New Under the Sun:
Volume 4, Issue 3
For the past several weeks, we in the Southwest have been singing “Let the Sun Shine In!!” We have been drenched by far more than our usual quota of rainfall. The spring wildflowers are glorious, but we crave the sunlight. The sun brings a smile to our faces and a bounce to our steps. As readers of this newsletter know, humans need exposure to sunlight to be optimally healthy. So here is to the sun shining on you this month!
Mammalian Brains: Maintaining Youthful Abilities: While not as closely related to us as are primates, dogs probably represent better comparative subjects than do rodents. Researchers in California recently published a fascinating study on the effects that an anti-oxidant diet, exercise, and an enriched environment had on preventing age-related cognitive deterioration in older beagles. Older adult beagles (aged 8 – 10 years) of equivalent cognitive abilities were put into one of four groups. One group was controlled on both diet and enrichment. That is, they had a normal diet and normal kennel environment. A second group had an anti-oxidant-enriched diet, but a normal environment. A third group had a normal diet, but an enriched environment involving outdoor exercise and a variety of play toys. The fourth group had both an enriched diet and an enriched environment.
The older dogs were also compared to two groups of young dogs, one receiving a normal diet, one with an anti-oxidant-enriched diet. Both groups of young dogs lived in an enriched environment. The purpose of the study was to see whether and how easily the dogs could modify their learned behavior on a box test. They were first trained to realize that a treat was hidden under a particular color box. In some groups, that box was black; in others it was white. After the dogs could reliably perform this operation, the conditions of the experiment were changed. The treat was now hidden under the other box. The dogs were allowed up to 40 attempts to relearn this activity. Sadly, only 25% of the control-control dogs were able to relearn the task. This was in stark contrast to the group of dogs with the enriched diet and environment, 100% of whom were able to relearn the task. Two-thirds of dogs with an enriched diet and controlled environment relearned the task, while 80% of those with the control diet and enriched environment managed the feat. Both groups of young dogs had no problem relearning the task indicating that an anti-oxidant diet has less effect on young compared to old animals and that there is a correlation between increasing age and increasing cognitive impairment. The authors conclude that an anti-oxidant rich diet along with exercise and an enriched environment can limit the extent of cognitive decline in older individuals. N. W. Milgram, E. Head, S. C. Zicker, C. J. Ikeda-Douglas, H. Murphey, B. Muggenburg, C. Siwak, D. Tap, and C. W. Cotma. Learning ability in aged beagle dogs is preserved by behavioral enrichment and dietary fortification: a two-year longitudinal study. Neurobiology of Aging. 2005: 26: 77-90.
Comment: Although we are only very distantly related to dogs, the results of this study are in line with current advice about preventing cognitive decline in humans. We should eat an anti-oxidant-enriched diet, get plenty of exercise, and engage in a variety of activities that keeps us mentally stimulated. By doing these we will not only be able to maintain our current abilities, but may be able to stay honed and sharp on the cutting edge of life.
Sunlight and Cancer: The majority of dermatologists would have us believe that avoiding sunlight will prevent cancer. However, their advice may actually result in an increase in the number of cancers and/or cancer-related deaths. This is because their “all or nothing” approach ignores the biological realties of primates, which humans are. We must maintain a delicate balance of exposure to UVB radiation. Yes, we need to avoid over-exposure, but under-exposure is just as harmful, perhaps more so than over-exposure. A recent study of melanoma patients found that those with the most exposure to UVB radiation (as evidenced by skin damage and exposure histories) actually had the best chances of survival compared to those with the least exposure. Berwick M, Armstrong BK, Ben-Porat L, Fine J, Kricker A, Eberle C, Barnhill R. Sun exposure and mortality from melanoma. J Natl Cancer Inst. 2005;97(3):195-9.
A study in Denmark and Sweden of patients with non-Hodgkins lymphoma (NHL) found that when compared to a control population without NHL that an anti-oxidant-rich diet was associated with reduced risk of NHL. In addition, the researchers found that increased UVB exposure was also associated with a reduced risk of non-Hodgkins lymphoma. Chang ET, Ekstrom Smedby K, Zhang SM, Hjalgrim H, Melbye M, Ost A, Glimelius B, Wolk A, Adami HO. Dietary factors and risk of non-hodgkin lymphoma in men and women. Cancer Epidemiol Biomarkers Prev. 2005 Feb;14(2):512-20.
The report for 2005 by the American Cancer Society on incidence and mortality risks for all cancer types was just released. It states that men of West African ancestry have a 40% higher mortality rate than men of European ancestry, while women of West African ancestry have a 20% higher mortality rate than is true of women of European ancestry. It may not be immediately obvious why this research is included in the sunlight and cancer section. However, when one remembers that melanin blocks UVB radiation from penetrating to lower layers of the skin, the relationship may be clearer. Ahmedin Jemal, Taylor Murray, Elizabeth Ward, Alicia Samuels, Ram C. Tiwari, Asma Ghafoor, Eric J. Feuer, and Michael J. Thun. Cancer Statistics, 2005. CA Cancer J Clin 2005; 55:10-30.
We need UVB radiation exposure of our skin to produce vitamin D. Vitamin D has been shown in many studies to be a tumor suppressor. Therefore, those with the greatest exposure to UVB radiation should have the highest levels of vitamin D, the lowest incidences of cancer, and the best chances of survival if they do contract cancer. Individuals with moderate-to-dark skin color have extreme difficulty in maintaining optimal levels of vitamin D in their blood. Therefore, it is probable that they will have higher rates and/or earlier onset of a number of types of cancer, and that they will have higher rates of mortality once they’ve contracted cancer. The skin cancers, including melanoma, would be least likely to affect them, which is indeed the case.
Moderately-to-heavily pigmented individuals are also at higher risk for a number of other health problems related to vitamin D deprivation, some of which have been highlighted in previous issues of this newsletter. These are discussed in more detail in my article on the topic 2003 Health Disparities: Reframing the Problem. Medical Science Monitor 9 (3): SR9-15.
The serious health issue of vitamin D deprivation continues to be ignored by the public health community and government organizations. In an effort to force attention, The Vitamin D Council has filed a civil rights complaint with the Department of Justice stating that more needs to be done to ensure that individuals of non-northern European ancestry who are lactose intolerant and cannot drink milk will be provided with other vitamin-D supplemented foods. Examples of possible foods to supplement include yogurt, hard cheese, and cereals. AnthroHealth and The Vitamin D Council would appreciate your help on this issue. You can contact Dr. Lester Crawford, the FDA Commissioner, and ask him to consider including more foods beyond milk in those required to be supplemented with vitamin D. He can be contacted here: firstname.lastname@example.org.
Until the public health problem of vitamin D deprivation receives adequate attention and amelioration, needless cases of morbidity and mortality will continue to take an increasing toll of the health of all Americans.
AnthroHealth Tip of the Month: Consider having a garden, even if it is just a few pots or a flower box. If it is still too cold where you live to plant outside, you can spend the month planning for your plot or pots. Gardening provides multiple benefits. You get some exercise while taking in the sunlight. And you are rewarded for your efforts with visual and/or edible delights.
© 2001-2009 Kathleen E. Fuller, PhD. All rights reserved.