Exercise Training, Omega 3’s and Fast Food

Some pearls for 6/29/2013
Exercise Training Frequency, Omega 3s and Breast Cancer, and Fast Food

Exercise frequency in previously sedentary women aged 60-74
Hunter, et al, MedSciSportsExerc, 2013Jul 45:1386

We know that aerobic exercise (in this study, treadmill and bike) and resistance training (circuit of 10 exercises done twice) can maintain physical performance as the years go by. It is unclear, though, if there is an optimum amount of exercise in this regard. This study looked at sedentary women aged 60-74 and randomized them to 3 different weekly exercise schedules. One group did 1 day of aerobic and 1 day of resistance per week (1+1), another group did 2 days of each per week (2+2), and the third did 3 days of each (3+3).

Surprisingly, after 16 weeks of this routine, aerobic fitness, strength and fat-free mass improved similarly in all 3 groups. BUT they also looked at energy spent on activities other than the scheduled exercise. The group that used the most energy was the 2+2 group; it actually decreased in the 3+3 group. This suggests that in this group of sedentary ‘older’ women – their term, not mine! – starting exercise 3+3 days per week may be too much, in that they then decrease their other normal activities. We should be alert to the idea that when our body feels like it needs a rest, we should listen. Exercise can be increased gradually, with gentler workouts, walking, etc, built in to the schedule.

Also, these results don’t affect the recommendation by the American Heart Association that 30 minutes of exercise should be done ‘most days of the week’ with regard to decreasing cardiac disease, high cholesterol and diabetes; these issues were not addressed in this article.

Effects of omega-3 ‘s on breast cancer
Ju-Sheng Zheng, et al. BMJ 2013;346:f3706.

Breast cancer is one of the most common cancers in the world. Higher intake of omega-3 polyunsaturated fatty acids (n3PUFAs) have generally been associated with lower breast cancer risk in rodent studies, but with somewhat varied results in human studies. In humans, fish oil probably reduces the risks of certain types of breast cancer, moreso in post-menopausal than pre-menopausal women.

This study, published in the British Medical Journal, looked at the combined results of 21 studies involving 900,000 participants, including almost 21,000 with breast cancer. It appeared that high intake of marine n3PUFA (think salmon, sardines and mackerel) was associated with a 14% reduction in breast cancer risk. The benefit was more evident in Asian than in North American or European countries. One thought is that fish intake is higher in Asian populations and that in the other countries, a large proportion of n3PUFAs may come from fish oil capsules. In other studies, the capsules have not had the same health benefits as eating the fish itself. There may be some other associated risk associated with fish intake in some areas, such as exposure to pesticides or organometallics. This study confirmed the protective effect of marine n3PUFAs regarding breast cancer in post- but not pre-menopausal women. They could not detect a beneficial effect on breast cancer risk of n3PUFAs from fruit, vegetables, vegetable oils, nuts or meats.

Consumers’ estimation of calorie content at fast food restaurants
Block JP et al. BMJ 2013May 23; 346:f2907

Underestimation of calories has been shown in actual restaurant settings, but this article, also published in the British Medical Journal, looked only at fast food restaurants. The actual calorie count for each meal was 730-830 calories, increasing from children to adolescents to adults. This represents a lot of calories for one meal, especially if it is not the largest meal of the day and doesn’t have the most nutritious fillings. The patrons under-estimated by 175-260 of those calories, with the most inaccurate group being adolescents. Of interest was that people underestimated the most at Subway, which demonstrates how effective their ad campaign was. If you recall, they showed people losing a huge amount of weight by eating only their subs. Perhaps the ads were truthful – but those people had to have cut their total daily number of calories and/or exercise more to lose that weight. The takeaway message is that fast food is even more calorie dense than people realize; even a turkey sub with lettuce and tomato can be a high calorie meal – reduce that by removing the inside of the sub roll as well as the mayo and other dressing.