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A recent large study found that getting high levels of vitamin D from foods, but not supplements, is linked to a lower rate of a common skin cancer (squamous cell carcinoma) years later. Once again: the beneficial health effect is associated with eating real foods, but not supplements.

Researchers found an inverse relationship with vitamin A intake and squamous cell carcinoma - those that had the highest dietary intake of vitamin A had a 17 % reduction of the skin cancer during the next 26 years. The inverse associations were highest among those with moles and those who had sunburns during childhood or adolescence.

The high intake group had the vitamin A amount equivalent to one medium baked sweet potato or 2 large carrots each day. Most of their intake came from fruitsand vegetables. Vitamin A (retinoids) is important in keeping skin cells healthy, and retinoids are considered cancer protective (or anticancer) for several cancers.

What foods are high in vitamin A?  Plant-based sources of vitamin A (carotenoids, including lutein and lycopene) include orange and yellow fruits  and vegetables, such as sweet potatoes, carrots, butternut squash, pumpkin, apricots, cantaloupe, red peppers, tomatoes, as well as broccoli, spinach, and leafy dark vegetables. Animal based sources of vitamin A  (retinol) are dairy foods (milk, cheese, yogurt), eggs, some types of fish (e.g. herring), and beef liver. (More information at National Institutes of Health.)

From Futurity: CAN GETTING MORE VITAMIN A CUT SKIN CANCER RISK?  ...continue reading "Vitamin A and Skin Cancer Risk"

New study in the Journal of Internal Medicine  with interesting results. In the study, women were followed for 20 years, and any  deaths were put into one of 3 groups: as being from: heart disease, cancer, or other (non-heart disease and non-cancer). Swedish women followed for 20 years found that the more sunlight exposure they had, the longer the life expectancy, the less death from heart disease (cardiovascular disease) and causes other than heart disease or cancer (non-heart disease and non-cancer group), but the more skin cancer (basal cell carcinoma, squamous cell carcinoma and melanoma) they developed. Thus the main finding is of a dose-dependent relationship between sun exposure and life expectancy.

One surprising result was that nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group. Those who avoided sun exposure had an increased risk of death mainly due to heart disease and "other causes" (non-cancer/non-heart disease). I wondered about other cancers in this study, and this is all they had to say in the journal article:  "Thus, women with NMSC (nonmalignant skin cancer) had a 37% higher prevalence of other internal cancers than those without NMSC and a fourfold increased prevalence of MM (malignant melanoma). The incidence of other internal cancer was not increased subsequently on NMSC diagnosis."  I now have another question:  How do the women with cancer in the high and low sun exposure group do after another 10 or 20 years?  I would have liked for this study to continue longer.

The researchers felt that sunshine and vitamin D had a role in these results, and suggested that we need to rethink the "avoid sunshine" advice now given to people. In other words, some sunshine is good for health. From Science Daily:

Why do sunbathers live longer than those who avoid the sun?

New research looks into the paradox that women who sunbathe are likely to live longer than those who avoid the sun, even though sunbathers are at an increased risk of developing skin cancer. An analysis of information on 29,518 Swedish women who were followed for 20 years revealed that longer life expectancy among women with active sun exposure habits was related to a decrease in heart disease and noncancer/non-heart disease deaths, causing the relative contribution of death due to cancer to increase.

Whether the positive effect of sun exposure demonstrated in this observational study is mediated by vitamin D, another mechanism related to UV radiation, or by unmeasured bias cannot be determined. Therefore, additional research is warranted. "We found smokers in the highest sun exposure group were at a similar risk as non-smokers avoiding sun exposure, indicating avoidance of sun exposure to be a risk factor of the same magnitude as smoking," said Dr. Pelle Lindqvist, lead author of the Journal of Internal Medicine study. "Guidelines being too restrictive regarding sun exposure may do more harm than good for health."

More studies need to be done, but the possibility of simply taking 500 mg twice a day of nicotinamide (a vitamin B3 derivative) to reduce the incidence of basal and squamous cell carcinoma is exciting. Nonmelanoma skin cancer is the most common cancer in the world. From Medical Xpress:

Study: Vitamin B3 may help prevent certain skin cancers

For the first time, a large study suggests that a vitamin might modestly lower the risk of the most common types of skin cancer in people with a history of these relatively harmless yet troublesome growths.

In a study in Australia, people who took a specific type of vitamin B3 for a year had a 23 percent lower rate of new skin cancers compared to others who took dummy pills. In absolute terms, it meant that vitamin takers developed fewer than two of these cancers on average versus roughly 2.5 cancers for the others.The study did not involve melanoma, the most deadly form of skin cancer. Instead, it aimed at more common forms—basal and squamous cell cancers. He and other doctors with the oncology group said the vitamin, called nicotinamide, could offer a cheap, easy way to lower risk.

The study involved 386 people who had at least two skin cancers in the previous five years. They took either 500 milligrams of the vitamin or dummy pills twice a day for a year. Neither they nor their doctors knew who got what until the study ended.

Besides reducing the rate of skin cancers, vitamin use also seemed to cut the rate of precancers—scaly patches of skin called actinic keratoses—by 11 percent after three months of use and 20 percent after nine months. Participants were tracked for six months after they stopped taking their pills, and the rate of new skin cancers was similar in both groups. "The benefit wears off fairly quickly," Damian said. "You need to continue taking the tablets for them to continue to be effective."

Nicotinamide is thought to help repair DNA in cells damaged by sun exposure. It is not the same as nicotine, the addictive stuff in tobacco. It's also not the same as niacin and some other forms of B3, which can cause flushing, headaches and blood pressure problems. Those problems were not seen with nicotinamide in the study. Nicotinamide is sold over the counter, is easy to take, and "there are essentially no side effects," Schilsky said.

 Credit: WebMD, Healthwise, Inc.