What is lactic acid?
Lactic acid is an organic compound that plays important roles in various biochemical processes. It is a carboxylic acid with a chemical formula of CH3CH(OH)COOH. Lactic acid exists in two optical isomer forms: L-lactic acid and D-lactic acid. L-lactic acid is the biologically important isomer and is produced naturally in the body during exercise or fermentation. Some key facts about lactic acid:
- It is a normal byproduct of anaerobic cellular respiration – the process cells use to produce energy in the absence of oxygen.
- It accumulates in muscles during intense exercise, causing fatigue and muscle soreness.
- It is produced by fermentation of carbohydrates like glucose by lactic acid bacteria.
- It is used widely in food manufacturing as a preservative, acidity regulator, and flavoring agent.
- In the body, it dissociates into lactate and protons, lowering pH and causing the burning sensation in overworked muscles.
- It is commonly found in fermented dairy products like yogurt, kefir, sour cream, buttermilk, etc.
So in summary, lactic acid is a carboxylic acid produced by cells under low oxygen conditions during exercise or by lactic acid bacteria during dairy fermentation. It is not an allergen itself but is commonly associated with dairy products.
Is lactic acid an allergen?
Lactic acid itself is not considered an allergen. Allergens are usually proteins that can trigger an immune response in susceptible individuals. Lactic acid is a small organic molecule, not a protein. There are no documented cases of lactic acid acting as a primary food allergen.
However, lactic acid is present at high levels in many fermented dairy products like yogurt, kefir, sour cream, etc. So people with milk/dairy allergies may react to the dairy proteins present in these foods rather than the lactic acid itself. The lactic acid contributes to the tart, sour taste but is not the source of an allergic reaction.
People can develop sensitivities to lactic acid over time with repeated exposure. This is not through an IgE-mediated dairy allergy mechanism but rather through irritation from the low pH of lactic acid. Symptoms are usually localized irritation or discomfort rather than systemic allergic reactions.
So in summary, while lactic acid is not considered an allergen, people with dairy allergies should still avoid fermented dairy products containing lactic acid as they will react to the milk proteins present. Lactic acid itself, however, is not the source of their dairy allergy.
Common symptoms of dairy allergy
Dairy allergy symptoms can vary widely but commonly include:
- Skin reactions like hives, rash, eczema
- Digestive problems like nausea, vomiting, diarrhea, abdominal pain
- Respiratory issues like coughing, wheezing, runny nose
- Anaphylaxis in severe cases – involving multiple systems like skin, respiratory, gastrointestinal, and cardiovascular
- Swelling of lips, face, tongue, throat
- Nasal congestion or hay fever-like symptoms
The time of onset and severity depends on the individual. With severe dairy allergies, symptoms often appear rapidly, within minutes or hours after ingestion. Milder allergies may cause delayed symptoms up to 48 hours after dairy exposure.
An IgE-mediated hypersensitivity reaction against one or more dairy proteins like casein, whey, alpha-lactalbumin, or beta-lactoglobulin causes these allergy symptoms. Even small amounts of dairy can trigger reactions in dairy-allergic individuals.
Common food sources of lactic acid
Lactic acid is present at high levels in fermented dairy products including:
- Yogurt
- Kefir
- Buttermilk
- Sour cream
- Some cheeses like cottage cheese, cream cheese
It is also naturally present at lower levels in:
- Tomatoes
- Pickles
- Sauerkraut
- Kimchi
- Sourdough bread
- Some fruits like apples, currants
Additionally, lactic acid is used as a food additive and flavoring agent in processed foods including:
- Pickled vegetables
- Cured meats
- Soft drinks
- Beer
- Baked goods
- Candies
- Gelatin
- Jams
So people following a dairy-free diet due to milk allergy should also avoid products containing added lactic acid, unless they know the lactic acid is plant-derived.
Is lactic acid vegan?
Lactic acid can be derived from both plant and animal sources, so it may or may not be vegan.
Lactic acid produced by bacterial fermentation of plant carbohydrates like corn, potato, or molasses is considered vegan. This process utilizes vegan medium and nutrients.
