High Fish & Vegetable Intake Reduces Risk of Breast Cancer

In a new study, researchers found a strong correlation between a diet high in vegetables and seafood and reduced risk of breast cancer. Lower BMI, high levels of dietary supplement use, and increased physical activity also correlated with reduced breast cancer risk.
After skin cancer, breast cancer is the most common type of cancer in women. In U.S. women, more than 1 in 4 cancers (28%) are breast cancers. Historically, breast cancer has been much more prevalent in Western countries than in Asian countries, although the gap has declined dramatically in recent years. A new study published by researchers at South Korea's National Cancer Center sheds new light on one possible explanation for this effect.

In this study, 357 breast cancer patients between the ages of 25 and 77 were matched with 357 healthy controls. A trained dietitian conducted face-to-face interviews with each study subject, collecting detailed information on lifestyle (including physical activity), demographics, and diet.

410 types of reported food were grouped into 39 food groups based on nutrient profiles and culinary usage. These food groups were then used to calculate two "dietary patterns": one characterized by regular consumption of a variety of vegetables, seafoods, and soybean products, and another characterized by above-average intake of meat (non-fish) and starch-rich foods (bread, noodles, pizza, etc). The "vegetable-seafood" diet is representative of a traditional Korean diet, while the "meat-starch" diet is representative of a traditional Western diet. Statistical analysis were then performed to look for correlations between demographics, lifestyle factors, and these two diet patterns.

Breast cancer occurrence in this study correlated strongly with higher BMI (p=0.006), lower levels of dietary supplement use (p=0.005), and low levels of physical activity (p=0.021). Additionally, a significant inverse association was seen between the vegetable-seafood pattern and breast cancer risk, while no correlation (positive or negative) was seen for the meat-starch group. Additional analysis correlated the vegetable-seafood diet with higher intakes of fiber, vitamin A, carotene, vitamin C, vitamin E, folate, and calcium (p < 0.001 for all).

This study provides strong evidence for a diet high in vegetables and seafood reducing the risk of breast cancer. As the authors note, the increasing Westernization of Korean diets may explain - at least in part - the rising rates of breast cancer in that country.

Cho YA, Kim J, Shin A, Park KS, Ro J. Dietary Patterns and Breast Cancer Risk in Korean Women. 2010. Nutrition and Cancer 62(8):1161-9.

New Diabetes Projections "Paint Sobering Picture of the Future"

Without widespread intervention, one in three American adults could have type 2 diabetes by the year 2050.

Type 2 diabetes is a chronic health condition that develops when the body becomes resistant to insulin, a hormone that regulates carbohydrate and fat metabolism. The exact mechanism by which type 2 diabetes occurs is unknown, but a number of correlating risk factors - particularly obesity and physical inactivity - are well-established. Unfortunately, the number of individuals with type 2 diabetes has increased sharply in recent years, with an estimated $174 billion cost to the United States in 2007 alone.

A number of papers have attempted to project type 2 diabetes prevalence 5, 10, and 20+ years into the future. Unfortunately, most of these projections have relied on weak or outdated metrics, including old census data, static mortality rates, and overly simple estimations of diabetes incidence. A recent paper from researchers at the National Center for Chronic Disease Prevention and Health Promotion hoped to overcome these weaknesses by utilizing recent census data and a matrix of factors derived from an extensive literature review.

The researchers describe their results as "a sobering picture of the future growth of diabetes." Their most optimistic values point to 21% of the U.S. adult population having type 2 diabetes in the year 2050. A middle-ground scenario predicts a prevalence of 25%-28%, while high-end data points to a diabetes prevalence of 33%, or 1 in 3 adults. To put these numbers in perspective, approximately 7% of the U.S. adult population had type 2 diabetes in 2007. In 1990, prevalence was below 5%.

Unlike some chronic diseases, type 2 diabetes risk can be reduced by relatively moderate lifestyle changes. Losing weight (if overweight or obese), improving dietary choices, and regular exercise are all known to reduce risk of acquiring type 2 diabetes. The authors of this paper note that such changes "can help to decrease loss in quality of life and the future cost of providing care for people with diabetes. Indeed, such efforts are essential if we hope to moderate or slow the growth of diabetes prevalence."

Boyle JP, Thompson TJ, Gregg EW, Barker LE, Williamson DF. Projection of the year 2050 burden of diabetes in the US adult population: dynamic modeling of incidence, mortality, and prediabetes prevalence. 2010. Population Health Metrics 8:29

Regular Exercise Reduces Risk of the Common Cold

New research shows a strong correlation between regular aerobic exercise and reduced risk of upper respiratory tract infections.


