Tanning increases melanoma risk
Vitamin D best taken with meals
Whole grains lower diabetic mortality
High fat/calorie meal worsens asthma
Mediterranean diet and the heart
Ultraviolet (UV) light exposure, whether from the sun or tanning beds, damages the skin and increases the risk of all forms of skin cancer. However, vitamin D produced in the skin after exposure to UV light decreases the risks of cancer, including skin cancers. This has led to some confusion about whether it is good to tan or not. A number of studies clearly indicate that any excessive UV light exposure is dangerous, strongly suggesting that it is better to get most of your vitamin D from supplements rather than from sun exposure.
A recent population-based study evaluated the risk of melanoma from indoor tanning beds. Among 1,167 cases and 1,101 controls, tanning beds were associated with a markedly increased risk of melanoma. (Lazovich D, et al., Indoor tanning and risk of melanoma: A case-control study in a highly exposed population. Cancer Epidemiol Biomarkers Prev. 2010 May 26. [Epub ahead of print])
In this study, those with frequent exposure to UVB tanning-beds had nearly triple the risk of melanoma, and frequent exposure to UVA tanning beds led to over four times the incidence of melanoma. The risk was directly related to the dose, so that at any age, the incidence of melanoma was increased with greater exposure. They studied subjects aged 25 to 59. Even with lower levels of exposure, the risk of melanoma was increased by 75 percent compared with those who never used tanning beds.
Several dermatologists who were interviewed on National Public Radio made it clear that any tanning is dangerous. Tanning is the skin response to damage, and the idea of getting a “base tan” to protect the skin from sunburns is dangerous in itself. It leads to photo-aging of the skin (UV-induced wrinkling) as well as skin cancers. They all thought that tanning beds should be prohibited because they are carcinogenic, and the FDA is now considering such regulation. (However, I am sure that financial interests will try to influence this decision.)
Protective clothing and sunscreen are the most effective ways to protect yourself from UV induced skin cancer. Not all clothing is adequately opaque. The safest and most protective skin products are those that contain zinc oxide or titanium dioxide, which create a physical barrier to the sun.
You want sunscreens that protect against both UVA and UVB rays. None of the chemical sunscreens are totally safe, containing hormone disruptors among other risky substances, and FDA approval does not reassure me of their safety. You can find good advice on sunscreens at www.ewg.org/2010sunscreen/
All of the dermatologists who were interviewed recommended getting vitamin D from supplements (at least 1000 IU per day according to them) rather than from the sun. This is partly because with age the ability of the skin to produce vitamin D declines and in certain latitudes or seasons very little vitamin D is produced from sun exposure regardless of age, making supplements even more important. The next section goes into even more detail on proper supplementation with vitamin D, including how to take it to derive the most benefits.
The importance of vitamin D makes it essential to take a dose that leads to increased blood levels, and this can only be determined by blood testing. The proper test is the 25 hydroxy vitamin D3 level (also called 25(OH) D3 level) in the serum, which should be 50 to 80 ng/ml (that is nanograms per milliliter). (Be sure you are not getting the 1,25 dihydroxy vitamin D level, which doctors sometimes order.) To achieve healthy levels, you may need to take 5000 to 10,000 IU/day, but without testing you won’t know.
Many people who take vitamin D supplements fail to achieve blood levels that are adequate for optimal health, even with high doses. Researchers at the Cleveland Clinic evaluated absorption of vitamin D in 17 subjects aged 55-75 over three months. These were all patients who were taking vitamin D in doses ranging from 1000 to 50,000 IU daily, but whose blood levels were still low. With age, it is not only UV production of vitamin D that declines, but also intestinal absorption.
Subjects were then instructed to take their vitamin D supplement with the largest meal of the day. Prior to this, their blood levels of 25(OH)D3, even with supplements, ranged from 21 to 38 ng/ml. After modifying the supplement timing, the serum level rose to a range of 34 to 74 ng/ml. (Mulligan GB, Licata A. Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D. J Bone Miner Res. 2010 Apr;25(4):928-30.) This is a significant improvement in blood level, but still not adequate for some of the patients, suggesting that they needed a higher dose to raise blood levels.
