B12 and the Luteal Phase
It goes together better than cookies and milk
Quick biology lesson if you forgot how the menstruation cycle functions or even if you’ve never known.
1. Day 1: The Period Starts
The cycle officially kicks off on the first day of the period. This is when the uterine lining, which had been building up in case of a pregnancy, sheds and exits the body. This phase, called the menstrual phase, typically lasts 3–7 days, depending on the person.
During this time, estrogen and progesterone levels are at their lowest.
2. The Follicular Phase: Body in Preparation Mode
Right alongside the period is the follicular phase. The brain (specifically, the pituitary gland) releases follicle-stimulating hormone (FSH) to encourage the ovaries to prepare eggs for ovulation. Estrogen levels start rising, and around Day 7, there might be a change of mood: feeling energetic and mentally clear.
This is also when the uterine lining begins to rebuild itself, the body is basically resetting for another chance at pregnancy.
3. Ovulation
Somewhere around between day 12 and 15, ovulation happens. One of the eggs prepped during the follicular phase is released from the ovary. This is because of a surge of luteinizing hormone (LH). The egg hangs out in the fallopian tube, ready for fertilization.
4. The Luteal Phase
After ovulation, the empty follicle that released the egg turns into the corpus luteum, which produces progesterone. This hormone helps thicken the uterine lining to prepare for a potential pregnancy.
If no fertilization happens, the corpus luteum dissolves, progesterone drops, and the body starts gearing up for the next cycle. This is also when PMS (premenstrual syndrome) might come into play, with symptoms like bloating, irritability, and cravings.
If you’ve noticed your luteal phase has shortened for no known reason, B12 deficiency might be the reason.
The length of your luteal phase matters. Ideally, it should be over ten days. Too short, and it might signal low progesterone levels or issues with your cycle that can affect your overall health.
This is where vitamin B12 comes into the picture.
What’s Vitamin B12 Got to Do With It?
Vitamin B12 is one of those nutrients that doesn’t get nearly enough credit. Sure, it’s famous for boosting energy and keeping your nervous system healthy, but it also plays a crucial role in reproductive health.
B12 contributes to the production of red blood cells and DNA synthesis, both of which are essential for supporting the uterine lining. A healthy uterine lining needs adequate blood flow and proper hormonal signaling to stay intact for the length of the luteal phase.
How B12 Supports Progesterone
B12 helps regulate progesterone levels. Progesterone is the hormone responsible for thickening the uterine lining during the luteal phase. Without enough of it, the luteal phase can be shortened, making it harder for an embryo to implant or the body to fully complete its cycle.
If you’re deficient in B12, you might experience:
A luteal phase shorter than 10 days (known as luteal phase defect).
Spotting before your period starts.
Fatigue and mood swings (beyond the typical PMS range).
By ensuring the body has enough B12, it has the tools to maintain progesterone levels and lengthen the luteal phase if it’s on the shorter side.
Who’s at Risk for B12 Deficiency?
Certain groups of people are more likely to have low B12 levels, including:
Vegetarians and Vegans: Since B12 is found mainly in animal products, plant-based eaters might need supplements or fortified foods.
People With Digestive Issues: Conditions like IBS, Crohn’s, or low stomach acid can affect B12 absorption.
Those Over 50: As we age, the bodies produce less stomach acid, which is needed to absorb B12.
If you’re in any of these categories and experiencing irregular cycles, it’s worth investigating your B12 levels.
How to Get More B12?
Diet: Include foods rich in B12 like eggs, dairy, fish, and fortified cereals.
Supplements: A B12 supplement (often in the form of cyanocobalamin or methylcobalamin) can help, especially if you have absorption issues.
Injections: For severe deficiencies, B12 injections administered by a healthcare provider can quickly boost levels.
But what is progesterone really good for?
1. Regulating the Menstrual Cycle
Progesterone plays a starring role in the second half of the menstrual cycle, the luteal phase. After ovulation, progesterone levels rise to prepare the uterine lining for a potential pregnancy. If fertilization doesn’t occur, progesterone levels drop, triggering the period. Without adequate progesterone, cycles can become irregular, and symptoms like heavy bleeding, spotting, or PMS may worsen.