Upper Respiratory Tract Infections (URTI) can be caused by more than 200 different viruses, and it is estimated that the U.S. population suffers more than one billion colds a year (2-4 per average adult, 6-10 per average child). A number of lifestyle factors contribute to URTI risk, including poor nutrient status, lack of sleep, and stress. A new paper published in the British Journal of Sports Medicine adds exercise habits to the list of lifestyle factors affecting URTI risk.

1,023 subjects between 18 and 85 years of age were recruited for this study, with 1,002 individuals completing all study requirements. Subjects were selected from multiple BMI groups (roughly one-third were of normal weight, one-third were overweight, and one-third were obese) to ensure adequate representation. A comprehensive validated survey on lifestyle, diet, activity levels, stress, and URTI incidence and severity was completed by each study participant.

After controlling for potential cofounders, total days with URTI symptoms were 43-46% lower in the highest third of aerobic activity when compared to the lowest third, while URTI severity was reduced 32-41% for the high group. Low stress levels, high exercise frequency (≥5 days/week), and high fruit intake (≥3 servings/day) also correlated with reduced URTI incidence.

The exact mechanism by which aerobic exercise reduces URTI risk is still uncertain, although it appears to be a combination of factors, including transient increases of certain immune cell types, a reduction of stress hormones, and specialized benefits to key organs (particularly the lungs, which serve as a primary barrier against URTIs).

Nieman DC, Henson DA, Austin MD, Sha W. Upper respiratory tract infection is reduced in physically fit and active adults. 2010. Br J Sports Med, ePub ahead of print. doi:10.1136/bjsm.2010.077875

Soy Phytates

Plants store phosphorus, an essential nutrient for plants and animals, in their seeds to support the growth of young seedlings. This phosphorus is stored in the form of phytate (inositol hexametaphosphate). Plant phytates are considered by some to be “anti-nutrients” because phytates consumed in the human diet can complex with essential minerals like iron and zinc and inhibit absorption in the gut. Others, however, consider phytates to be important food constituents that act not only as natural food-preserving antioxidants, but also help reduce risk of heart disease and cancer in those who consume whole grains, beans, seeds and nuts.

Soybeans contain significant amounts of phytate (1.3-1.4%), and some point to this as a reason to avoid soy foods.  However, it is important to note that most whole grains, beans, seeds, and nuts are also rich in phytates (Table 1), and there is a wealth of science to support the fact that these foods are important constituents of a healthy, well-balanced diet that supports longevity and reduced disease risk. As such, it is difficult to argue that soy should be avoided based on its phytate content when so many healthy foods contain comparable levels of phytates.

It is also important to note that on a percent basis, isolated soy protein contains far less phytate than do whole soybeans.






Table 1.  Phytate contents of some common grains, beans, and nuts.  Values from NR Reddy and SK Sathe (eds).  Food Phytates.  CRC Press, 2001. 

Food	Phytate Content (%)
Whole Wheat	0.7-1.1
Wheat Flour	0.3-1.4
Wheat Bran	2.0-5.3
Corn	0.8-1.0
Oats	1.0
Barley	1.0
Brown Rice	0.9
Soybeans	1.3-1.4
Soy Protein Isolates	0.7-0.9
Kidney Beans	2.6-2.9
Lentils	0.4-0.5
Chick Peas	0.6
Small White Beans	1.2
Great Northern Beans	2.6-2.9
Peas	0.8-1.2
Hazel Nuts	1.9
Walnuts	0.6-2.4
Almonds	1.3-3.2
Cashews	0.6-2.0

Soy and Thyroid Function

Some claim that soy foods should be avoided because they contain compounds (isoflavones) that disrupt thyroid function. We view this as a “half truth” that has little relevance for healthy individuals who consume soy at moderate levels as part of a healthy, balanced diet.

The relationship between soy consumption and thyroid function has been studied for more than 70 years. Interest in the topic grew during the 1950’s and 1960’s when several cases of goiter were identified in infants who consumed soy formulas. Subsequently, using in vitro and animal research, scientists found that at high concentrations the soy isoflavones genistein and daidzein can inhibit the activity of thyroid peroxidase and 5'-deiodinase, key enzymes involved in thyroid hormone biosynthesis.

Since that time, 14 human clinical trials have evaluated the effects of soy foods and soy isoflavones on thyroid function. All involved presumably healthy subjects, and with few exceptions the soy product used was isolated soy protein.

