Time to make up for our vitamin D deficiency

The benefits of vitamin D are fairly well known, particularly when it comes to bone and teeth health. Not so well known, however, is its proven benefits for the normal functioning of the immune system as well as muscle function. In addition, the latest research has indicated likely benefits in relation to weight management, type 2 diabetes, resistance to cancers, and cardiovascular health.

Unfortunately, a lot of people in this country, particularly males, are deficient in this wonder vitamin. According to Linda Giblin of the Teagasc Food Research Centre in Moorepark this is partly due to our geographic location.

“Ireland’s latitude is 53 degrees north but you can’t make vitamin D from the sun at latitudes further north than 37 degrees during winter”, she says. “This means that we have to get all of our vitamin D from our diet during the winter months. Oily fish and eggs are good sources of vitamin D but the average Irish person doesn’t consume enough of these.”

There are two possible solutions to this problem. The first is, of course, for all of us to eat more fish and eggs, but behavioural change like that takes a very long time to bring about. The other is to fortify foods like milk and other dairy products with vitamin D, so that we take it in as a part of our normal diet.

Giblin favours this latter solution, in the short term at least, and is trying to encourage the food industry to start adding vitamin D to a lot more products.

“We are trying to increase the intake of vitamin D in the population”, she says. “A lot of dairy companies already put vitamin D in milk and it is actually required by law in Canada to add it to certain dairy products.

“The European Food Safety Authority says that there is sufficient evidence to prove that it vitamin D is required for the bone health and the normal functioning of muscles and the immune system,” she continues. “There is also lots of evidence to show that it has an anti-cancer effect as well as playing a role in cardiovascular health and preventing diabetes. There are lots of health benefits, some proven and some preliminary.”

With this objective in mind Giblin led a team that carried out research into the health benefits of high vitamin D, half fat cheddar cheese.

The aim was not only to demonstrate health benefits but to show that they could be easily realised by adding vitamin D to cheese.

The research was carried out towards the end of 2015 and involved feeding vitamin D-enriched cheese to mice.

They didn’t all get the same cheese or the same dosages or vitamin D, however. And the cheese was only part of the overall diet of the mice.

“Do mice even like cheese?” Giblin asks.

The mice received four different options – full-fat and half-fat cheese each with high and low doses of vitamin D.

“We fed the cheese to the mice for 12 weeks,” she explains. “They also received all the other nutrients which would be part of a normal mouse diet. We couldn’t feed them exclusively on cheese. The diets were balanced to ensure each had the same calorific intake regardless of whether they were being fed full- or half-fat cheese. We just wanted to compare the cheeses not different diets.”

The overall aim was for the mice on higher doses of vitamin D to achieve the levels of the vitamin in their bloodstream that humans should be at to prevent diseases.

“We found that the mice receiving the half-fat cheese with higher doses had most vitamin D in their blood stream. We also found that their fat cells had very good glucose uptake and this is very important for type 2 diabetes.”

Another interesting effect was observed in relation to the weight gain of the mice. While all of them consumed the same number of calories each day those on the full-fat, low vitamin D cheese put on most weight.

“All of the mice took in the same amount of energy so the vitamin D clearly had some sort of interaction. This indicates that if you increase the level of vitamin D in your diet it may help with weight management. As a scientist I would always say that diet and exercise are the best ways to manage weight, but having proper levels of vitamin D can also help.”

The choice of cheese was important for the study. “Vitamin D is a fat-soluble compound so you have to have a food with fat in it to add it to – cheese and milk are good vehicles to use. We wanted to make the food industry aware of the opportunity to use cheese for this purpose. It doesn’t have to be half- fat, it can be full fat as well, but we found that half-fat was best in terms of the uptake of vitamin D.”

The research results were presented at the recent International Dairy Federation conference in Dublin and Giblin is hopeful that it may at least provoke some thought in the food industry.

“The Americans have recently increased the recommended daily intake of vitamin D to 15 micrograms. In Europe it is still five and needs to be increased. The clear health benefits of vitamin D in our diet mean that the food industry should be adding more of it to foods.”