Today Rosie explains the two strongest theories about diet and acne.
Catch up on Rosie’s previous post about the history of research around blemishes and what we eat here.
The glycemic index (GI) is a number given to a food to reflect its effect on a person’s blood sugar. High GI foods include sugar breakfast cereals, white flour, biscuits and sweets.
The GL is based on the portion sizes we eat, so is a practical extension of GI science to our daily lives.
The theory is that foods with a high GL are rapidly digested and absorbed, causing a rise in blood glucose. This sends a message to the pancreas causing an acute rise in insulin along with other hormones.
GL and acne research
Overall, this seems to be a controversial area with conflicting evidence between studies.
In a recent study, 248 males and females living in New York were asked to fill out a validated food frequency questionnaire and report their acne severity. Results showed that participants with moderate to severe acne had a significantly higher GL diet and added sugar consumption.
Randomised controlled trials (the gold standard study design) have also been conducted.
There is another theory that milk may aggravate acne development by increasing concentrations of insulin and and hormone called IGF-1 in the blood. Since milk contains carbohydrates, it leads to a rise in blood sugar and insulin, similar to the effects of a high GL diet.
Interestingly, milk has a 3-6 fold higher GL than expected and the addition of just a small amount of milk to a low-GI meal increases the insulin response to levels characteristic of a high-GI meal. This accounts for skimmed milk, whole milk but not for cheese.
Milk may also contribute to acne because of its hormone content which includes IGF-1. This, if drunk in high quantities, has been shown to increase IGF-1 levels in the blood.
Dairy and acne research
In both cases they asked the participants to note down what they ate and followed them for 3 years. In both studies, high milk intake increased risk of acne by about 20%.
Another trial, found that acne was positively associated with frequent milk consumption, but not whole milk or cheese.
The problem is that literature investigating milk and acne is observational. There are no randomised controlled trials looking into a dairy–acne link.
This means we can’t conclusively prove that milk causes acne, but we can suggest drinking milk may increase the risk.
Since milk contains over 60 different molecules, it’s extremely difficult to tease apart which of these components might be having an acne promoting effect, especially when there is such a broad range of dairy products.
Scientists are still trying to discover if it is the hormones, its GL effect or protein in milk that drives any associations.
So if you’re prone to acne, what should you do?
- Book an appointment
See your GP to discuss medical treatments such a topical creams which can be used alongside making any dietary changes. The British Association of Dermatologists discuss treatment options [here].
- Go non-comedogenic
Consider choosing makeup and face products which are oil-free or water-based and labelled non-comedogenic (free from pore blocking ingredients).
Pai’s geranium and thistle rebalancing day cream would tick this box.
Keep a food/symptom diary and look for patterns between foods and breakouts.
- Manage your weight
If you are overweight, consider losing some pounds. Some researchers believe being overweight drives the production of a male hormone called androgen which promotes skin cell growth and oil production, leading to acne.Aim to have a lean body-type with a BMI between 20-25 kg/m2.
- Trial cutting dairy
Consider a milk or dairy exclusion period for a couple of months. Make sure you are getting enough calcium by using this British Dietetic Association [star guide].Be aware that organic dairy alternatives will not be fortified with calcium. You may need to consider taking a calcium supplement if you are not getting enough.
- Go low GL
Consider a low GL diet. This [low GL recipe book] by Registered Dietitian Nigel Denby is excellent. He explains that a GL rating of <10 = low, 11-19 = medium and 20+ = high.To have a low GL day, you would be aiming for a GL total of 80 or under. A total of 120 or over would be a high GL day.
An example low GL day:
Breakfast: Two poached eggs, one slice of pumpernickel bread, avocado and fresh tomatoes.
Snack: Small handful of almonds
Lunch: Lentils with fresh spinach, grated fennel and goats cheese.
Snack: Two oatcakes with a tablespoon of hummus.
Evening meal: Chicken and quinoa salad with butternut squash, chilli and broccoli
There is no strong evidence that diet causes acne, but there is emerging evidence it can aggravate it and there are some dietary strategies worth trying alongside medical treatment.
A typical Western diet based on refined high GL carbohydrates and dairy may be accountable.
Eating a healthy varied diet, high in plant-based whole-foods such a fruit, veg, pulses and nuts is not a bad idea, so there would not be much harm in trailing this way of eating to see if acne symptoms improve.
The exclusion of milk could also be considered, as long as daily calcium levels can be met.
Looking into the future, we need research to understand what’s going on before any evidenced-based recommendations can be developed.
Registered Nutritionists, Dietitians and Dermatologists should be open-minded and aware they have the potential to make an extremely a positive impact on someone’s life by improving their skin with food.
Hopefully we will see more collaboration between both professions in years to come.
Rosie Saunt (Registered Dietitian) @rosie-saunt