Nutrition and Immunity – the case for vaccination.

Some people claim that the children who get sick and die of measles are Vitamin A or Zinc deficient. The people making this claim then go on to say a healthy diet protects all children against measles.

Vitamin A

Vitamin A deficiency is one factor that increases measles deaths and long term complication. There are other things that increase these risks. Diet alone won’t alter the severity of an infection. When we talk about healthy diets we must remember one thing. Food is only nutritious if your child eats it. Many kids are fussy eaters. If a kid is fussy enough there is a risk of insufficient vitamin A .
In New Zealand we get Vitamin A in dairy and meat. We consume beta-carotene to make up the recommended intake of Vitamin A daily. Our bodies can convert beta-carotene to vitamin A. We don’t have data for children about their Vitamin A status. Around 1/3 to 1/2 of 15-18 year olds have insufficient Vitamin A intake. They don’t eat enough fruit and vegetables.

Can you take Vitamin A supplements?

Vitamin A in toxic doses can cause birth defects and liver problems. Vitamin A accumulates in the liver and fatty tissue, so it builds up over time. If someone is taking multiple supplements, the first thing I check is vitamin A. I have rung clients at home to stop them taking an excess. I do not believe Vitamin A tablets are is safe except under supervision. The highest risk group for insufficient Vitamin A is children with a restricted diet. Kids who eat mostly “white and tan” carbohydrate rich foods are the most at risk. If this describes your child’s diet I suggest seeking a dietitian to advise you. They would work with your medical team to prescribe appropriate supplements

What about zinc to support the immune system?

It is generally older adults who have insufficient zinc intakes in New Zealand. Zinc usually comes from meat and grains. Zinc is a co-factor for many processes in the body. There is no research to support the use of zinc in measles infection or prevention. I am always hesitant to supplement with single nutrients when there is no evidence of deficiency. In the case of zinc,it is taken up via the same pathways as iron, copper and calcium. High doses of zinc over time could compromise these other nutrients.

Why vaccinate?

I have family members who have health consequences of illnesses we vaccinate for. The statistics are that 1 in 1000 children will have serious long term effect from a case of measles. Vaccine related harm occurs less than 1 in 100,000 and most of those are events like a one off seizure event. I feel very sorry for people who have children who have severe reactions to vaccines. Any tragedy involving the life of a child is awful. Vaccines along with good nutrition and good hygiene, means most of us have not seen the illnesses or their consequences. So the last thing I want to see is a return of conditions we can minimize through use of vaccination.

Individualized Nutrition – what this means and why it is important

Our population is getting both older and sicker. One reason for the increasing incidence of poor health is the increasing weight on the average New Zealand adult.
On an individual level excess body weight is a poor predictor of health. On a population level, people who have excess weight are more likely to develop long term health issues. So with this change in the population body weight adult New Zealanders are developing long term conditions such as diabetes, heart disease and kidney disease younger.

Considerable time and money is spent promoting public health messages. Although many people believe healthy behavior is an individual responsibility, it is economically sensible to reduce harm through public health campaigns. The majority of public health campaigns focus on these areas of physical health.

4 ways we can all improve our health are:

  • Don’t smoke, or if you smoke stop
  • Drink alcohol within the safer drinking limits
  • Be active at least with 30 minutes of moderate intensity activity daily.
  • Eat plenty of vegetables and fruit, get your 5 servings daily.

Mathematical models suggest that if everyone followed these recommendations, we would have a very healthy population, with far less chronic disease.
At this high level there are only two messages associated with nutrition. Anyone who eats food will tell you that there are many more things suggested as important. So where do these other messages fit in?
Many of the other messages are around factors have smaller influence on health outcomes than these big 4. Take for example reducing the amount of saturated fat into your diet to the recommended level of 10%. If you modify your fat intake it may reduce your risk of heart disease by ½, which is a relatively small margin. Whereas with smoking the risk of heart disease is 5 times that of a non-smoker. If you stop smoking, you reduce your risk by a big margin. It is simpler to understand if you try to explain it as a fraction of populations.

  • If you have 1000 smokers, 200 to 400 of them die from heart disease directly caused by their smoking
  • If you had 1000 people who had a diet high in saturated fat, 20 to 40 of them will die from heart disease directly caused by their diet.

Many people look at the risk of death associated with saturated fat intake and say they are willing to live with those odds and stick with the diet they like. What they miss is that heart disease deaths is only one factor influenced by the saturated fat. Other health consequences including disability and other conditions such as Type 2 diabetes are influenced by saturated fat intake. Many risk factors are cumulative, so high saturated fat and low vegetable intake magnifies risk. Other risk factors such as genetic history or childhood experiences are often unmodified by lifestyle change.

When it comes to dietary advice, we are now on the edge of a revolution in thinking. Dietary advice could be individualized based on genetic and epigenetic testing, giving the “best diet” for your genes. That holds some promise, but it fails to recognize one thing. We eat for many reasons. Food is not just nutrition, and the other reasons are why we need to get individualized advice.

As a clinician my heart sinks if someone asks me for a diet sheet. I have never met someone who has stuck to one in 20 years of practice. Some people can make a good attempt, but others are completely unable to follow a prescribed diet and in that case we need to individualize the advice to take into account non-nutritional eating.

Recently I had a lady who was eating broccoli. She HATED broccoli, but broccoli was a super food, so she was having it daily. I helped her see there were foods that were just as useful to her as broccoli that she liked. What was the difference between her eating broccoli and not? It was the advice of a dietitian.

Why see a dietitian

A dietitian is a registered health professional. They have to have a post-graduate qualification in dietetics after an appropriate undergraduate. To maintain registration they must demonstrate life long learning. Dietitians must abide by a code of practice and can be disciplined if there is a breach of ethics or a significant complaint.

Dietetics is the interface between the science of nutrition and medicine. It involves modifying the diet to optimize well-being of individuals. The ultimate goal of dietetic intervention is either to prevent or manage health problems which have a dietary component.

I supervise young Dietitians and love that part of my job. Initially young Dietitians will struggle because they have license to practice but don’t feel competent. In supervision I liken the experience to riding a bike. Initially you have to concentrate on the skills needed to ride a bike. After practice you become a skilled bike user. You can start enjoying the scenery and navigating complicated terrain. Dietetic practice starts with giving advice based on theory and develops over time as the practitioner becomes more skilled to include practical knowledge about how to make changes. Dietitians are trained in the science of nutrition. Their skill is to help the patients translate the science into a diet they can eat. A competent dietetic practitioner practices holistically. The British Dietetic Association poster I am using as the image on this article is my favorite representation of the complex process in my head when I talk food to someone. As we discuss their diet I am gathering knowledge, as we start discussing intervention I am looking for cues and clues that this intervention will work for them in their current life stage. Ultimately I would hope to form a relationship with them and they come back for further assistance as their life circumstances change.


As of January 2019 I have started a major refresh of my blog. Lots of my blog will be about the science of nutrition. Some will be about the art of making the vegetable eating more possible. Other topic suggestions are welcome. With the pace of nutrition science I am not always going to be answering what you want…so please feel free to ask me questions or send me information you would like me to discuss.