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. 

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. 

.

Yogurt for your health!

Using data from EPIC-Norfolk study, a large European study on nutrition and disease, researchers O'Connor, Luben, and Wareham recently found an interesting effect of yogurt consumption: lowered diabetes risk. This study was published in the European journal, Diabetologia, and included data from 4000 participants originally in the EPIC-Norfolk study. The participants noted their food consumption in a diary and also followed up with the researchers for 11 years to assess health outcomes.

Although total dairy consumption didn't end up affecting development of diabetes, the consumption of low-fat (<3.9% fat) fermented foods, especially yogurt, lowered the risk of diabetes by 28%! Specifically, participants seemed to benefit from eating an average of 4 standard 125g yogurt pots a week. Researchers hypothesize that these benefits are attributed to a certain types of vitamin K and probiotic bacteria in fermented products.

It should be noted, however, that it's not certain if yogurt itself caused the lower diabetes risk, or if those who ate yogurt were already healthier to begin with. Nonetheless, there seems to be increasing evidence on the many benefits of yogurt and low-fat dairy products.

Take home message: 
1) Yogurt consumption may lower the risk of diabetes, among other well-recognized benefits. So the next time you crave a little snack, consider substituting yogurt for your chips!

2) When considering food choices, it's important to not just look at the major food groups, but also at the subtypes within each food group (in this case, low-fat fermented dairy).



Sources:

1.

O’Connor L, Luben R, Wareham N. Dietary dairy product intake and incident type 2 diabetes: a prospective study using dietary data from a 7-day food diary. Diabetologia. 2014 Jan 7; 

A1C: Predicting Diabetes in High-Risk Individuals

There are many known risk factors for diabetes: age, family history, weight, high cholesterol, and even race. In fact, many people are living with what is called "pre-diabetes", in which there are many risk factors present and blood glucose is higher than usual (but not high enough to be considered diabetes). It's important to be able to screen which of these individuals are at high risk for diabetes. Currently, some of the most recommended screening tests include the fasting blood glucose test and the oral glucose tolerance test; though accurate, these can be expensive and inconvenient.

A recent study by Lerner et al. shows that HbA1C, a value which indicates average blood sugar levels over months, can help to determine risk of developing diabetes. In over 10,000 patients, it was shown that an HbA1C value over 5.5% led to increased risk of developing diabetes over the next 5-8 years, with risk doubling for every A1C increase of 0.5%.

Currently, an A1C greater than 6.5% is considered diabetic, but the World Health Organization says that there is not enough evidence to interpret values below 6.5%. This study, on the other hand, supports the notion that perhaps A1C can serve as an efficient and easy screening tool, and that people with slightly elevated A1C (above 5.5%) may be at higher risk for diabetes. However, it must be noted that the majority of the 10,000 participants was already overweight, so using A1C as a screening tool may be most applicable to individuals who already have diabetes risk factors.



Sources:

1.

Lerner N, Shani M, Vinker S. Predicting type 2 diabetes mellitus using haemoglobin A1c: A community-based historic cohort study. European Journal of General Practice. 2013 Nov 29;1–7.

2.

American Diabetes Association. Screening for Diabetes. Dia Care. 2002 Jan 1;25:s21–s24. 

Maintain your weight: What to eat?

Through a large-scale study which took place in 8 different European countries, scientists tested what kind of diet to have when trying to prevent weight gain after losing weight. 1208 overweight adults were screened, of which 938 adults underwent a low-calorie diet to lose body weight. Of these, 773 adults made it to the "next round" and were randomized to one of five different types of diets:

1) High-protein, high-glycemic index
2) High-protein, low-glycemic index
3) Low-protein, high-glycemic index
4) Low-protein, low-glycemic index
5) Control (the "recommended" food balance of each respective country)

Results showed that option 2 (slightly higher protein, slightly lower glycemic index) helped in maintaining weight loss. Meanwhile, participants in option 3 (low protein, high glycemic index) tended to regain their weight. Maybe this will give you some ideas as to how to balance your nutrition during and after weight loss.

However, it should be noted that less than half the initial sample completed the study, meaning that perhaps the people who remained in the study are different from the ones who dropped out, and are not accurate representation of the real population.


Food for thought: 
It's not just about losing weight - how will you maintain it?


*Low Glycemic foods include: most fruits, wheats, oats, barley, beans, nuts, seeds
*High Protein Foods include: Turkey/Chicken, lean meats, beans, egg whites, yoghurts, nuts, seeds



Source:

1.

Larsen TM, Dalskov S-M, van Baak M, Jebb SA, Papadaki A, Pfeiffer AFH, et al. Diets with high or low protein content and glycemic index for weight-loss maintenance. N. Engl. J. Med. 2010 Nov 25;363(22):2102–13. 

Omega 3: A Miracle Compound

There's a lot of buzz out there on Omega 3 fatty acids right now: we see it in supplement pills, healthy food labels, and even orange juice cartons. This "miracle compound", found in seafoods and certain plant oils, supposedly helps with cognitive ability, heart disease prevention and stroke recovery, inflammation, arthritis, and the list goes on. Although the American Heart Association, Health Canada, and World Health Organization all agree that intake of Omega 3 promotes health, there is not a lot of strong research evidence out there on the optimal intake amount, long-term safety, and molecular mechanisms; in fact, there's even some contradictory evidence as to whether Omega 3 is actually that great for you.

Researchers at the Oregon State University may have just added a new piece to the puzzle. By analyzing liver metabolites in mice after they were treated with DHA (a compound from the Omega 3 family), researchers found that Omega 3 affects a broader range of molecular pathways than previously thought, helping with sugar, amino acid, and vitamin metabolism. In fact, this study even suggests that Omega 3 may be beneficial for individuals with fatty liver disease, reducing inflammation, fibrosis, and oxidative stress. Although shedding promising light onto the molecular benefits of Omega 3, this study was done in mice, meaning that more research is needed for these results to translate to humans.

There seems to be a lot of promise in Omega 3, but there are also some concerns about the health consequences of consuming too much seafood and fish oils. So before you buy yourself a truckload of Omega 3 pills (read: put your wallet on a diet) or schedule daily all-you-can-eat-sushi (read: gluttony), ask your doctor if Omega 3 supplements are right for you!



Sources:

1.

Government of Canada HC. Prenatal Nutrition Guidelines for Health Professionals: Fish and Omega-3 Fatty Acids [Health Canada, 2009] [Internet]. 2009 [cited 2014 Jan 31]. Available from: http://www.hc-sc.gc.ca/fn-an/pubs/nutrition/omega3-eng.php

2.

Kris-Etherton PM, Harris WS, Appel LJ. Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and Cardiovascular Disease. Circulation. 2002 Nov 19;106(21):2747–57.

3.

Depner CM, Traber MG, Bobe G, Kensicki E, Bohren KM, Milne G, et al. A Metabolomic Analysis of Omega-3 Fatty Acid-Mediated Attenuation of Western Diet-Induced Nonalcoholic Steatohepatitis in LDLR-/- Mice. PLoS ONE. 2013 Dec 17;8(12):e83756.