Delectable Science

Nutritious and Delicious Explorations

Fruit Restriction for Type 2’s: Good or Not?

In another study on fruit and diabetes (Fruit Restriction for Type 2’s: Good or Not?), this time with actual diabetics instead of non-diabetics it was found that fruit consumption did not affect relative HbA1c levels, amount of weight loss or waist size as compared to the group that consumed less fruit.

According to the article, one reason that standard nutritional advice to diabetics to lower fruit consumption could be wrong is that it

does not always take into account the importance of fiber within fruits. Whole fruits contain a number of long-chain polysaccharides such as pectin which have been shown to reduce glycemic levels and balance blood sugar.

So the message is to eat whole fruit along with whole seeds, nuts, and other whole plants.

Blueberries! What can’t this magic fruit do? Today’s blueberry magic: Lower diabetes risk!

Reported in MedScape: an interesting study on the effect of certain fruits on diabetes risk. It turns out that blueberries (magical berries as my husband calls them) may reduce diabetes risk.

The investigators combined data from 3 studies: the Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-up Study where study participants had filled out questionnaires on their eating habits and were followed for years. They then calculated a hazard risk for diabetes based on fruit consumption. As my husband opines there is no surprise that blueberries are good for one. The surprise for me comes from one of the other conclusions:

In a secondary analysis, the investigators found that the consumption of high glycemic load fruits was linked to a lower risk for type 2 diabetes (HR, 0.93; 95% CI, 0.91 – 0.96), as was consumption of moderate glycemic index fruits (HR, 0.94; 95% CI, 0.90 – 0.97).

So, what are the best fruits to eat to lower  your diabetes risk? Here’s the list from the study. Note that HR means hazard ratio. A hazard ratio of one is the norm. Higher than one increases your risk. Lower than one reduces the risk. (CI stands for confidence interval and lets you know what the range is for the hazard ratio.)

  • blueberries: HR, 0.74; 95% CI, 0.66 – 0.83;
  • grapes and raisins: HR, 0.88; 95% CI, 0.83 – 0.93;
  • apples and pears: HR, 0.93; 95% CI, 0.90 – 0.96;
  • bananas: HR, 0.95; 95% CI, 0.91 – 0.98; and
  • grapefruit: HR, 0.95; 95% CI, 0.91 – 0.99
  • cantaloupe (HR, 1.10; 95% CI, 1.02 – 1.18)
  • fruit juice (HR, 1.08; 95% CI, 1.05 – 1.11)
 So, eat your fruit but eat it whole (no juice). And avoid cantaloupes apparently.


Whole Grains and Diabetes

This is the result of a review of many studies on whole grains in the literature and it has good news on Whole Grains and Diabetes. Researchers suggested that:

“consumption of foods rich in cereal fiber or mixtures of whole grains and bran is modestly associated with a reduced risk of obesity, type 2 diabetes, and cardiovascular disease. Researchers also noted that consuming fiber may allow a diabetic patient to eat relatively more carbohydrates without running the risk of hyperglycemia.”


Restaurant Sodium Levels and Other Shockers

I know that restaurant food is bad, but it always shocks me to see studies on how bad. Here is the latest reported in MedScape:

Canadian researchers, including senior author Dr Mary L’Abbe (University of Toronto, ON), found that breakfast, lunch, and dinner meals from restaurants that provide table service contained more than half of the daily recommend calorie content and exceeded the daily recommended amount of sodium[2]. In addition, these restaurant meals contained nearly 90% of the daily recommended intake for fat and 60% of the daily value for cholesterol.

The survey included 19 chain sit-down restaurants that had at least 10 locations. In total, the researchers analyzed 3507 variations of 685 meals, as well as 156 deserts. On average, the breakfast, lunch, and dinner meals contained 1128 calories, a number that is 56% of the average daily 2000-calorie recommendation. The average sodium level of each meal was 2269 mg, or 151% of the amount it is recommended adults consume in a single day. The meals contained an average of 58 g of fat, 16 g of saturated fat, and 0.6 g of trans fat. Desert added another 549 calories, 27 g of fat, 13 g of saturated fat, and 46 g of sugar.

Regarding the “healthy” option identified on some menus, these meals contained 474 calories, 13 g of fat, 3 g of saturated fat, and 752 mg of sodium.”

Racing at High Altitude

As I was writing my previous post, WordPress recommended by MountainGirl, which contains a nice set of points on racing at altitude. My best wishes go to all the amazing athletes undertaking the Pikes Peak Marathon and the Leadville 100!

Nutrition at High Altitude

I’m suffering from altitude sickness after deciding to do Denver without the drugs I normally take to prevent it. Sadly, that was not my best idea. However, in my research on altitude, I’ve found some interesting information on nutrition at high altititude from a Consensus Medical statement by the  International Mountaineering and Climbing Federation.

