The January issue of American Journal of Clinical Nutrition reported a protective effect from higher dietary zinc intake from dying of prostate cancer.
It involved 525 Swedish men, all under the age of 80, who had been already diagnosed with prostate cancer. They were followed for an average of 6.4 years. Responses to dietary questionnaires administered upon enrollment were analyzed for the intake of calories, and iron and zinc from food sources. The subjects were followed through February 2009, during which time the causes of any deaths were determined.
“Over the 6.4 year average follow-up period there were 475 deaths, of which 218 were attributed to prostate cancer. Men whose intake of zinc was among the highest 25 percent of participants at greater than 15.6 milligrams per day had a 36 percent lower adjusted risk of dying from prostate cancer compared with those whose intake was among the lowest fourth. For those whose tumors were localized, there was a 76 percent lower risk of death among those whose intake was the highest compared to men whose intake was the lowest. Iron intake was not significantly associated with prostate cancer survival, and zinc was not associated with death from other causes."
The authors of the report note that the results of previous research concerning a protective effect for zinc in the prevention of prostate cancer have been inconsistent, and suggest that zinc could play a greater role in determining outcome of the disease rather than in its development. They remark that zinc is involved in a number of cellular functions, including maintenance of the immune system and DNA repair.
"These results suggest that high dietary intake of zinc is associated with lower prostate cancer–specific mortality after diagnosis, particularly in men with localized disease," Mara M. Epstein and her colleagues write. "These findings should encourage future studies of zinc and prostate cancer to include survival endpoints in an attempt to confirm our conclusions."
Being a man and having a prostate gland, I am impressed with these results. It has been suspected for a long time that zinc has a protective effect against prostate cancer, and now it looks like it really does. Zinc is considered a marginal nutrient, especially within plant-based diets, such as I eat and recommend. The fiber, oxalates, and phytates in plants all inhibit zinc availability and absorption. Is it a significant problem? It’s hard to know. I suppose it depends on the exact composition of the diet, and surely, there are individual variables involved, just as there is with iron.
Iron, too, is said to be difficult to absorb from plants. For instance, I have a friend in his 70s who has been a healthseeker for over 50 years, and he has been very serious about it. He not only eats all-organic food, but most of what he eats he raises himself on his organic homestead in Virginia, close to the Chesapeake Bay. He is raising many kinds of fruits, vegetables, nuts, and berries. And in many ways, his health had been extraordinary and exceptional, especially for his age. However, recently, he has come down with iron-deficiency anemia. It’s not severe, and he’s not feeling terrible, but it is unmistakably that. Surely, there is plenty of iron in the food he is eating. So, why isn’t he absorbing it? I really can't say. Any answer I were to give would only be speculation. I eat similarly to him and my iron level is fine. So obviously, there are individual factors involved.
And it may be similar with zinc. Determining a person’s zinc status isn’t that easy. A serum zinc test is not considered to be reliable, and it fluctuates a lot. There is a taste sensitivity test that some are using as a proxy for zinc status, but I don’t know how valid it is, although it is true that zinc is involved in taste acuity.
Note that those who eat ultra-low-fat diets, such as the Pritikin diet or the McDougall diet may be sabotaging their zinc status. Dietary fats increase zinc absorption. The USDA did extensive testing showing that the lower the fat content of the diet, the greater the amount of zinc that passed through the body unabsorbed and wound up in the toilet. At least I know I am not making that mistake. I know that when I eat healthy fats, such as nuts or avocados, I am enhancing my mineral absorption. And remember that the plant food that is highest in zinc is the mighty pecan- and it has healthy, monounsaturated fat and relatively low fiber content to enhance mineral absorption. I eat pecans almost daily.
Nevertheless, I don’t mind a bit that my Extend Core multi from VRP provides 15 mgs of highly absorbable zinc. It’s a very safe dosage, and zinc is too important- to immunity, to sexuality, to cancer prevention, to eye health, to memory- and even to digestive and glandular function- to leave it to chance.