2. Supporting Fertility
Progesterone is essential for a healthy pregnancy, but it also supports fertility in general. By thickening the uterine lining, it creates an environment where an embryo can implant. Low progesterone can lead to difficulties conceiving, as the uterine lining may not be ready to support implantation.
3. Balancing Estrogen
Progesterone acts as a counterbalance to estrogen, another key hormone in the cycle. While estrogen builds the uterine lining and stimulates growth, progesterone ensures it doesn’t grow out of control. When progesterone levels are too low compared to estrogen, it can result in estrogen dominance, leading to:
Heavy or irregular periods.
Breast tenderness.
Mood swings.
Weight gain.
Balancing these hormones is crucial for maintaining overall health.
4. Reducing PMS and PMDD Symptoms
For many women, PMS (premenstrual syndrome) and PMDD (premenstrual dysphoric disorder) are linked to a sudden drop in progesterone levels right before menstruation. Adequate progesterone can help:
Stabilize mood by interacting with GABA receptors in the brain, promoting calmness and reducing anxiety.
Reduce physical symptoms like bloating and breast tenderness.
Minimize irritability and depressive symptoms often associated with hormonal fluctuations.
5. Promoting Bone Health
We might associate bone health with calcium and vitamin D, but hormones like progesterone play a supporting role too. Progesterone helps stimulate bone-building cells, contributing to stronger, healthier bones. This becomes especially important as we age, when hormone levels naturally decline and the risk of osteoporosis increases.
6. Improving Sleep
Progesterone has a calming effect on the brain and body, thanks to its interaction with GABA receptors. These receptors are part of our nervous system and are known for their role in promoting relaxation and good-quality sleep. Low progesterone levels can lead to insomnia, restless nights, or difficulty falling asleep, particularly during the premenstrual phase or menopause.
7. Supporting Thyroid Function
Progesterone has a symbiotic relationship with the thyroid, one of the most important glands for regulating metabolism. Low progesterone can disrupt thyroid function, contributing to symptoms like:
Fatigue.
Weight gain.
Cold intolerance.
Hair thinning.
By ensuring balanced progesterone levels, you support optimal thyroid health. It seems every woman is getting diagnosed with anemia as soon as cold intolerance comes in, but checking hormone imbalances is just as important. Misdiagnoses are very common.
8. Protecting Against Certain Cancers
Progesterone’s role in balancing estrogen also extends to cancer prevention. Unchecked estrogen levels can contribute to the development of estrogen-sensitive cancers, such as breast and endometrial cancer. Progesterone helps regulate cell growth in the uterine lining, reducing the risk of these conditions.
9. Skin and Hair Health
Progesterone has a direct impact on your skin and hair by regulating oil production and reducing inflammation. Balanced progesterone levels can:
Prevent hormonal acne.
Keep skin hydrated and supple.
Reduce hair thinning or hair loss caused by hormonal imbalances.
10. Mood Regulation
Low progesterone can lead to mood swings, irritability, or feelings of depression, especially during the luteal phase of your cycle. Progesterone’s calming effects on the brain (via those trusty GABA receptors) can help stabilize emotions, reduce anxiety, and promote a sense of well-being.
Lengthening the luteal phase with B12 isn’t just about fertility, it’s about improving the overall balance of the cycle. A well-functioning luteal phase means better hormonal harmony, fewer PMS symptoms, and a stronger uterine lining, whether trying to conceive or just live a healthier life.
So, if you’re struggling with a short luteal phase, feeling fatigued, or noticing irregularities in your cycle, a little B12 boost could make a world of difference. It’s always a good idea to consult with your doctor or a nutritionist to check your levels and determine what’s right for you.
You may also need to evaluate what you consider normal. If you’ve been on the pill all your life and stop, or IUD (hormonal or copper) and now you aren’t, you may have never known what your normal luteal phase is.
