Science still does not know whether diet and acne are related, but evidence is starting to trickle in. Based on what we are seeing in clinical research, it seems prudent to eat a relatively low-glycemic diet rich in colorful fruits and vegetables and omega-3 fats and to perhaps supplement with 30mg of zinc gluconate per day. However, due to our modern diets and Western style of living, achieving sustainable relief of acne from changes in diet alone remains an elusive goal.
No matter what anti-acne diet you embark upon, while you may see a short-term reduction in acne while your body loses weight, symptoms are likely to return as your weight levels off. If your goal is to achieve completely clear skin, your time is likely much better spent effectively treating your skin than chasing any theoretical, yet unproven, diet.
Dairy and Acne
Due to the lack of concrete evidence on the subject of dairy and acne, and major design limitations in the studies researchers have performed thus far, scientists in the Journal of Clinics in Dermatology wrote after a review of the existing evidence, "Our conclusion, on the basis of existing evidence, is that the association between dietary dairy intake and the development of acne is slim."1
It makes common sense based on the hormones present in milk that dairy products could affect acne, but study results remain inconclusive, and evidence of an association between dairy and acne is sparse.
IGF-1: Milk contains insulin-like growth factor (IGF-1).4IGF-1 is a hormone which helps the body build necessary tissues. Increased levels of IGF-1 result in increased skin oil production. Since over-production of skin oil is a contributor to acne, some scientists hypothesize that milk, and its IGF-1 component, could potentially lead to increased skin oil production and resulting breakouts.
IGF-1 also stimulates the body to produce cells. Acne is thought to sometimes begin with an over-production of skin cells inside the pore which causes the pore to become clogged. Thus, some scientists also hypothesize that milk may lead to over-production of skin cells within pores which cause the pores to become clogged and produce the beginning stages of acne lesions.
Androgens: Milk also contains male hormone (androgen) precursors.4-5These precursors require enzymes to convert them into actual male hormones in the body, and these enzymes are readily available in the pores of the skin.6Similar to IGF-1, male hormones have been implicated in increased skin oil production and increased skin cell production.
Iodine in milk
At large doses, iodine can cause what are called acneiform (pronounced "ack-nee-form", the i is silent) eruptions.16-17While unproven, some scientists postulate that the iodine content of milk, due largely to the sterilization of the teats of cows with an iodine solution prior to milking, may also contribute to acne vulgaris.
Glycemic Index / Glycemic Load
At this time, we do not know if low-glycemic diets reduce acne symptoms based on the glycemic load of the foods eaten, or simply based on the accompanying weight loss of such diets.
What does the glycemic index refer to? The glycemic index compares different foods, giving them a numerical ranking, based on how quickly they spike blood glucose levels (the time it takes for the blood sugar to rise when you eat that food).
What does glycemic load mean? The glycemic load takes the glycemic index one step further by calculating how much the blood sugar level rises when you eat a particular quantity of that food (the degree to which the blood sugar rises when you eat that food).
Eating lots of high glycemic foods (i.e. sugar, white bread, white potatoes, white rice) which are prevalent in modern diets cause people to live with chronically elevated insulin levels. These chronically elevated insulin levels may lead to problems with:
IGF-1: Increased blood insulin levels lead to increases in insulin-like growth factor (IGF-1), a hormone in our bodies which promotes increased cell growth. Scientists hypothesize that this could lead to an overgrowth of cells inside pores and/or an increase in skin oil production, which could cause pores to become clogged, leading to acne.2-7Scientists also hypotesize that high IGF-1 levels could lead to increased skin oil sebum production which may lead to breakouts.