However, some lactic acid is produced from lactose in dairy whey, a cheese production by-product. This animal-derived lactic acid is not considered vegan.
For commercial uses, only the optical isomer L-lactic acid is useful, as it is the naturally occurring isomer. Vegan production of L-lactic acid utilizes bacterial strains that selectively produce the L-isomer.
So when checking if foods containing lactic acid are vegan-friendly, one must determine if the lactic acid used was fermented from dairy whey or plant sugars. Plant-sourced lactic acid can be safely consumed by vegans and dairy allergy sufferers.
Can yogurt help or worsen dairy allergy?
Many yogurt brands contain live cultures of bacteria like Lactobacillus bulgaricus and Streptococcus thermophilus. Some promising research shows these probiotic yogurt cultures could benefit dairy allergy sufferers:
- Probiotics may improve gut barrier function and reduce inflammation, contributing to allergy prevention and management.
- Consuming fermented milk products with live cultures may allow dairy-allergic children to tolerate them better compared to milk.
- Probiotics may modulate immune function in infants, possibly reducing risk of allergies.
- Fermentation breaks down milk proteins like beta-lactoglobulin, a major dairy allergen, which could reduce allergenicity.
However, individuals with dairy allergy should not consume yogurt without consulting an allergist, as risks include:
- Yogurt still contains casein, whey, and other dairy proteins that can cause reactions.
- The amount of allergenic proteins varies based on the starter cultures and fermentation process.
- Cross-contamination with milk ingredients can occur during yogurt production.
- Probiotics have not been proven effective for treating existing dairy allergy through large randomized controlled studies.
So while promising, yogurt or its cultures have not been consistently proven to reduce dairy allergy severity or build tolerance. Most dairy-allergic individuals still need to avoid yogurt due to remaining allergenic proteins. More research is needed on using probiotics to manage dairy allergies.
Role of lactic acid in exercise performance
During intense exercise like sprinting or weightlifting, cells switch to anaerobic respiration to rapidly generate ATP energy. This anaerobic respiration causes lactic acid to build up faster than the body can remove it.
The role of lactic acid in exercise has some key points:
- It allows muscles to function in oxygen deficit and produces more ATP energy than aerobic respiration.
- Excess lactic acid dissociates into lactate and protons, lowering pH in muscles.
- This drop in pH impairs muscle contraction, causing fatigue, soreness, and reduced performance.
- Lactic acid levels return to normal after exercise as the liver and heart oxidize lactate to pyruvate.
- Regular training improves the body’s ability to clear lactic acid delaying fatigue from buildup.
So while lactic acid itself does not directly cause muscle soreness, its acidic dissociation byproducts contribute to fatigue during intense exercise. Proper training and recovery practices can boost the clearance of lactic acid and lactate.
Key strategies for managing lactic acid buildup during exercise include:
- Interval training to improve lactate removal capacity
- Proper cool-down periods to promote lactate clearance
- Massage to increase blood flow and lactate transport after exercise
- Stretching which enhances lactate removal compared to passive rest
- Sports drinks or carbohydrates to provide glucose for lactate metabolism
Following these types of evidence-based practices can help reduce lactic acid-related effects on performance during intense exercise.
Lactic acid as an exfoliant in skin care
Lactic acid is commonly used as a mild exfoliant ingredient in skin care products. It offers several benefits:
- Removes dead skin cells by dissolving the bonds between them
- Increases cell turnover rate and collagen production for smoother, brighter skin
- Improves skin hydration by attracting moisture
- Reduces acne breakouts by decreasing clogged pores
- Evens out skin discoloration from photodamage
- Decreases appearance of fine lines and wrinkles
- Has antibacterial properties to fight acne
As an alpha hydroxy acid (AHA), lactic acid is gentler than other popular chemical exfoliants like glycolic acid. Key facts about using lactic acid for skincare:
- Best for sensitive or dry skin types prone to irritation
- Concentrations between 5-12% are ideal for exfoliation with minimal side effects
- Start with applying every 2-3 days, gradually increasing frequency based on skin tolerance
- Use adequate moisturizer and sun protection when exfoliating with lactic acid
- Temporarily causes mild stinging or redness in some individuals right after application
With controlled use, lactic acid serves as a safe, multi-benefit exfoliant that enhances skin renewal, radiance, and texture without harsh side effects. It is considered a pregnancy-safe skincare ingredient as well.
