Research demonstrates that development of PMS is connected to the fluctuations in the levels of estrogen and progesterone hormones. For some women, PMS comes as early as the pre-ovulation stage, when estrogen is at its peak, while for others it happens about 5-7 days before the onset of menstruation when progesterone levels decrease dramatically, prompting the development of relative hyperestrogenemia.
Estrogens promote retention of natrium and water and that leads to swelling, tender breasts, flatulence, headaches, and fatigue. Excess estrogens also reduce the level of glucose in our blood stream, and this increases overall appetite and cravings for something sweet.
The high estrogen level increases the level of prostaglandin, which begins to act aggressively at a time when progesterone is in deficit, and that may result in spasms and stomach aches.
Estrogens also stimulate the central nervous system, and this effect is manifested in greater irritability and anxiety. Progesteron usually works as an anti-anxiety hormone, and therefore its deficit in the common days of PMS increases irritability and cravings for sweets.
The important thing to remember is that food can actually help you deal with the symptoms.
If your most bothersome symptom are the mood swings, you should reorient your diet towards legumes and complex carbs rich in vegetable fibre, B vitamins, and magnesium. Eating such foods will increase your consumption of tryptophan and tyrosin, two amino acids required for synthesis of serotonin and dopamine (commonly known as happiness hormones).
If stomach aches and cramps are your biggest problems, consumption of foods rich in vegetable fibre will help to normalise the work of your GI tract. The plant fibre is also able to sorb the estrogens on its surface, preventing their reabsorption from the intestinal lumen.
To avoid exacerbating your PMS symptoms, avoid foods rich in protein and fat.