might the researchers introduce by letting patients "choose their own diet"? Perhaps healthier or more knowledgeable participants just naturally like to choose low-carb diets...but we'll save this discussion for another day.

So what does this all mean? There are way more studies out there on dieting than I could possibly write about - take a look for yourself! I personally don't think that we'll ever have a "miracle" diet, and that awareness and moderation go a long way - but that's just personal opinion.



Sources

1.

Jenkins DJA, Wong JMW, Kendall CWC, Esfahani A, Ng VWY, Leong TCK, et al. Effect of a 6-month vegan low-carbohydrate (’Eco-Atkins’) diet on cardiovascular risk factors and body weight in hyperlipidaemic adults: a randomised controlled trial. BMJ Open. 2014;4(2):e003505.

2.

Freeman JM, Kossoff EH, Hartman AL. The Ketogenic Diet: One Decade Later. Pediatrics. 2007 Mar 1;119(3):535–43. 

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