IGFBP-3: Chronically elevated insulin levels lower the amount of insulin-like growth factor binding-protein 3 (IGFBP-3) in the blood. IGFBP-3 regulates IGF-1 and keeps it in check by preventing IGF-1 from binding to its cellular receptor. So, lower amounts of IGFBP-3 means even higher IGF-1 levels. As we have discussed, scientists postulate that increased IGF-1 may lead to overgrowth of cells inside pores.2-4A second way that low levels of IGFBP-3 may potentially affect acne is through lowering the effectiveness of the natural retinoids in the skin. These retinoids prevent cell overgrowth. When IGFBP-3 is low, these retinoids can't do the work they are made to do.8-14
Androgens: Insulin acts as a "master" hormone. Increased insulin levels raise androgen (male hormone) levels. Increased androgen levels are well known for their effect on stimulating sebum production, which can lead to more severe acne symptoms.12-13
mTORC1 and Fox01 proteins: Could our Western, high glycemic diet be suppressing and/or over-activating cell proteins which in turn unbalance hormones and increase skin oil production, leading to acne? Scientists are discussing it.6,17-18
If in fact lower calories help with acne symptoms, this may be why almost any "acne diet" appears to work. When we remove foods from our diet and do not replace them with others, we are eating less calories, and thus losing weight. It is important that scientists flesh this out. Until then, we cannot say whether any acne diet is working based on the content of what is eating or simply the overall calories. An article in the Journal of the Academy of Nutrition and Dietetics puts it well: "These gaps in the literature should not intimidate but rather challenge dermatologists and registered dietitians to work collaboratively to design and conduct quality research."1
Can increased calories cause acne?
The argument for: Increased calories result in higher male hormone (androgen) levels. Higher androgen levels can lead to skin cell growth and increased skin oil (sebum) output. Skin cell overgrowth may clog pores, leading to acne formation, and increased skin oil may lead to worsening of acne symptoms.
Doctors have noted that in hard-hit parts of the world, starvation level calories result in dramatic reduction in skin oil production and a complete halting of acne symptoms.2-3This is obviously not a sustainable way to treat acne. However, even when exposed to a moderate calorie deficit the body becomes insulin sensitive. Insulin is a master hormone, and insulin sensitivity lowers levels of insulin (this is because your body needs less insulin to do the same job since it is more sensitive to the hormone). This results in a hormonal cascade which theoretically would help prevent pores from becoming clogged and help the skin produce less oil. After a period of lowered calories, however, when calories resume to a maintenance level, this could also theoretically lead to an acne symptom recurrence. Therefore, it is more important, and practical, to focus on the quality of calories (by cutting down on junk foods and increasing the proportion of colorful fruits and vegetable in our diet), rather than their quantity.
Increased body mass (BMI) was found to be correlated with acne in one study of young males.4In another study, no significant correlation was found in young men, but a significant correlation was found amongst young women.5
Obesity is correlated with other skin diseases such as psoriasis.5
The argument against: From three studies, obesity and body mass index do not appear correlated with acne.6-8
It is far too early to draw conclusions between chocolate and acne. While there may or may not be a correlation between chocolate and acne, singling out any food as an acne villain is likely to be a wild goose chase. The combined stress involved in nervously avoiding chocolate and other perceived "bad" foods may itself lead to stress-induced acne.
History of the debate
For decades in the early 20th Century, doctors and medical texts warned acne prone people to avoid chocolate. This advice was put to the test with two studies in 1969 and 1971.1-2Both studies showed no correlation with chocolate intake and acne. However, these studies were small, uncontrolled, short duration, subjective, included very short follow up, and employed inadequate statistical analysis. They also did not account for the sugar or dairy content of chocolate being ingested. Despite the severe design limitations inherent in these chocolate-specific studies, not only did the dermatology community dismiss the possible chocolate/acne correlation, but also sent out the message that diet and acne are not related. This massive overstating of flawed evidence is an historic and staggering error of the entire dermatology community. However, as time has moved on, modern scientists are putting diet, and along with it, chocolate, back under consideration.
A 2003 study showed insulin levels raised after meals which included chocolate, especially chocolate mixed with milk (chocolate milk) in lean young adults.3While it is certainly too soon to draw conclusions, this could theoretically be the result of the active compounds in chocolate spiking insulin levels and/or the combination of the amino acids in chocolate mixed with carbohydrates and causing an insulin spike.4-7If in fact elevated insulin levels lead to acne symptoms through increased skin cell production which cause clogged pores and/or increased skin oil (sebum) production which provides a breeding ground for acne bacteria, chocolate could theoretically be part of this insulin cascade and resulting acne symptoms.
Protein signaling or something else entirely
Scientists have uncovered a small amount of evidence pointing toward chocolate perhaps increasing IL-10 protein production.4Might this, or something else entirely such as the unique effects of the monounsaturated and saturated fats in cocoa butter contribute to acne?5
Beneficial effects of chocolate
On the other hand, chocolate contains antioxidants, which could theoretically help with acne symptoms.