With only one exception, all of the studies showed either no effects or minor and clinically irrelevant effects of soy on thyroid function. The one trial that noted marked anti-thyroid effects (and the one often cited in anti-soy literature) involved Japanese adults who were fed roasted soybeans that had been pickled and stored in rice vinegar. The soy protein and isoflavone content of this food was not characterized, and the study involved no control group. As such, its relevance must be questioned.

One large study evaluated the specific effects of soy isoflavone supplements on thyroid function. Postmenopausal women between the ages of 64 and 83 were given daily doses of 90 mg of soy isoflavones or a placebo. Thyroid hormone levels were tested at baseline and again at 90 and 180 days. After six months, any differences in thyroid hormones between the groups were statistically indistinguishable.

Today, most experts agree that soy foods and isolated soy protein have little if any effect on thyroid function in normal, healthy adults. That said, the potential for soy isoflavones to disrupt thyroid function should not be ignored by people who have compromised thyroid function and/or people with suboptimal iodine status. But these groups aside, we contend that soy is a good source of protein when consumed in moderate amounts as part of a healthy, balanced diet.

In support of this position, note that Asian populations have a long history of consuming soy products without significant occurrence of goiter. This also holds true for vegetarians who consume not only higher levels of soy, but high levels of fruits and vegetables that contain other flavonoids known to inhibit thyroid enzyme activity. These flavonoids include kaempferol (found in apples, onions, green tea), naringenin (found in citrus fruits), and quercetin (found in fruits and berries). Such compounds are widely distributed in plant-derived foods and are consumed at relatively high levels (up to 1 gram or more per day) by vegetarians and vegans. Despite this, vegetarian diets have not been linked with decreased thyroid function.

Serum 25-Hydroxyvitamin D Concentrations

Serum concentration of 25(OH)D is the best indicator of vitamin D status. It reflects vitamin D produced cutaneously and that obtained from food and supplements and has a fairly long circulating half-life of 15 days. However, serum 25(OH)D levels do not indicate the amount of vitamin D stored in other body tissues. Circulating 1,25(OH)₂D is generally not a good indicator of vitamin D status because it has a short half-life of 15 hours and serum concentrations are closely regulated by parathyroid hormone, calcium, and phosphate. Levels of 1,25(OH)₂D do not typically decrease until vitamin D deficiency is severe.

There is considerable discussion of the serum concentrations of 25(OH)D associated with deficiency (e.g., rickets), adequacy for bone health, and optimal overall health (Table 1). A concentration of <15 nanograms per milliliter (ng/mL) (or <37.5 nanomoles per liter [nmol/L]) is generally considered inadequate; concentrations >15 ng/ml (>37.5 nmol/L) are recommended. Higher levels are proposed by some (>30 ng/ml or >75 nmol/L) as desirable for overall health and disease prevention, but insufficient data are available to support them. Serum concentrations of 25(OH)D consistently >200 ng/ml (>500 nmol/L) are potentially toxic.

Table 1: Serum 25-Hydroxyvitamin D [25(OH)D] Concentrations and Health*

ng/mL**	nmol/L**	Health status
<10-11	<25-27.5	Associated with vitamin D deficiency, leading to rickets in infants and children and osteomalacia in adults
<10-15	<25-37.5	Generally considered inadequate for bone and overall health in healthy individuals
≥15	≥37.5	Generally considered adequate for bone and overall health in healthy individuals
Consistently >200	Consistently >500	Considered potentially toxic, leading to hypercalcemia and hyperphosphatemia, although human data are limited. In an animal model, concentrations ≤400 ng/mL (≤1,000 nmol/L) demonstrated no toxicity.

* Serum concentrations of 25(OH)D are reported in both nanograms per milliliter (ng/mL) and nanomoles per liter (nmol/L).
** 1 ng/mL = 2.5 nmol/L

An additional complication in assessing vitamin D status is in the actual measurement of serum concentrations of 25(OH)D. Considerable variability exists among the various assays available and among laboratories that conduct the analyses. This means that compared to the actual concentration of 25(OH)D in a sample of blood serum, a falsely low or falsely high value may be obtained depending on the assay or laboratory used. A standard reference material for 25(OH)D became available in July 2009 that will now permit standardization of values across laboratories.

What is Choline

Choline is a dietary component necessary for cell membrane integrity and facilitating the movement of fats into and out of cells. Choline is also a precursor for acetylcholine, an important neurotransmitter in the brain. Choline also works with folic acid, vitamin B12, and methionine in methyl group metabolism and maintenance of healthy homocysteine levels. Since high levels of homocysteine increase the risk of cardiovascular disease, an adequate intake of choline may be important in reducing risk.