Vitamin D is a fat-soluble nutrient, and taking it with a meal should improve absorption, but this assumes that the meal contains some fat. This can be olive oil, flaxseed oil, nuts, seeds, peanuts or peanut butter, oily fish, soyfoods, or coconut (based on other research, it is likely better that it is not land-animal fat such as cow, pig, fowl, or sheep). The researchers in this study probably assumed that the largest meal would contain adequate fat to enhance absorption, but this is not necessarily the case.
In February I reported that whole grains in the diet were associated with a decreased risk of developing diabetes as opposed to refined grains (white rice and white flour), which increase the risk. A new study shows that consuming whole grains or bran results in a decreased mortality among diabetics and lowers cardiovascular mortality specifically in diabetic women (they only studied women).
Researchers evaluated 7822 women with type 2 diabetes (also known as adult onset diabetes, but increasingly being seen in young people) who were part of the Nurses’ Health Study. They were followed for up to 26 years. Those with the highest whole grain, cereal fiber, and bran intake showed a 16 to 31 percent lower all-cause mortality. (He M, et al., Whole-grain, cereal fiber, bran, and germ intake and the risks of all-cause and cardiovascular disease-specific mortality among women with type 2 diabetes mellitus. Circulation. 2010 May 25;121(20):2162-8.)
Bran is the hard, indigestible outer coating of grains such as wheat, oats, and rice, and it is typically removed in processing to make white flour and white rice. Women with the highest whole-grain intake had a 35 percent lower risk of death from cardiovascular diseases and a 28 percent lower all-cause mortality. Those with the highest added bran intake had a 55 percent lower all-cause mortality and a 64 percent lower cardiovascular mortality than those with no added bran intake. Whole grains reduce inflammation and improve endothelial function, but this is unlikely to be due to the bran, which is not absorbed.
Meals that are high in fat and calories can quickly worsen asthma. Inflammation and spasm of the airways are characteristic of asthmatic patients. Dietary fat activates immune responses and can increase systemic inflammation, and researchers set out to determine more specific effects of fat intake on airway inflammation and bronchial function.
They studied 14 non-obese asthma patients given a high fat and high calorie meal (HF) and 16 obese subjects given the HF meal, and compared them with 16 non-obese patients on a low-fat and low-calorie meal (LF). They evaluated the subjects four hours after the challenge meals for signs of inflammation, immune response, and airway function and compared the results with baseline function. The results were presented at the American Thoracic Society’s International Conference in May. (Wood LG, et al., [Poster Board # 706] A high fat challenge enhances innate immune responses in asthmatic airways, Am J Respir Crit Care Med 181;2010:A5182.)
When tested at four hours, the subjects on the HF meal showed five times higher white blood cells in the sputum and twice the level of inflammatory markers compared to those on the LF meal. In response to their medication, the HF subjects had only a 1 percent increase in function, compared to a 4 percent increase in the LF group. The high fat meal consisted of burgers and hash brown potatoes (which are commonly soaked in highly processed shortening, loaded with trans fats until recently). Land animal fats are associated with inflammation, unlike unprocessed vegetable oils.
A Mediterranean style diet is known to reduce the risk of heart disease. A new study shows that it is also beneficial to people who have already had a heart attack. It reduces the likelihood of recurrence within the next two years. The diet emphasizes fresh vegetables, fruits, legumes, whole grains, nuts, and fish, and is low in meats and full-fat dairy products.
New research shows that adhering more closely to this dietary pattern also can reduce the risk of recurrence in patients who have already had heart attacks. Researchers evaluated 1000 patients who had heart attacks or severe chest pain at rest or with minimal exertion. They rated them on a scale of 0 to 55 based on how closely their diets followed the Mediterranean style.
Among those with the higher scores on the scale, the odds of having ventricular dysfunction while in the hospital or within the first three months after discharge were significantly reduced. At two years, the chance of a recurrent heart attack was 40 percent lower. (Chrysohoou C, et al., The Mediterranean diet contributes to the preservation of left ventricular systolic function and to the long-term favorable prognosis of patients who have had an acute coronary event. Am J Clin Nutr. 2010 May 19. [Epub ahead of print])
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