It is now widely known that sufficient quantities of folic acid in a pregnant woman's diet can help to prevent neural tube defects like spina bifida in her baby. Now it seems that eating folic acid has even more benefits, regardless of whether you're pregnant or not.
According to a study conducted by the CSIRO, taking three and a half times the recommended daily intake (RDI) of both folic acid and vitamin B12 can lower your risk of contracting heart disease and cancer.
This is because they have been found to minimise damage to DNA and lower plasma homocysteine. Elevated DNA damage is a risk factor for cancer and above average levels of plasma homocysteine is a risk factor for heart disease. For instance, people with above-average rates of DNA damage have two to three times the risk of cancer compared to those who have low DNA damage.
Homocysteine, a by-product of protein metabolism, is a toxic amino acid when present in high concentration.
Dr Michael Fenech, the CSIRO Health Sciences and Nutrition scientist who led the research, says that his team's findings suggest that eating more folic acid and B12 actually slows the wear and tear of DNA.
"We have found that people with above-average damage to their DNA may reduce some of the damage by boosting their intake of these vitamins," he says.
At the same time, Dr Fenech says it may be difficult to obtain the necessary boost of folic acid (or folate, which is folic acid found naturally in food) by eating foods which are good natural sources of it.
"Folate is temperature-sensitive, so you can't cook food much without losing a large proportion of it," he says. "When you cook broccoli, for example, you may lose about 50 percent of the folic acid content."
Broccoli, spinach, asparagus, avocado, pulses and wholegrains are some of the plant foods which are good sources of folic acid, but you wouldn't eat these (except avocado) without cooking them first.
Vitamin B12 is found in meat, chicken, fish, liver and kidneys. Although not so much B12 is lost in the cooking, it is still difficult to eat the quantities of food needed to obtain the required dose of B12 to prevent DNA damage.
For instance, according to Dr Fenech, the RDI for vitamin B12 is contained in approximately 100g of meat or chicken. Three and a half times that much each day would be difficult to eat, and even harder for children.
The RDI for folic acid at the moment is 200 micrograms (or 400 micrograms for both women of child-bearing age and pregnant women). Dr Fenech's study recommends an intake of 700 micrograms a day in order to minimise DNA damage, plus 7 micrograms of vitamin B12, the RDI for which is currently 2 micrograms.
"The RDI was established to prevent deficiency and to ensure growth but not to minimise disease," says Dr Fenech. "So we still need to learn more about that. There is some evidence that above RDI levels might be needed."
The findings are part of continuing studies that measure the types and levels of DNA damage in cells' chromosomes among a group of 1,000 South Australians.
The study found a 25 percent reduction in chromosome damage among the high-damage group after their diet had been supplemented with folate and B12 for 12 weeks. Those in the low-damage category had no change.
"The message is that it is essential to take care of your DNA, as this should optimise your chances for longevity and reduced cancer risk," says Dr Fenech. His whole family is now taking folic acid and B12 supplements.
Dr Fenech's study also found that when it comes to minimising DNA damage, there is no point in taking more than three and a half times the RDI for folic acid and vitamin B12. People who took 10 times the RDI had the same results as those who took three and a half times the RDI.
New studies will now determine the optimum level of other vitamins needed to minimise DNA damage.
By Carolyn Parfitt