Vegan Diets Short on Omega-3 and Vitamin B12 May Increase Cardiovascular Risk

According to a new review, vegetarian and vegan diets may require additional omega-3 and vitamin B12 supplementation to reduce factors that increase heart disease risk.

A new review in the Journal of Agricultural and Food Chemistry indicates that many vegetarians, especially vegans, may unknowingly be at risk for certain cardiovascular health problems due to inadequate intakes of omega-3 fatty acids and vitamin B12.

The review stated that although meat eaters are known to have a significantly higher combination of cardiovascular risk factors than vegetarians, people following strict vegetarian and vegan diets are not invulnerable to risk. These diets tend to lack several key nutrients, including iron, zinc, vitamin B12, and omega-3 fatty acids.

Meat eaters are known to have a significantly higher incidence of certain cardiovascular risk factors compared with vegetarians, including increased BMI and waist-to-hip ratio, and higher blood pressure, plasma total cholesterol, and triglycerides. However, after reviewing 30 years of studies on vegetarianism, vegetarians and vegans typically have lower concentrations of serum vitamin B12 and omega-3 polyunsaturated fatty acid levels in tissue membrane phospholipids when compared to meat eaters.

Risks associated with low vitamin B12 and omega-3 status include an increase in blood clotting (platelet aggregation) due to increased levels of homocysteine, and decreased levels of ‘good’ HDL-cholesterol. Low HDL cholesterol and high homocysteine levels may be linked to an increase in cardiovascular and stroke risk.

The authors suggest that vegetarians, especially vegans, could benefit from increased dietary intake of omega-3 fatty acids to improve the balance and ratio of omega-3s to omega-6s. They can also benefit from increased vitamin B12 intake, including use of supplements containing vitamin B12 if necessary. Increasing dietary or supplemental omega-3 and vitamin B12 may reduce clotting tendencies that increase vegetarian and vegans’ otherwise low risk of cardiovascular disease.

Duo Li. Chemistry behind Vegetarianism. 2011. J Agric Food Chem 59(3):777–84.

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

Maternal Vitamin B12 Levels Influence Cognitive Development in Children

A recent study demonstrates an association between maternal vitamin B12 status during pregnancy and children's cognitive functioning at age 9. Higher maternal plasma vitamin B12 concentration in pregnancy was an independent predictor of the child's cognitive performance.

Vitamin B12 is an important nutrient for brain development and function. Since fetal requirements are provided by the mother through the placenta, inadequate maternal levels directly affect the amount available to the fetus. Research has consistently shown that maternal nutritional status can influence metabolic, cardiovascular, and psychiatric health of their future children.

In a recent study, investigators analyzed the relationship between maternal plasma vitamin B12 status during pregnancy and the child's cognitive function at 9 years of age. Previous research had shown that maternal vitamin B12 status influenced intrauterine growth and insulin resistance in children at 6 years of age.

Subjects included two groups of children born in the Pune Maternal Nutrition Study. The two groups were selected based on the maternal plasma vitamin B12 concentration at 28 weeks of gestation. Group 1 included 49 children born to mothers with the lowest plasma levels of vitamin B12. Group 2 included 59 children born to mothers with the highest plasma levels of B12.

The differences in tested intelligence and visual agnosia (the ability to recognize shapes, people, sounds, smells, and objects) were not significantly different between the groups. However, children from group 2 performed significantly better on a test for sustained attention and on a test of short-term memory. The differences were still significant after appropriate adjustments for confounding factors.

Result of this study support the idea that maternal vitamin B12 status in pregnancy influences cognitive function in offspring

Bhate V, et al. Vitamin B12 status of pregnant Indian women and cognitive function in their 9-year-old children. 2008. Food Nutr Bull 29(4): 249–54.