Dark chocolate may actually reduce blood pressure as well. Might reduced blood pressure in some way promote oxygen and nutrient distribution to the dermis, thus preventing acne in some marginal way?5
Fatty / Oily Foods
Fat is needed for our overall health and well being. However, whether saturated, unsaturated, and/or hydrogenated fats affect acne remains unknown.
Current evidence shows that the fat we eat is in fact used to make skin oil (sebum). In addition, at least one study has shown that fatty diets lead higher fat content in sebum.1The evidence stops there. Whether more fatty sebum leads toward increased or decreased acne symptoms is up for debate. Scientists are looking into the nature of sebum, particularly its saturated or unsaturated content, to see if they can find clues to acne development.
Most people living in modernized societies eat far more Omega-6 fats from foods such as grains, vegetable oils, nuts, and poultry than they do Omega-3 fats from foods such as fish and fish oils, grass fed meat, seeds such as flax seeds and chia seeds, and hemp.1This is in stark contrast to hunter/gatherer societies and to what our ancestors evolved to eat. Eating a more balanced ratio of Omega-3:Omega-6 fats can help modulate inflammation in the human body.2Since acne is an inflammatory disease, it makes sense that anything that can reduce inflammation would also help reduce acne.
Omega-3 fats, especially the omega-3 fatty acids from EPA and DHA commonly found in cold-water fish, work by reducing the production of inflammatory cytokines3-5and inflammatory leukotriene B4 molecules.6EPA and DHA also inhibits mTORC1, a protein which can signal skin oil glands to produce more oil.7-9
Omega-3s are known to improve mood and reduce stress and anxiety.10Since stress and acne are linked,11this is another way omega-3 fats could theoretically help reduce acne symptoms.
EPA in particular is anti-bacterial12and along with other fatty acids can inhibit the growth of Propionibacterium acnes (P. acnes) as well as Staphylococcus aureus bacteria, both of which have been associated with acne.13
Omega-3s also help keep IGF-1 (insulin-like growth factor) levels in check,5which theoretically could help keep the skin from overproducing skin cells, and skin oil thus preventing breakouts.
Korean researchers in one study demonstrated that taking 2000mg EPA + DHA alongside 400mg of gamma-linoleic acid, a type of omega-6 fatty acid, significantly reduced inflammation and acne.14More studies attempting to link Omega-3 intake and acne are needed.
As far as supplementation goes, zinc stands alone with the most evidence pointing toward a beneficial effect on acne, however moderate that effect may be. Over-the-counter zinc supplements normally come in 30-50mg tablets. The National Institutes of Health put tolerable levels of zinc for adults (19 years and above) at 40mg a day.1Zinc gluconate may be a better choice than zinc sulfate due to its superior bioavailability. Since meat and poultry provide the majority of zinc in Western diets, vegetarians may want to take special care to ensure they are ingesting adequate amounts of zinc. A systematic review of medical literature in the Journal of Drugs in Dermatology concludes, "The preponderance of evidence suggests zinc has anti-bacterial and anti-inflammatory effects and that it may decrease sebum production."2Six percent of our body's supply of zinc is in our skin,3and after years of study and quite a bit of evidence, it appears that zinc supplementation may help with acne symptoms.
Multiple studies have been performed on people with acne who are administered oral zinc supplementation.4-7Overall results show a reduction in acne lesion count above that of placebo, albeit only moderately. The dosage of zinc in these studies is normally quite high,8and more studies are needed to see if the reduction in acne symptoms could be sustained at lower levels of zinc. However, since other studies show lower blood zinc levels in people with acne,9-10keeping zinc levels up to par is a compelling option. The Recommended Daily Allowance (RDA) of zinc in adults (19 years and above) is 11mg (which includes supplements and the food we consume).
How Zinc works
Zinc helps maintain skin integrity, reduces inflammation, promotes wound healing, helps kill and suppress acne bacteria, and may reduce skin oil production.11-15
Getting zinc naturally
A variety of foods contain zinc. Oysters contain about 5X that of the Daily Value (DV) of zinc (which is the recommended daily intake of zinc through natural foods). Eating 2 ounces (about 4 oysters), twice a week, is a fun way to get 100mg of zinc per week.
