July 2008 Newsletter

Lycopene and cancer
B vitamins, homocysteine, and bones
Acrylamide and kidney cancer
Vitamins help diabetics’ brain function
Fish oils (EPA) and strokes
Diet, heart deaths, and mortality
Are chickens fed antibiotics?

Lycopene and cancer

Lycopene is a plant pigment in the carotenoid family, but unlike beta-carotene it is not converted in the body to vitamin A. It is well known as the red pigment in tomatoes, but it is also present in red grapefruit, red navel orange, papaya, and watermelon (which has more lycopene than tomatoes). As an antioxidant, it is known to protect against some forms of cancer, particularly prostate cancer.

A new review of its effects shows that lycopene concentrates in the nuclei of prostate epithelial cells. In addition to its antioxidant effects, it has other cancer-protective actions. It induces apoptosis (programmed cell death) in cancer cells, and it stimulates production of cell-protecting enzymes. (van Breemen RB, Pajkovic N, Multitargeted therapy of cancer by lycopene. Cancer Lett. 2008 Jun 26. [Epub ahead of print])

As a result of these actions, lycopene can not only help prevent cancer, but also reduce the growth of tumors and block metastasis (spread to other sites). High levels of lycopene in fat tissues have also been associated with lower levels of heart disease.

Americans get a lot of their lycopene from tomato products because processed tomatoes (tomato sauce, tomato paste, and tomato juice) are concentrated from the fresh, raw tomatoes. Even so, watermelon has at least as much available lycopene as tomato products. It is also readily available as a dietary supplement.

B vitamins, homocysteine, and bones

A high level of homocysteine (a metabolic byproduct) in the serum is a risk factor for arteriosclerotic heart disease, and it is also associated with low B-vitamin status. It now appears that low B-vitamin status is also associated with an increased risk of developing hip fractures independent of the association with homocysteine.

In a study of 1002 men and women averaging 75 years old, B vitamin status was compared with bone fracture risk and homocysteine levels. After statistical analysis, both high homocysteine and low B vitamins are independently associated with bone loss and hip fracture. B6 and B12 each were linked to a 60 percent increase in hip fracture risk over the four years of the study. (McLean RR, et al., Plasma B vitamins, homo-cysteine, and their relation with bone loss and hip fracture in elderly men and women. J Clin Endocrinol Metab. 2008 Jun;93(6):2206-12. Epub 2008 Mar 25.)

B vitamins are readily available from healthy diets rich in vegetables, fruits, whole grains, beans, nuts, seeds, eggs, non-fat dairy products, and fish (if choosing to eat such animal products, I recommend only organic and non-fat varieties, or wild fish). The B vitamins are also commonly present in multivitamins or plain B-complex supplements (this is important for people on vegan diets because B12 is reliably available only from animal products).

Acrylamide and kidney cancer

Acrylamide is a carcinogen found in carbohydrate foods that have been cooked to high temperatures (above 120 degrees Celsius or 248 Fahrenheit), such as French fries, potato chips, cakes, toast, and some breads. It is also found in coffee. It is not formed if foods are simply boiled (100 degrees C, or 212 F). (Exposure also comes through cigarette smoke and some cosmetics.) The darker brown a food gets with cooking the more acrylamide it will contain.

A new study shows that a high intake of acrylamide is associated with an increased risk of kidney cancer. Researchers in Holland evaluated 5000 participants in the Netherlands Cohort Study, all of whom are from 55 to 69 years old. They assessed acrylamide intake with food frequency questionnaires and followed the subjects for over 13 years.

Compared to those with the lowest intake (averaging 9.5 mcg per day), those with the highest intake (40.8 mcg/d) had a 60 percent higher incidence of kidney cancer. The study found no statistically significant relationship of acrylamide to bladder or prostate cancer. Smoking added to the risk. (Hogervorst JG, et al., Dietary acrylamide intake and the risk of renal cell, bladder, and prostate cancer. Am J Clin Nutr. 2008 May;87(5):1428-38.)

Vitamins help diabetics’ brain function

Adults with type 2 diabetes have mildly impaired memory function, and after meals this deficit is even worse. In 16 subjects with an average age of 63 years, a high-fat meal led to poorer performance on particular cognitive testing compared to performance after just consuming water.

