May 19th, 2015

Eating a Varied Diet Inversely Linked to Obesity

obesityIntroduction:

Most Americans eat a very limited range of foods and consume a very monotonous diet as a result. It seems entirely possible that excessive calorie and food consumption may be some sort of physiological craving gone awry. In other words, perhaps the brain is seeking to help improve nutritional intake, but somehow it is just causing excessive cravings for additional calories in general instead.

Despite this obvious possibility, there is not a lot of research in this area. A new study from researchers at the Harvard School of Public Health and NYU School of Medicine suggests that dietary variety may help prevent obesity. Increasing the intake of a variety of higher quality foods is associated with a lower risk for being overweight.

Background Data:

There are numerous case histories in the medical literature of people having specific food cravings indicating some sort of physiological basis. For example, the eating of dirt or chewing ice cubes is often an indication of iron deficiency. Research done by the U.S. Army showed that when well-nourished men were placed on monotonous diets, it led to increased food craving for foods other than those provided in the monotonous diet. But there is little research into whether individuals self-selecting a very monotonous diet, are more likely to consume more calories than those consuming a more varied diet.

New Data:

To evaluate the role of food variety on body weight, researchers evaluated data from the National Health and Nutrition Examination Survey (NHANES) 2003-2006 of over 7,000 men and non-pregnant, non-lactating women aged ≥20 years old with two 24-hour dietary recalls. Dietary variety was determined by using the US Healthy Food Diversity (HFD) index, which measures dietary variety, dietary quality and proportionality according to the 2010 Dietary Guidelines for Americans. The subjects were dividing into groups 1 through 5 with the higher number reflecting greater dietary variety.

Both men and women in the group with the greatest degree of dietary variety had a roughly 50% reduced risk for being obese. These results indicate that greater dietary variety is inversely associated with obesity in both sexes, indicating that greater healthful food variety may protect against excess body weight. This study explicitly recognizes the potential benefits of dietary variety in obesity management and provides the foundation to support its ongoing evaluation.

Commentary:

The bottom line is that I am a big proponent of eating a wide variety of health promoting foods. My reasons are that I appreciate the important role that eating a broad range of food components play in promoting human health. In particular, the importance of the long list of phytochemicals in fruits, vegetables, legumes, nuts, seeds, and other plant foods. We need variety in our diet to make sure we are getting the full spectrum of protection. Plus, I also think that a varied diet makes our food choices more interesting and less boring. Eating the same foods and menus over and over is a sure path to food boredom. Dietary variety wakes up the senses.

One of my key dietary axioms is to eat a rainbow assortment of fruits and vegetables. It is has been convincingly shown that a diet rich in fruits and vegetables is your best bet for preventing virtually every chronic disease especially heart disease, cancer, strokes, macular degeneration, and cataracts. By a “rainbow assortment,” I simply mean that by selecting fruits and vegetables in a variety of colors including red, orange, yellow, green, blue, and purple. By eating a wide variety of these colorful foods, you’ll be giving your body the full spectrum of a wide-range of compounds known as phytochemicals – an umbrella term that includes pigments such as carotenes, chlorophyll, and flavonoids; dietary fiber; enzymes; vitamin-like compounds; and other minor dietary constituents. And, according to the study just reviewed, it may help your brain feel more satisfied so that you consume fewer calories helping you to fight off obesity.

Reference:

Vadiveloo M, Dixon LB, Mijanovich T, Elbel B, Parekh N. Dietary variety is inversely associated with body adiposity among US adults using a novel food diversity index. J Nutr. 2015 Mar;145(3):555-63.

Dr. Michael Murray
5/19/15

May 12th, 2015

Maybe Nuts are Not a High Calorie Food After All

health benefits of almonds & nuts

Introduction

Nuts and seeds are rich in nutrients and phytochemicals, but they are also high in fat. So, many people avoid nut consumption out of fear that it will counteract their efforts to achieve or maintain their ideal body weight. Large population studies have shown that the people who consumed the most nuts were less obese. A new study from the UK’s Institute of Food Research indicates that although almonds contain more than 50% fat, the fatty acids are not easily digestible or absorbable. Perhaps they are not as calorie dense as we previously thought.

Background Data:

It has been previously shown that nuts produce two key effects that help fight obesity:

  1. They promote satiety, the feeling of appetite satisfaction.
  2. They increase the action of the hormone insulin, thereby improving blood sugar control, appetite regulation, and metabolism.

Nonetheless, it seems counterintuitive to many that such a high calorie food would actually fight obesity. It has been suggested that nuts may not be as high in absorbable calories as previously thought. Researchers have primarily looked at the absorption of almonds as an example. Studies have shown that even after thorough chewing, a high proportion of the fat remains encapsulated in the cells of the chewed almond tissue and is therefore less available for digestion. This effect is easily measured by examining the rise in fats in the blood after consumption of almonds. It is thought that the calorie content of almonds, and perhaps nuts in general, is overestimated by about one-third.

New Data:

The particle size and structure of chewed almonds has a significant impact on nutrient release (bioaccessibility) and digestion. The goals of this new study were to quantify the effects of chewing (mastication) on the bioaccessibility of the fats of almond and examine microstructural characteristics of masticated almonds.

In the study, 17 healthy subjects chewed raw natural almonds (NAs) or roasted almonds (RAs) in 4 separate sessions. After chewing thoroughly, subjects spit out the food bolus so that researchers could measure the particle size using mechanical sieving and laser diffraction. The microstructure of masticated almonds, including the structural integrity of the cell walls, was examined with microscopy. The bioaccessibility of the fat was predicted by using a theoretical model, based on almond particle size and cell dimensions, and then compared with empirically derived data.