Is lactic acid bad for your skin?
Lactic acid is generally considered safe and beneficial for skin when used properly at appropriate concentrations. However, there are some potential risks with incorrect use:
- Over-exfoliating or using solutions over 10% concentration can damage skin barrier function.
- Increased UV sensitivity requires diligent sun protection when using lactic acid.
- Can cause irritation, redness, peeling with overly frequent application for given skin type.
- High concentrations can cause temporary stinging or burning sensations.
- Risk of infection if applying to open wounds or broken skin.
To avoid potential issues when using lactic acid for skincare:
- Start with lower concentrations around 5% and infrequent application.
- Slowly increase concentration and frequency based on skin tolerance.
- Always apply sunscreen in the AM when using lactic acid.
- Stop use and see a dermatologist if signs of damage like blotchiness, excessive flaking, hives appear.
- Avoid applying to irritated, sunburned or broken skin.
With controlled use following directions, low concentration lactic acid is considered very safe for improving skin texture. But misuse of overly strong solutions carries risks of skin damage and irritation versus proper application.
Lactic acidosis explained
Lactic acidosis is a buildup of lactic acid in bodily fluids to dangerous levels, causing acidification of blood pH. It has several potential causes:
- Tissue hypoperfusion – Reduced oxygen supply to tissues increases anaerobic respiration and lactic acid production.
- Intense exercise – Vigorous activity generates lactic acid faster than the body can metabolize it.
- Liver disease – Impaired liver function reduces lactate clearance.
- Cancer – Some cancers change cell metabolism to favor lactic acid generation.
- Medications – Drugs like metformin can increase lactic acid production or reduce clearance.
- Genetic disorders – Mitochondrial diseases affect cellular energy production.
Symptoms of lactic acidosis include:
- Nausea, vomiting, diarrhea
- Abdominal pain
- Fatigue, muscle cramps, weakness
- Trouble breathing
- Dizziness, headaches
- Tachycardia
Lactic acidosis is diagnosed by blood tests showing pH under 7.35 and high lactate levels (>5 mmol/L). Finding and treating the underlying cause is key. Severe lactic acidosis has a high mortality risk if left untreated. Supportive care aims to improve tissue oxygenation. Dialysis can remove excess lactate and alkalinize blood in serious cases.
Is lactic acid bad for gut health?
Lactic acid has complex effects in the gut. High levels of lactic acid are associated with some negative health impacts:
- May contribute to intestinal permeability and microbial translocation.
- Can be pro-inflammatory at high concentrations.
- Linked to intestinal diseases like inflammatory bowel disease, colitis.
- Correlates with metabolic endotoxemia in obesity.
However, lactic acid bacteria play key beneficial roles in gut health:
- Produce bacteriocins that prevent growth of pathogens.
- Support gut barrier integrity.
- Contribute to normal microbial balance.
- Modulate mucosal and systemic immunity.
- Produce metabolites that regulate intestinal homeostasis.
So in moderation, lactic acid is an important metabolite for normal gut function. But excessive lactic acid, from say a highly refined diet or impaired microbial flora, may contribute to intestinal issues. More studies on lactic acid and gut health are still needed.
Conclusion
In summary, lactic acid itself is not a dairy allergen, but can be associated with allergenic dairy proteins in products like yogurt and cheese. While promising, current evidence does not yet support using yogurt or probiotics to reduce existing dairy allergies. In the body, lactic acid poses benefits such as energy production during exercise as well as risks like acidosis at high levels. Topical lactic acid also provides advantages for skin exfoliation when used properly. Research continues to emerge on how levels of lactic acid impact human health and disease.