  • Appetite and taste perception are both suppressed at high altitude. Increased satiety occurs with reduced meal sizes – i.e. you fill feel ‘full’ on smaller portion sizes. This ‘mountain anorexia’ effect can result in a significant loss of body weight beginning at altitudes around 3600m for some, and at around 5000m for most (i.e. weight loss 1-2 kg/week) [2]. This is thought to be induced by changes in hormonal levels experienced at altitude, notably leptin.
  • Irrespective of one’s physical training status, hypoxia can also alter which energy source (fat or carbohydrate) is preferentially used by the body, and this can vary between genders
  • Hypoxic exposure can alter hormonal balances, create fluid shifts between tissue compartments in the body, and even alter amount of urination. Some studies suggest that when individuals are exposed to acute hypoxia, those who experience fluid retention in the first few hours are more likely to develop AMS
  • In extreme cold environments, BMR can be increased fivefold at rest because of the body shivering to try and keep warm. In a tropical climate, it is raised by 5-20%, plus another 5% when exercise performed. On first reaching a new high altitude, BMR is increased at altitude by 10-20% or more.
  • Fats required more water to break them down and result in a greater fluid loss that needs replacing.

Here is the recommended macronutrient breakdown at altitude: Carbohydrates 56%, Fats 29%, Protein 15%. Avoid alcohol at altitude.

Worthy Quotation by Herophilus of Chalcedon

This is taken from Dean Karnazes’ newsletter. I love it.

“When health is absent, wisdom cannot reveal itself, art cannot manifest, strength cannot fight, wealth becomes useless, and intelligence cannot be applied.”

~ Herophilus of Chalcedon, 335 – 280 BC, Physician to Alexander the Great

Intermittent Fasting and Type 2 Diabetes

This article in MedScape suggests that intermittent fasting may be helpful in improving diabetes and reducing weight. They defined intermittent fasting as a program that

alternates days of ‘normal’ calorie consumption with days when calorie consumption is severely restricted. This can either be done on an alternating day basis, or more recently a 5:2 strategy has been developed (Figure 1), where 2 days each week are classed as ‘fasting days’ (with <600 calories consumed for men, <500 for women).

Interestingly, the authors claim that it is easier for people to deal with than overall reduced calories each day and that it improves insulin sensitivity, reduces inflammation, and

represents a potential therapy for those at high cardiovascular risk. Intermittent fasting in animal models can reproduce some of the cardiovascular benefits such as improvements in blood pressure and heart rate that are seen with physical exercise.[59] Caloric restriction studies have shown improvements in circulating cholesterol, triglycerides, improved blood pressure, and reduced carotid intima-media thickness.

I am not sure what to think of this. I’m the person who can’t manage a fast on Yom Kippur without much unhappiness so it is not something that strikes me as being a program that I could comply with. And yet the authors claim that they showed greater compliance with it than just eating lower calorie each day. What prevents their patients from eating their weight in food the day after a fast day?

Mediterranean Diet is Good for Dialysis Patients

This is an interesting study ( The Mediterranean Diet has received a lot of praise for its positive effect on heart disease. Another benefit of the plant-based, omnivorous diet is that it is better for renal patients. According to Dr. Huang’s earlier research the benefit for dialysis patients appears to be coming from linoleic acid, which is associated with reduced inflammation and better survival in dialysis patients. Linoleic acid is an Omega-3 fat found in olive oil, flax seed oil, walnuts, soy beans, and fatty fish like salmon, tuna, sardines, and herring.

The study referenced above studied people with kidney disease and showed that those patients who adhered most closely to the Mediterranean diet were 18% less likely to die from kidney disease than those who were were not as scrupulous in their adherence.

So the take-away is that even for those with kidney disease, a diet rich in fruits, vegetables, and Omega-3 fats (and low in Omega-6 fats) is associated with better survival.

Genetics of Obesity — Stephan Guyenet

Steven Guyenet has started an impressive series on the genetics of obesity. (Things like this are why I’m so grateful that I live in the age of the Internet! It is so wonderful to have access to the best minds on any topic.)

Part I:

In other words, nearly every major aspect of food behavior is strongly impacted by genes*.  Other papers from the same study showed that genes have a strong influence on the amount of food it takes to feel full, how likely it is that the sensation of fullness will terminate a meal, the perception of palatability, how much influence palatability has on calorie intake, cognitive dietary restraint, and almost every other measurable characteristic.

Part II:

A good review of the work done on identifying the elements that influence the genetics of obesity. Lots on Leptin studies:

He concludes with:

The genetic data converge powerfully with other fields such as neurobiology, endocrinology, and physiology, together demonstrating conclusively that:

The brain is the main regulator of body fatness.

The brain regulates body fatness in response to internal signals of energy stores, particularly leptin.

Genetic variability in body fatness is likely predominantly determined by genetic differences in brain function, particularly the hypothalamus.

See also the comment by one of the readers of the blog (Ness Clark) saying that:

My daughter is 2 years old and seemingly has unlimited appetite. At 7 weeks old she was almost at the 100th percentile for weight on breast milk. By 6 months old she was well off the charts. I read an article about the MC4R mutation and have wondered since if she has inherited it – her nana on her dads side has been obese since late childhood but also has low blood pressure which apparently fits with this.

It really puts the lie to the idea that if we only were perfectly natural in our habits that no one would be obese. Clearly if an infant can be at the 100th percentile in weight eating only breast milk, there is something going on other than will or natural food sources. I am looking forward to his next piece on why genetics is not necessarily destiny.

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