When the same subjects were given the high-fat meal along with supplements of 1000 mg of vitamin C and 800 IU of vitamin E, the cognitive function was not impaired. It was at the same level as after consuming water alone. Because these are two anti-oxidant nutrients, the authors concluded that the memory impairment is likely to be due to oxidative stress. (Chui MH, Greenwood CE, Antioxidant vitamins reduce acute meal-induced memory deficits in adults with type 2 diabetes. Nutr Res 2008 July;28(7):423-429.

(The meal was a Danish, yogurt, cheddar cheese, and whipped cream – enough to cause far more problems than mild memory impairment.) The same team previously showed that cognitive function is improved after meals containing fruits, vegetables, cereals, and fish, and worsened after fats, including trans fats. They suggested that these effects might be due to alterations in insulin regulation and neuroinflammation. (Parrott MD, Greenwood CE, Dietary influences on cognitive function with aging: from high-fat diets to healthful eating. Ann N Y Acad Sci. 2007 Oct;1114:389-97.)

Fish oils (EPA) and strokes

Japanese researchers evaluated 18,645 subjects with high cholesterol levels. Half were on low dose statin drugs, and the other half were given the statin drugs with 1800 mg EPA derived from fish oil. They followed them for five years, evaluating them for the incidence of strokes. (Tanaka K, et al., Reduction in the recurrence of stroke by eicosapentaenoic acid for hypercholesterolemic patients: subanalysis of the JELIS trial. Stroke. 2008 Jul;39(7):2052-8. Epub 2008 May 1.)

Although the incidence of new strokes was the same in both groups, among those who had already had a stroke at the start of the study the incidence of second strokes was 10.5 percent in the statin-only group, and 6.8 percent in the group taking added EPA.

EPA (and other omega-3 oils) influence blood pressure, platelet adhesion, inflammation, cholesterol, and arterial smooth-muscle contraction. These physiological effects might contribute to the benefits seen in this study. Non-fish sources of omega-3 oils include flaxseeds and walnuts, which contain alpha-linolenic acid (which the body converts to EPA). It is not clear that these would provide the same benefits as taking EPA itself, as some people do not convert efficiently.

Diet, heart deaths, and mortality

Enough incentive already exists to follow a healthy eating pattern, but a new study confirms the benefits of making better dietary choices. Researchers followed 72,113 women who were healthy at the start, from 1984 to 2002. They used validated food frequency questionnaires to categorize them into a “prudent” dietary pattern (high in vegetables, fruits, legumes, whole grains, fish, and poultry), or a “Western” diet (high in meat, refined grains, french fries, and sweets/desserts).

Each group was divided into five sections, depending on whether they were in the high or low end of their dietary pattern. Among those with the greatest adherence to the prudent pattern, the risk of cardiovascular mortality was 28 percent lower than those with the lowest adherence to that diet. The risk of overall mortality during the study was 17 percent lower in the high-adherence group.

On the other hand, among those on the Western-diet pattern, the highest adherence led to a 22 percent increase in cardiovascular mortality, a 16 percent increase in cancer mortality, and a 21 percent increase in overall mortality, all compared to those with the lowest adherence to that diet. (Heidemann C, et al., Dietary Patterns and Risk of Mortality From Cardiovascular Disease, Cancer, and All Causes in a Prospective Cohort of Women. Circulation. 2008 Jun 23. [Epub ahead of print])

This says little about which component of the Western diet led to such significant increases in risk.

Are chickens fed antibiotics?

A reader noted that current poultry farming (conventional) does not include routine hormone or antibiotic use to stimulate egg production, as I stated in my last newsletter. I am investigating this further, because as of 2003, an article from a symposium on the subject said “Antibiotics are used by the poultry industry and poultry veterinarians to enhance growth and feed efficiency and reduce disease...allowing the consumer to purchase, at a reasonable cost, high quality meat and eggs.” (2003 Poultry Science 82:618–621, Donaghue, DJ, Dept of Poultry Science, University of Arkansas.) The author noted only “few violative antibiotic residues” which means that the residues were within “acceptable” levels, but these levels might not be acceptable to all consumers. As of 2006, antibiotics were still present in chicken feed, although they may have phased this out recently. For a host of reasons, I still recommend organic eggs. I’ll let you know if I come up with further data, and I welcome your comments on the subject. Please send me an email if you have reliable, documented information covering this issue.