We do not have enough evidence to convict or acquit iodine in acne vulgaris formation at this point.
High levels of iodine have been shown to illicit what are called acneiform eruptions. These eruptions are different from run-of-the-mill acne and are evidenced by a quick onset, wide distribution on the body, and pustule-only outbreaks. Whether smaller levels of iodine affect acne is unknown. According to an overview of the latest evidence regarding diet and acne published in the Journal of the American Academy of Dermatology, "Iodine has been implicated as a cause of acne vulgaris, however, no literature to date supports iodine as a culprit in comedonal acne."1
The evidence is sparse. It appears that consuming very high levels of iodine containing kelp and iodine containing drugs can cause acneiform eruptions.2-3However, in one study from 1961, people who ate a lot of seafood and fish, a food group which contains high levels of iodine, were shown to actually have lower levels of acne.4Other studies have shown no correlation between fish/seafood and acne.
Eating a diet rich in colorful fruits and vegetables will help your overall health and may or may not help reduce the inflammation inherent in the acne process.
Acne is partly an inflammatory disease. The inflammatory process is what causes acne affected pores to become characteristically inflamed and red. Antioxidants in the body help resolve this inflammatory response.
People with acne tend to have less antioxidants, such as vitamin A, vitamin E, and selenium, in their skin.1-3It makes common sense that bringing antioxidant levels up to par would help calm the inflammatory response. However, we do not have enough evidence at this point to definitively say whether or not antioxidants in food or supplements help with acne. Topical antioxidants on the other hand, have shown promise in reducing acne lesion count. Examples of topical antioxidants include green tea, resveratrol, and licochalcone.
Acne rosacea AKA (Rosacea), a disease which presents somewhat similar symptoms to acne vulgaris (run-of-the-mill acne), tends to show a strong correlation with intestinal issues, including bacteria overgrowth.
Acne vulgaris is not the same disease as acne rosacea, and intestinal discomfort is not as common amongst acne vulgaris sufferers. However, this would be an interesting area of study. Would a high fiber diet help with acne? What about probiotics?
There is limited evidence on the relationship between gut bacteria and acne vulgaris. Some studies have shown that consuming probiotics leads to an improvement in acne symptoms. The proposed theory for this effect is that probiotics help to maintain the balance of bacteria in the gut, which helps to decrease systemic inflammation, which in turn may reduce inflammation and oil production in the skin. However, further research is required to confirm a definite relationship between gut bacteria and acne, and whether taking probiotics would be beneficial.
Presentation of bias
"As a critical sociology major in college, I learned that it is important for an author to present his or her bias. Because we are human and it is impossible to be completely unbiased, the presentation of bias allows the reader to take the author's bias into account when absorbing content.
My bias: Throughout my adolescence and early adulthood, I read in various places that chocolate and sugar were bad for acne. I carefully avoided chocolate and sweets for years, which did not end up helping with my acne, but did harm social interactions. I finally gave up on eliminating so-called "bad" foods from my diet, and my acne did not change considerably. Years later, after I had already discovered The Acne.org Regimen and cleared up, I decided to attempt to clear my skin from the inside out by eating in a hunter/gatherer way, thus eliminating any potential "modern" dietary causes of acne. About 25 Acne.org members joined me in stopping The Acne.org Regimen and instead eating a caveman style diet, which consisted of only food which was available before modern civilization emerged about 10,000 years ago. This meant vegetables, fruit, tubers (potatoes, yams, sweet potatoes), nuts, seeds, and meat. I completely eliminated sugar, added salt, all grains, legumes (beans), and dairy. The diet seemed to work at first. My skin did not break out much for the first month or so. However, during this first month I was also losing weight from eating in such a clean way. About six weeks into the diet, as soon as my weight leveled off, the acne returned. Unfortunately, due to the rigors of eating in such a strict fashion, none of the 25 Acne.org members kept to the diet as strictly as I did, so I am left with only my anecdotal experience. My conclusion, drawn from personal experience, was that no matter how cleanly I ate, it was not enough to stay clear. I slowly returned to a Western style of eating, but still try to remain aware of my glycemic load and I also try to eat lots of colorful fruits and vegetables and take a 30mg zinc pill most days. My common sense tells me that eating sugar and high glycemic processed food can’t be a good thing for my overall health or the health of my skin."