A group of researchers from the New Zealand, US, UK, and Netherlands, said that the RDA of vitamin C should be increased to 200mg and vitamin D to 2000 IU in their review published in Nutrients.
“The immune system is more important than before to reduce the risk of infection. A low RDA is a risk factor for an impaired immune system,” one of the researchers, Dr Manfred Eggersdorfer told NutraIngredients-Asia.
“The industries and the authorities now have the opportunity and responsibility to adjust the RDA,” the professor for Healthy Ageing at the University Medical Center Groningen stressed.
For some countries, the last time that they revised their RDA was nearly 20 years ago, such as Indonesia and Vietnam, added Dr Anitra Carr, from the University of Otago, who was also involved in the research.
“Countries might have reassessed the RDA but have not made the actual revision throughout the years,” she said.
Their suggestion to raise the RDA of vitamin C to 200mg is double the level of what China, Japan, Singapore recommend – and these are the APAC countries which currently have the highest RDA within Asia – but still stays within the safe upper limits.
The RDA of 200mg can be achieved by eating two to three kiwis or oranges.
However, for individuals down with infection, Dr Carr recommended an intake of 1-2g divided over different timings throughout the day.
She explained that this was because vitamin C would deplete faster when one was unwell.
Recent meta-analysis also showed that vitamin C supplementation reduces the risk and impact of upper and lower respiratory tract infections.
The suggestion of increasing the RDA of vitamin D is about three to 10 times higher than what most of the Asian countries have recommended.
It is also over twice the amount of what some European countries such as Germany and Switzerland have recommended (800 IU/day).
Vitamin D has now come into the spotlight for improving immunity due to a series of new findings.
A new study has called for vitamin D supplementation because researchers believe it could play a role in suppressing severity of COVID-19 infections
Dr Eggersdorfer and his team also cited meta-analyses on how vitamin D supplementation could reduce the risk of respiratory tract infections in both children and adults, especially in those consuming the vitamin daily or weekly.
Countries with low RDA
In APAC, India, together with Australia and New Zealand have some of the lowest RDA of vitamin C at 40mg/day and 45mg/day respectively.
RDA varies across different countries because different countries use different criteria to make their decision.
For some, it could be for prevention of disease, for others, it is about maintaining good health, Dr Carr said.
Setting an RDA does not necessarily guarantee that the population’s actual intake will be close to the recommended intake.
“India has one of the lowest actual intake of vitamin C at 18mg, which is less than half of the RDA. This could be due to the rice-based diets and cooking methods which lower the amount of vitamin C in foods,” Dr Carr said.
In contrast, while the RDA is low in Australia, New Zealand, the actual intake is about 110mg – more than double the RDA.
Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections
Authors: Manfred Eggersdorfer, et al