Nutrition news for endurance sports

Long-distance swimmers, cyclists, and runners need special nutrition to keep from running out of fuel or becoming dehydrated. The traditional “carbo-loading” involves a big supper of pasta the night before, to enable the body to build quick-energy glycogen stores. During the race, athletes ingest low-fibre, high-carbohydrate foods and slightly salted and sugared water such as Gatorade. This research suggests how athletes can meet their needs without loading up the night before: “Nutrition for endurance sports” by A. E. Jeukendrup.

Endurance sports are increasing in popularity and athletes at all levels are looking for ways to optimize their performance by training and nutrition. For endurance exercise lasting 30 min or more, the most likely contributors to fatigue are dehydration and carbohydrate depletion, whereas gastrointestinal problems, hyperthermia, and hyponatraemia can reduce endurance exercise performance and are potentially health threatening, especially in longer events (>4 h). Although high muscle glycogen concentrations at the start may be beneficial for endurance exercise, this does not necessarily have to be achieved by the traditional supercompensation protocol. An individualized nutritional strategy can be developed that aims to deliver carbohydrate to the working muscle at a rate that is dependent on the absolute exercise intensity as well as the duration of the event. Endurance athletes should attempt to minimize dehydration and limit body mass losses through sweating to 2-3% of body mass. Gastrointestinal problems occur frequently, especially in long-distance races. Problems seem to be highly individual and perhaps genetically determined but may also be related to the intake of highly concentrated carbohydrate solutions, hyperosmotic drinks, as well as the intake of fibre, fat, and protein. Hyponatraemia has occasionally been reported, especially among slower competitors with very high intakes of water or other low sodium drinks. Here I provide a comprehensive overview of recent research findings and suggest several new guidelines for the endurance athlete on the basis of this. These guidelines are more detailed and allow a more individualized approach.

PMID: 21916794 [PubMed – in process]

Christian obesity

Northwestern University reports an 18-year study that finds that young adults in the U.S. who are religious and go to church are 50% more likely to become obese as they age, compared to people who don’t.

Low-carb diets cut cravings

This is old news, but summarizes a study where participants ate a low-carbohydrate diet, and found it easy to lose weight. Without trying, they ate 1000 calories less per day. It seems to reflect the old wisdom that some foods “stick to your ribs” and avert hunger.

ScienceDaily (Apr. 7, 2005) — PHILADELPHIA (March 15, 2005) — A new three-week in-hospital study of 10 volunteers found that during the two-week period on a strictly controlled very-low carbohydrate diet, participants lost an average of 3.6 pounds, voluntarily reduced their calorie intake from 3,111 calories per day to 2,164 calories per day, and did not eat more of the readily available fat and protein to make up for the lost carbohydrate calories.

The study, “Effect of a Low-Carbohydrate Diet on Appetite, Blood Glucose Levels, and Insulin Resistance in Obese Patients with Type 2 Diabetes,” compared a very low-carbohydrate diet with a regular diet. It is published in the March 15, 2005, issue of Annals of Internal Medicine.

Research on mice links fast food to Alzheimer’s

Should e be blaming sugar or fat?

LONDON, Nov. 28, 2008 (Reuters) — Mice fed junk food for nine months showed signs of developing the abnormal brain tangles strongly associated with Alzheimer’s disease, a Swedish researcher said on Friday.

The findings, which come from a series of published papers by a researcher at Sweden’s Karolinska Institutet, show how a diet rich in fat, sugar and cholesterol could increase the risk of the most common type of dementia.

“On examining the brains of these mice, we found a chemical change not unlike that found in the Alzheimer brain,” Susanne Akterin, a researcher at the Karolinska Institutet’s Alzheimer’s Disease Research Center, who led the study, said in a statement.

Nutrition to combat addiction

The Economist has a nice article about research into nutrition that helps people to resist the lure of addictions: “Treatment on a Plate.”

What ages people? Smoking and obesity

This might be old news but it’s good to remind ourselves: Eat healthy food and don’t smoke!

Smoking accelerated the ageing of key pieces of a person’s DNA by about 4.6 years. For obesity it was nine years.

These genetic codes are important for regulating cell division and have been linked to age-related diseases.

The study in the Lancet was based on 1,122 twins from a database held by St Thomas’ Hospital in London.

Canada adopts “leaner” growth charts

These are the World Health Organization’s charts showing normal, healthy weights for children at each age. There are separate charts for boys and girls. The horizontal axis is age and the vertical axis is weight.

WHO age-for-weight charts for boys 5 to 10 years old

Canadian health organizations are ready to adopt standard growth charts for babies and children that are based on World Health Organization standards. The charts use the growth pattern of a healthy, breast-fed baby. The charts being discarded are the U.S. charts created by the Centers for Disease Control, which are patterned on a bottle-fed baby. Breast-fed babies grow more slowly and with less fat. The new charts will put children at the top of the U.S. “healthy” range into the “obese” category. And fewer children will be marked as failing to thrive.

While they [the charts] are a standard tool for detecting potentially serious dips in a child’s development, they don’t always capture the whole picture. This is especially true of breast-fed infants, who can be leaner than formula-fed babies, especially in the six- to nine-month age range.

Now, a number of Canadian public health organizations representing doctors, nurses and dietitians are poised to adopt the 2006 World Health Organization international growth charts in place of the U.S.-based growth charts that were created by the Centers for Disease Control and Prevention.

In addition to recognizing the growth patterns of breast-fed babies, the WHO charts are also likely to reclassify those whom the CDC charts may have termed normal as overweight or obese.

“The WHO is the newest kid on the block in evaluating growth,” says Calgary pediatrician Ted Prince, adding that with the U.S. charts, weight has been steadily climbing, and the WHO standards “have been more constant.”

The Canadian Paediatric Society’s nutrition and gastroenterology committee, led by Valérie Marchand, a pediatric gastroenterologist at St. Justine’s Hospital in Montreal, is one of the groups looking at updating measurement policy. Dr. Marchand expects the committee to release the new policy by the end of the year.

The CDC charts are based on data gathered in five nationally representative surveys conducted between 1963 and 1994 in the United States. The 2000 charts are based on a representative sample of breast-fed and formula-fed children.

The recent WHO charts are based on a sample of 8,500 children between 1997 and 2003 in Brazil, Ghana, India, Norway, Oman and the United States.

Only breast-fed children in healthy environments – non-smoking households, for instance – are included in the sample. Measurements were taken 21 times between birth and the age of 5.

“The WHO charts are excellent because they are based on how a child in the best condition should grow,” Dr. Marchand says. She and her colleagues will recommend the adoption of the organization’s weight, height, BMI (body mass index) and head circumference measurements, based on age.

By conducting an international study, the WHO found there is actually little difference between children from different races or continents, Dr. Prince says. “Even across different socioeconomic populations, the growth is pretty constant.”

It may also be a relief for parents of breast-fed children. The growth of those babies often slows for a few months at around the age of six months.The CDC charts can create doubt in a mother’s mind, Dr. Marchand says.

“You’ll think, well, my child is not growing properly,” she says. “Maybe I don’t have enough milk, maybe I’m doing something wrong. Using growth charts that are for breast-fed babies will help those mothers feel more secure about their breastfeeding.

“Now that we are promoting breastfeeding, we really want to have a growth chart to reflect that to avoid misconceptions about growth and breast-fed infants.”

Over all, the weight-for-height and BMI figures are a little lower on the WHO charts compared with the CDC’s. As excess weight and obesity have grown in the United States, the heavier weights have been normalized.

WHO girls weight-for-age charts, age 5 to 10 years

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