Results showed that the bioaccessibility of fat from the almonds masticated by the human volunteers was approximately 8% and 11% for NAs and RAs, respectively. This low percentage of fat bioaccessibility is attributable to the high proportion (35-40%) of large particles (>500 μm) in masticated almonds. Microstructural examination of the almonds by microscopy indicated that most of the fat remained undisturbed in intact cells after mastication.

These results indicate that almonds have a much lower calorie content than previously thought due to 90% of the fat in almond not being absorbed.

Commentary:

This study adds to the growing list of studies highlighting that frequent nut consumption makes sense in improving nutrition and promoting health. In addition to the reduced risk of obesity with nut consumption, numerous large studies have also found that higher nut consumption is also associated with a protective effect against cardiovascular disease and type 2 diabetes.

Key takeaway point – eat a moderate amount of nuts each day. About ¼ of a cup or a small handful is all that you need to see the health benefits. I would still recommend that you keep the portion size moderate and don’t overdo it.

Reference:

Grundy MM, Grassby T, Mandalari G, et al. Effect of mastication on lipid bioaccessibility of almonds in a randomized human study and its implications for digestion kinetics, metabolizable energy, and postprandial lipemia. Am J Clin Nutr. 2015 Jan;101(1):25-33.

Dr. Michael Murray
5/13/15

May 5th, 2015

“Super” Broccoli Lowers LDL Cholesterol

health benefits of broccoliIntroduction

Many of our modern vegetables were developed from wild plants during the Roman Empire and later-day Italians through traditional crossbreeding techniques. This process involves taking pollen from one plant and placing it on the flowers of another to produce a hybrid. The goal in many cases involved removing undesirable traits, such as extreme bitterness or small size, or accentuating positive traits. Crossbreeding is much different than genetic modification through the insertion of genetic material to produce an entirely new trait.

A new form of broccoli rich in beneficial compounds known as glucosinolates has shown impressive results in two clinical trials in humans in lowering LDL cholesterol levels. There are several ironies about this “super” broccoli with the first one being that the researchers created this natural hybrid by going back to the wild form in Southern Italy rich in glucosinolates.

Background Data:

The modern broccoli is one of the most nutrient dense foods. It is especially rich in vitamin C. A one-cup serving a broccoli provides about the same amount of protein as a cup of corn or rice, but less than one-third the amount of calories. Broccoli also contains the carotenoid, lutein. Broccoli is an excellent source of the vitamins K, C, and A, as well as folate and fiber. Broccoli is a very good source of phosphorus, potassium, magnesium and the vitamins B6 and E.

Broccoli, like the other members of the cabbage family, broccoli is demonstrating remarkable anticancer effects, particularly in breast cancer. Compounds in broccoli known as glucosinolates (specifically indole-3-carbinol and sulforaphane) increase the excretion of the form of estrogen (2-hydroxyestrone) linked to breast cancer.

Preliminary studies suggest that, in order to cut the risk of cancer in half, the average person would need to eat about two pounds of broccoli or similar vegetables per week. With the new form of broccoli this level of protection against cancer could be provided by eating 1/3 this amount.

This new “super” form of broccoli was developed at two world-leading research institutes in the UK, The Institute of Food Research and The John Innes Centre, to be approximately 3 times higher in glucosinolates (specifically glucoraphanin the precursor to indole-3-carbinol and sulforaphane) that typical broccoli.

This broccoli, Beneforté, was developed through conventional breeding techniques, crossing a wild broccoli variety into commercial breeding lines to produce a broccoli variety that has all of the characteristics consumers, growers and retailers want in broccoli, but with the added benefit of the higher levels of glucoraphanin. Beneforté broccoli is now a commercially grown crop and is available in Europe.

New Data:

The studies involved 130 volunteers who were assigned to consume either 400 g of standard broccoli or 400 g of Beneforté broccoli per week for 12 weeks. In the first study consisting of 37 subjects, the Beneforté broccoli diet reduced plasma LDL cholesterol by 7.1 percent, whereas standard broccoli reduced LDL by only 1.8 percent. In the second study there with 93 subjects, the Beneforté broccoli diet resulted in a reduction of 5.1 percent, whereas standard broccoli reduced LDL by 2.5 percent.

Because of the small sample size, the results had to be combined to reach statistical significance. When both studies are combined, the Beneforté broccoli lowered LDL cholesterol by roughly 6% while the standard broccoli lowered it by 2%. This difference mirrors the three times greater concentration of glucoraphanin in the Beneforté broccoli.

Commentary:

Here is another irony of this story. Beneforté broccoli is produced by the seed giant Monsanto. What is the irony? Most people are aware that Monsanto is the leading developer of genetically modified foods and producer of pesticides, but here they are marketing the Beneforté broccoli with the claim that it “helps maintain your body’s defenses against the damage of environmental pollutants and free radicals.” Interesting?

As consumers, we are going to have to make choices that influence big companies. With Beneforté broccoli, I really don’t like the idea of supporting Monsanto, but I do like the idea of using natural breeding techniques to improve our food supply and the health benefits of foods. Will I buy Beneforté broccoli and similar foods produced by Monsanto when they eventually find their way to the US? And, will you?

Reference:

Armah CN, Derdemezis C, Traka MH, et al. Diet rich in high glucoraphanin broccoli reduces plasma LDL cholesterol: Evidence from randomised controlled trials. Mol Nutr Food Res. 2015 Apr 7. doi: 10.1002/mnfr.201400863. [Epub ahead of print]

Dr. Michael Murray
5/5/14