Frequently Asked Questions

Vitamins are organic compounds produced by plants or animals, whilst minerals are inorganic substances found in soil and water. Your body needs both to function properly. Vitamins can be broken down by heat or air, whereas minerals maintain their chemical structure. For example, vitamin C comes from fruits and vegetables, whilst calcium comes from rock-based sources. Both are essential for different bodily processes — vitamins support metabolism and immunity, whilst minerals build strong bones and regulate nerve signals.

The recommended daily intake of vitamin D for adults aged 19-70 is 15 micrograms (600 IU) per day, and 20 micrograms (800 IU) for those over 70. However, individual needs vary based on sun exposure, skin tone, and geographic location. People in the UK often require higher intakes during winter months when sunlight is limited. The best sources include fatty fish, egg yolks, and fortified dairy products. Many nutritionists recommend checking your vitamin D levels through blood tests to determine your personal needs.

Some nutrients work well together, whilst others can interfere with absorption. For instance, vitamin C enhances iron absorption, making them good partners. However, calcium can reduce iron absorption if taken simultaneously. Fat-soluble vitamins (A, D, E, K) should be taken with meals containing healthy fats for optimal absorption. It is best to space out minerals like zinc, copper, and iron by several hours. Reading the label on your supplement or consulting our educational guides will help you create an optimal timing schedule for your personal needs.

Iron comes in two main forms: haem iron (from animal sources) and non-haem iron (from plant sources). Haem iron is more easily absorbed by your body and is found in red meat, poultry, and fish. Non-haem iron sources include lentils, beans, spinach, and fortified cereals. Pairing iron-rich foods with vitamin C sources like citrus, tomatoes, or bell peppers significantly boosts absorption. For vegetarians and vegans, combining iron-rich plant foods with vitamin C is especially important. Adult women aged 19-50 need 18mg daily, whilst men aged 19-50 need 8mg daily.

Yes, excessive intake of certain vitamins can be harmful, particularly fat-soluble vitamins A, D, E, and K which store in body fat. Water-soluble vitamins like B and C are typically excreted in urine, making toxicity less likely from food sources. However, high-dose supplements can still cause problems — too much vitamin A may affect bone health, and excessive vitamin D can raise calcium levels dangerously. This is why understanding the upper tolerable intake levels for each nutrient matters. Whole foods rarely cause vitamin overdose because the concentrations are naturally lower and balanced with other nutrients.

Common signs of nutrient deficiencies include fatigue, weak immune function, poor wound healing, and hair loss — though these can stem from many causes. Specific deficiencies have characteristic signs: vitamin B12 deficiency may cause numbness, whilst iron deficiency often leads to dizziness. The most reliable way to identify deficiencies is through blood tests ordered by your healthcare provider. Risk factors include restrictive diets, digestive disorders, certain medications, and specific life stages like pregnancy. Our comprehensive vitamin and mineral guides explain how to assess your diet and recognise which nutrients might be lacking in your current eating patterns.

Electrolytes including sodium, potassium, magnesium, and calcium maintain fluid balance, support nerve transmission, and enable muscle contraction. Potassium helps regulate blood pressure and heart rhythm, whilst sodium maintains proper hydration. These minerals work together in a delicate balance — too much sodium combined with insufficient potassium may increase cardiovascular strain. Most people consume plenty of sodium through processed foods, but many lack adequate potassium. Good potassium sources include bananas, sweet potatoes, beans, and leafy greens. Athletes and those in hot climates lose electrolytes through sweat and may need additional intake.

For most vitamins, the body cannot distinguish between natural and synthetic forms — they have identical chemical structures and are absorbed similarly. The key difference lies in supporting factors: whole foods contain additional nutrients, fibre, and phytochemicals that enhance overall nutrition. Synthetic supplements are often more affordable, shelf-stable, and precisely dosed. Some people report better tolerance with specific forms — for example, certain individuals prefer methylcobalamin over cyanocobalamin as a vitamin B12 source. The most important factor is choosing a form your body absorbs well and taking it consistently. Our mineral guide breaks down which forms work best for different nutrients.

Nutrient requirements shift throughout life — children need less of most nutrients than adults, whilst older adults require more vitamin D and B12. Pregnancy and breastfeeding significantly increase needs for iron, folic acid, calcium, and other minerals. Physical activity demands more B vitamins for energy metabolism and additional antioxidants for recovery. Smokers need more vitamin C, and people with limited sun exposure require more vitamin D. Stress depletes B vitamins and magnesium. Alcohol consumption impairs nutrient absorption and increases deficiency risk. Our educational resources provide age-specific and lifestyle-specific recommendations to help you understand your unique nutritional requirements.

Bioavailability refers to the percentage of a nutrient your body can actually absorb and use effectively. A supplement may contain 100mg of iron, but if bioavailability is only 20 percent, your body uses just 20mg. Factors affecting bioavailability include the nutrient form, food combinations, digestive health, and individual metabolism. For example, vitamin C dramatically improves iron absorption, whilst calcium reduces it. Fermented foods enhance mineral bioavailability through enzymatic breakdown. Taking supplements with meals often improves absorption compared to taking them on an empty stomach. Understanding bioavailability helps you maximise nutritional benefit from both food and supplements.

B vitamins play central roles in energy production by helping your body convert food into usable fuel. Iron carries oxygen throughout your bloodstream — without adequate iron, tissues lack oxygen and fatigue sets in. Magnesium is essential for ATP production, the energy currency of cells. Zinc and coenzyme Q10 support cellular energy processes. Vitamin D deficiency is associated with fatigue and low mood. However, simply taking supplements won't create energy if you're not sleeping well or consuming enough calories. Addressing underlying deficiencies combined with proper rest, exercise, and balanced nutrition creates sustained energy. Our vitamin guide explains which nutrients most directly impact energy metabolism.

Look for information from peer-reviewed scientific journals, established health organisations, and registered nutritional professionals rather than unverified websites. Government health agencies and academic institutions provide evidence-based dietary guidelines. Be cautious of sources making extreme health claims or selling products alongside educational content. Fitnessvitamincore focuses on education and independent research rather than product promotion. Check whether authors have relevant credentials and whether sources cite scientific studies. Cross-reference information across multiple reputable sources. Our FAQ, mineral guide, and vitamin resources are designed to provide balanced, research-informed education to help you make informed nutritional choices.