Pregnancy and lactation are periods when maternal reserves of choline risk becoming depleted. Because the availability of choline for normal fetal development of the brain is critical, expectant and nursing mothers should make certain their choline intake is adequate.

Although choline can be found in a wide variety of foods, some of the richest sources are foods high in cholesterol and fat (e.g. beef liver). Because many Americans have been advised to decrease their consumption of fatty foods, choline intake in some populationi groups may be inadequate. Healthy sources of choline include Brussel sprouts, broccoli, eggs, lean beef, milk, peanuts, and certain seafoods (shrimp, salmon, and cod).

High Vitamin B Levels Associated With Reduced Risk of Colorectal Cancer

In a recent population-based European study, individuals with higher vitamin B2 and B6 levels had significantly decreased risks of colorectal cancer.

New research reported in the October 2010 issue of Cancer Epidemiology, Biomarkers and Prevention shows a correlation between higher levels of vitamins B2 (riboflavin) and vitamin B6 and a reduced risk of developing colorectal cancer. B-vitamins are essential for metabolism and have been linked to a reduced risk of colorectal cancer in previous studies. Since associations with the B-vitamin folate have been studied most often, researchers in the current study focused on potential associations of other B vitamins (B2, B6, and B12) and colorectal cancer.

This European population-based study included subjects who were participants in the Prospective Investigation into Cancer and Nutrition (EPIC) cohort. The study included 1,365 adults diagnosed with colorectal cancer and 2,319 age and gender-matched control subjects. Blood samples were taken at enrollment and analyzed for vitamins B2, B6, and B12, as well as 8 variants of genes that relate to the function of these vitamins.

After an average follow-up of 3.6 years, individuals whose vitamin B6 levels were among the top 20 percent of participants had a 32 percent lower risk of developing colorectal cancer when compared to those whose levels were in the lowest 20 percent. Among those whose vitamin B2 levels were highest, the risk was 29 percent lower than those whose levels were lowest. There were no significant associations for vitamin B12 and colorectal cancer. Vitamin levels were lower in smokers compared to nonsmokers, and the benefits for vitamin B6 were stronger in males who consumed ≥30 g (one ounce) of alcohol per day.

This research is the first population-based study to indicate that vitamin B2 is inversely associated with colorectal cancer, and it supports previously suggested inverse associations of vitamin B6 with colorectal cancer.

Simone J.P.M. Eussen et al. Vitamins B2, B6, and B12, and Related Genetic Variants as Predictors of Colorectal Cancer Risk. Cancer Epidemiol Biomarkers Prev; 19(10); 2549–61.

Folic Acid (Vitamin B9)

Folic acid is a water-soluble B vitamin with a role as a regulating coenzyme for cellular metabolism and cell division.

Folic acid helps form the building blocks of DNA and RNA needed for protein synthesis in human cells. Rapidly growing tissues - such as those of a fetus - and rapidly regenerating cells - like red blood cells and immune cells - have an especially high need for folic acid.

Folic acid requirements increase during pregnancy. Deficiencies of folic acid during pregnancy are associated with low birth weight and an increased incidence of neural tube defects, including anencephaly and spina bifida. In one study, women at high risk of giving birth to babies with neural tube defects lowered their risk by as much as 72% by taking folic acid supplements prior to and during pregnancy. Medical experts, other healthcare professionals, and the March of Dimes recommend that all women of childbearing age supplement with 400 mcg of folic acid per day. Such supplementation would protect against the formation of neural tube defects during the time between conception and when pregnancy is discovered. If a woman waits until after pregnancy to begin taking folic acid supplements, it is likely too late to prevent a neural tube defect.

Folic acid deficiency has also been associated with high homocysteine levels and an increased risk for stroke, heart disease, and cognitive diseases like Alzheimer's disease. A folic acid deficiency may also result in a form of anemia (which can be remedied with supplementation).

It is difficult to accurately estimate how much folic acid is present in food. The best food sources appear to be vegetables (asparagus, broccoli, brussels sprouts, legumes), nuts, and seeds.

Additional Resources:

• Dietary Supplement Fact Sheet: Folate (from the National Institute of Health)
• Folic acid (folate) - U.S. National Library of Medicine
• Folic acid - Centers for Disease Control and Prevention (CDC)
• Folic acid - American Pregnancy Association
• Folic acid - American Cancer Society
• Folic acid - Wikipedia
• Folic acid - Linus Pauling Institute