Copper IUD is not hormonal however the very nature of it is to provoke inflammation in the uterus. Periods are heavier and the cycle may not be what it would be if the uterus wasn’t inflamed at all times.
When choosing a vitamin B12 supplement, you’ll often see terms like cyanocobalamin or methylcobalamin on the label. These refer to different forms of B12, each with specific characteristics. Understanding these forms can help you make an informed decision, especially if the label doesn’t specify which type is included. Here’s a breakdown:
1. Cyanocobalamin
What It Is: Cyanocobalamin is the most common and cost-effective synthetic form of B12. It’s widely used in supplements and fortified foods.
How It Works: Once ingested, your body converts cyanocobalamin into active forms of B12 (methylcobalamin and adenosylcobalamin).
Pros:
Stable and has a long shelf life.
Generally effective for most people.
Affordable and easy to find.
Cons:
Contains a cyanide molecule (in trace amounts, far below harmful levels).
May not be ideal for individuals with impaired liver function or difficulty converting B12 into its active forms.
2. Methylcobalamin
What It Is: Methylcobalamin is a naturally occurring, bioactive form of B12 that your body can use immediately without conversion.
How It Works: This form directly supports methylation, a process essential for DNA synthesis, detoxification, and nerve function.
Pros:
Easily absorbed and utilized by the body.
Supports neurological health more directly.
Better for people with genetic mutations or difficulty metabolizing cyanocobalamin.
Cons:
Less stable and shorter shelf life than cyanocobalamin.
Typically more expensive.
3. Adenosylcobalamin
What It Is: Adenosylcobalamin is another bioactive form of B12 that is stored in the liver and mitochondria (the energy centers of cells).
How It Works: It plays a key role in energy production by supporting metabolic pathways.
Pros:
Ideal for addressing mitochondrial health and energy production issues.
Naturally occurring in foods.
Cons:
Less commonly found in supplements.
Typically paired with other forms for a more complete B12 profile.
4. Hydroxocobalamin
What It Is: Hydroxocobalamin is a naturally occurring form of B12 often used in clinical settings for B12 injections.
How It Works: It converts into both active forms (methylcobalamin and adenosylcobalamin) in the body.
Pros:
Long-acting and stays in the bloodstream longer.
Commonly used to treat severe B12 deficiency.
Suitable for individuals with cyanide toxicity.
Cons:
Less common in over-the-counter supplements.
Primarily available through prescription or injection.
What If the Label Doesn’t Specify the Form?
If the supplement label doesn’t indicate the form of B12, it may contain cyanocobalamin, as it’s the most common form in generic supplements and fortified foods. However, you can confirm this by contacting the manufacturer directly or choosing a brand that transparently lists the form.
Always check with a healthcare provider for guidance tailored to your needs.
Dosage And Safety Considerations
The information provided in this book is for educational and informational purposes only and is not intended as medical advice, diagnosis, or treatment. Herbal practices and uses discussed are not a substitute for professional healthcare.
While herbs are natural, they are also bioactive substances, and proper dosage, preparation, and use are important. Always follow reputable dosing guidelines for each herb and consult with a qualified healthcare provider before using any herbs, especially if you are pregnant, nursing, taking medications, have known allergies, or have existing medical conditions.
Anyone experiencing severe symptoms or managing chronic health issues should seek professional guidance before using herbs.
Individual responses to herbs may vary, and no outcomes are guaranteed. The author makes no claims regarding the effectiveness, safety, or suitability of any herb for any particular person.
Readers assume all responsibility for their personal health decisions based on the information presented. The author disclaims all liability for any loss, injury, or damage allegedly arising from the use or application of the information in this newsletter.
Camille Charles is the voice behind The Minimalist Herbalist. She is an Herbal Researcher, Best-Selling Author and Consumer Advocate. You can find her distilling rose water in her instant pot, repurposing olive jars to store her cacao butter and overnight nettle infusions. She talks way too much about tinctures for womb health. When not writing or checking on her brews, she designs graphics.