The famed Ancient Greek philosopher, Hippocrates understood the relationship between food consumption and health. In fact, one of the memorable pillars of his teachings was “Let food be your medicine and let medicine be your food.” As we now know several thousands of millennia on, Hippocrates was right. The correlation between our diet and overall health cannot be dismissed. With our growing understanding on how specific foods are digested and received by our bodies, research has come to find that certain food groups can impact different aspects of our internal and external health. One topic of conversation that has gained continual traction is the connection between diet and skin health; specifically, the types of foods to avoid for acne.

Acne is of course, an entirely genetic condition; and while your diet will never directly give you acne, it can impact or irritate existing skin problems. Here, we touch on nine specific food groups that have been proven to cause inflammation, increase sebum and oil in the skin and affect gut health.

1. Dairy

As written in the journal article, Significance of diet in treated and untreated acne vulgaris, research into the causal relationship between dairy products and acne first begun in the 1940s. If you're wondering what it is in milk and dairy products that can potentially trigger acne, it has to do with the level, and type, of hormones that are present in a cows body during pregnancy. According to the study; "It is believed that the constituent of milk that mostly stimulates the pilosebaceous unit is insulin-like growth factor 1 (IGF-1), whose concentration in the blood varies depending on the severity of acne." In layman's terms, this insulin-adjacent growth factor is the same one that increases when the body is going through puberty, and "positively correlates with the clinical course of acne."

To further complicate the matter, research has found that it's not only the hormone that can influence acne, but also the biochemical relationship between them. For example, milk that is sold in a store or supermarket is not only rich in placenta-derived progesterone, but is matched with dihydrotestosterone – the androgen hormone that is crucial during male puberty.

A study conducted in 2018 found that "intake of any dairy, any milk, full-fat dairy, whole milk, low-fat/skim milk, and yogurt regardless of amount or frequency were associated with a higher odds ratio for acne compared to no intake in individuals aged 7–30 years." Interestingly, however, a study by the Journal of The American Academy of Dermatology also found a link between skim milk and acne when looking specifically at teenagers; but the correlation wasn't present when they looked at the effects of full-fat milk.

2. Coffee

One of the biggest talking points in the discussion around foods to avoid for acne is that coffee can directly cause a breakout. Thankfully, all the research so far has disproven this theory to an extent, but it's not to say that overconsumption of coffee can't have a negative effect on existing lesions. Studies have found that coffee has a direct impact on increasing cortisol levels; otherwise known as the stress hormone. As we know, cortisol has been proven to cause the skin to produce more sebum or oil, which can both be attributed to acne breakouts.

It's also worth noting that not all coffee beans are made equal, and some of poorer quality can directly disrupt your digestion and microbiome. As we're understanding more, gut health has a correlation to skin health; and when your stomach is inflamed, that same inflammation can present itself on the skin. You can read more about how your gut health could be impacting your acne here.

3. Meat

Similarly to coffee, meat consumption hasn't been proven to directly cause acne. But certain meat products like beef and chicken do contain a naturally high amount of an amino acid called leucine. When high levels of leucine are present in the body, they can initiate the chain reaction that stimulates the skin's oil glands and makes acne breakouts more likely.

Additionally, red meats often contain high levels of saturated fat and cholesterol, which can directly increase inflammation in the body. Meats that contain added hormones, or those which already have naturally high hormone levels can also be bad for those suffering from hormonal cystic acne when consumed in excess.

4. Refined sugars

The connection between acne development and refined sugars has been a topic of research and conversation for many decades. Generally, the research has shown that keeping to a low glycemic (GI) diet, which means lowering both natural and processed sugars can positively impact the appearance of acne. "Diet based on products with a high glycemic index leads to hyperinsulinemia," found a recent study. As mentioned above, when insulin levels are heightened, it can "stimulate the secretion of androgens and cause an increased production of sebum, which plays a fundamental role in pathogenesis of acne vulgaris."

5. Omega-6 fats

This one may come as a surprise, but diets that contain high levels of omega-6 fats have been linked to increased levels of inflammation and acne. This has a particularly prominent in Western diets, but it isn't all omega-6 rich food that can have an impact on your skin. The main foods to avoid for your acne are the fatty acids that are found in oils such corn, safflower, sunflower, grapeseed, soy, peanut and vegetable.

The key to managing your omega-6 intake is to find the balance between omega-6 and omega-3. This is because omega-3 fatty acids can reduce levels of inflammation and have been found to reduce acne severity.

6. Alcohol

While it doesn't directly cause acne, alcohol has been found to tigger skin conditions such as rosacea, acne and psoriasis through its other negative side effects – it's no surprise that alcohol isn't good for just about any bodily functions. From dehydration to inflammation, it's one to watch out for in your diet and in your skincare products (topical products containing alcohol can also be quite stripping on the skin). Healthy skin is a reflection of other healthy functioning ecosystems in your body, so it's a god idea to reduce your alcohol consumption for a healthy liver, gut and hormones.

7. Fast food

For obvious reasons, highly processed foods like those available at most of our favourite fast food outlets are not great for the body, or for acne and skin health. The high saturated fats and processed ingredients in fast foods can create imbalances in your blood sugar and hormone levels, which in turn can lead to increased skin issues. So if you're looking to improve your skin health (and health overall), it's probably time to sadly say goodbye to your late-night McDonalds order.

8. Chocolate

The age old adage may have had some truth to it. Chocolate – at least most of the kinds accessible to us on shelves at our local grocery store – are often full of sugar and dairy, both of which are not friends to healthy, acne-free skin. If you're looking for something to fulfil your chocolate cravings, it's best to lean toward vegan and raw chocolate alternatives (brands like Pico, Pana, Alter Eco or Loving Earth are available in most good supermarkets), or a good-quality dark chocolate from brands like Lindt (usually it's optimal to aim for at least 70% or higher).

9. Whey protein

Protein powders like whey are rich sources of the amino acids leucine and glutamine, and can influence spikes in testosterone production, which can cause blemishes. In essence, high levels of testosterone can create an excess production of sebum in your skin, causing blocked pores and subsequent breakouts. If you're looking for an alternative protein source to pair with your next high-intensity gym work out, try opting for some non-dairy options, like bone broth, pea protein, brown rice protein or egg whites.